Thermal breaks for RSJ's

[RichD1]

Having a single storey extension built which has two bifolds along the wall facing the garden. The small one can be covered with a standard thermal break catnic but the larger doors have box sectin steel columns and an RSJ over the top. The structure sits on the inner cavity and a plate is welded to the underside of the RSJ to support the outer brick wall.

What is the best approach to minimise potential condensation through to the head of the aluminium track of the bifolds?

 

[Swwils]

Insulated reveals.

 

[RichD1]

Yes, I’ve already planned for insulated reveals, but it’s the head of the aluminium track which is up against the steel.

Whilst writing this I’ve just realised that the window fitter will use plastic packers between the track and steel so that will provide the thermal break.

 

[Swwils]

Why is the steel not broken?

 

[RichD1]

Because the RSJ has a plate welded under it to take the outer brickwork as per the Structural Engineers requirements.

 

[Swwils]

Sounds like someone has been given a bonkers tight deflection tolerance and as a result a bonkers detail has been imagined up.

Probably the result of a plan drawer rather than architect. Really outer steel should have been totally inboard of the glazing and the glazing support bracketed out... Not an uncommon problem. Too late now?

A salutary lesson in employing a qualified industry expert with experience.

 

[freddiemercurystwin]

It's a pretty standard set up, a beam with a plate welded to the underneath, you would normally pack the beam with insulation and hope for the best, you can fix a thin layer of PIR on the underside of the beam behind the PB internally to help. Is your bifold thermally broken?

There are solutions floating around on google using 10mm aerogel on the underside of the beam but I've no experience of using it, I'm also unsure as to how you would finish the underneath. Might be worth getting in touch with them. https://enviroform-insulation-com.s...016/03/Thermo-Pro-Steel-Lintel-Insulation.pdf

 

[freddiemercurystwin]

Probably the result of a plan drawer rather than architect. Really outer steel should have been totally inboard of the glazing and the glazing support bracketed out... Not an uncommon problem.

Prey tell how would the external skin be supported?

 

[Swwils]

Cantilevered brackets, another lintel. Many ways.

Even catnic do a 4.8m 32 SWL.

 

[freddiemercurystwin]

You don't know the opening, concrete lintel for the outer brick skin? Nice.

 

[^woody^]

Poor design. Designing a suitable beam is not just about the load it will carry.

You'll need to see if there is enough room to add a layer of insulation of sufficient thickness to the opening head, and maybe the internal face.

 

[freddiemercurystwin]

Sky hooks?

 

[RichD1]

Sounds like someone has been given a bonkers tight deflection tolerance and as a result a bonkers detail has been imagined up.

Probably the result of a plan drawer rather than architect. Really outer steel should have been totally inboard of the glazing and the glazing support bracketed out... Not an uncommon problem. Too late now?

A salutary lesson in employing a qualified industry expert with experience.

It wasn’t the Designer/Architect but the Structural Engineer!

 

[RichD1]

It's a pretty standard set up, a beam with a plate welded to the underneath, you would normally pack the beam with insulation and hope for the best, you can fix a thin layer of PIR on the underside of the beam behind the PB internally to help. Is your bifold thermally broken?

There are solutions floating around on google using 10mm aerogel on the underside of the beam but I've no experience of using it, I'm also unsure as to how you would finish the underneath. Might be worth getting in touch with them. https://enviroform-insulation-com.s...016/03/Thermo-Pro-Steel-Lintel-Insulation.pdf

Yes, the bifold frame has a thermal break

 

[noseall]

Jeepers, steel beams with plate welded beneath is standard stuff. Has Swwils not seen one? Woody (he who thinks raw steel belongs in scrapyards) will be chuffed when he sees our latest painted Hammerite black fella, we're installing tomorrow. We'll try and introduce insulation where the jambs will allow, using foam fix etc.

200kg.jpg

• noseall
• 14 Aug 2023