I had a long term leak from a shower that crept behind skirting board and has rotted a section of (chipboard) subfloor and the near side of the floor plate from the adjacent stud wall (see photo). The floor joists run parallel with the wall, so the subfloor runs under the wall. Only about 50cm of floor plate is affected, but it spans one of the studs. The bathroom side of the plate is crumbly, but the other side is sound. Part of the stud end is soft. The subfloor in the same area has softened, but it has not extended as far as the next joist in the bathroom. Nor does the joist beneath the stud wall show any signs of damage.
My plan was to cut out the damaged subfloor and replace with 18mm waterproof ply, and cut out the damaged floor plate section and replace with new CLS timber. I would support the new ply with pieces attached along both joists and with noggins spanning between the two joists (which would also support the floating ends of the cut chipboard). The joist under the stud wall is actually set back about 5cm from the base plate edge, but it will be accessible when I’ve removed the damaged subfloor. I plan to cut the subfloor as close to the joist as possible and leave it there, but if I find that it has rotted then I’ll need to remove it and either pack it out with a ply piece or cut the new subfloor piece larger to extend onto the joist. I’d be painting everything I’m leaving in place with Cuprinol as I go.
My concern is around replacing the base plate section. I’m not sure that the stud wall isn’t load bearing. The facts are: - it’s an original timber and plaster internal stud wall - there is nothing in the ground floor underneath it - the joists in the floor underneath run parallel, and there is one (just about) underneath it - the joists above it in the loft run perpendicular, but they don’t line up with the studs - joists above are 38x97mm at 450mm centres
If it is load bearing (or perhaps even if not – part of this wall has some heavy tiles), then is there a risk that the centre part of the wall would sag or collapse when there is nothing underneath the one unsupported stud? I’d thought perhaps of splitting the move into two – adding an extra centre noggin close to the stud, cutting out half of the base plate and subfloor first and replacing those without disturbing the stud. Then perhaps I could attach a stout angle bracket to secure the stud to the new base plate piece, then cut out the remaining piece of base plate and subfloor (leaving the stud supported by the bracket) and insert the other half of the new subfloor and base plate under the stud. Does this sound feasible?
Hi peripatus With the floor joist almost under the wall floor plate suggest you do not replace this or the stud wall upright. You could cut and glue in repair pieces if you need sound timber for fixings. Regards S
Hi Stoneboy, to be clear, do you mean that I leave the stud wall as is, and sister in extra pieces as necessary for fixing? Am I OK to leave the decayed sections of the base plate, if I cut away the damaged subfloor flush to them, dry everything out as much as I can and treat everything with preservative?
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