Green Building Forum - U-value calculations / Thermal Bridging Mon, 25 May 2026 12:13:00 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260040#Comment_260040 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260040#Comment_260040 Sat, 29 Jul 2017 18:45:07 +0100 rytech
I am new here so please accept may apologies if I have posted this in the wrong place.

I wondered if anyone may have advice on how best to calculate the timber bridging factor where the
Engineer specifies the use of double studs? I make it as 2 x 38mm studs =76mm
600 cts - 76/600 = 0.127 or 12.7%
400 cts - 76/400 = 0.19 or 19%

The default factors within the U-Value conventions are 12.5% and 15% so the above seems a little low? Any advice would be gratefully received.

Many thanks,
Ryan]]> U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260043#Comment_260043 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260043#Comment_260043 Sat, 29 Jul 2017 19:37:19 +0100 goodevans U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260046#Comment_260046 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260046#Comment_260046 Sat, 29 Jul 2017 20:52:12 +0100 Nick Parsons U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260047#Comment_260047 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260047#Comment_260047 Sat, 29 Jul 2017 20:57:09 +0100 djh U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260049#Comment_260049 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260049#Comment_260049 Sat, 29 Jul 2017 21:32:21 +0100 rytech
The U-Value conventions are the 2006 edition by Brian Anderson (BR 443)

I guess the default values will have the head and sole plates accounted for too.]]> U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260050#Comment_260050 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260050#Comment_260050 Sat, 29 Jul 2017 22:50:00 +0100 goodevans U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260051#Comment_260051 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260051#Comment_260051 Sun, 30 Jul 2017 00:50:39 +0100 djh
BR443 is not a particularly good basis for thermal calculations, IMHO.]]> U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260055#Comment_260055 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260055#Comment_260055 Sun, 30 Jul 2017 08:56:55 +0100 Peter_in_Hungary Posted By: rytechEngineer specifies the use of double studs? I make it as 2 x 38mm studs =76mm

Posted By: rytechThe panels were detailed with studs doubled up (side by side) at 600mm cts.

A bit off topic but could someone explain the advantage of double studs rather than 1 x 76mm stud. Could it be the availability (or cost) of 38mm timbers over 76mm timbers and are the doubled studs nailed together.]]> U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260069#Comment_260069 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260069#Comment_260069 Sun, 30 Jul 2017 14:13:58 +0100 djh Posted By: Peter_in_HungaryA bit off topic but could someone explain the advantage of double studs rather than 1 x 76mm stud. Could it be the availability (or cost) of 38mm timbers over 76mm timbers and are the doubled studs nailed together.
Partly availability, yes, since double studs are normally fairly rare. A double stud is nailed or screwed together, but even so it is not as stiff as a single piece of wood so orientation matters. It is slightly less likely to have a flaw since it is kind of poor-man's laminated. In some circumstances it can cause an airtightness trap for the unwary since air can pass between the two studs, but with good design this isn't an issue.]]> U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260070#Comment_260070 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260070#Comment_260070 Sun, 30 Jul 2017 14:54:10 +0100 CWatters U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260074#Comment_260074 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260074#Comment_260074 Sun, 30 Jul 2017 15:22:28 +0100 rytech U-value calculations / Thermal Bridging https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260251#Comment_260251 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204&Focus=260251#Comment_260251 Fri, 04 Aug 2017 09:01:09 +0100 neilu One item you'll need to know is the type of breather membrane that will be installed. Low emissivity membranes give better U-values.]]>