Durabase WP

[osmyth]

Even if the 6mm ply is on top of 22mm t&g chip which is glued and screwed?
The floor is pretty solid as it is already, without the ply on yet. Oversized joists spanning 2.6m.

 

[grumpygrouter]

Even if the 6mm ply is on top of 22mm t&g chip which is glued and screwed?
The floor is pretty solid as it is already, without the ply on yet. Oversized joists spanning 2.6m.

6mm ply is not a suitable surface to tile onto, irrespective of the board size underneath. It is affected too much by the moisture in the adhesive and becomes unstable. Much better to use 6mm cement based backer board if your floor is solid. If the floor has bounce, it needs to be strengthened by overboarding with 18mm ply as a minimum.

 

[osmyth]

Thanks, I've just got the same answer after popping in to the tile shop (where i'm getting the tiles from, well their second shop anyway).
Fella seemed to know what he was talking about and recommended a 6mm cement board, which negates the need for the membrane (in the dry area at least). (The ply hasn't been put down yet, just the 22mm chip).

The tiles are 22kg per sq.m. and I was thinking of the durabase wp on the walls in the wet area, which would mean 2 lots of adhesive. The fella thought there would be no problem with the weight issue.

Do you think that weight is ok for skimmed plasterboard.

I suppose the other option would be to rip out the plasterboard and put cement boards up.

 

[osmyth]

...and is putting a backer board down on 22mm chip using adhesive ok, as the chip will be just as susceptible to water ingress as the ply, if not more. Is it because it's the depth of 22mm that makes it ok?
Should the chip be acrylic primed same as ply would be?

Thanks again.

 

[doug boardley]

Thanks, I've just got the same answer after popping in to the tile shop (where i'm getting the tiles from, well their second shop anyway).
Fella seemed to know what he was talking about and recommended a 6mm cement board, which negates the need for the membrane (in the dry area at least). (The ply hasn't been put down yet, just the 22mm chip).

The tiles are 22kg per sq.m. and I was thinking of the durabase wp on the walls in the wet area, which would mean 2 lots of adhesive. The fella thought there would be no problem with the weight issue.

Do you think that weight is ok for skimmed plasterboard.

I suppose the other option would be to rip out the plasterboard and put cement boards up.

and then factor in adhesive and grout at 4kg per m2, pushing it way over safe limits. However unskimmed plasterboard would bear this weight and the WP membrane safely.

 

[osmyth]

and then factor in adhesive and grout at 4kg per m2, pushing it way over safe limits. However unskimmed plasterboard would bear this weight and the WP membrane safely.

so how easy is it to take skim off the plasterboard?!

 

[doug boardley]

so how easy is it to take skim off the plasterboard?!

Not easy, best to rip it out and re-board. Then I'd use Hardibacker 500 in the "wet areas" and 12.5mm plasterboard in the dry areas.

 

[CarlGHudson]

Hi, Hope I'm not breaching some etiquet by jumping on your thread but its very similar to what I'm up to so my questions are related and might be useful:

I am using C1 on 22mm plywood and an Impey Aquadec; does the plywood need coating in anything?

I am using WP on skimmed plasterboard and intend sticking on some mosafil glass mosaics; what is the maximum weight limit on skimmed plasterboard - I'd only considered the weight limit on the WP?

I have tried sticking some of the C1 on to the Aquadec using Mapei Buildfix C2F Stone and Porcelaine Rapid Set White mixed with Buildfix Flexible additive and it doesn't stick too well; it would be OK for floor but certainly not for wall tiles. Any idea why this might be the case?

 

[osmyth]

Hi, Hope I'm not breaching some etiquet by jumping on your thread but its very similar to what I'm up to so my questions are related and might be useful:

I am using C1 on 22mm plywood and an Impey Aquadec; does the plywood need coating in anything?

I am using WP on skimmed plasterboard and intend sticking on some mosafil glass mosaics; what is the maximum weight limit on skimmed plasterboard - I'd only considered the weight limit on the WP?

I have tried sticking some of the C1 on to the Aquadec using Mapei Buildfix C2F Stone and Porcelaine Rapid Set White mixed with Buildfix Flexible additive and it doesn't stick too well; it would be OK for floor but certainly not for wall tiles. Any idea why this might be the case?

Carl, re weight limit on skimmed plasterboard - 20kg per sq.m including adhesive/grout.
Our tiles alone were 22kg so with adh/grout of about another 4kg, it is reasonably above the limit.
We're changing to tiles which are 16kg, just to be safe.

Ci is designed for the floor as it decouples as well as waterproofs, hence 3mm thick.
WP is designed for walls just as a waterproofer, hence just 0.15mm thick.

 

[CarlGHudson]

Thanks for this; do you know if the grout I have got is suitable as it wasn't sticking to the Aquadec?

Also do I need to do anything to the plywood?