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Tuesday, 29 November 2011

Getting a smooth finish on a lime plaster

Some people are looking for a gypsum style finish on their lime plastered walls. The temptation for some (especially builders) is just to plaster gypsum onto the lime plaster. This is not a pretty relationship between the two and even LaFarge (main supplier of gypsum based products) state that it should not be used over lime plaster / render. So if you are looking for a silky smooth finish what can you do?

It can be achieved in a couple of ways.

1. When the lime plaster is still slightly pliable push in a top coat of lime putty. This is incredibly fine and will be a really smooth finish. If the plaster has dried out too much then you can still apply it, but you will need to give the surface a once over with limewash first and apply the putty whilst the limewash is still slightly damp.

2. Use a clay plaster. This again is a very fine plaster. You will need to slow its drying down a bit as the lime plaster underneath will suck out the moisture really quickly. Using a primer to do this is the best solution. Clay Works in Cornwall have a lot of advice and information on clay plasters. Eco Home Centre will also be running a clay plaster course in the New Year, so look out for that.

These finishes are really fine and also give excellent breathability to the room. If the surface is rubbed against then the main complaint is that you can get dusting from the clay or lime. However this is easily cured either with painting (use a natural breathable paint like a clay paint) or by glazing (a breathable glaze is available from earthBorn - Wall Glaze)

Saturday, 26 November 2011

Guttering - getting it square to a fascia board

Getting guttering square to the fascia can be a problem. If the fascia is not perfectly vertical (and many on older buildings aren't) then when fixed gutter brackets are attached they either need to be packed to make them square or, more commonly, they are left at odd angles either sloping into or away from the wall.

This can cause problems in heavy rain showers. If there is any slight blockage the gutters don't work as they should and can easily overflow either against the wall or over the outer edge and then to who knows where. This can be a major cause of damp in a house.

Packing the bracket will probably work in the short run, but if the packing falls out this can cause even more problems. So, a sustainable solution.

We deal with Lindab guttering and they offer an Adjustable Snap-on Bracket (Code SSK). These are very similar the normal fascia brackets, but rather than being solid metal they have an adjustable metal arm that clots into a grooved receptor and this gives a wide variety of choice to get the guttering square to the fascia. So effectively they twist the guttering into shape to give the best result in ensuring that the gutters run true.

So if you are concerned with the angles of your fascia it is worth stipulating adjustable brackets rather than then fixed ones. If you think that you might have some issues with the fascia then I would go with a 50:50 mix between the two. Cost wise they are similar (adjustable slightly more expensive), but it could save you a lot of headaches and hassle when fitting and living with a new system on an old building.

I have also been informed of the following that might be of import to your particular project -

In order to use the standard fascia bracket (KFK) you really need to be able to snap the guttering in at the back. If the existing roof overhangs the fascia this may be impossible. When you are on a ladder it is difficult to get the gutter to snap in at the front due to the strong rolled edge. In this situation, even if your fascia is vertical, you need the adjustable fascia bracket (SSK) because the guttering can be placed into it underneath the existing roof and the bracket has a snap-on front clip. Not all of the suppliers stock both kinds, and the Lindab literature does not seem to explain the problem!

Wednesday, 23 November 2011

Insulating flat roofs

Many people have flat roof extensions. Seems that they were all the rage some time ago. We were obviously hardier then as well given that most are poorly insulated, draughty and can be cold and quite miserable places. This is commonly re-enforced by the fact that they were often designed to be bathrooms.

Bathing in a room that is exposed on two or three sides with a cold roof is not particularly pleasant in the winter unless one has a suitable radiator on full and the extractor fan on a humidity control.

These flat roof extensions are therefore having to do a lot, especially with regards to moisture. Cold walls, windows and roofs with high levels of humidity just leads to one thing. Condensation and mould.

Most of the heat in the room will be lost through the roof (assuming that it has minimal insulation). So the most obvious job is to get the roof well insulated.

When looking at this the most obvious solution seems to be to install the insulation to the underside of the ceiling. However this can lead to problems. If you have insulation below the ceiling then any warm and very moist air that manages to get above this will condense on the even colder underside of the felt / top covering of the roof. This will then condense and fall back on top of the insulation. This can cause a lot of problems with electrics, damp, rot etc. So this solution is not recommended.

So unfortunately the roof has to be taken apart somehow to either install the insulation just below the main roof covering, or above it. Putting the insulation on top seems to be a easy option, but there is the issue of air circulation, so just plonking some rigid waterproof insulation on top doesn't work as there is an air flow through the existing roof structure that needs to be altered as well otherwise the external cold air will just flow under your lovely new insulation and effectively make it useless.

So the only real way of tackling this is to look at seriously upgrading the roof when replacing the roof covering. This allows you to change around the air circulation so that there is no external air source into the structure. This then allows you to insulate next to the underside of the roof covering. Airtight and water tight membranes are important here though. Your roof covering does not breathe and so you must stop any warm moist air from reaching it. By using membranes and also by adhering the insulation to the roof covering you effectively create a warm surface in the room, thus stopping condensation from forming on it.

All in all, it might be worth thinking about replacing the flat roof with a well insulated sloping roof!

To make all of this clearer follow this link to Brian Murphy's excellent GreenSpec website - he has pictures that speak a lot of words!

Tuesday, 22 November 2011

Mouldy window reveals

On my house I have a problem with mould in the window reveals. This is because it is a cold spot in the construction of the house. The walls here are effectively thinner than the rest as the window only sits back a few inches from the outside of the house. With my windows also not being the best it is a perfect haven for condensation and hence mould. Cool and wet is not the best combination in a room.

So what to do about it?

Well basically it just needs some additional insulation to keep it warmer. By doing this it will stop the water in the air from condensing on the walls and hence stop the perfect conditions for mould.

There are a few products that can help here. I will avoid using the phenolic backed plaster boards as I have developed a loathing for them. They are a legacy waste (what do you do with them at the end of their life?) and also can trap moisture behind if not installed perfectly.

Given that your walls will no doubt already have paint on I think that the easiest solution is to use InsOwall insulating plaster. It is very sticky and so you can prep the walls easily just by scratching back some areas to the plaster and then just with some wood to give an edge you can easily apply the plaster (up to 40mm thick) into the reveals. This can then be plastered over to give a really good finish with lime plaster, clay plaster or gypsum (if you must). It is possible to get a final finish with the InsOwall, but in reveals this can be a little tricky to the DIYer.

Other options would be:

Hemp / Lime plaster for those homes where good breathability is essential (InsOwall is a semi-breathable material)
Calsitherm, again where good breathability is required, but also some additional thickness and strength

You could also use Aerogel, but it is expensive and getting it in small enough quantities would be an issue.

Saturday, 19 November 2011

How to dry out damp solid walls

The solid walls so common in Wales are prone to damp after the 'modernisation' they have received over the past hundred years. The addition of external cement renders especially has locked moisture into the walls and the remedial work of injecting damp proof courses just doesn't work. I have covered this point on numerous occasions in previous posts. I might be getting obsessed!

So the scenario posed here is having an issue with rising damp with an external cement render. So how to cure this problem in a quick and relatively easy way?

The best thing is to remove the offending cement render to allow the wall to breathe. In order to achieve this at lower levels (assuming that the upper levels of render are sound - no hairline cracks etc) you can cut a straight line in the render using an angle grinder. The lower render can then be knocked off using a hammer and bolster - it may well come off relatively easily as it has probably 'blown' away from the wall. Unfortunately this process may well take off the glazed surface of the bricks. So in order to create a finished surface we would recommend applying three or four coats of lime wash.

Limewash is really breathable / porous. This has two advantages for us:

1. It will help to suck out the moisture from the walls on drying days (these are effectively any day where is it dry, windy or with light rain)
2. On heavy rainfall days it will help to keep the wall dry. Basically the limewash gets saturated with the rain and then it sheds the excess rainwater off of the surface

This gradient of porosity / breathability is the key to a successful wall. The inner finish should be between 3 and 6 times less porous than the external finish. The internal pressure and breathability gradients then encourage any moisture in the walls to the external surface where they can be dried by the weather.

Ultimately if you want a render finish again on the external wall, then look to render it with a lime putty stone dust render topped off with the limewash again. Note that the limewash and putty should be 'hard' lime putty that comes from limestone rather than the 'soft' putty from chalk.

Thursday, 17 November 2011

Gypsum plaster and lime render

One of the major mistakes that we see in refurbishment of old solid walled houses is the use of modern materials over over the original substrates. I have written before about the use of cement render over these types of walls and what damage this can cause in terms of damp and potential structural failure. However, we now need to look at the inside walls.
Gypsum plasters are too hard and brittle to flex and move with the building, and most of them will break down in the presence of moisture. Lime of course allows moisture to pass through it and hence can allow moisture into the gypsum (in the case of rising damp or rainwater ingress.) When gypsum has lost its structure it cannot regain it and so it will then become hygroscopic and just attract more moisture to it. If then happens then it has to be removed.

Some gypsum has water repellents added to it, but this then just seals the surface of a wall and prevents it from 'breathing'.

So either way the gypsum and the lime just don't work together. So really if you are working on the internal walls of your home it is best to steer away from combining the two as there is a lot of room for conflict. So when replastering the walls we would recommend using lime plaster.

If you want a really smooth finish you can still get this by using a clay plaster skim coat or by pressing in pure lime putty into the plaster / render when it is still slightly pliable. Remember though that you will need a breathable paint finish to maintain the original functionality of the wall. We would recommend either a claypaint, a limepaint or a limewash for this.

Wednesday, 16 November 2011

Sound and thermal insulation all in one

Eco Home Centre recently helped a local home-owner to insulate their home. However the pressure was not for thermal insulation more for acoustic. The house, built in the 1980's, was typically badly built. Little insulation in the external walls and ceiling, but also none in the floors or internal walls. The house therefore reverberated with noise from any corner of the house.

The house was also built in a terrace and the sound leakage between the houses was also noticeable. So we devised a plan of using one product to solve the problem rather than using a conventional thermal insulation and a separate acoustic solution. This product was a wood fibre board. The product was a 40mm deep board and it was finished with a plaster applied directly onto surface (although the belt and braces approach is to use a mesh as well).

This solution has really 'deadened' the sound in the room and also provided a good level of thermal improvement with minimal loss of space in the room.

The sound inbetween the floors was dealt with using a dense sheep's wool insulation. Ideally a hemp wood fibre mix would have been used, but this was in short supply and transport costs took it out of the financial picture.

The sound inbetween rooms was sorted by using the same sheep's wool insulation in the stud walls (75mm in a 100mm gap so as to leave an air gap that gives better acoustic insulation) and then re-boarding using and woodwool board. These boards are less uniform than plasterboards and also heavier and thicker, hence they give better acoustic properties.

So with all these simple improvements the choice of materials had a number of benefits:
  • It was cheaper than using specialist thermal and acoustic insulations
  • It was thinner than using stud work on the walls
  • It was healthier as the woodfibre boards help to temper chances in humidity levels
  • The products are recyclable
  • The products had a lower carbon footprint
  • The products are natural and contained no harmful materials
All in all the house is now warmer and more pleasant to live in. Also the work was done by a general builder with a little instruction from the Eco Home Centre. Eco Home Centre also sourced all of the 'non-standard' materials and products for the project.

Tuesday, 15 November 2011

Eco Paint Chooser

This is a post with a question. Would you like to see an Eco Paint Chooser? We are looking to develop a tool for the website so that we can guide people towards the right paint for their particular situation.

Basically all natural paints are a sum of their parts and so behave differently from conventional paints (that are designed to all work in the same way - so as not to confuse builders and decorators). People also live differently and rooms in homes have different functions and hence demands upon them. So there is a supply and demand equation here that needs to have some guidance for the users / choosers.

Would you like us to develop this as a function on the Eco Home website? If so please let me know and I will put something together. Many thanks, Peter

Friday, 11 November 2011

Mould in difficult places

Sorting out mould and damp is a bit of a nightmare in older homes. I have dealt with the causes of damp and hence mould in other posts on this blog, but in many situations it is difficult corners and walls that need attention, but the costs of actually solving the issue with beyond current budgets.

The first thing to know is where the damp and mould are coming from. Having a longer term plan of how to deal with the issue with important so that you don't double up on work. If the render on the outside of the house is making the wall damp and cold for example the best solution is to deal with this externally. So doing a lot of internal work may not be necessary. So are there some 'holding measures' that you can do that are simple and relatively cheap that are also eco-friendly?

One 'solution' is to use a mould treatment. Auro do a step by step system that kills the mould, then a spray of paint that stops the mould from returning. It does this using hydrogen peroxide and then a lime based paint. The additional alkalinity of the paint inhibits the mould from returning.

Another possibility is to keep the wall surface a little bit warmer. An insulating paint will do this and may well be able to keep the surface warm enough to stop the mould from finding it attractive. You will though have to kill the mould first as otherwise the vast amount of latent spores will give the mould a fighting chance. Thermakote have an additive that can be added to any paint to achieve this.

Ventilation might also a root cause. Just by creating an airspace around the mouldy area might be enough to reduce its attractiveness, but again you will need to kill the mould first. Moving sofas etc away from walls can facilitate this air flow. People also fear losing heat and higher bills by having extractors on. However by not having them on in key rooms like kitchens and bathrooms can really give mould the conditions it needs to grow. Think about it like this. When having a bath or shower, or when you are cooking, you are introducing a lot of heat into the room, so by having an extractor on you are effectively just removing this excessive heat as well as the excessive moisture. Trying to keep hold of the heat as well as getting clean or a meal is just being a little too greedy!

Not introducing any more moisture into the house is also key. So drying clothes on radiators is another major cause of mould at this time of the year. A difficult one I know as it has been known to rain in Wales during the Autumn and Winter, but it is worth planning washing around the weather if you can.

If you are feeling a little more DIY-ey then there is not a great deal of cost involved in solving some of the fundamental problems associated with damp. Removing render up to a metre outside can just be the case of using / hiring / borrowing a disk cutter (to make a nice straight horizontal line in the render), a hammer and bolster (to knock off the cement render) and then some limewash (really cheap breathable external paint) to cover up the exposed brick and stone. This will allow excess moisture to escape the walls to the outside and hence dry up the internal walls. Mould does not like dry walls!!

If you need a little bit of proper insulation but don't have the space to put in stud work etc (keep away from dry lining please!) then think about the InsOwall insulating plaster. It can go over existing plaster and so you can add 10, 20, 30 or even 40mm of insulation that will better the thermal performance of the wall by a minimum of 35%. Again having a properly insulated wall will stop the mould from returning.

For individual mould and damp advice please give the centre a call, or book for an Eco Home Report.

Thursday, 10 November 2011

Can I stop external wood from greying?

Wood will naturally change colour as it ages. Some people like the fact that woods like oak and cedar grow grey with age, a reflection of us as humans I suppose. Others though like the elixir of youth and want to maintain the colour, depth and vibrancy of wood in its prime. So how can we do this?

Well, if the wood (patio / cladding etc) has started to grey, you can get it back to looking great by using Oxalic Acid. Osmo's Wood Reviver is the product that we stock to do this job. A good covering and a scrub will bring the wood back to its original colour. Once the colour has been retrieved, work can start to preserve it.

The wood basically needs some sunscreen to reduce the effect of UV rays. Most preservers have a colour in them and this acts as a good UV protector, however clear oils and preservers commonly do not provide any UV protection. So the best advice is to use a coloured wood oil and to ensure that this is topped up annually to give ongoing protection. However if you wanted to use a clear oil then you can get some UV protection from products like Osmo's 410 and 420 Clear UV Protection Oil. These give a factor 12 level of protection (effectively reducing the greying effect by a factor of 12).

Wednesday, 9 November 2011

Bongaboard and the Eco Home Centre

Now this is a tad strange. Bongaboard - a balance board - and the Eco Home Centre? Well Andrew from Bongaboard is an entrepreneur in Cardiff who has just started making personalised balance boards for the skating and surfing market. Being a conscientious chap he wanted to use eco-friendly products in his designs and boards, so after a few weeks of to-ing and fro-ing  we came across a formula of products that work brilliantly on the boards.

Andrew has used Auro Wood stain and earthBorn varnish to make these boards and they look great. So if you are looking for a present for Christmas / Birthdays for balancing boys and girls you would be hard pressed to find a better one than a Bongaboard. You can have any design you like, or just get one of Andrew's funky ones.

So it is lovely to see quality eco-products making it into the manufacturing process. Bongaboard website is

Friday, 4 November 2011

Insulation and airtightness

These are two peas in a pod. We had a presentation last year from ProClima about airtightness and its importance and some of the figures were terrifying. The effect that a lack of airtightness has on insulation values is dramatic. When one thinks about it, the correlation is obvious. If cold air is being driven through, or around, the insulation by draughts then it becomes irrelevant. Good airtightness is therefore important for preserving insulation properties as well as managing ventilation effectively.

We have no real appreciation for airtightness in the UK. Our mild and breezy climates has meant that we have learned to live with draughty homes and we sort of accept it. But in these days were energy efficiency is more and more important we really do need to start to get to grips with airtightness and all the various materials that come with it.

We use insulation in a strange way in the UK. Builders rarely follow instructions from manufacturers on how to fit their products as normally this involves some attention to detail with its associated costs and time. So we often see new buildings going up with phenolic boards in cavities, but are the boards taped together? Rarely.

Membranes are also a whole new building material that is not widely understood. Membranes are used commonly on roofs and timber framed buildings, but until recently they were commonly just stapled to the wood and left. No tape in sight and also no thought for how to join it to elements like brick, block and stone. So again little point in membranes if they are not fitted correctly.

Longevity of seal is also overlooked. With many projects the airtight membrane is an integral and hidden element to the building, so it is very unlikely ever to be checked after the build is complete. Many sealants are not very long lasting (especially in certain harsher areas of the house like on the roof - extremes of heat, or in a floor - exposure to damp) and so when they fail after a few years, all the good work of sealing it up may be wasted. A good quality seal and tape is therefore essential to ensure that the property retains its airtightness into the future.

So be careful when having work done. Insist on using airtight tapes and sealants where required, otherwise the warm home that you were hoping for may not fully appear, especially on the cold windy days that we occasionally have in a Welsh winter.

NOTE. I have just been to a large supplier of insulation and membranes to pick up some stock for a customer. They had the membrane that I needed (a breather one for underfloor insulation), but NO tapes or sealants to go with it!! Apparently there is no demand for the tapes etc so they don't keep them in stock. See how the conventional builder works?!

On the back of that I have now got some ORCON F sealant and TESCON No.1 tape in from ProClima.

Wednesday, 2 November 2011

Multi-foil insulation - does it work?

The construction industry is seen as being very conservative on the whole. Trying to get new materials to be used is seen as a difficult and costly exercise. We have stuck with brick and block for many years on individual builds and extensions, but there are a few exceptions. Multi-foil insulation being one of them.

Loft conversions have fuelled the demand for multi-foil with its attractive looking headlines of 200mm worth of insulation in 20mm. Headroom issues can rapidly disappear when these figures are being bandied around. Also it is seen as a clean and quick way of insulating. No fibres to worry about and a few staples later the roof is done! Not only that, some come with BBA certificates to prove that they work.

I like to think that I am not too sad when it comes to looking at product data, but I did feel compelled to have a closer look at the multi-foils, because if they did work, it would be a great relief (given all the roofs that they are 'insulating') and also something to promote. This is what I found:

The BBA certificate for a leading brand was tested under the following conditions:

Roof make-up was:
Batten (non vented void)
Batten (non vented void)
50mm phenolic board insulation

With these factors and additional insulation in place it worked. Hooray!


1. You need another insulation in place - they do not pass the test on their own
2. You need to tape all the foils together to help form the airtight (non vented) layer
3. You need to create a permanent airtight seal against the wall / structure to ensure that the non-vented layer stays unvented

Only three BUTs, however they are pretty major ones. I don't know of any jobbing builder who would really know about the need for the additional insulation or the reliance on airtightness. So if the insulation is not fitted correctly, diligently and ultimately checked for airtightness then what? Well I think that we can safely say that virtually all homes insulated with multi-foils are not performing as specified and consequently we have created another potentially great product (except that it doesn't deal with decrement issues) that has been mis-used, potentially mis-sold and has led us to higher energy use than would have normally been expected.

So if you are thinking about using the multi-foils for a loft conversion you will have to insist on:

All foils being taped together using a very long lasting tape
50mm of additional insulation being added
All joints with the wall, roof etc being sealed with a very long lasting airtight sealer / tape

Good luck!