10 x 2 joist centres for flat roof

[Thepenetrator1]

Hi all,

I'm putting 10 x 2 joists in for a flat roof. The span is about 3m from wall plate into steel and then the same out of the other side of the steel to the fascia.
The steel section is 254 tall so I've gone for 10x 2 to give a flat roof and a flush ceiling. Can anyone advise on the centres for these joists please?
Is 600mm any good or is it not much for the plaster boards to fix into?
Thanks all

 

[ladylola]

I'd personally put them in at 450mm (or 16"in old money) . The wider spans may very well be ok for the plasterboard but if it were to start to sag and bow it would be a lot more work to rectify it later whereas the cost of sticking a few extra joists in at this stage would soon be forgotten about.

 

[vinn]

With respect ladylola, 450mm is 18 inches 400mm is 16" - however I agree with you always go 400mm centres for residential joists. Never skimp on structural detail.

 

[Thepenetrator1]

Cheers boys, I went for the 400.
thanks

 

[ladylola]

With respect ladylola, 450mm is 18 inches 400mm is 16" - however I agree with you always go 400mm centres for residential joists. Never skimp on structural detail.

Oh yes , you're right , mental arithmetic gone to pot there. I do normally work in inches and seeing as the OP used just metric I thought I'd better do the same but obviously should have checked with the tape