Joist size/spacing

[teleskopjo]

I am making a roll off roof, 2.7m span, with corrugated steel sheeting on top.

What is the typical layout for the underlying frame to take the sheets? I was considering 37mm x 100mm softwood (painted) spaced at 1m.

Any thoughts from own experience?

[jnb]

16" spacing is standard. Sheet materials are usually 8' x 4' and insulation etc is 16".

1m will sag. 1.2m will definitely sag. If it sags water will pool and eventually leak.

So although it will make the roof heavier and cost more I would definitely use a 16" spacing.

[jnb]

Oh just to add you could use a 24" spacing but 16" is more common so if in future someone wants to do some work on that roof and finds one joist it would be normal to expect to find the next 16" away, but 24" is used sometimes.

[teleskopjo]

I will be using 9' x 3' galvanised corrugated steel.

http://www.steelsheet-suppliers.com/photo/pl900512-sgcc_sgch_g550_jis_hot_dipped_steel_galvanized_corrugated_roofing_sheet_sheets.jpg

similar to this.. am getting it later today, will see how much it would sag!

Other question, what do you use to close of f the corrugations at the eaves, I cannot find any profile closure strips or whatever they are called!..

[Clockwork_Orange]

I have seen the closure stuff on one of my many visits to Wickes the stuff they sell is :-

PVCu Corrugated Eaves Fillers

Product Code: 240165

Regards

John

[Paul M]

Some sheet materials now come in metric sizes i.e. 2400 x 1200 (or even yucky 2000 x 1000) as opposed to the old 8 x 4 which was 2440 x 1220. 

So depending on whether you have metric or imperial sheets will decide whether you go for 16" or 400mm centers.

It can really mess things up on longer runs!

Looking on-line at corrugated roofing it comes in weird and wonderful sizes anyway. So long as the joints are supported and Building Control have no reason to be interested there is lots of room to be creative. It isn't just the wight of the roofing to consider. A foot of compact snow weighs a bit too!

Anyway, I'd be equally concerned about having adequate pitch and closure round the perimeter

Edit: ignore me, you've all moved on since I started typing my reply!

[Gina]

I considered various types of corrugated sheeting for my roof too but decided it was too difficult and went for EPDM rubber roofing on plywood and framework instead.