strengthening loft floor

Doglover88

im currently boarding out the loft and am going to go across the existing joists with 4x2" timer from side to side (existing joists are front to back = cross hatch) i thought this best as it would spread the weight of any load up there. Do i have to use joist supports, or will the fact they are overlapped at 90 degrees be sufficient? Its not going to be a living space, may put a weight bench up there and all the usual rubbish

weekendwarrior

It depends on a few factors such as how much support is underneath and how many stringers there are, personally I would use joist hangers as well, to be on the safe side.

Mr_Warren_2

A weight bench is quite a substancial weight. I had my loft converted and planning authorisation had to be given. Steel girders 2" above existing joists were necessary in order not to put any additional weight on said joists.
Too much additional weight could cause your ceiling to crack.

bcoman

imho the ceiling will still deflect with the load being spread as you suggest. Better if you can to place bigger joists in between the existing and pack them clear of the ceiling by 15mm or so. That way if they do deflect the ceiling wont be affected. Could be complicated if you already have timbers at right angles (binders) as this means the ceiling joists are already overspanned. FYI to take load of 50kg per sq metre 50x100 at 400centres will span 1.93 metres whereas 50x175 will go 3.55 metres. A garden shed might be the cheaper option