Dodgy-diver Posted November 10, 2020 Share Posted November 10, 2020 can anyone please confirm the minimum U value for a timber framed external wall and where the info came from . I keep finding different answers im trying to find out what thickness of Celotex or similar I need thanks so much for any help Link to comment Share on other sites More sharing options...
Temp Posted November 10, 2020 Share Posted November 10, 2020 (edited) Is it a new building or an extension? There are two versions of Part L one for each. https://www.gov.uk/government/publications/conservation-of-fuel-and-power-approved-document-l Edited November 10, 2020 by Temp Link to comment Share on other sites More sharing options...
A_L Posted November 10, 2020 Share Posted November 10, 2020 32 minutes ago, Dodgy-diver said: im trying to find out what thickness of Celotex or similar I need If a new build in England allowing for a 15% timber fraction you need 120mm of PIR (U=0.295), ignoring any other fabric layers. There are variations in Scotland and I think in Wales. Link to comment Share on other sites More sharing options...
ADLIan Posted November 10, 2020 Share Posted November 10, 2020 For a new extension wall you need 0.28 W/m2K. For new build house it depends upon the numbers that come out of the SAP assessment, looking at better than 0.25, ideally better than 0.20. After the revelations at the Grenfell Inquiry this week not sure why anyone would consider Celotex or Kingspan. Link to comment Share on other sites More sharing options...
Thorfun Posted November 10, 2020 Share Posted November 10, 2020 22 minutes ago, ADLIan said: After the revelations at the Grenfell Inquiry this week not sure why anyone would consider Celotex or Kingspan. just briefly read up on this and it doesn't seem that PIR was at fault and I presume your statement comes from the fact that Celotex and Kingspan knew about the issues with the PE and so should be avoided as they obviously have no morales at all.? in that case, other PIR manufacturers are available, right? Link to comment Share on other sites More sharing options...
Dodgy-diver Posted November 10, 2020 Author Share Posted November 10, 2020 1 hour ago, Temp said: Is it a new building or an extension? There are two versions of Part L one for each. https://www.gov.uk/government/publications/conservation-of-fuel-and-power-approved-document-l just a rear extension . many thanks 34 minutes ago, ADLIan said: For a new extension wall you need 0.28 W/m2K. For new build house it depends upon the numbers that come out of the SAP assessment, looking at better than 0.25, ideally better than 0.20. After the revelations at the Grenfell Inquiry this week not sure why anyone would consider Celotex or Kingspan. what would you suggest instead please Link to comment Share on other sites More sharing options...
ADLIan Posted November 10, 2020 Share Posted November 10, 2020 We may drift off topic here. But basically both lied about fire performance, used outdated test data, changed the chemistry of products, openly confused the market.....Does not make for good reading. Celotex also admitted overstating thermal performance just after the Grenfell fire. Yes, other manufacturers are available. Link to comment Share on other sites More sharing options...
Thorfun Posted November 10, 2020 Share Posted November 10, 2020 5 minutes ago, ADLIan said: Yes, other manufacturers are available. but that doesn't mean the other manufacturers are any better of course! it's definitely food for thought as I was planning to use some PIR in our wall make up. Link to comment Share on other sites More sharing options...
ADLIan Posted November 10, 2020 Share Posted November 10, 2020 Could try Recticel or Extratherm, they don’t appear to be caught up in this mess. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted November 10, 2020 Share Posted November 10, 2020 47 minutes ago, Thorfun said: it's definitely food for thought as I was planning to use some PIR in our wall make up. You are not building a block of flats, the fire issue was caused by a number of failings, not just one. 1 Link to comment Share on other sites More sharing options...
A_L Posted November 10, 2020 Share Posted November 10, 2020 @Dodgy-diver, here is a solution using Frametherm32, U=0.26 https://www.buildingmaterials.co.uk/knauf-earthwool-frametherm-roll-32?ps=MjA5PTgxMDgmMzY2PTEwMzYyJjM3MT0xMDU1NCY0MzE9MTU3NTI=&gclid=EAIaIQobChMIg4z05df47AIVDO7tCh35nwObEAQYASABEgIOGfD_BwE&gclsrc=aw.ds#209=8108&366=10362&371=10554&431=15752infinity=ict2~net~gaw~ar~441793144077~kw~~mt~~cmp~Shopping_Smart+Shopping_Insulation_All~ag~Insulation+Only Link to comment Share on other sites More sharing options...
scottishjohn Posted November 11, 2020 Share Posted November 11, 2020 surely latest regs for smoke detectors and linked alarms will take care of any possible problem there -- law in scotland from 2022 Link to comment Share on other sites More sharing options...
Thorfun Posted November 11, 2020 Share Posted November 11, 2020 18 hours ago, A_L said: @Dodgy-diver, here is a solution using Frametherm32, U=0.26 https://www.buildingmaterials.co.uk/knauf-earthwool-frametherm-roll-32?ps=MjA5PTgxMDgmMzY2PTEwMzYyJjM3MT0xMDU1NCY0MzE9MTU3NTI=&gclid=EAIaIQobChMIg4z05df47AIVDO7tCh35nwObEAQYASABEgIOGfD_BwE&gclsrc=aw.ds#209=8108&366=10362&371=10554&431=15752infinity=ict2~net~gaw~ar~441793144077~kw~~mt~~cmp~Shopping_Smart+Shopping_Insulation_All~ag~Insulation+Only @A_L what software is that? I've been using https://www.changeplan.co.uk/u_value_calculator.php which seems to work but the software you're using looks very interesting Link to comment Share on other sites More sharing options...
A_L Posted November 11, 2020 Share Posted November 11, 2020 2 hours ago, Thorfun said: what software is that? It is part of a package (NHER Evaluator) which was state of the art 2000-2010 but is no longer publically available. 1 Link to comment Share on other sites More sharing options...
Gone West Posted November 11, 2020 Share Posted November 11, 2020 I used BuildDeskU which I managed to download on two occasions each for 30 days free. It had a similar looking output but I used it in 2009. http://www.builddesk.co.uk/software/builddesk-u/download-builddesk-u/ 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now