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Dazzler

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Hi to all
I have a flat roof approximately 2.8m by 3m, I want to install a glass roof similar to the top of a conservatory roof how do I support the joists after I've cut the hole as the glass is 1.8m by 2m
 
Without seeing it and in a perfect world I would say,

If the joists are of a large enough section (and that's a big if, a flat roof of that size are probably small ish section) you would frame it up like a stairwell, joist hangers at the junctions double up the edge joists (the last whole ones if that makes sense) and it should be fine in theory. You need to check the joists are adequately fixed at their ends or ideally cantilevered over a wall or partition.

However, it wouldn't be a bad idea to have a structural engineer pop round and do some calcs, for the sake of a £100 or so it might save a lot of anguish. It's not something I'd attempt if I was in any doubt without seeking guidance re loads etc.

Hope this helps,
Craig
 
Mark out the glass panel, plus whatever lining or framing being used and cut out, allowing double rafters width, along the rafter's you have just cut, similar to setting a stair well.
You may need expansion joints on some systems.
You should be aware that all glass supply and fixing are covered by a official body that I cant remember.
Google it, perhaps "glass and glazing safety"
If you see you're glass supplier with a sketch plan of you're needs then see what they say. If you're concerned about the outcome see a supplier you don't know.
Should any big kids go through it, or you wish to sell, you may well have problems.
Regards Rodders
 
Introducing a glazed roof falls under building regs if its a room in a house, so prob best to get calcs done. Calcs will allow for snow loading, somewhat topical as there have been roofs collapsing in the US due to snow, although they have rather a lot, 100 inches in some states.

A small roof like this can probably be done by doubling up the rafters and fitting trimmers to pick up the cut joists and fit them on jiffy hangers.

Im not sure I understand the glazing detail, is this a glass lantern, or just some flat glass?
 
It's a pirimid roof thanks for all your advice think I will get a structural engineer out to just asess it see what my options are cheers
 
Hi Dazzler
I'm a builder, well soon retiring and as Rodders says, you need to obtain building regs approval.
If you build without, you will have problems when you sell in future or if some nosey neighbour reports it. It's unlikely you'll need planning approval but is possible in some situations.
If you build without and there is an accident or damage your insurance company will refuse to pay.

cheers
Bob
 
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