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Flooring weight limits

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mg123

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Hi guys, first post and seeking some knowledgeable advice. I've been transforming my garage into a usable workshop space for the last few months and am looking at my floor construction and what sort of weight limits there will be.
The garage is a concrete block built structure with a galvanised steel roof. Approximately 2.6 x 6 metres floor space with a 2.6 to 2.8 metres in height (sloped roof). Its on good solid concrete foundations around the perimeter but the middle was made up of flags and there was also an inspection pit in the middle.
I opted for a timber floor, I've used 4" x 2" C24 timbers spaced at 40cm centres across the width with a ledger board at either end and on joist hangers. Ive then added an 18mm water resistant tongue and grooved chipboard.
In short, I'm wondering what I could realistically put in there in terms of kilos per square meter. I've obtained an old school 1.2 x 0.8 metre workbench with a record 52 vice and a tail vice built in which his very heavy and will be building a frame which will add to the weight.
Appreciate any support.
 

RichardG

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I can’t answer your question but this may help you work out your loading.

Floor joist span tables for surveyors - Floor construction | Right Survey

My gut feeling is that it’s a undersized for a normal floor, I would have expected 6x2 or 7x2, to be used on a 2.6m span. However, are the 4x2 laying on the flags or are they totally suspended, as this would make a huge difference.
 

Jameshow

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If it is too springy I'd lift the floor and put concrete blocks / treated timber pads under the beams either side of the pit.

You could cut a hole 2x2' in the floor to save lifting it to gain access.

Cheers James
 

mg123

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I can’t answer your question but this may help you work out your loading.

Floor joist span tables for surveyors - Floor construction | Right Survey

My gut feeling is that it’s a undersized for a normal floor, I would have expected 6x2 or 7x2, to be used on a 2.6m span. However, are the 4x2 laying on the flags or are they totally suspended, as this would make a huge difference.
I'd seen another build using 5x2 but that was over a 5 metre span. My floor is suspended but I have added some supports under the beams on each joist which is basically wooden blocks between the joist and the flags, they're placed around midway on all joists apart from ones above the pit where i've supported these at either end.
 

Jameshow

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I think it will be fine! The largest span isn't going to be more than 1m.

Unless you start restoring heavy iron machinery you should be fine.

If you do have any spot loads it might be worth knocking up some plywood furniture cups to spread the load esp of casters.

Cheers James
 

RichardG

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I'd seen another build using 5x2 but that was over a 5 metre span. My floor is suspended but I have added some supports under the beams on each joist which is basically wooden blocks between the joist and the flags, they're placed around midway on all joists apart from ones above the pit where i've supported these at either end.
That's fine then, you only have a 1.3m span, a 2x4 C24 will span 1.9m so you will not have any problems.

The span tables are worked on deflection not failure, so even if it was undersize the floor would flex but not fail....
 

Lard

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in a previous life I worked as a building surveyor and very often went out with building control and/or the structural engineer. There were many instances where they had to make somewhat instant judgements on whether or not a joist had been suitably sized etc. They had a GENERAL rule that I’ve used for years (eg building/drawings)......take your span and convert it into feet. Divide it by 2, round UP to next whole and, finally, add 1.
Eg....4m span = ~13ft......div by 2 = 6.50.....round up to 7 and add 1 = 8
4m span therefore requires an 8x2” joist.
👍
 

treeturner123

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Lard

Like your method. In the old days, the Building Regs actually had full tables for floor and roof joist sizes and spans which made life really easy for a building surveyor like me.

Phil
 
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