Wood filler will run down into the gaps.

I'd use a Fein or similar and cut out the broken area until you get a square edge all round.  Then cut a small piece of wood to fit, glue up.  If you are re-carpeting then that's all you need do.

If you are worried about the wood falling through while the glue sets then put a screw into the piece of wood enough that you can grip it.  Put whatever glue you have on most of the edge of the small piece of wood but leave a couple of bare bits at either end.  Get yourself something fast-curing like MitreMate and apply that to the bare bits.  Put the wood in position holding onto the screw until the MitreMate has set (20 secs or so).  That will then hold the wood in place while the proper stuff goes off.

My pleasure!   Fein Multimaster was what I was suggesting. It's got me out of more holes than I care to remember,. Best bit of kit I've bought for a long time.

Other brands are available !

Natedog wrote on Oct 1^st, 2018, 4:38pm:



You're dead right there. My Fein has got me out of so many holes.  I remember laying some Click'n'Curse engineered boards in a flat. Started at the window and worked my way back to the door.  Only thing is, the door was still fitted and as I got towards the door realised that I could no longer open it enough to get out of the room as it fouled on the new floorboards.  Since disassembling the floorboards was a right PITA, I stuck my hand through the gap to see what tools I might be able to pick up to help me get out of the predicament I'd got myself into.

My hand grasped the Fein and I used it to cut the bottom off the door and escaped.

Don't know why that pic came out upside down  

Please remember if the pipe is touching wood or tight in the hole it will click and creak.
If you have room put a bit of pipe insulation below the floor, if its an unheaded subfloor area it's a good idea to insulate as much as possible anyway