Joist sizes for large unsupported span

[Steve_W]

Afternoon all,

I can't find the grid that I thought I bookmarked re joist sizes, so can anyone give me an idea on sizing please?

To be able to span 5250mm unsupported, at 600mm centres, what size joist timbers am I looking at?

Just to add to the fun, one of the rooms above may well be a candidate for conversion to a bathroom - so all the additional weight of a full bath etc. - maybe I need the joists closer in that case?

The room that these form the ceiling to is 5250 x 4200, so maybe I should be looking at spinning things round to span the 4200 width instead (although the exisiting old joists run the long way).

Thanks,
Steve

[Size Nine Elm]

We're just converting an attic/loft space. The joists were all 1x6s (1960s house) and should have done the job fine, but the structural engineer wanted them all doubled up with 25x200s. Span was (IIRC) about 5000mm too.

There are SE tables for these things - worth doing more searching online...

[ncs]

Size Nine Elm said:

We're just converting an attic/loft space. The joists were all 1x6s (1960s house) and should have done the job fine, but the structural engineer wanted them all doubled up with 25x200s. Span was (IIRC) about 5000mm too.

There are SE tables for these things - worth doing more searching online...

Are you sure you've got that size right?

If so, may I respectfully suggest you dont go upstairs

Nick

[Size Nine Elm]

Maybe was 500x200s (2x8?) on 600 centres. Looks fine anyway. Bigger issue is the buggers look like they won't be finished before we're meant to move in. Maybe should keep the wardrobes downstairs then

[robinhood21]

This should be of help.

[Steve_W]

Cheers all,

Doing some poking around I found the following too (at the bottom of the page) - this is similar to what I thought I had bookmarked: Building regulations Table A1

Now all I need to do is work out the loads imposed by a full bath, etc. Perhaps I need an engineer!

[herbialfa]

Have a butchers at Posi joists!