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Wednesday, 17 December 2014

Lime wash on, it can be hot in the winter!


Welsh Lime Works have finished my house!! Hooray. They have managed to work around the scaffolding and all the problems left by the last lime company to produce a lovely white house.

The final coat to this lime putty render has been the limewash. There are a number of special properties to this covering, firstly it is the same lime as was used in the render mix, i.e. a limestone derived lime. This is important when rendering (as opposed to plastering) as it is a hard wearing material. Some limewashes in the past were chalk based as they expected them to be used internally, but you will need a limestone based limewash.

Secondly, the boys (and girl) put the limewash on as a 'hot mix', so basically they used quicklime to make up the limewash just before it was applied and this meant that the limewash went on hot (due to the slaking process). Welsh Lime Works think that this provides a better longer lasting finish due to the reaction that is ongoing when it is applied, so it bonds better with the underlying render. Great to see steaming 'paint' being applied to your house, especially in the winter months (mine you it was still above 5 degrees when it was done).

I have been very impressed with the level of skill and knowledge from Welsh Lime Works and their attention to detail. The house was also left nice and clean.

Scaffolding Abandoned


I have had scaffolding left at my house for the past few months that I have been desperate to get rid of, but will the scaffolder come and collect?? The heck he will. Unbelievable.

The scaffolder was arranged by the original company who walked off site and left me in the lurch, so no happy with either of them.

In the end I have been forced into drastic action, thanks in part to a great piece of advice from Citizens Advice that sets out what you can and cannot do. So I will be selling the scaffolding off and then giving the company any proceeds.

Tuesday, 2 December 2014

Plastering. Is it the same as Rendering?

Plastering with gypsum is obviously different from rendering with sand and cement

When doing 'conventional' works to buildings it is a clear distinction of trades between internal and external works. This is because there is a difference in some of the materials used and also because there is a large enough market to have specialist firms doing one operation or the other.

In the lime world, it tends to be that people do both rendering and plastering. This is driven by the fact that the materials used can be much more similar. Most people will use a NHL Hydraulic lime for both internal and external works.

If you look for a Lime Render course you will generally find one day courses that cover both plastering and rendering as well as everything else lime!

Given that plastering and rendering courses are normally at least two years long it seems a bit much to expect people to be able to render and plaster with lime after a couple of hours. Maybe this is why lime can have an application issue attached to it. After all lime is a much less predicable material than cement and gypsum. 

Having seen the boys from Welsh Lime Works doing a very professional job on my house you realise that that there is no substitute for experience and knowledge. There have been a number of key points in the work where you just know that someone who has just done internal lime plastering would have made some fundamental mistakes.

Welsh Lime Works are keen that their workmanship and knowledge that has been built up over the years is not shared carelessly, so if you want any info I would recommend getting in touch direct with them. http://www.WelshLimeWorks.com. However I think that it is fair to say that the key points around door and window reveals, wall corners and floor junctions are where their work stands out and will pass the test of time where others may well fail. Not to mention the issues around potential lamination of the render. All of these key factors require a professionals eye and years of experience in order to get right. So it has been fascinating seeing the process, the method of application, the changes in mixes, the subtlety in timings etc.

So if you have been on a lime plastering course be very aware that applying lime externally is very different from doing the same internally. The effects of the weather, temperatures, orientation and the various pressures on the fabric due to the use of the building all need to be taken into account if the job is to be a long lasting and high quality one.

Extractors and wind

Most extractor fans come with a basic louvres system to reduce back draughts
Most houses have extract fans fitted to them, mostly in our bathrooms and kitchens. However, we rarely think about which way they are facing. Most commonly they are fitted to the nearest wall, simple.

The UK is one of the windiest countries in the world and so the chances are that the prevailing wind will have a large influence on the effectiveness of the extractor, especially if it is facing west. Anyone who has a west facing extractor will be very aware of the level of noise generated by flapping louvres and also by back draughts and the inability of the fan to clear the room of water vapour. So, if possible fit fans away from the prevailing wind so that they can function properly and quietly.

Fitting fans to the lee sides of a building is not always possible, so what to do then?

There are a couple of solutions, firstly you could fix an in-line back draught shutter system. I haven't tried these myself, but they are on the market and should provide you with some protection, however if the fan is on and the wind blowing then my money is on the wind winning! One also fears that they too might suffer from acoustic issues.


Back draught shutters can be used to create a better solution but may still rattle around and also be blown shut when trying to extract
The system that I have used at home is to replace the louvres with a louvres and hood combo. This has altered how the system works quite dramatically for us. The two bathrooms are much quieter and the fan seems to be more effective.

The basics are that the fan can now work without fighting the wind so much and also that the protection stops the rattling of the louvres as the pressure changes due to the wind are now just coming from below. It also has the advantage of protecting the vent from the rain more.
A simple hood to go over the louvres can help reduce noise and also protect against wind driven rain
So it is worth having a think about extractors and how well they are working and what, if anything, can be done to improve their efficacy.


Monday, 24 November 2014

Ventilation vs Energy Efficiency

Ventilation does not mean uncontrolled draughts!
Ventilation is key for all buildings, after all we do need a bit of the fresh air stuff to stay alive! However for older buildings it is even more important. Solid walled buildings should be regarded as having 'moist' walls and hence they dry to the inside as well as the out (assuming that they have not been covered with cement render!) They therefore allow moisture into the internal environment and this needs to be wicked away along with all the moisture that we bring into our homes.

To illustrate this one study found that in a house we produce the following daily:
1.25 litres per person (just by breathing and sweating)
2.40 litres by showering, bathing etc
1.75 litres from a gas oven
1.00 litres from plants (assuming 25-30 plants per house)
....

So we are looking at around 10 litres of water per day from a family of four. All this water needs to be removed from the house and this requires ventilation.

Understanding how this works is really important, but actually very difficult. Where does the fresh air come from? Draughts around doors and windows? Chimneys? Punctures through the walls that have been poorly sealed? Where does it leave the house? Mechanical extracts? Chimneys? Trickle vents? Windows? Lofts?

Housing Associations and others are now wising up to the need for ventilation (after all many of their complaints are about damp and mould). Most are now fitting 2 x low energy vents in houses that run constantly. These only cost around £5 a year to run and can help tremendously with ventilation, but still people will turn them off! This is because people associate ventilation with increased energy consumption and hence costs.

Energy efficiency though is affected by poor ventilation. If walls are wet due to poor ventilation then the walls will be less efficient (by a factor of around 30%). So actually having good ventilation can help with energy efficiency. However most importantly ventilation is important for the health of the occupants and the health of the building itself. Without ventilation we are more likely to end up with mould and damp issues and this then leads to additional expense dealing with this. So it is a false economy in not venting well.

Ventilation is therefore linked to energy efficiency in several ways
So how to go about this?

Well there is no easy answer as each house is different (construction, levels of moisture, knowledge of occupants, lifestyles etc etc). So the best way is to use tools that measure what is actually happening and then automatically adjust ventilation rates.

Modern systems monitor and control a range of factors like temperature, humidity and CO2
These systems are not cheap and generally require a whole house solution with heat recovery (MVHR). These systems require vents to be placed in each room for either extract or input (or both). These are then combined (via ventilation ducts) in a central unit where the outgoing warm moist air help to pre-warm the incoming fresh air. These systems can work really well, but they need the house to be well sealed before they are fitted. They also require the ducts to be passed through the house etc. So these are quite complicated systems, but certainly the most effective as they help save the warm air in the house and therefore are more energy efficient.

Older houses of course are more difficult as they are harder to make airtight. However due to improvements over time many of these houses are now lacking in ventilation. People have fitted doubled glazed windows and doors (many of which have not had trickle vents specified), chimneys have been blocked up, suspended floors have been replaced with solid, lofts have been insulated, hatches draught proofed etc.

This has meant that whilst many houses do not have the required airtightness for efficient MVHR they are lacking in the required background ventilation to remove the 10 litres of water a day needed. Rock and a hard place territory!

So the exercise becomes a little vague and distinctly difficult, especially where people are not used to having (or paying for) pressure tests on their homes. So we are in the territory of 'guestimating'. This is not ideal, but it is really poorly understood area of housing. So you may well find that you are the best person to make decisions on this, after all you will know how bad issues like condensation, mould and stale air are in the house and whereabouts it occurs most and when. So spend a little time thinking about where any problems are and what the root cause may be.

Windows and trickle vents
Chimneys and vents
Draught proofing measures
Extract fans and their direction of venting
Floor ventilation
Airflow in and between rooms (is furniture hard against walls? Is there an airgap at the top or bottom of internal doors? Are certain areas sealed off from the rest of the building?)
Functions of rooms (bedrooms, kitchens and bathrooms are subject to high humidity)
Thermal bridging / cold spots (these attract condensation)

Uncontrolled ventilation via major draughts around doors and windows, floors etc is not the answer though. This can be a real drain on resources as you cannot adjust the airflow to meet the ventilation needs of the building, so make sure that any major draughts are dealt with properly, but be aware that by reducing the uncontrolled airflow that you should be thinking about installing controllable airflow. For example, if you are replacing some old draughty windows then replace them with well sealed units that have adjustable trickle vents on.

Many social housing providers now also fit Positive Input Ventilation systems to reduce humidity levels in their houses. These systems can be simple and easy to install in houses with lofts. Basically they pump air from the loft into the house constantly and the warm moist air is pushed out of the various holes in the housing envelope. They have had a variety of reviews, but those houses that suffer most from high humidity / condensation issues seem to see the best results. I may well try a system in my house and then I can speak with a bit more authority!

Personally I think that buildings need to have:

- extracts in the main moisture generating areas, i.e. kitchen and bathrooms (these should be through walls that are not subjected to the prevailing winds and where this is necessary they should have vent covers installed).
- background trickle vents in windows
- where no trickle vents then 2 x background vents should be installed, ideally these will be heat recovery units that can exchange warmth from the stale air and impart it to the incoming fresh air
- all chimneys should be vented (both at the top and at each breast)
- ideally the whole wall structure should still be breathable
- suspended floors should be vented correctly
- all loft space should be vented correctly
- potentially a Positive Ventilation System installed

This should be treated as guidance to minimise the risks associated with poor ventilation. Most importantly remember that ventilation is not an 'enemy' of energy efficiency. It is a requirement of a healthy house.

Thursday, 20 November 2014

Check your extractors

A problem that is easy to miss

Many homes now have bathroom extractors that feed through the loft space and out through vents. This system has some advantages over systems that go straight through walls, but having just been in a house in Penarth there are some disadvantages as well!

The vents are commonly joined together using tape, but this tape is subject to a wide range of pressures and temperatures which can cause some cheap tapes to fail. What sort of tape do you think is used for most joint sealing? High quality tapes designed for high temperature range conditions or standard duct tape?

So this is the problem, What happens if the tubes that are meant to be feeding warm moist air to the eave or roof vent are actually feeding this same air into the cold loft space? Lots of moist air condensing on the cold felt and timbers.

The rafters in the attic I was in were very damp and it felt very muggy, so drastic action to reduce the amount of water in the structure is needed. Having put the extracts back together I also noticed that the well insulated loft space had been done in such a manner to block the eave ventilation. So this had compounded the problem.

Ventilation is often seen as the antithesis of energy efficiency, but actually you need good ventilation to keep buildings and people healthy. There is a balance to be struck. Maintaining good levels of ventilation is as important as creating an insulated fabric, especially in older buildings where the actual breathable fabric may also need its own ventilation to keep dry.

With most housing problems it comes down to maintenance and being aware of how your building works. Neither of these two factors are glamorous, but they are both essential if we are to have a healthy built environment. So check your vents, especially in areas where you rarely go.

One last note - try to fix vents on elevations that are away from the prevailing winds - the wind will just blow the louvres shut and make it ineffective. You might also think about alternatives to the £20 standard vents. How about one with a cover? Or one that is controlled by humidity levels, or potentially the ultimate where you have a room based heat recovery system!

Friday, 7 November 2014

Osmo White on White


Getting a lovely white finish to a floor can be a bit tricky and so here is a little tip that I gleamed from Osmo last week.

If you are wanting to get a 'pure' white finish on a floor it is better to use 'White on White' rather than 'Clear on White'. What this means is that it is better to use a white base colour and then top it with a white tinted top coat. If you put a clear on a white base then it can turn it slightly yellowy due to the oils in the clear.

So the recommended type of formula would be:


Note that it would be one coat of each maximum!

This combination will produce a lovely clean white finish and also quite a whitened effect.

Thursday, 23 October 2014

New fascia for gutter


The guttering at the front of the house is aluminium and so is well worth keeping, so I am planning to rub them down and repaint. However, the last set of workers managed to dislodge all the brackets on it. This means that re-attaching the gutter to the house is a little trickier than might be expected.

The new lime render will be 'soft' for a while. The curing process where it carbonates takes quite a while and during this it lacks the sort of strength associated with the old cement render. Being in Wales I cannot really afford to go without gutters, especially with winter approaching!

So the answer will be to attach a new fascia board and then fix the gutter to this. So I dashed out and bought some 5 x 1 PSE timbers. Now PSE is not treated, so I have spent a few minutes over the last couple of evening putting on the following:

For the ends I have pre-treated the boards using Osmo 4005 Wood Protector. This will act as an anti-fungal treatment to the weakest point in the wood and also help to stabilise it. I have then applied Osmo's Opaque White Wood Stain over the top using two thin coats. This is Osmo's specialist treatment for high exposure areas (particularly doors and windows). This should last a good number of years, especially since the wall is east facing. My philosophy is to use products that work with the wood in a sympathetic manner and so will last much longer - less maintenance to worry about in the long term!

Wednesday, 22 October 2014

Concrete blocks full of water


I hope that you can see from this photo that in the corner of the wall there is a dark rectangular patch. Under here is where an old doorway was blocked up using concrete blocks. The first coat of lime render is finding it hard to dry in this area and another similar one. Where it is on bricks and stone the render is rock hard and curing, but it is amazing how much water is being retained by the blocks.

The lime render will of course allow this area to dry out fully in time, but for the time being it is holding up work a tad as the amount of water that needs to be removed is astonishing.

Part of this problem is that since the first lime renderers walked off site it has been raining quite a lot and hence the blocks became sodden. One of those issues that you cannot really foresee, but it does mean that I am even more annoyed with that original company. Very irresponsible and unprofessional.

This acts as a warning to others that if you are lime rendering concrete blocks make sure that you do not wet them too much. It also highlights that when people cement render over these blocks that, if they are wet, they will trap a heck of a lot of moisture in the structure for a long time.

The house is coming along, the base coat is on all over as can be seen in the following shot:



Friday, 3 October 2014

The strength of cement


Look no hands! Nine bricks being supported by their edges by a 10mm thick piece of cement render.

I was planning on capping the wall that abuts into my house (this was to reduce the amount of water that is being channeled into the main house from the wall's poor structure). So I started to rake out the pointing where there was a loose brick. One of course lead to another and before I knew it I had taken down four courses of bricks and it didn't stop there.

The neighbours side had a lovely big ivy growing out of it (unknown to me) and this had blown the render on their side and so I had to remove this (a quick yank on the ivy sufficed!) The missing render can be seen on the left hand edge of the picture. The rest of their render was basically intact and so I left it.

I returned to my side and continued to identify the loose bricks. As it turned out this was a further twelve - all the roots from the various plants that were growing out of the wall had destroyed the mortar between the bricks. As I removed the bricks one by one I was amazed as the top two rows of bricks didn't move at all. As you can see from the picture this meant that the two courses ended up being suspended in mid air just by the cement render on their sides. Needless to say I then had to quickly replace the bricks (this time using a lime mortar) to ensure that it all stayed there.

The great thing of course with the old mortar was that it had left the bricks intact and it was easy to dust them off and re-use them. So I have rebuilt the wall and am now awaiting the caps to ensure that the wall stays a lot drier than it has been for the past couple of decades. More on this with the next post!

Monday, 29 September 2014

Lime render and doors

Replacement doors tend to be held in place by screws, not inbuilt frames
The door on my house has seen a lot of changes. Since I have owned it we have had 2 doors. The removal of the render showed that the original door and frame must have been at least 10cm wider (there is a pillar of bricks on the far side in this photo).

When we changed the door we fitted a new frame as well. However, this frame is held in place using screws set into rawl plugs in the wall. This gives a firm enough finish, but it does move when slammed, so what to do with the new lime render, will this get affected by repeated use?

Well the thought is that yes the door will effect the render. As the door vibrates the render can be weakened and a really hard slam could shift and crack the new finish. So the plan is to counter this by using a cement and mesh to really tie the frame into the wall. With a firm and secure frame in place the covering render will be protected from any movement.

Purists might be up in arms about this as it is not lime (well cement is a lime, just a particularly hard and strong type), however this is about being sustainable and I feel that having something that will last longer in a potentially susceptible zone is better than having a purer version fail. The other important element to remember here is that the cement will be covered with the lime putty render, so this will be effectively buried into the wall and the lime will keep it dry.

Friday, 26 September 2014

Brick detailing ruined by cement

Lovely brick arch revealed on front of house
If it weren't for the addition of cement render over the years I think that this detail would have been recoverable, however the cement has pulled off the surface of the bricks and also caused them to break over time.

This detail would have been nice to re-instate on an otherwise bland looking terrace house, but without replacing all of the bricks it is just not possible.

The use of inappropriate materials therefore has an aesthetic effect on older properties as well as the fundamental damage that they cause by changing the way in which they work.

The damage is caused by the cement being too hard and strong. Basically the mortar and / or render should be weaker than the underpinning structure. Having a harder material means that it is the structure that is damaged when the outer coating is removed. Mortars should just be there to keep the main structural blocks apart and the render is there as their protective external wearing layer. Instead cement changes this to a system where the render is the dominant player and the main structure becomes it servant. Surely we can see that this is fundamentally wrong.

Anyway, my wall will just be a plain render finish (as planned), but seeing that lovely level of detail that was in the original house just illustrates to me what has been lost through the use of modern building materials on an old property. Shame.

Monday, 22 September 2014

Steel reinforced lime

Stainless steel EML screwed into place over areas with different materials / old cracks
I have been busy on the house preparing it for its new coat of lime putty render. One of these jobs has been to mesh over any major cracks in the sub-structure and where there are different materials exposed. This is because the movement in the house may crack the new render. Whilst this is not catastrophic for the render, it is always better to have an uncracked surface aesthetically.

So I have been using stainless steel EML (Expanded Metal Lath) AND stainless steel screws and washers. So I have been drilling into bricks, mortar and an occasional stone to ensure that the mesh is tight to the wall.

The high spots of the dubbing out had to be rubbed back (using a nasty looking studded float) so that the EML would sit quite flush to the wall.

The only major issue was that I was doing this on my own and the EML is really sharp, even on the main surface, so I have managed to cut my fingers quite a lot!

So the EML now covers the main wooden lintel at the front of the house, a thin brick pillar that was constructed to make the door opening narrower, the zone between an old extension where the bricks were not tied in very well, a wooden strip that runs horizontally along the first floor and the junction between a brick element of the house and an infilled concrete block area (an old door way).

So the wall is getting there for being ready for the render. Welsh Lime Works starting today!!

Friday, 19 September 2014

Cement render = Rotten wood

Removing render exposes timber issues under cracks
One of the other issues that the removal of the cement render exposed was the condition of the wood in the structure.

Admittedly the house has a strange array of wood that has appeared in the most unusual places - joists that go all the way through the house from external surface to external surface. The trouble is that this change in underlying surface meant that the cement render was more likely to crack here. Of course, being cement, it did and this in turn allowed water to get behind the render. This concentration in damp behind the cement of course then fed into the wood.

This is one of the big concerns with cement rendering old houses as it it not obvious until it eventually gives way. One of the many problems that we are storing up for the future generations, by not understanding older properties well enough.

So, if you do have a solid walled house make sure that you maintain any render really well - remove cracks when they form etc. If you do get around to needing to re-render, then do so using a lime based render but also expect to un-earth a range of problems.

I feel that this is a similar situation to the climate change arguments. It is out of sight and so out of mind. It is also largely controlled by large companies with vested interests and so they will not lead the way for change as their industry is profitable as it stands, so why rock the boat, even if you know what you are supplying is ruining the environment (the built one that is rather than the natural one).

Dubbing Out

Haired lime putty render thrown into deep holes in wall
One of the jobs associated with re-rendering the house has been to make good the walls before the main render coat is applied. This involves getting hold of some lime putty render (same as the top coat) and throwing it into the main holes that were left by the removal of the old cement render.

The walls were quite a mess after the initial removal. The cement render is far too hard for the walls and so it takes off lots of the underlying mortar and also breaks bricks etc when it is removed. The removal process also involved fairly heavy equipment in the form of breakers and if they are not used carefully then they too can remove parts of the wall. If using breakers then it is advisable to use lower powered ones rather than being all macho about it. So medium breaker, with a wide chisel end, used in as parallel an angle as possible is the way forward.

Anyway the upshot of the job is that rather than expecting some areas of render to be 10cm deep and others 2cm it is best to 'dub out' the holes to make the surface more even.

The process I have used is to throw the mix into the holes as this gets more air into the mix and hence it cures quicker. I have also had to replace some half bricks. Any exposed wood has been treated using Osmo 4005 and the windows have been insulated into any void reveals. Next will be to sort the various joints in the wall so that any variety in movement of the walls does not crack the new render.

Friday, 12 September 2014

A trip around the block in Canton Cardiff

Part of my walk around the block
We are based in a residential part of Cardiff. Lots of solid walled properties and also some newer infill houses with cavities. Despite the ravages of time that have been served out by well meaning but not necessary best informed builders and DIYers, it still has great character - lots of different colours, features etc all based on a common theme.

All looks rosy then and in fact it is an area in demand as far as estate agents are concerned. Can you feel a but.... coming on??

Letting my casual eye wander across the urban landscape I did spot lots of very common issues affecting the houses, so here goes:

No end of cement render (should be lime based and ideally the mix I advocate)
Cracked render everywhere (letting rain into the structure)
Re-pointing with cement (rather than lime)
Damp proof course injected into bricks (should be into the mortar - if used at all)
Damp proof course holes not filled (thus letting water into the structure above the DPC)
Ground levels clearly above the internal floor level (there should be a 15cm difference between inside and out)
Blocked vents for the floor (suspended floors require good draughts under them)
Paint peeling off of dress stonework (should be left bare, or painted with a breathable paint eg. silicate)
Guttering broken, warped, joints snapped, loose downpipes, .....
Window seals broken (they need to be checked and repaired regularly)
Phone and internet lines roughly drilled through walls leaving holes around them (should be sealed up properly)
PV panels covered in pigeon poo (aerials need to be moved to remove the temptation!)
Letter boxes broken (should be repaired to ensure better airtightness)

And that was a quick 15 minute stroll along three streets!!

Correct maintenance is really important with buildings otherwise we shall see these houses slowly degrade. In the heart of the city we need a well informed population, but who apart from us is trying in Cardiff??

Invisible touching up


I was a little perplexed about which picture to choose for this post and I eventually realised that the only one really is the one pictured.

Basically I had to paint over a mark on my bedroom wall. Now with many paints this touch up would have been visible, but thanks to the anti-static nature of the claypaint it is virtually invisible. Why anti-static you ask, well...

Most conventional paints have oils in them and this has a slight charge associated with it. This static charge attracts dust to it, so over time the walls become dirty. However you would not notice this until you get around to having to touch it up. You are then left with the choice of having a visible repair, washing down the whole wall or not bothering in the first place.

Claypaint, doesn't have any oils in it and so does not actively attract dust to it, so when you have to do a bit of a repair, you can just get the left over paint out (or in my case a small tester pot) and paint it over. Job done.

Although I do have to admit that it took me two testers to find the right colour!! So another tip is to ensure that when you have finished painting your room, decant the remainder of the paint into an airtight jar / container and then remember to label it both with the colour and the room that you used it in!!

Monday, 8 September 2014

Earthborn Moisture Vapour Transmission Test

A piece of testing equipment!
I had a question last week about which paint to use on a lime plastered wall that would be subject to heavy traffic. Now I had always used the official data for this answer, which was that the sd value for the Earthborn EcoPro and the Claypaint were the same at 0.2. However, being an inquisitive sort I thought that I had better check with the powers that be at Earthborn.

I was answered very promptly (as they are very good there) with the following chart. 

Product
Moisture Vapour Transmission (g/m²)
1115
727
481
1157

So the solution was to use the claypaint with a couple of coats of wall glaze over the top. This is especially important on the internal surface of external walls as they need to be the most breathable. Internal wall surfaces on internal walls could take the EcoPro, but I would not really recommend that Midsheen here as it is not porous enough. 

All paints will of course be fine on gypsum plastered walls, but for lime we would recommend using the clay paint at all times (unless you wish to use an alternative silicate or lime paint - Auro do an excellent white lime paint for instance) and if you need the extra protection of the glaze to make it more wipeable, then the earthborn wall glaze is a great partner to the claypaint.

Thursday, 4 September 2014

Lime and Steel

The difference can make or break (literally) your project
These products do the same job. 
They also look very similar
One will work, the other will not

Fixings are used a lot in the construction industry. My render job on the house is no different. I shall have the following types of metal in my wall:

Expanded Metal Lath (EML)
Stop Beads
Screws
Washers

The EML will be used to tie together those parts of the wall where there are junctions (points where the risk of movement and cracking is most acute).
The Stop Beads will be used around the base of the wall
The Screws and Washers will be used to hold the Beads and EML in place

The important thing is that they are ALL stainless steel. Lime (and cement) attack steel and galvanisation is only a thin coat of zinc over the top of mild steel, so any slight removal of this protective covering will allow the moisture in the render to rust the steel. The galvanised steel will also slowly react with lime and this will cause the structure to fail as the rust expands and cracks the render.

Using galvanised and stainless steel together also creates a electrolytic reaction between the two and this will also lead to the render failing.

So when you are using a lime product it is vitally important that you use ONLY stainless steel (and / or plastic) in your fixings. Don't think that you can get away with using good quality beads and EML and then fixing them with some ordinary screws / nails. It will not work.

Stainless is a bit more expensive than galvanised, but in the long term it is very much cheaper! No point having work done only to need it redoing in a couple of months / years.

It is also worth noting that on a recent visit to a newly built school they had the same problem. All the drip beads had failed and had 'blown' the cement render. So it is not just old buildings where care needs to be taken with regard to material selection and combinations thereof.

Friday, 29 August 2014

Rising damp?? Maybe not!

The common thoughts about the cause of damp at ground level - rising damp
Damp - It is a problem for many houses. Trouble is that we have coined a phrase that clouds our thoughts - 'Rising'.

Damp is the presence of water in the structure. This water could come from a variety of sources, but we tend to assume that if it is close to ground level that it must be 'rising damp'. As you can see from the picture above there are a number of routes that 'rising damp' can take, however there is a blinding omission.

Lets assume that a wall has had a damp proof course (DPC) installed - this could be physical one (in the form of slates / bitumen / plastic) or an injected chemical one. Most walls these days have such a feature, although there are many reasons against having an injected solution in many solid walls, and we generally assume that they work to a certain extent. So effectively we have a water proof / resistant layer in our walls. Now this layer does not discriminate between water wishing to come up into the structure and that which comes downwards.

This is the missing link in the thought process when it comes to damp. What if it is not 'Rising Damp', but instead 'Falling damp'?

Many walls are covered with cement renders and also suffer from a lack of maintenance by owners leading to cracks and gaps around windows, doors, services etc. These faults lead to water entering into the main wall structure. The water cannot escape to the outside due to the cement render, so it succumbs to gravity and tracks its way down and into the wall. If this is happening around ground floor level (around windows, cills, plumbing etc) then it can easily find its way to the DPC. Then of course the DPC (assuming that it is doing its job) will stop it and the damp will appear just above the DPC in the inner wall. Also worth noting that the plaster on the face of the wall will soak up the water and hence track it below the DPC as well.

So when we get damp meters out it is very easy to diagnose rising damp, when in fact the DPC is working well and the water ingress is from defects in the wall above rather than any other source. So guess what? People are then recommended to have another DPC installed! This of course does not solve the problem.

We really need to get back to first principles, use our brains and diagnose our buildings correctly. Falling damp is very likely in the UK, especially with all the cement renders that have been applied to older solid walls. 

If you want a good and intelligent diagnosis on damp then give the Eco Home Centre a call and get a true independent assessment, do not rely on 'damp specialists' from damp proofing companies because, guess what, they have products to sell.


Wednesday, 27 August 2014

New drain around the house

As you know I am in the full flow of getting my house sorted for damp. One of the main problems has been the fact that the outside ground is at the same level as the internal floor. This means that any rainwater is encouraged to make its way into the wall and hence the inside because the lower levels are always wet.

On the south and west facing walls this is particularly difficult as this is where I get the wind driven rain issues. It just so happens that this zone is an area of concrete that has steadily built up over time. So I took the plunge (as I did on the north wall) and created a trench along the perimeter of the wall. I effectively lowered the ground level back to what it would have been when the building was constructed, but with the amount of water that accumulates here I need to ensure that it can drain away quickly and easily so that I don't get any standing water.

One choice would have been to remove the whole of the concreted yard and to lower this whole area, but given my resources and love of my back I decided to keep the concrete yard and create a graveled drain.

So I popped to a local DIY store and found that they didn't have any land drains in stock, I soon found that this was typical and so I improvised. I bought some downpipes and joints and used a 10mm drill to create a makeshift drain. Note that the holes are along the top (this was because it has a slight indent in its squareness and this would be exacerbated by the stones to be placed onto it) and along the lower edge. This means that any water that rises up from the ground will feed into the holes and then track down the drain and away.

My make-shift drain with 10mm holes drilled in
 I then used the trusty spirit level to ensure that it was running down to the main drain. I will be placing some sort of barrier across the top to ensure that the chippings don't fall into the drain and block it.

The outlet of the land drain into the main drains
The trench was then back filled with the 20mm limestone chippings. The 20mm chippings were used as they should not fall into the 10mm holes, thus creating a long term fix. I shall also at some point get some geo-membrane and put this down below the top layer of chippings so that any dust / dirt etc doesn't get carried into the drain and block it.
The trench back filled with 20mm limestone gravel
With the rain that we have had over the past couple of days it was good to see that the trench has not filled up with water, so I think that it must be working.

Tuesday, 26 August 2014

Lime philosophies leave me in the lurch




Lime is a interesting subject and one that I have covered on a number of occasions in this blog. The reason why it is a controversial topic that it is a really important one where there are lots of vested interests and little in-situ research. Lime is material that is a vital element to the construction industry, especially in the traditional building element of it. Lime, though has become a generic term. We use it all the time to express the need for a breathable mortar, plaster and render. You will commonly hear people use the term lime render, but do we actually know what it means?

Some people use cement and just add powdered hydrated lime into it and then refer to it as a lime mix. Others will use the other common powder form of lime (Natural Hydraulic Lime) and use it with a sand aggregate. The purists will stick to Lime Putty. However, even the purists then disagree with the aggregates that should be used and also on how to apply it.

All this is a bit more confusing and less clear cut than the term 'lime' conveys. This is why I worry sometimes about the conservation industry and its use of the generic term.

I have always been clear on my thoughts about lime render and the aggregates that support it. These are the reasons why. I believe that:
  • The walls of houses, where rendered, should have the most breathable (porous) element on the outside. So one should create a gradient of porosity from the main structural wall to the outer finish. This means that the outer surface will always help to draw moisture away from the inner structure, thus keeping it as dry as possible
  • The pressure to take the movement of water through a render should be shared as evenly as possible between the lime and the aggregate. This means that the lime is not taking all the responsibility for the movement of the water, thus allowing the water to move more easily through the structure
  • Lime renders need a consistency of mix through the structure in order to minimise the risk of de-lamination. Using different mixes and limes can create this difference in the structure and so should be avoided.
  • Application of the render is really important as one needs to apply the mix in such a way as to encourage the different coats to chemically bond together. This again minimises the risk of de-lamination in the structure
Having sorted a specialist order for a limestone mix from a local supplier, the combination of lime putty and limestone aggregate has proved too much of a leap of faith for my current lime specialists on site. They have backed out of doing the job (unless I forgo by principles and stick to the common knowledge of the 'lime industry'). This means that I have been left with a house that has been hacked back to the stone / brick / concrete blocks etc and no contractor to put a proper lime render back on. I was a tad 'hacked off' as you can imagine!

Knowing that I am right (see picture above) is proving to be a problem!

However, there is a knight in shining armour. Mark from Welsh Lime Works has offered to step into the breach and do the rendering. This means more of a wait, of course, due to his other commitments, but at least I will be able to get what I want and have it done by people who know what they are doing. A huge thank you to Welsh Lime Works for this, true saviours.

Friday, 15 August 2014

Tracking down lime sources

A limestone quarry
What a palaver! Being a bit of a fuss pot over lime I wanted to check the lime credentials of the lime putty that is being ordered for my render. I seem to have been around the proverbial mulberry bush, but at last I feel at ease with the source that shall adorn my walls.

The lime putty that shall be used will have come from Cheddar (an Oolitic Limestone) as a Quicklime and then slaked in Brecon (at Ty Mawr Lime), left for a minimum of three months and then mixed with an aggregate including limestone from the Cotswolds.

I feel it is really important to know the source of lime as some limes are made from chalk. I think that an external render needs to be made from a limestone base rather than a chalk one. Ultimately it will be harder and more durable. Chalk derived products are fine for internal applications, but I am not so convinced with being exposed to the winds and rains that we can get (only occasionally mind) in Cardiff.

The limewash will also be a limestone based product as well.

Wednesday, 13 August 2014

Windows shrink with age

Having knocked off most of the render around my house (we are leaving those walls that will not benefit from a new lime render) the original reveals for the windows and doors are fully exposed. This then gives one a chance to see how big the original frames would have been.

One downstairs window has a gap of 3 inches / 75mm each side, so over time my window has effectively been shrunk by 6 inches / 150mm. That's quite a lot of light that I have lost!


What happens is that when windows are replaced we don't hack off the render or plaster to see where the structure is. The windows are measured using the visible reveal. No installer wants to estimate depths that they cannot see and most people don't want to have their reveals knocked around just to get an accurate measurement. So windows get smaller.

When the windows are installed, they do have to 'mess' with the reveal and then you find out that you could have had a larger window, but by then it is too late. The new windows are fitted and the reveals are extended so that the window frame is enclosed with plaster etc. Next time, of course, your reveal is now smaller and the process repeats itself.

I would estimate that around 0.5 - 0.75 inches (12 - 18mm) is lost per fitting, so this would mean that this window has been replaced about 5 times since construction.

One of the other common occurrences with this process is that this gap is often filled with that days newspaper. So, you can often catch up on the news from a couple of decades ago! Nowadays fitters tend to use expanding foam to seal up these gaping holes around your windows which is not so much fun. I am not a fan of this foam and so I have used some fluffy insulation in the gaps to provide a little more warmth (and more importantly) fewer thermal bridges around the edge of the window.

So, if you want to keep your windows as big as possible, you will need to allow fitters to remove the plaster around the window so that they can accurately measure the size of the original window void. This is unsightly and dusty, but it is the only way that a company can reliably measure up. They are not keen on making windows too large or tight as it means that they are responsible for getting it right, so their eye on caution is understandable given the costs of re-making the frames and glazing.

Thursday, 7 August 2014

Lime rendering my home

Money where mouth is moment!

I have long been an advocate of treating old solid walls correctly. This means allowing them to breathe using a lime based render (where render is needed of course).

Anyway my house has been suffering from damp for a while and so eventually we have managed to get enough money together to start to put it all right. So we are taking the correct approach of getting the outside done first before moving inwards. So, first part has been to remove all the old cement render from the solid walled parts of the building. Note that we are not taking off the render on the already lime renders timber frame walls, or the newer block cavity walls, that form the end extension on the property.

Front of house is stone, behind door is solid brick wall, next extension is early cavity, still rendered is block cavity at ground level and timber frame above

Front door separates different materials

First floor timber joist exposed. Southern side of building is suffering from rot due to trapped moisture from cement render
I have long been a follower of Harry Cursham at Traditional Technologies (http://www.tradtech.net/) and Welsh Lime Works (http://welshlimeworks.com/) and so I have been very specific about the type of render that will be used. I have chosen the following:

1:3 Mix of Lime Putty (from Limestone NOT Chalk) and Aggregate (and this is one of the keys!)

As you may have read in some of my earlier posts, I see aggregates as being the vital, but often overlooked, element to renders. The aggregate mix that I have chosen is:

1:1 Limestone (3mm to dust) with Sand (50:50 mix of coarse and fine)

The key ingredients are the limestone dust and the limestone putty with the sand acting as a filler. The limestone and lime will do all the work in the render as it is these two elements that will carry the water in and out of the wall. Getting consistency of material, avoiding weak points and ensuring that de-lamination is avoided mean attention to detail!

Monday, 7 July 2014

Ventilation - Its an IAQ issue!

IAQ = Internal Air Quality

Shame that she has her mask upside down, but nevertheless she is asking a question that many of us are just not fully appreciative of.

Internal Air Quality is becoming an area of study that gaining in prominence. The main factor driving this is that houses are becoming more airtight and hence reliant on controlled ventilation more. The massive improvements in levels of airtightness in housing that is being experienced by high efficiency designs like Passive House and Code for Sustainable Homes Levels 5 and 6 means that we are more susceptible to all the toxins and gases in these homes. Furniture, plywoods / MDF, cleaning products etc can all of-gas chemicals into the air. When airtightness is increased it also means that ventilation is reduced dramatically. Ventilation systems can then be managed to provide the air that we need in the house to breathe etc, but nevertheless the number of air changes per hour are still reduced significantly.

Research is now underway across Europe to look at the potential effects of these airtight homes on our health. Of course it is not the actual airtightness which is an problem, it is the things that off-gas or that we use in these homes that can cause the issues. So there will probably be a series of guidelines with high performing homes to ensure that people use them appropriately and also use healthy materials and products in them. The ventilation systems in these new homes also need to be capable of easily removing any harmful air borne contaminants. This research can be followed at the ECO-SEE project.

Ventilation is also a really important element of refurbishment of older buildings. This though tends to affect buildings and their inhabitants in a different way.

Solid walled buildings when they are in their original pristine condition allow moisture to flow through them. This means that moisture is given off into the internal environment as well as the external. Our modern 'improvements' and drive for energy efficiency means that people have been sealing up their homes. We are installing windows with no trickle vents, removing chimneys, replacing sash windows with casements, fitting draught excluding products etc. So on one hand we are making our homes more energy efficient (which is great), but we are also making them more airtightness. This reduces airflow, hence trapping in staler air and also moisture.

Getting the balance right is not a science that is easily applied, we are only just getting to grips with moisture in solid walls, let alone air movements. It really is a 'suck it and see' approach that is needed, even if you did an Air Pressure test this will only give you part of the picture. It is also down to how the building is used (windows left open, exposed location, internal doors open or shut etc.) However there are some elements that one can control easily, these include:

Use zero VOC paints (Auro, earthborn etc)
Use solid wood rather than MDF, ply etc
Use natural cleaners around the house
Use natural fabrics whenever possible
Be aware of IAQ and take appropriate actions when required (open trickle vents etc)
Minimise use of sprays and aerosols
Get a spider plant - many plants absorb toxins and impurities from the air

If you do have a problem with IAQ then it might also be worth looking at the Auro Airfresh Wall Paint product as this has a catalyst in it to help remove certain elements from the air. Note that we can supply all Auro and earthborn products.

Tuesday, 10 June 2014

Concrete floors - hate them!

Typical suggestion for a replacement concrete floor

My house is a very typical Victorian Welsh terrace. Solid walls made from a mix of local and imported stone, bricks around the windows, doors and chimney etc. It has also had the typical 'improvements' over time:

Replacement windows
Replacement stairs
Replacement tiles
Toilet moved inside
Rendered with a water proof concrete
Chimneys blocked and replaced with gas boiler and radiators 
etc etc

One of major changes was the replacement of the old suspended floor with a new concrete one. This is proving to be a real pain.

What happens when people replace a suspended floor is that they line the new floor with a Damp Proof Membrane (DPM) underneath and fold it up around the edges of each room. This is meant to tie in with a damp proof course (DPC) in the walls. Unfortunately this is a real weak point as injected DPCs are not very reliable (due to poor installation and not really being the ideal solution in the first place - but it is quick and cheap!) So what happens is that the damp (that was under the floor and previously being wicked away by a healthy draught under the floor boards) now has to find another way out. It does this be focusing on the internal (and external walls) through the foundations of the building. It is carried up by capillary action into the walls (this should be stopped in theory by the DPC, but often is not). If the old plaster was left there then it would travel through this and out into the internal environment (this is why internal ventilation in an old building is really important), however what happens is that the old plaster is removed and replaced with a water proof plaster. This effectively seals any water into the wall and hides it from view. Hooray!?!?

In my house what has happened is that this water has appeared above the new plaster and also crossed through it - water is a persistent beast. So it is my internal walls that are now giving me hassle. The external ones I have largely dealt with by removing the cement render and also creating a drainage channel around the house, but the internal ones!! I recently did a quick damp meter check on the walls and where the external walls are now giving me a figure of 7 - 10% damp but I am getting 30% on the internals. Needless to say the dehumidifier is running on our free PV electric during the day now to try and dry the walls out during the summer months. I will have to re-inject as well to try to slow the next batch of damp that will no doubt be keen to get into the walls. I might even bite the bullet and get a physical DPC installed. The dust, the dust!!

So as a word of advice don't install a concrete floor in an old house, refurbish the old suspended floor, insulate it, ensure that the vents are clear and working etc as it will save you a lot of headaches in the future. If you are really keen on removing the wooden floor then look at using a limecrete floor solution, anything but DPMs, DPCs and concrete!

Wednesday, 21 May 2014

Eco Pro Emulsion used in Cardiff Eco Home


One of our customers has built a great new eco-home in Cardiff (see above) and used our lovely earthborn EcoPro Emulsion paint throughout. Looks great both from the outside and the in!
Have a look at http://earthbornpaints.co.uk/case-study/architects-home-is-a-statement-in-sustainability/

Nic and Carolyn from Downs Merrifield Architects were keen to use a real eco paint that would deliver performance: usability, no odours and great obliteration. The house is currently white throughout, but once they have lived there for a bit a splash of colour will be applied in the appropriate areas.

The Eco Pro range can be found at permanently discounted prices from us @ http://www.ecohomecentre.co.uk/index.php/eco-paints/interior-paints.html?p=2


Tuesday, 20 May 2014

Sheep or balloon for your chimney?

Welcome to Chimney Sheep - the draught excluder for chimneys - the Chimney Balloon alternative

Chimneys in older houses can be a real source of draughts. Whilst a good bit of air circulation is required in older homes you can get too much of a good thing!

In the past there has been little choice with blocking up chimneys, but a small company up in Cumbria has developed a great alternative to the chimney balloon. The Chimney Sheep (TM), see http://www.chimneysheep.co.uk

I have used both and I can say that I prefer the sheep as my balloon keeps on slowly deflating and falling out of the flue. The 'sheep' has stayed in place. The sheep is a felt made from Hardwick wool and so has a lot of 'sustainability' advantages over the balloon. It is a natural product (although the handle is plastic) and hence it is breathable, it is also easy to wash and to store when not in use.

So if you are looking to reduce draughts when the stove / fire is not in use then it is a good option to look at.

I would always recommend that you have a cowl on your chimney to reduce water infiltration from above as any draught excluder doing its job will reduce airflow and hence you will need to ensure that the chimney is kept as dry as possible from above. Always remember to remove the draught excluder when using the fire and also during the summer months as this will promote good air flow in the home (which can help with damp issues and internal air quality).

Friday, 16 May 2014

Damp proofing cellars

Some old houses have partially buried walls
Like dealing with solid walls you have a couple of choices here when dealing with rooms that are below ground.

Choice 1 - Work with nature
Choice 2 - Try and work against nature

I am a Choice 1 type of guy, as nature will always find a way of getting through our defences. Ask King Canute!

So we are looking at solid walls that are porous and a subterranean location that may well be permanently damp. How to keep the cellar dry?

Well, this is a difficult aim to achieve with 100% success rate and I think really depends on each households sensibilities and access to a range of resources.

If you find that the walls are not very damp and that you are using the space as a typical cellar function (i.e. there is no pressure on keeping the room totally damp free) then the walls may well be easily treated by using a breathable finish on the walls and ensuring a good air flow. So leaving the walls bare (or painted with a lime / clay / chalk paint) and having a good draught will allow any moisture coming through the walls to be vented away before presenting any problem. Note, though that furniture etc should not be placed too close to the wall as this will restrict air flow and could lead to mould formation.

If you want to use the room as a more conventional living space then keeping it dry gets more important. Having lots of ventilation in this type of room then gets more difficult as we are not so fond on a keen breeze around our ears! So how can we allow the walls to breathe whilst keeping damp at bay?

The way the English Heritage recommend is to use a dimpled membrane. Basically this is a plastic sheet that has dimples in that create a vented space around the wall. See below:


So the plastic keeps the damp away from your new wall, but what happens to the water?

Well this is where individual factors come into play. If the walls are really wet and literally running with water then you will need to install an internal drain rather than relying on ventilation only. This drain can be directed straight into the main drains, or it might need to be fed into a sump and then pumped out (via an automatic pumping system).

So the 'Heritage' system is a bit of a hybrid that wants to work with nature, but has to provide some very clear guidelines in which elements are not acceptable! Purists will no doubt say that it is case of using very breathable materials, drains and ventilation, however I feel that it is down (as ever) to the individual site conditions, usage patterns and sensibilities of the client.

Definition of Economic



There was a great presentation at a Wales Zero / Low Carbon Hub meeting this year and it mentioned the original definition for Economic. It comes from the Latin Oeconomicus and means management of the household. This is obviously quite different from our current meaning based almost purely on finances.


In the wider sense it is easy to extrapolate 'household' to 'world' given the current state of globalism. So do Economics need to be purely about money? After all, as the picture above illustrates, what would we prioritise about our homes? Probably:



  • Cleanliness
  • Comfort
  • Health

  • We probably would not want:

  • Disruption
  • Mess
  • Stress
  • Conflict

  • Yet, we are encouraged to behave in our global household in a manner that pursues material gain and money. How disconnected we have become from what we fundamentally know to be important (the power of advertising and corporations eh!). The pursuit of 'monetary wealth' adds to our carbon emissions and hence will help bring about future chaos predicted by the IPCC.

    The IPCC state that we have to reduce carbon emissions by around a 80% reduction by 2050 if we are to avoid a >2 degree rise in global temperatures (this is seen as a tipping point in the climate). So in theory we have to reduce the carbon emissions of our 1.3 million households in Wales by 80% by 2050. This means radical improvements at a rate of around 36,000 houses per annum (in Wales we have the ARBED programme and this huge 'improvement' project is only tackling around 1,000 per annum!)

    As you may have gathered from reading this blog, getting reductions of 80% in emissions from older terraces is just not viable. It has been done with some TSB Retrofit for the Future projects but they are really expensive and also rely on people living in the buildings in an efficient manner. So what can we do? After all, doing nothing will just help to create an uneconomic situation (think of the issues and costs associated with a >2 degree rise in temperature: mass migration, water shortages, crop failure, flooding, forest fires, sea level rises, ocean acidification, disease spread etc). I think that we are limited to a few options.
    1. Improve our homes to as good a condition as possible (this may only be 20-40% and may be achieved through simple draught proofing, insulation, efficient boilers etc)
    2. Maintain our homes (check rainwater goods, repair silicone seals, repair cracks etc)
    3. Use lower energy materials (wood fibre, recycled insulation, lime etc)
    4. Service infrastructure annually (boilers, mechanical vents)
    5. Install renewable energy generation where possible (PV panels are now much more affordable and provide a good rate of return financially)
    6. Manage energy use wisely (for example only heat areas that you need to a temperature that is as low as feasible)
    7. Think about how we use energy and what we really need rather than what we want
    8. Reduce water consumption with some simple and cheap retrofit devices
    9. Change your energy supply over to a green tariff
    We have the potential for greater impact outside of our homes though. How about?


    1. Walk and cycle wherever you can
    2. Use public transport
    3. Buy things that you actually need rather than what you want
    4. Invest in quality goods rather than throwaway goods
    5. Holiday close to home
    6. Only travel when you need to
    7. Buy foods that are in season (in the UK) or if not grown in the UK when in season in the northern hemisphere
    8. Grow your own food at home / allotment
    9. Get an electric car (second hand electric cars are now well under £10,000 for a 5 door)
    10. Invest in some community renewable projects
    11. Keep fit


    It is essential that we practice old school 'economics' in our lives and this means both looking after our own households, but also the our wider home of the planet. The time to act is now so that we can all help to avoid the costs, heartaches and resource demands of an unsustainable, uneconomic future.

    Do your bit and do think about your children / grandchildren. It is worth it economically, just maybe not financially in the immediate future. That is our choice to make.

    Monday, 12 May 2014

    Insulating window reveals


    Last year I decided to do something about the growing about of mould on my window reveals in the bathroom, but what?

    My situation was as follows:

    High humidity (bathroom)
    Thin double glazed windows
    Cavity wall construction (that has been 'filled')
    Single storey with insulated pitched roof above
    Sill is tiled
    Max of 10mm between reveal and glazing (frame recessed into wall)

    So basically I was suffering from condensation associated with cold spots along the reveals.

    The easy answer was to insulate the reveals internally, but I only had around 10mm of depth available to take any. The thinnest boards are 25mm and this includes plaster board of 12.5mm. They also come in 244 x 122cm boards and this was far too much for the reveal area.

    So what was my solution? 

    Cork tiles were ideally sized as they were thin and came in pack sizes that minimised any potential wastage
    I bought a pack of cork tiles and cut them to size. The reveals were cleaned and then I applied a coat of adhesive all over the reveals so that moisture would not be able to get behind the tiles (this is important to stop mould growing behind the insulation). I then fitted the tiles, waited for them to adhere properly and then repeated the exercise so that there was a double layer of cork. The cork adhesive was then left to dry again.

    I used a breathable natural paint on the cork (earthborn eco-pro emulsion) and so I had to pre-coat the areas where the adhesive was visible using the earthborn Isolating Primer. This was to stop the paint drawing the oils in the adhesive through it. Once the Isolating Primer had a second coat and dry I painted the reveals.

    To date (and this includes a winter and spring) there has been no condensation on the reveals and consequently no mould growth. This solution was cheap, effective and resource efficient (as I only used what I needed with very little waste generated).