My house was built in 2003 and has a 300mm outside cavity wall, constructed of brick outer, thermalite block inner with plasterboard attached via metal framework. Looking through various holes into the cavity, it appears that the inner solid poly foam is attached to the outsdie of the inner course of blocks, leaving a 10-15mm cavity. Could this be filled with injected foam?
If so, then this would improve the U-value of the walls and therefore reduce my heating bill.
Is this a 'do-able' job or would I encounter problems?
The house is detached, 2 1/2 storeys in height, buit by Persimmon Homes.
|Cavity Wall Insulation - Possible or Not???||Peter Harris - 2008-09-12 15:27:00|
|Re: Cavity Wall Insulation - Possible or Not???||muymalestado - 2008-09-12 19:35:52|
My query exactly - does CWI apply only to double-brick construction? What is the efficacy for block exterior wall with insulated timber frame interior wall?
It worries me that closing the air gap will prevent evaporation of moisture.
|Re: Cavity Wall Insulation - Possible or Not???||Peter Harris - 2008-09-13 19:20:04|
Yes, this is my concern too! Are there any members out there who are 'subject matter' experts in CWI that can advise us on this?
If CWI is added, is it likely that any trickle vents or breathers above door and window frames would become blocked therefore increase problems with moisture build up?
Your advice would be gratly appreciated in this matter!
|Update Re: Cavity Wall Insulation - Possible or Not???||Website Administrator - 2008-09-30 12:06:54|
Just to let you know I've emailed the National Insulation Association to ask them this question, as no-one hereabouts seems to have the appropriate knowledge to answer it.
If I get a response, I'll post it here (or they may decide to post themselves).
Update: See the CWI FAQ on the NIA's website for some useful info.
|Re: Update Re: Cavity Wall Insulation - Possible or Not???||Peter Harris - 2008-10-02 07:39:07|
Thanks for your help and advice with this. It will be inetersting to hear as there are definately two scholls of thought as to whether this is possible or not.
Lets hope we get an answer.
|Re: Cavity Wall Insulation - Possible or Not???||Peter Harris - 2008-10-27 11:56:38|
I have now recieved a reply from the Head of Policy and Communications, of the National Insulation Association regarding this matter.
He states "As a matter of best practice we would not recommend insulating any cavity of less than 50mm or where it has been part insulated."
The cavity between the inside of the outer leaf of brickwork and the rigid insulation board in the wall cavity is about 25-30mm, so I will take this as a NO then!
So it appears that in dwellings where the cavity is of sufficient width, retro-filling with CWI could be an option. However, in most cases with new builds, CWI should not be a recommendation.
I think this has probably answered my original question now.
|Re: Cavity Wall Insulation - Possible or Not???||Website Administrator - 2008-10-27 12:30:28|
Useful to know, glad they got back to you.
A neighbour of mine has recently had his entire house clad (externally) with a 2.5" thick layer of insulation board which was then rendered and painted to match the original exterior finish.
Doesn't seem to be an option for me (with a brickwork exterior), which is a shame because I - like you - have a part-insulated cavity wall.