Thermal bridging at window detail

[Nic]

Hi 

timber frame ( triple glazed Norrsken windows ) attached on outside stud work.

 

what sort of thermal bridging detail do I need to have / consider ?  Is what’s shown enough? 
 

 

[Redbeard]

A quick check is can you draw a line straight to outside without hitting any insulation. As far as I can see, yes you can, straight through the syuds to outside, so it needs mitigating. I don't know the scale on the plan of the window, but it seems like at very least you could insulate the reveal. Could use PIR and 9.5mm plasterboard or splash out and use Aerogel and Magnesium Oxide  board. It is expensive but for a relatively small area it might be worth the £££ expense /m2.

[Iceverge]

What type of windows are they?

 

Inwards opening or ouward openers?

[Nic]

Top hinges outwards 

thanks 

[Nic]

53 minutes ago, Iceverge said:

What type of windows are they?

 

Inwards opening or ouward openers?

 

1 hour ago, Redbeard said:

A quick check is can you draw a line straight to outside without hitting any insulation. As far as I can see, yes you can, straight through the syuds to outside, so it needs mitigating. I don't know the scale on the plan of the window, but it seems like at very least you could insulate the reveal. Could use PIR and 9.5mm plasterboard or splash out and use Aerogel and Magnesium Oxide  board. It is expensive but for a relatively small area it might be worth the £££ expense /m2.

Any chance you can draw and show what you mean please 🤗

[ETC]

https://www.gov.scot/binaries/content/documents/govscot/publications/advice-and-guidance/2020/03/accredited-construction-details-scotland-2015---timber-frame-construction-details/documents/accredited-construction-details-scotland-2010---timber-frame-junction-details/accredited-construction-details-scotland-2010---timber-frame-junction-details/govscot%3Adocument/Accredited%2BConstruction%2BDetails%2B%28Scotland%29%2B2010%2B-%2Btimber%2Bframe%2Bjunction%2Bdetails.pdf

[Iceverge]

1 hour ago, Nic said:

Top hinges outwards 

thanks 

 

 

PIR + plasterboard or insulated plasterboard to the head jambs and sill. 

 

 

[Redbeard]

14 hours ago, Nic said:

Any chance you can draw and show what you mean please 🤗

 

At this stage sorry, no, as it's a tedious drawn-out (sorry!) process with my level of un-technology. @Iceverge has drawn my answer for me, in any case (Thank you!). For future reference in such situations, take the line which terminates at '3,373'. Angle it R or L and for a good while you still have the 3G window 'interrupting' the potential heat-loss. Then move it a little further till the line intersects one of the pairs of studs on either side, and the only thing between inside and outside (apart from the external sheathing boards and membranes) is those studs. That then shows you where action is needed. Similar diagonal lines on a ground floor/foundation section often highlight similar lack of 'cloaking' to potential thermal bridges.

 

Edit: Interestingly the 0.83W/m2K which @Iceverge's detail shows is probably v close to that of a high-spec 3G window, which is good compared to the 'base case' shown, but not as good as better 'wall' insulation. What are the actual dimensions and could you perhaps get say 40 or 50mm PIR on the reveals (or use v expensive Aerogel as I mentioned)?

Edited Monday at 08:22 by Redbeard

[Iceverge]

3 hours ago, Redbeard said:

which is good compared to the 'base case' shown, but not as good as better 'wall' insulation.

 

The best windows with the best install are typically still worse than the worst new build wall by about a factor of 4. 

 

3 hours ago, Redbeard said:

What are the actual dimensions and could you perhaps get say 40 or 50mm PIR on the reveals (or use v expensive Aerogel as I mentioned)?

 

Depends on your window frames. 

 

I would leave say at least 10mm of the frame exposed. Beyond that fit as much insulation as you can.