Tiling Dilemma With Damp Wall Substrate

[mika_98]

Hello all,

I seem to be in a dilemma with the tiler and tiling my bathroom. First of all, things to bear in mind are that the walls are slightly damp and I have gone for porcelain tiles. The walls have been treated with a damp proof course but I have been advised any previous damp may remain for a while.

With that in mind, I'm assuming the best method is to fit a board of some sort to tile onto. If that is correct, which method should I use - dot and dab with adhesive or studwork?

I'd rather go with the dot/dab as my bathroom is very small (1.8 x 1.5m). Batons plus boards, followed by tiles will take up what little space I already have. If I go down this route, which boards (apart from plaster/MR) can I fit using adhesive? I'd love to use something like Aquapanels but was advised they have to be fitted using batons. Are there any other alternatives?

However, if its best to go with batons+boards, which combination can I go with (again apart from plaster/MR) that will take up less space? Aquapanels I believe require a 38mm baton according to the manufacturer!

Also, I've never heard of this but the tiler wishes to add some kind of waterproof additive to the grout I prefer, which is one from the Mapei range. Anyone ever heard of such practice?

I would be very grateful of any advice as it's causing me some bother

 

[Dan]

Dot and dab plasterboard and then tank the shower area. I assume the damp is visibly gone and just still in the wall? When was the course put in?

Not heard of a waterproof additive for grout.

Only epoxy is waterproof and can be used as a grout, or adhesive. Expensive to do a whole bathroom though and a bit of an overkill.

Tank it and use the normal Mapei grout and it'll be fine.

If the damp is still quite bad you might need to avoid plasterboard. That won't mix well with moisture.

 

[Dave]

First off, what's caused the damp walls ?

 

[Unused Account 1]

Dry the room out totally ,then see if damp comes back ,worth it ,rather than tile it then mess up ,then decide wether to board or any other method ,its there for ten years ,do it right

 

[WetSaw]

Damp problem needs to be confirmed as completely eliminated before any type of finish. Is the damp coming from inside or outside?

 

[mika_98]

Thanks for the response guys.
The moisture in the walls was due to rising damp. A dpc was done about 3 weeks ago. So hopefully, there will be no further damp but just taking precaution with what moisture is left and if rising damp causes issues in future again.

If I dot/dab, are there any boards that I can use with this fixing method which are better than plaster/MR?

 

[SJPurdy]

Wedi Boards of 20mm thick or more can be dot/dab fixed over uneven walls, thinner Wedi boards can be fixed on a notched trowel bed of adhesive over flat walls (additional dowels/screws and washers also required). Very easy to use, lightweight and good surface to tile onto. Impermeable to water. Expensive?
"No More Ply" boards of 6mm can also be fixed dot/dab again with additional screw fixings. Will also need priming (SBR) both sides to improve adhesion.
"Google" both for full details, confirmation of my notes and fixing instructions.

 

[AliGage]

After 3 weeks.........How much damp is still in the wall. Is the wall an external wall, or internal brick partition?

 

[White Room]

I wouldn't be putting anything on the walls until any damp has gone, you also don't want any gypsum products on the wall...Over the years I've used Sovereign Render lite after damp injection or sand/cement with an integral waterproofer.

 

[p4ulo]

Might be worth running a de-humidifier in the room for a week to really try and drag the moisture out....leaving it damp will only store up problems for the future (unless you are selling the place soon of course?!)

 

[Unused Account 1]

P4ulo ,good advice ,ive done this a couple of times over the years ,just hired a de humidifier ,it solved the. Problem

 

[mika_98]

I like the idea of using No More Ply boards. A decent board for a reasonable price.
Assuming if I go with the dot/dab then screw in process, the idea would be to let the adhesive set and then screw in?

Not sure how much damp remains to be honest, its down to bare brick. Could always get someone in to check with the damp meter again. As for the dehumidifier, that's something I was considering so thanks for the reminder.

 

[Unused Account 1]

If its down to brick. Heat will dry the bricks out ,then youll see if its coming in from the outside.

 

[p4ulo]

@mika_98 - you screw whilst the adhesive is setting, so it squidges down tighter....

 

[Old Mod]

@mika_98 - you screw whilst the adhesive is setting, so it squidges down tighter....

Surely p4ulo u'd knock it out of plumb that way, u make sure it's bedded well, plumb and level it then mechanically fixed once dry?
Unless I'm doing it wrong?