Floor Joists

Roofer · 5 Oct 2012

I am intending to build an extension on top of an existing flat roof which means the existing roof joists will become the new floor joists.

The joists are 150 x 50 at 400 ccs with a 2 metre span. Will these be adequate as floor joists or do I need to think about beefing them up?

Thanks for any input.

tony1851 · 5 Oct 2012

They will be fine; 6"x2" will go up to 3m for a floor.

Is the level right, though? It's probable that you will get either a step up or a step down to the new floor as the chances are that the exising roof joists won't be at the same level as the floor.

geraldthehamster · 5 Oct 2012

Roofer said:
I am intending to build an extension on top of an existing flat roof which means the existing roof joists will become the new floor joists.

The joists are 150 x 50 at 400 ccs with a 2 metre span. Will these be adequate as floor joists or do I need to think about beefing them up?

Thanks for any input.

According to the span tables in the old (1991) Part A, you're OK. In Table A1, 50x147 at 400 centres spans from 2.81 to 3.27 metres, depending on dead load.

Cheers
Richard

big-all · 5 Oct 2012

are the foundations up to it ??

^woody^ · 5 Oct 2012

Don't forget to take the furrings off. Lol

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Floor Joists

Roofer

tony1851

geraldthehamster

big-all

^woody^

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