Decoupling membrane direct onto floorboards for tiling?

andybookie

I am installing decoupling membrane in my upstairs bathroom.

https://www.youtube.com/watch?v=wMzXu1NRMAM

I removed the existing tiles and along with it the plywood (as they were stuck together), to leave sturdy wooden floorboards.

I was recommended the membrane to use instead of putting plywood down as it would do the same job as plywood (only in a different way of allowing movement)

The floorboards as I said are sturdy and level.

Am I okay to put membrane directly onto floorboards?
I have had different opinions said to me.

Andy

agusta

6mm magnesium board is another good option,not expensive either

andybookie

agusta wrote: »

6mm magnesium board is another good option,not expensive either

As far as I know magnesium board is not a good solution for possible movement in the sub-floor. Expansion and contraction will be common in the bathroom and I would need something that either restricts the movement (e.g. plywood) or counteracts the movement (decoupling membrane).

Regardless I was wanting to know whether I could put decoupling membrane direct onto floorboards, which I am still unsure of.

Thanks anyway

monseiur

I'm not an expert in this field but it would be advisable to cover the existing floor boards with good quality ply, like marine ply or similar using stainless steel or brass screws.
If you ever have to lift the tiles again you just lift the ply with tiles whereas if you stick the membrane directly to floor boards the whole floor may have to come out.
Marine ply is expensive but considering it's a bathroom 2 or 3 sheets should go a long way. Do not, under any circumstances, use OSB or similar boards
M.

andybookie

monseiur wrote: »

I'm not an expert in this field but it would be advisable to cover the existing floor boards with good quality ply, like marine ply or similar using stainless steel or brass screws.
If you ever have to lift the tiles again you just lift the ply with tiles whereas if you stick the membrane directly to floor boards the whole floor may have to come out.
Marine ply is expensive but considering it's a bathroom 2 or 3 sheets should go a long way. Do not, under any circumstances, use OSB or similar boards
M.

Thanks.
This does make sense and I did think about this.
My only concern with using ply and membrane is now the height difference between rooms (and possible space under door).
Ply and membrane would mean, tiles on adhesive on membrane on adhesive on ply. I'd say you're taking 20mm with all that stacked up.

com1

Yeah, but you already had ply and tiles and adhesive that you removed so the only difference is the thickness of the membrane (as long as the old and new tiles and ply are the same thickness). So, if you still have some - get a section of what you removed and put the equilivant thickness (of the membrane) ontop and see if the door opens over it.

andybookie

com1 wrote: »

Yeah, but you already had ply and tiles and adhesive that you removed so the only difference is the thickness of the membrane (as long as the old and new tiles and ply are the same thickness). So, if you still have some - get a section of what you removed and put the equilivant thickness (of the membrane) ontop and see if the door opens over it.

Sort of but it is the adhesive under the membrane and the membrane that will be extra. But yeah I'll measure up and make sure it is okay.

If I am only using the ply for almost protection for the boards then, it could be relatively thin ply. The decoupling membrane should counteract any movement in the floor.

Thanks

agusta

andybookie wrote: »

As far as I know magnesium board is not a good solution for possible movement in the sub-floor. Expansion and contraction will be common in the bathroom and I would need something that either restricts the movement (e.g. plywood) or counteracts the movement (decoupling membrane).

Regardless I was wanting to know whether I could put decoupling membrane direct onto floorboards, which I am still unsure of.

Thanks anyway

It is not movement for contraction and expansion your counteracting.Its the spring effect from one floorboard to the next floor board.Magnesium board being the most popular board for tilers and builder providers in my area.other options,6mm high grade marine ply[was popular 10 years ago] ;cement board,jacko board or similar.i cant see the point in fitting the membrane unless you expect lateral movement.