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I have one bog standard detached 1970's house: brick-60mm cavity-breeze block-plaster construction. We have had cavity wall insulation injected in the past year. This is supposed to drop the overall U-value down to around 0.6, apparantly. It has definitely improved the heat retention. Are there any options for improving on this without knocking down and starting again?
Thanks,
Mark
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Only 2 options now. A layer of rigid insulation outside or inside.
Outside means new exterior cladding and a few architectural problems around windows and doors etc.
Interior layer of rigid insulation, smaller rooms, finishing of interior surface keeping in mind the flamability of rigid insulation.
Always a good idea to find out where you are loosing the most heat, its possible that your walls are not the main culprit. Check the ceiling, windows and air exchange rate.
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I agree with Rod about checking ceiling, windows and air leakage. The insulation you have installed should be making a significant difference and any further wall improvements will not be as effective. There is a law of diminishing returns with insulation and weighing up any 'payback'is very difficult-but-doubling the insulation does not double the savings!
Mike
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Yes they have got it. Don't bother with any more wall insulation go for ait tightness and draught proofing. Up to 300 mm of loft insulation would be the next most cost effective thing to do.
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Thanks guys.
I agree with your views that attention should be paid to loft insulation, draft proofing and windows first. I actually have this in hand - each presenting its own little problems. (We've lived here for a year or so now and its quite amazing how poorly insulated/draft excluded it actually is). I have also been looking into electrical energy efficiency - use of lighting, applicances etc. All these measures yield higher returns.
I have a feeling that the solid concrete floor would be my next greatest source of heat loss. Given construction methods in the 70's - unlikely to have been insulated.
I guess I am really looking far ahead. How far can one realistically go? I am intrigued by the practical limits of converting bog standard housing to the newbuild super insulated ones people often raise questions about in this forum.
Back to extending wall insulation ...in pratical terms is it a case of bonding Celotex or the like to the internal wall and covering with new plasterboard/plaster?
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Yes you could do that or buy an already laminated product. But you would then loose a big chunk of the thermal mass of your house ( and thence your comfort and ability to store solar gain). Further you would gain problems with thermal bridges at windows and where the internal walls meet the outer ones. How about effort between the floor and the ceiling a plethera of nasties exist there especially round the perimiter.
The floor won't be insulated and I have often wondered about the milage to be gained by digging down to the foundations all round the outside and placing expanded polystyrene against the below ground blockwork turning the whole lot of floor hardcore etc into a giant resovoir of thermal stability. There are a few more problems that would need to be solved but it would beat messing with the floors
Another interesting problem is that wood windows decay very fast once cavities are filled. This is most likely because air can no longer whistle arround in the cavity and keep the wood nicely dried out?
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