This study has demonstrated the importance of insulated walls and in homes older 1920′s with solid walls, this can be a challenge. Many of the houses in Llanrhaeadr are built of solid stone, and are in a conservation area, so options are few as to how to insulate external walls.
Ideally, insulating solid walls externally works the best as the stone then becomes part of the thermal mass of the building, kind of acting like a storage heater. This is often however very impractical, expensive and changes the external appearance of the building. So lining walls on the interior then becomes the only option. We has specific challenges at Pen Y Lan, as the house is a mixture of very old, 500 years, timber frame and solid stone with a concrete block extension built in the 1990′s. We wanted to sue the best eco , natural materials we could to insulate as much of the hosue as we could, however this turned out to be complicated.
We are very grateful to Ty Mawr who produced this in depth report after a thorough survey of the house. We then worked with Conservation Building Services, who did the actual work. There was much debate between the building contractors and the coop members as to how to get the best value from the investment.
With a total budget of £21,000 or thereabouts it seemed like a lot of money for insulation, however the complexity of tackling such an old building with some deep and complicated problems made it clear that we would only be able to do some of what we wanted. An on going problem is that over the years much of the pointing on the house had been repaired with cement, a very common occurrence, however I think it is only more recently that it has become apparent that this is in fact mistake. Lime mortars and putty as would have originally been used are porous and breathable letting moisture and air in and out… whereas the cement doesn’t do this and moisture becomes trapped in the wall, causing long term problems like mould and damp. This is not easy to fix, takes a lot of time, and isn’t the most pressing job, so our fix for this was to train one of the coop members, Ritchie, in how to use lime putty etc and to provide him with some materials. this should enable the coop to fix such issues, themselves over time. Ritchie took a 2 day course with Ty Mawr, reporting back that it was an excellent learning experience.
In the end the focus of the work was on the extension part of the house, where there was an insulated and poorly ventilated bathroom, with a very poorly insulated bedroom above. We used standard materials in the roof space and the walls upstairs.. basically cellotex and went for the high eco-finish downstairs where there wold be the most benefit. The bathroom walls were lined with calsitherm board, which is a material made from lime that has all it porous qualities, with an insulating render on top of hemp and lime. other gaps were insulated with thermafleece, sheep’s wool insulation.
The use of lime renders means it has taken a while to finish, as they need to dry-out very slowly but the final result will be a very high quality finish and greatly increased comfort levels.
Please get in touch with me directly via this website, if you would like to arrange a visit to see the final results or ask questions about chices and recommendations in this proejct. We are keen to share the learning.
There is a photo album (PDF) HERE for down load of the insulation works at Pen Y Lan.