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Tuesday, 22 October 2013

Which Cavity Wall Insulation?

Cavity Wall insulation for typical existing homes comes in a number of forms:
  1. Beads
  2. Beads with adhesive
  3. Mineral fibre
  4. Foam
I recently looked at a couple of the more popular options in the UK and found to my surprise that there is very little technical information available on them. No technical details on installers or manufacturers websites and when I called one of the biggest installers I was told that there was no-one there who could answer my questions (despite being quite basic) and that I would either have to speak to a surveyor or have an on-site visit. So they are keeping some basic data hidden away. Not sure why as there is nothing really to hide. Also all the sites give out basic info on the process of installing, benefits etc, but there is no mention of any particular issues to bear in mind.

All of cavity wall products are injected and all will do the required insulation job on paper, however there are some major differences between them. I shall also highlight some concerns / factors that you might wish to bear in mind when choosing.

One major factor before you even start is to ascertain whether your property is actually suitable for cavity wall insulation. Many cavity walled properties that were built before WW2 did not have wide cavities and many are also full of builders waste. So make sure that your wall is capable of safely having insulation installed.

Second major factor is: How exposed is the site? Is it prone to wind driven rain? The way that cavities are designed to work is that the outer 'skin' is allowed to get wet and then the cavity keeps the inner wall dry. This means that the walls are actually quite poor at insulating, but that they are at least dry. By filling the cavity with a material, this can allow water to pass from the outer skin into the inner one. Not good! So your outer wall needs to be in good condition with intact render / mortar, not affected by leaking gutters or down pipes etc.

Third major factor is: Are you planning on any replacement doors / windows / extension works etc in the future? Some insulations are loose fill and so if you disturb the wall then they will just fall out. Thinking ahead will allow you to make the right choice in the longer term, otherwise you are just making extra work for you or for future occupiers.

Fourth major factor is: Do you have good seals around anything that goes through the wall? Insulation companies are not good at making good a wall before work. So if you have penetrations through the wall for waste pipes, drains, water connections, gas connections, air bricks etc, or even poorly sealed doors and windows the companies often just fail to inject insulation in these areas. Thermographic images taken on insulated properties often show that cavities are not insulated around 'weak points' like doors, kitchens (where there are lots of services), above window lintels etc. This causes cold spots in these areas and can lead to damp and mould forming.

So back to the choices.
  1. Beads - Beads on their own form some of the most insulating choices. The beads that are injected though are loose fill. They can also form a bridge between the two skins. They can rely more on gravity to fill the cavity rather than pressure when installing.
  2. Beads with adhesive - These are generally less insulating, but are pressure injected in order to make the glue work. They are regarded as being water proof and so should keep any water away from the inner leaf (assuming that they is installed correctly). The pressurised installation should mean that it is more likely to fill all of the cavity (and blow out of any weak points!)
  3. Mineral fibre - These are sold quite often as being fire proof. However, fires in cavities are not very likely and so the toxic fumes from beads are not too much of real hazard. Mineral fibre is also a loose fill, although it does bind together better than beads. It can also form a bridge between the skins if the outer skin fails (just like the beads).
  4. Foam - This is not fitted these days as there have been numerous cases where the foam has failed over time and left a right old mess in the cavity. If you did have foam installed years ago then you may wish to revisit the condition of your walls. There are companies who will remove failed foam and re-install a more appropriate insulation. A thermographic image should identify if your walls do have a problem.
Overall then, there is of course a need for cavity wall insulation in many houses, but you need to think about the suitability of the walls, the need for continual maintenance of the outer skin to ensure that it is not compromised and also the choice of the material for the fill. Good luck!

Thursday, 17 October 2013

CADW Heritage Cottage U Value data

CADW purchased this old terrace in Cwmdare in order to preserve it for future generations to see how workers cottages were originally built, but also to see what sympathetic improvements can be made in order to bring it up to more modern standards.

This is a balancing act for the team, but they have already done a lot of work to see how the building actually performs compared with our modern expectations. One of the most important elements in today's world is how insulating the fabric of the building is. Walls form a major component of this. If you are a reader of this blog you will not be surprised to find that the walls were actually 30% better than predicted by our modern spreadsheets predicted.

More information on CADW Heritage Cottage and its refurbishment can be found by clicking here:

Monday, 14 October 2013

Ultra Insulating Windows and Doors

Eco Home Centre has a great relationship with ARU Joinery in Estonia. Now the lovely people at ARU have developed a brand new ultra insulating range of doors and windows for the Passive House / Code for Sustainable Homes Level 5 and 6 market.

The Nordic Range is made from solid wood so there is no chance of the frames de-laminating. (De-lamination has been a cause for concern on insulated windows and doors as there is an inherent weak point in the structure.) These frames are chunky at 92mm thick, but this is required to house the 52mm deep triple glazed units. The frames, though, do not look over heavy (despite being very heavy!)

The U values achieved are very impressive. The glazing itself gives a Ug of 0.47 and a standard window gives an overall Uw of 0.78. Compare this to the Building Regulations standard of around Uw of 2 and we start to see how well these windows and doors perform.

The Nordic series of products is wide ranging and includes:
  • Inward and outward opening doors and windows;
  • Sliding patio doors; and
  • Folding patio doors
All are also available in aluminium cladding for extra weather protection for those hard to service areas.

So if you are looking for some great high performance, high specification windows or doors then have a look at or give us a call.

Friday, 11 October 2013

Green Electricity Price Freeze and Other Good News

Ecotricity Transformer

Just had an email through from Ecotricity (whom we use at home, both on our Dual Fuel, but also for the Feed In Tariff for our PV panels), that states:

1. Price Freeze until 2014. So they will be freezing their prices until the New Year
2. 100% Green Electricity tariff is now their only tariff
3. They will cost less than each of the Big Six standard regional tariffs
4. Green Gas will be guaranteed 'Frack Free'

So, with prices increasing for many people, it might be worth investigating a fully green option that may well be cheaper both for you and the planet.

Another option for those in Wales is that DTA (Wales) have negotiated a deal with the big energy boys to reduce costs by a mutual buying arrangement in partnership with The People's Power CIC. So if you are more worried about cheaper prices rather than a green tariff then check out

As winter approaches it is important that we take control over our use of energy and these are two really great ways forward.

Thursday, 10 October 2013

Osmo Powergel tested

As I am a believer in trying out all the products that we sell (I always want to be sure that the products work as expected to) and this summer I had a chance to try out Osmo Powergel on my parents oak bench.

I was a little nervous as it does appear to be too good to be true. Just put the Power Gel on, leave it and then wash and brush off using a stiff scrubbing brush. I was unsure as to the effectiveness of the Gel and was expecting the brushing off to do most of the work.

So I was very pleased to see that after a few minutes the old colour of the wood started to show through. After half an hour I could clearly see that the oxalic acid (from rhubarb) was working its magic. The brushing off was easy enough and the wood looked great.

The process does get the wood very wet and so you need to do this on a good sunny day so that it can dry out quickly again.

I then used an Auro product to refresh the bench with a new coat of teak oil. However I was surprised a bit as the Auro product has a tint in it (to give it a UV protection value). I was expecting a clear Teak Oil, but the colour that it gave has proved to be a hit with the parents. This also means that the colour and finish should last a bit longer than using a clear oil.

So, all in all, a successful trial that has proved to be as easy and effective as billed on the tin. So thanks to Osmo and Auro for your well designed products for wood.

Monday, 7 October 2013

Home Grown Hemp is back

Hemp insulation is a fine alternative for the more commonly known sheep's wool insulation, but in the past it has had some issues. The main one being that it was manufactured in France. So the UK grown hemp was being transported across Europe to be processed and returned. Now, however this is changing. Black Mountain Insulation (now owned by IPP) have recovered from their fire and is re-starting a new factory up in Yorkshire. The Norfolk grown hemp is therefore facing a much shorter journey for its processing. This will significantly reduce the carbon associated with Life Cycle Analysis even further (it was already good!)

Hemp is a great alternative to conventional insulation for a number of reasons. It has a high thermal mass (this helps to keep a building cool in the summer, as well as warm in the winter), it is breathable (this allows for moisture to be absorbed and released, thus keeping relative humidity more constant), it is a carbon sink (this ties up embodied carbon into the fabric of the building), it is not prone to moth infestations (this was an old worry about the sheep's wool), it maintains it integrity well (this means that it does not slump over time, which is a common concern for insulation like glass and mineral wool).

Eco Home Centre will be able to access Hemp Insulation after it becomes available from the end of the month, so give us a call and we would be happy to provide a quote for you.