Has anyone seen a copy of PAS2035? Looks like a great solution to a lot of woes, if only we could find the staff that could be relied upon to do a job...

PAS2035 is understandably big on boundaries edges junctions of retrofit insulation. And this is focus of my query.

Have retro fit of early 90s terrace apparently built by apprentices. External walls will have IWI applied. Question is whether to extend this down party walls. I don't really want to do that as the intent for party walls is to apply acoustic solutions so I don't hear quite so much of the neighbors.

Block and brick. Party cavity 10cm will be rockwool filled. External cavity 10cm will be EPS bead filled. Blob and dob plasterboard will be stripped from all blockwork walls before application of IWI to external and acoustic to party walls.

Question is do I need to extend insulation some distance down party wall to prevent thermal bypass of IWI on external wall.

M

Acoustic will be some laminate of acoustic plasterboard, these are usually 15mm, with layers of closed cell foam and mass loaded vinyl. With the possible exception of the foam non of these layers have a presentable thermal resistance. I've queried to the soundproofing store the lambda values for the foam and MLV they use (as their spec sheet quotes only for the plasterboard layer), but realize that nothing dense is going to be anything but thermally conductive.

External wall IWI will be aerogel.

Simply wonder whether the issue might best be addressed by extending a (thinner) aerogel layer down the party wall under the acoustic assembly. Its immobilized air content would contribute to acoustic objectives and obviously also to thermals.

Probably need some PSI (?) figure calculations but where how to get those done; the software isn't exactly open acces

Posted By: cc64Has anyone seen a copy of PAS2035

Check to see if it's available through your local library. I find it very annoying that standards like this aren't freely available.

Simply wonder whether the issue might best be addressed by extending a (thinner) aerogel layer down the party wall under the acoustic assembly. Its immobilized air content would contribute to acoustic objectives and obviously also to thermals.

I can't see that that would cause any problems and it's simple. So go for it if you can accept the extra cost etc.

Probably need some PSI (?) figure calculations but where how to get those done; the software isn't exactly open acces

You mean psi values (Ψ) - thermal bridging calculations? If so, the go-to software is Therm and it's freely available.

Hi @cc64

I have a pdf copy of

"PAS 2030:2014 Edition 1
Improving the energy efficiency of existing buildings
Specification for installation process, process management and service provision "


I suspect 2035 may be similar and not that much practical help.

However if that would be of any use PM me and I can email it to you


Have you a quote on the aerogel ?

I would like to try it in some places but have never found a source that I could justify the cost

good luck with the project
cheers Patrick