Sliding door/ windows fitting below steel

[trialuser]

I'm sure many of you have done this so I'm hoping you can help please.

We have several 3M to 4M openings spanned by rsj's where we will be fitting either windows or in one case a lift and slide door.

I have to give the final sizes to the window company butI'm not sure how to detail the underside of the steels. Presumably there should be some insulation between the steel and the frame of the aluclad windows / door? I cant find anything in the accredited details (were in Scotland). How have others detailed this please. Would say 50mm of PIR be acceptable, with the windows secured at the top through this into the bottom flange of the steel?

Another question. The build is timber frame with cedar cladding to the ground floor and wriggly tin to the first floor. Because of the lead time for the windows, I would like to clad the first floor and run the reveal corner flashings into the window openings, then fit the windows inside the clad opening, probably with a compriband and foam or similar seal. Is that acceptable.

Widow company (Norsken) say ask the fitter, which may well be me. I'm awaiting quotes for fitting but need to give final sizes to supplier asap. I have more questions on firestopping, but one thing at a time. Thanks

[Mr Punter]

The 50mm PIR should be OK.  There more insulation around the steel the better.  ROckwool can sometimes work OK if you need to fit into gaps.

 

It is quite common to clad / flash the reveals then Compriband outside, foam inside and seal the inside polythene vcl to the frame before plasterboarding.

[trialuser]

Great thanks

[craig]

On 05/10/2020 at 10:55, trialuser said:

Widow company (Norsken) say ask the fitter,

That annoys me, actually really p****s me off. It is their responsibility to check the details with you.

 

Did you give them the defection rate of the steel? Did they give you recommended tolerance? Did they advise what material to use for insulation during installation between head and steel?

 

If sitting directly under the steel, using a solid insulation for example, steel deflects, pushing down on slider.

 

Then only one thing happens, compression on head and operational issues with the slider.

[Pete]

1 hour ago, craig said:

That annoys me, actually really p****s me off. It is their responsibility to check the details with you.

 

Did you give them the defection rate of the steel? Did they give you recommended tolerance? Did they advise what material to use for insulation during installation between head and steel?

 

If sitting directly under the steel, using a solid insulation for example, steel deflects, pushing down on slider.

 

Then only one thing happens, compression on head and operational issues with the slider.

I agree totally. Internirm said we needed at least 20mm gap filled with expanding foam tape so when/if the frame settles then there will be no pressure on the window/sliding. As it turned out we needed the 20mm or we would have been in a right pickle

[trialuser]

10 hours ago, craig said:

That annoys me, actually really p****s me off. It is their responsibility to check the details with you.

 

Did you give them the defection rate of the steel? Did they give you recommended tolerance? Did they advise what material to use for insulation during installation between head and steel?

 

If sitting directly under the steel, using a solid insulation for example, steel deflects, pushing down on slider.

 

Then only one thing happens, compression on head and operational issues with the slider.

Hi Craig, thanks for the reply.

I've summarised a bit. Norrsken are unable to supply and fit because of distance and the chance that remedial work would prove expensive in terms of time and travel, fair enough.

They have given me the name of a fitter they recommend and I'm waiting for a price, but he is still 4 hrs away. I did mention the 7mm max deflection, and they have told me their usual fitting allowance (7.5mm all round), I am supplying the structural measurements and have asked for 10mm all round . I did ask about insulating under the steel and was told ask the fitter, fair enough the salesman isn't a fitter, I'd rather that than a made up answer. I would allow the extra 7mm between any insulation and the frame?

I'd be really grateful if you could let me know how best to detail/ insulate the underside of the steel / window head junction.

This problem arose because we were living in Oxon and saw and liked Norrsken at the Swindon selfbuild place, but have now moved to Dumfries and Galloway.

 

Cheers

Edited October 7, 2020 by trialuser

[trialuser]

8 hours ago, Pete said:

I agree totally. Internirm said we needed at least 20mm gap filled with expanding foam tape so when/if the frame settles then there will be no pressure on the window/sliding. As it turned out we needed the 20mm or we would have been in a right pickle

Thanks for the reply Pete. Can I ask, is your frame skinned outside with brick / blockwork? Mine is clad with wood and tin and I intend to sit the windows within the thickness of the frame, so no differential movement.

[Pete]

2 hours ago, trialuser said:

Thanks for the reply Pete. Can I ask, is your frame skinned outside with brick / blockwork? Mine is clad with wood and tin and I intend to sit the windows within the thickness of the frame, so no differential movement.

My windows sit within the timber frame but I have some settlement which reduced the gap between the frame and the window. The gap between the sliding section of our doors and the frame is about 10mm (ish) so not much room for deflection. The exterior of our frame is battened with render board and thin coat Render.

[trialuser]

Blimey...thanks.

I'm going to have to think about this hard.

Presumably, even if I leave a decent gap and have compressable filler, any fixings fron the head of the frame into the steel will transfer any settlement or deflection load through to the frame.

[craig]

If your steel deflects 7mm max deflection, then do not use a rigid PU foam.

 

10mm would do but tight, I’d go 20, use a compriband on the head which is compressable. So when it does deflect that deflection is taken by the compriband. You should pick one up with a 10mm to 20mm expansion rating. 
 

That basically means 10mm in the roll, expanding to 20mm, so can compress back down by 10mm.

[trialuser]

Thanks for that, can I fix into the steel, or will that transfer any deflection load?

[Pete]

9 hours ago, trialuser said:

Thanks for that, can I fix into the steel, or will that transfer any deflection load?

You must leave room above so if you need to tighten screws you can do. I had to this on my build. The screws through the head of the window/sliders are there to prevent lateral movement afaik so you can always tighten them to counteract the deflection

[trialuser]

Thanks all.