Removing part of subfloor under stud wall

[daggermark]

A section of upstairs ply subfloor was lifted for some plumbing that I had done. The board was cut flush with a stud cupboard wall that is sat directly on a joist.

Time has come to re-lay the floor and I need something to fix onto. I was hoping to somehow cut out the ply to about 25mm depth from under the cupboard wall sole plate, so that I can push the replacement piece under the wall enough that it is supported on the joist.

Any ideas how I could do it? I was thinking of drilling it with a depth gauge and tidying up with a chisel but it seems very slow.

 

[Deleted member 174758]

Forget that. Assuming that the wall runs along the line of the joist either install a series of "noggins" between the joists at 300 to 400mm centres or sister the joist with some 2 x 3in PSE softwood.

 

[daggermark]

Fair shout. I wasn't sure about sistering the joist, as I believe that is ideally done with coach bolts and I don't have easy access to the rear face of the joist. Is that right or can I just screw it?

 

[Deleted member 174758]

In this instance unless the intention is to add some massive load on top like a full size solid bronze statue of The Sasquatch, I'd just screw it with maybe some PU glue to bond the two parts together a bit better. 5 x 80 or 90 screws should do for 45 to 50mm thick stock

 

[daggermark]

I have to admit, I've done exactly this elsewhere some years ago. I also didn't see much issue with it, if one screw can withstand 50kg shear strength then glue+screw every 300mm should surely be plenty of strength. I guess it could apply twist load to the joist it is screwed to, but I don't intend on any Sasquatch!