Replacing cavity floor joists - timber sizes

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Evening all,

We're currently renovating a 1930s property and one of the tasks is dealing with a tiny amount of woodworm in the timber floor of the ground floor cavity and at the same time insulating under the floor. We have removed all of the floor boards across the whole ground floor, disposed of those with apparent woodworm, treated everywhere else and kept the remaining boards where the T+G is intact to use as a floor covering for one room when we've finished. All downstairs will be covered in flooring chipboard with insulation between the joists.

We found a little bit of woodworm in one of the joists so have removed that and we've also removed a fireplace so need joists to span that too. The size of the existing joists is 50x75mm. Unfortunately, I cannot find treated, graded timber in this exact size! C16/C24 all appears to come out at 47x72mm finished size which would cause a dip once the new chipboard floor goes down.

I'm content from spanning tables that I've found that C24 47x72mm can be used for spans up to 1421mm so is suitable as the distance between sleeper walls is only about 1200mm.

I wonder if anyone could advise of anywhere I may be able to find custom size C24 or am I looking at having to replace all joists?? Obviously not ideal as it means more work and there will be a slight discrepancy with another floor downstairs!

Thanks in advance,

John
 
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get some bigger timber and rip it down or alternatively notch it over the sleeper wall
 
You dont need "treated graded timber" for such short spans.

If you are worrying about a possible 3mm difference (1930's joists would have been 2" x 3" BTW) then forget about it.
Just use the 47 mm joists as they are available, and after positioning them check out if there's any "dip" in height - if there is then slip some firm packing below the joists to lift them level.

FWIW: you can brush the new stuff with the woodworm chemical.
Most woodworm is old flight holes - dig out a little wood and see if any of the little mechanics are still active.
 
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Where abouts are you? I've got a some 75x50 from a ceiling I pulled down.

I can spare some, I'm in Rochdale, Lancs if that helps.

Otherwise I bet a local reclamation yard will have some.
 

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