Steel frame garden room with no lintel in order to achieve particular aesthetic

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Hello! I am going to build a steel frame garden room (light guage steel) of size 6m x6m, with slimline sliding doors spanning the whole width of the front wall. There is essentially no steel on the front wall apart from where the side walls (150mm studs) come up to the doorline and past it on the left side for the 750mm overhang. I wanted to achieve that true floor to ceiling look with the sliding doors so opted to have no lintel underneath the roof joists where the sliding doors will sit. I'm now worried that this will lead to a compromise in the structure either from day 1 or some point down the road. I have attached an image of the structure I am looking to build which will hopefully make what I'm saying make sense. Any advice would be greatly appreciated!
 

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That building is going to love water vapour and cold weather. Faraday would be proud though.:mrgreen:
 
general comments
will need planning permission and comply with building regs
no expert but expect a heavy duty rsj and matching legs on the front like a goal post to take the load and prevent racking
 
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That building is going to love water vapour and cold weather. Faraday would be proud though.:mrgreen:

Why do you think that? If we insulate with pir on the outside of the frame and insulation with superglass superwall on the inside, plus have an internal Vapour barrier underneath the Plasterboard surely we would ensure the building is well insulated and avoids condensation? Also don't you think steel is a superior material to timber? Steel is not susceptible to rot and termites like timber is and will not warp over time..
 
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general comments
will need planning permission and comply with building regs
no expert but expect a heavy duty rsj and matching legs on the front like a goal post to take the load and prevent racking

So do you think the way the structure is currently designed would not work? That front plate perpendicular to the roof studs over the doorline is not acting as a lintel here in your opinion?
 
it needs to be significantly rigid enough to support the front edge load and the racking load
in your design, half the roof load or there about will be over the front opening now timber i can work with and be reasonably confident but steel is an art i can only suggest from a position off informed but open knowledge meaning i am still learning
you need someone experienced in this actual situation to give a proper answer i am not fully confident but to be fair i tend to fully overengineer but thats in my mind so maybe correct or not correct and misguided but who can tell (n)
 
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Also don't you think steel is a superior material to timber?
In what sense? In a practical sense (domestic scenario) - no.
If we insulate with pir on the outside of the frame
You will need to do it robustly and do it well. You will have the headache then of making it very difficult to fix your external clad to because of the thickness of PIR and the length of the screws. Plus you are having to fix to steel.:(

Detailing around openings will be a ball ache too.
 
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I was going to fix 50mm pir to the outside of the frame, then osb to the outside of that. Then a Breather, then batten and Clad. My cladding was just going to be fixed to the battens, not all the way through the battens and the osb and pir to the steel. So why does insulating the outside of the frame make it difficult to clad? And why will detailing around openings be a problem, because we'll create a recess? Won't it just be a recessed look window? Also for fixing to the steel frame can I not just use a nail gun designed for firing through concrete/steel?
 
I was going to fix 50mm pir to the outside of the frame, then osb to the outside of that. Then a Breather, then batten and Clad. My cladding was just going to be fixed to the battens, not all the way through the battens and the osb and pir to the steel. So why does insulating the outside of the frame make it difficult to clad? And why will detailing around openings be a problem, because we'll create a recess? Won't it just be a recessed look window? Also for fixing to the steel frame can I not just use a nail gun designed for firing through concrete/steel?
50mm PIR may not be man enough to stave off extreme temp's. You may need to double it. But in doing so you can forget about any internal insulation. You are basically creating a warm frame, which is good as it is steel.

I honestly don't know much about shot fired fixings into steel especially as you will need hundreds and quite lengthy ones that wont just puncture the ply.
 
50mm PIR may not be man enough to stave off extreme temp's. You may need to double it. But in doing so you can forget about any internal insulation. You are basically creating a warm frame, which is good as it is steel.

I honestly don't know much about shot fired fixings into steel especially as you will need hundreds and quite lengthy ones that wont just puncture the ply.

Why do we need to forget about insulating within the frame? Also do I need to puncture all the way through the ply into the steel? Can't each layer of the wall build up just be fixed to the next layer?
 
Why do we need to forget about insulating within the frame?
Because You need to treat the metal frame as a 'warm' design meaning any further insulation will be pointless.

Also do I need to puncture all the way through the ply into the steel?
What I meant was I'm not sure how you control the fixings as they are fired into the steel through the ply via a soft (PIR insulation) medium. There is a risk that they could just punch through the ply unless there is a large washer type head on the fixings.
 
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Because You need to treat the metal frame as a 'warm' design meaning any further insulation will be pointless.

What I meant was I'm not sure how you control the fixings as they are fired into the steel through the ply via a soft (PIR insulation) medium. There is a risk that they could just punch through the ply unless there is a large washer type head on the fixings.
What's wrong if the cladding is fixed just to the osb(ply you were referring to). Will it not be secure enough. Because I was planning to have the pir fixed to the steel frame, then the osb just fixed to the pir (not all the way through into the steel), then the cladding fixed onto the battens that will be fixed onto the osb(not all the way through the pir and into the steel). Will this not be secure enough/what problems could it lead to?

Also do you think the building will have good acoustic insulation with just insulating with pir Outside the frame? As it is light guage steel after all and is hollow unlike timber.

Also how would you recommend fixing a big set of aluminium sliding doors to the frame at the opening?
 

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Before you get bogged down with vapour barriers and PIR, you need to consider the potential for serious side-sway, particularly if using light-guage steel.
Ideally, you should have a properly-designed moment frame at the front, but that might need some conventional hot-rolled sections of a larger section than you envisage. The roof plate should also be made as rigid as possible, and securely fixed to the tops of the perimeter walls.
 
Have a look at aluminium orangery roof kits, there are specialists that make them all welded and ready to bolt together on site.

And the designs are structurally proven and have been designed to comply with building regs on insulation levels



your big problem is a structural engineer won’t want to calculate your design, so will specify beams, posts etc to pass.
 

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