Conservatory Roof Joist Spacing

[mrmoose]

Hi I am building a 4m deep 2.2m wide conservatory with 45x145mm C16 joists on top of which I am putting on 25x1080mm Polycarb sheets, can you tell me if I need intermediate joists ? eg at 550mm centres or just noggin supports ? Any advice would be great

 

[catlad]

They will self support like that but it sounds flimsy to me, are you filling in between to walls.

 

[mrmoose]

Catlad not sure what you mean, are you talking about noggins between joists from side to side ? I was going to space joists at roughly 400/500 centres but wondered if I needed to use so many when the polycarbonate sheets are 1080 wide ! But still using noggins side to side spaced approx a metre apart

Moose

 

[Ronob]

I'd reconsider 25mm polycarbonate sheets and go for 35 or glass, we have 35mm and lose a lot of heat thru the roofing

 

[catlad]

Why not use the ali self supporting bars then you will only need three.

 

[s60tsy]

have you compared your materials to the cost of a lean too conservatory?

 

[mrmoose]

I had considered the self support system but there is a need to access a window above so in terms of supporting weight with crawl boards I think the joist option is better. The actual cost of the joists is an extra £80 if I went for the 4/500mm centres

 

[s60tsy]

A conservatory roof would support the weight with boards if it was the right system, for extra strength you could run a beam across underneath, halfway down, roughly £800 for the full lean too roof with poly in white upvc