Hi chris, if you drop me a line I can send you some stuff on this

whilst its good you know Chris,

I would also like to know the answers to your Questions.

thanks Arnold

Please also see thread running below on EPCs and piece-meal internal thermal insulation of walls.

Mike,

I am convinced that a number of builds were done well into the 80s with no fill - perhaps v lightweight insulating blocks? I remember some builders expressing surprise that we were fully fi;lling cavities on our first new-build in '84/'85.

So, to summarise:-

pre 1930, solid walls, so we should be be identifying people who are doing re-plastering and re-rendering work who ought to be informed that the walls should be upgraded to current building regs at least at the same time.

1930-1978, likely to have been built with clear cavities so advise to have them them filled (if not already done so) under a grant scheme or through the energy supplier if not on any qualifying benefits.

1978 to 1991, some insulation in the cavity but perhaps not much. Is it likely that these homes have partially filled cavities and could still be fully filled in the normal way (injection of insulation)?

post 1991, reasonably well insulated walls (by UK standards anyway...) perhaps not worth upgrading further with other measures being more cost effective?

Obviously, check the loft for at least 270mm insulation while you're at it.

mike, i noticed you said that cavity wall insulation was made a requirement in 1978. but i have found a book (solar energy applications in houses) whilst researching and it states that in the building regulations (1965) a u vlaue of 1.7 was specified for walls!! does that mean that houses constructed from 1965 onwards from 1965 would have some form of cavity insulation??

Posted By: lloyd-morganmike, i noticed you said that cavity wall insulation was made a requirement in 1978. but i have found a book (solar energy applications in houses) whilst researching and it states that in the building regulations (1965) a u vlaue of 1.7 was specified for walls!! does that mean that houses constructed from 1965 onwards from 1965 would have some form of cavity insulation??

Hi Lloyd, It's easy to hit 1.7W/m2K in masonry without insulation in the cavity. Example here:

Dantenz, I too have heard of contractors refusing to retro-fill when there is already partial fill. I too would love to know why. I cannot think why it would cause any more problem than filling an unfilled cavity.

Somebody enlighten us please! Anyone from CIGA?

Posted By: Nick ParsonsDantenz, I too have heard of contractors refusing to retro-fill when there is already partial fill. I too would love to know why. I cannot think why it would cause any more problem than filling an unfilled cavity.

Somebody enlighten us please! Anyone from CIGA?

There's 2 reasons I can think of.

1) Technical. Some plastics don't like each other. Polystyrene is one of them - but I can't remember what it doesn't like. If the original insulation boards come into contact with some solvents or blowing agents, they might be affected. Alternatively it could be due to condensation type problems. I.e. rather than having to carry out an instersitital condensation assessment - which they will need details of the wall construction for, then they just pass. Presumably they can't get the CIGA warranty to cover an "unknown" use of the product.

2) Financial. The CERT scheme on which the grants are based assume you have no insulation to start with. The payments are based on the number of bedrooms of your house and the assumed carbon emissions. That's why it costs the same to do a 2 bed flat as a 4 bed detached house - the carbon savings from the detached house will be much higher. The actual cost of doing a house is about £600-700, a flat about £300, but you get a much bigger grant on the bigger house so you usually pay about £250-£300 regardless of what you live in. If you have insulation already then you won't achieve the expected savings. For the same reason you get a bigger grant for lofts if you have no loft insulation, and less if you have some, or none if you have more than 100mm already. Although not very eco friendly - if you have say 50mm of tatty old insualtion, get it out and hoover up before you ring for a quote!. But do it in summer - or your house will be freezing until the installers come out! Recycle the insulation in your shed or freecycle it. Note - the itchy stuff needs protective gear!

To be honest, you won't make much savings if you have insulation already. The first 50mm of insulation is the most important. You'll drop the U from 1.5 to 0.5 if you had non to start with. If there's some in already it will probably mean the wall has a U around 0.35. A better - but much more expensive strategy - might be to externally insulate and make it airtight at the same time. Go from U approaching 0.15 and make it imprevious to wind (which will be the main cause of remaining heat loss).