Bathroom floor

[Cardon]

We are about to put in a new floor in the bathroom. We have wooden floorboards, generally in good condition the few loose ones we have replaced. Over the floor boards we will be putting 1cm underlayment board (not sure if this is correct name in English, but it is board made up from several layers of wood), then 2cm Wedi (brand name) boards...over the top of this we will be tiling. Do you think this will be ok to tile over? I am not sure whether it will be good enough to prevent movement in the tiles...

Any advice is really appreciated.

Don

 

[Richard C]

Sounds like your underlayment board is similar to what we call plywood. Using 1 cm ply & 2cm Wedi over floorboards seems to be rather excessive let alone the huge difference in height it’s going to create at the door threshold by the time you get the tiles on there. I’ve no personal experience with Wedi & don’t know how it behaves but think maybe using ply & 2cm Wedi boards over floor boards runs the risk of actually introducing movement due to the number of layers you’re putting down, the opposite of what you’re trying to achieve. I also have no idea about the general rigidity & construction of suspended floors in the Netherlands & that could be a significant factor; what I generally recommend over here is;

To replace the floorboards with 1.8-2.5cm thick WBP exterior grade water & boil proof plywood; exterior grade underlayment board? - basically it uses waterproof glue in the construction so it won’t fall apart when it gets wet. Personally I don’t like over overboarding floorboards & prefer to take them up as it makes for a much more stable tiling surface & you don’t have to contend with a huge step at the door threshold. If overboarding, I generally recommend a minimum 1.2 cm thick WBP ply but I would rather not do it.

Also have a look at the sticky in the Tiling Forum & have a read through the archive posts.

 

[Cardon]

Thanks Richard for your advice.

The floorboards are supported by joists but there aren't any counter supports (noggins, i think), the joists are approximately 50-60cm apart. It may be worth putting in the extra support I guess

I'll have a look for the exterior grade board, I am sure they will think I have gone totally mad in the dutch B&Q equivalent!

 

[Richard C]

The floorboards are supported by joists but there aren't any counter supports (noggins, i think), the joists are approximately 50-60cm apart. It may be worth putting in the extra support I guess

The joist spacing seems a little more than here (normally 40cm), what size/span are the timbers? You would normally only need noggins to support the ply (or Wedi) at joint lines across the joists or in the 2 unsupported edges around the edge of the room which may be subject to loading.

I'll have a look for the exterior grade board, I am sure they will think I have gone totally mad in the dutch B&Q equivalent!

I’m sure they must have & use exterior grade ply in construction.