I'm looking at buying a property, the EPC shows three stars for walls - it states: cavity wall, filled cavity.
I would have thought it was a simple matter of solid wall, cavity wall or cavity wall insulation giving none, three or five stars respectively.
Anyone able to enlighten me please?
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Not sure how the ratings work but are you aware of potential issues around cavity wall insulation? if not installed properly or if used in unsuitable properties or locations it can allegedly cause damp and reduce the insulative effect.
The old building columnist in the Daily Telegraph used to get quite agitated about it.
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My late FIL was against it, because he reckoned it blocked water running down the cavity. He didn't have an answer for why water would be running down a cavity.
My current, '60s, Wimpy built had blown fibre cavity insulation installed twenty-odd years ago with no apparent disadvantages. The place I'm looking at was built in a similar time.
New build have it installed as standard.
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Cavity insulation can block airbricks and cause rot. Seeing my walls being done, a Rentokil operative working next door said that his outfit got a lot of work as a result. I made sure mine were not blocked
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I have just been watching some clips regarding the fitting of cavity trays above windows during construction with weep vents to channel the water outside. Building regs requirement.
If there is the possibility of water running down walls why restrict to just above windows?
And if cavities are filled with any form of insulation then surely it has the propensity to soak up any moisture.
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I think the cavity trays and weep vents are to ensure water that finds it way behind the outer skin doesn't use window frames etc as a way of bridging into the inner skin and causing damp in the interior.
The inside of external skins shouldn't run with copious water on the inside face but bricks and mortar breathe and are not impermeable so moisture can get in and severe driving rain can make this worse.
Houses designed and built with insulation will have all the necessary moisture barriers and other features bulit in. These. Should be totally fine. Back to the OP these may be the ones that get top EPC ratings?
Retrofitting is entirely different. The idea that a couple of blokes with a blowing machine can uniformly fill a cavity with fluffy stuff has always seemed a bit optimistic to me. Clearly it's not always problematic but it has to be a bit hit and miss.
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EPC ratings are out of step with government legislation.
They give a very high rating to homes with gas fired condensing boilers such that any lack of energy saving measured can be cancelled out.
However, take a refurbished and converted office building which is now a block of flats, with high levels of internally installed insulation, all lights are LED and timer controlled electric heating. The best EPC rating I have seen is D. A poor result for what should be a very efficient home. Of course by 2025 no new homes are permitted to have gas fired appliances......
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>>Of course by 2025 no new homes are permitted to have gas fired appliances......
Is that right? I recall it being 2030 and Labour wanting 2025.
We're doing a self build this year. My inclination is to go straight for an air-source, even though gas CH should be cheaper to run at this point, as well as being about £5k cheaper to install.
It will be a comparatively well insulated house, and well sealed with a heat recovery ventilation system, so I hope it won't need much heating anyway. Comments welcome, we have a million things to specify.
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Nothing useful except a link to a set of sub-forums which you may find useful for new technologies, if you haven't already.
www.navitron.org.uk/forum/
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Property buying decoding EPC - martin aston
