DIY Doctor UK DIY Forums

I have a (wood frame and plasterboard) stud wall separating my upstairs bathroom from an adjacent toilet. The entire wall frame sits on the floorboards which run under the wall at 90 degrees (the joist are parallel to the wall). The problem is that the stud wall is sitting on the floorboards between two joists.

I want to replace the floorboards in the bathroom (with ply) but can’t figure out how to keep the wall supported while I do it (I don’t want to change the toilet floor). I suppose I could cut all the boards off at the last joist before the wall, but that would mean I’d have about 5in of “old” floor and the new stuff would have to be the same thickness to avoid a ridge.

Grateful if someone could offer a solution that doesn’t involve a sky-hook!

hi bemused, without making whole thing to complicated, I thing you have reached the solution yourself, my question is what are going to do with floor when replaced and why are you taking old one up?
If the house is of the imperial age you may get that step, this could be planed down or you could pack up on joist to make level floor.
KB

Hi KB, thanks for your reply. The boards are 22mm thick and some of them have bowed, becoming high in the middle along their length so I'd like to replace them. Other than that, I'm rebuilding the whole bathroom and the rather uneven floor is the only original bit left, so I'm quite keen to replace it, just out of a sense of having everything renewed. I'm not sure yet if I'll tile the floor so a new ply job would be a good base. Thanks for confirming the lack of options!

If your current floor boards are 22mm thick and you cut at last joist prior to wall. You can buy ply at different thickness, normally i'd be recommending 18mm but that will leave a step of 4mm which is not what we want!
If I remember right the thickness go up like so 3mm, 6mm, 9mm, 12mm.
Can't say for sure but I think there could be a 7mm too.
So if you put a double skin down of 18mm and 3mm you will only have 1mm step.
Is that an option?
KB

I did think about that, but I didn't easily find a good combination. It's certainly worth a bit more effort. Thanks for the input.

Are you tiling the floor (ceramic or whatever) or laying vinyl sheet or vinyl tiles after you've finished laying the ply?

Theres a slightly different solution to sort out a minor "step" depending which one.

Cheers

The truth is we haven't decided which way to go yet, but the choice will be either tiles or laminate.

If you haven't decided then I'd use ply and make sure it is higher than the 22mm boards which are left. That probably means 25mm. For ceramics it must be screwed firmly down every 6 inches and additional timber put in between joists as noggins at the edges of each sheet of ply.

You can then overboard the residual small area of 22mm boards with a thin piece of ply to make the level the same.

You are then set for either ceramic tiles or laminate floor whichever youi chose. If laminate you need do nothing else under the underlay.

You now have a very rigid and flat surface for tiling and you'll probably be safe with a good quality bagged (don't use the tubbed stuff from the sheds) flexible floor tile adhesive. To absolutely certain and deal with any deflection in the floor I'd recommend using a decoupling membrane like Ditra.

Cheers

Thanks a bunch rosebery, that sounds like a pretty stable platform.
Cheers

and that's the point LoL. Good luck with it.

Cheers