That is my worry too. I am thinking of priming with weak PVA then applying a tough paint (eggshell or scrubbable emulsion) to protect the paper face. The old 1930s eggshell on plaster seems as tough as old boots.
Moving a door in a plasterboard wall
- Thread starter joewa
- Start date
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Interesting comment, Richard, regarding no sealer if you are tiling, I may be wrong but I seem to recall that it said on the tin to use 3 coats before tiling in a bathroom to provide a vapour barrier, which I did and the tiles are still on. I think the sealer was Knauf from BuilderCenter.
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Well that's what the manufacturer of a proprietary sealer would say; in many cases an SBR based sealer probably won’t do any harm & just be an unnecessary expense. The adhesive manufacturer’s recommendations are the ones to follow in the 1st instance but neither does British Gypsum recommend a primer/sealer. The biggest danger is that you can reduce tile adhesion which could cause problems both initially & in the longer term, especially with large/heavy tiles. You should never use PVA under tiles & it can prove disastrous in wet areas.
Actually their white book states use of 2 coats of their sealer OR use MR boards.
- Gyproc moisture resistant grade boards, Glasroc F MULTIBOARD or
Rigidur H are recommended for intermittent moisture applications,
including splashbacks. Alternatively, for splashbacks, boards can be
coated with two coats of Gyproc Drywall Sealer to prepare for
tiling.
White Book states “The application of Gyproc Drywall Sealer provides surface water absorbtion resistance only & does not meet the performance for moisture resistant grade boards”.
The recommendation for sealer in this instance is as a surface sealer on Standard Wall Board used in moisture applications, it's not to enhance tile adhesion. I would only ever advise using MR boards in bath/shower rooms & tile adhesive manufacturers usually recommend tanking wet areas which is really the only suitable method; better still, use waterproof tile backer board. The white book doesn’t specifically mention the effect sealing has on tile adhesion but just a little further on the same page it recommends tiling directly onto the background for tiles exceeding 20 kg/sqm up to 32 kg/sqm. Another pdf guide here;
http://www.british-gypsum.com/pdf/sb_tiling_200701.pdf
Agreed, MR for humid rooms - no sealer. It's just I cannot see anywhere that says sealer on plasterboard cannot support the maximum 32 kg/sq m. I'm a novice trying to learn here, so please bear with me. I do appreciate your time.
If you seal the surface of PB with a waterproof sealer, the water in the adhesive will not be drawn into the board surface &, initially, it will take longer to grab & set. As I said, the White Book doesn’t specifically mention the effect on tile adhesion (but I think it must) &, with regular size/weight tiles, it won’t be important but there is a recommendation to tile directly onto the background where tile weights up to 32 kg/sqm are involved.
Incidentally you must prime MR PB with a bonding primer if you intend to plaster it due to water repellant additives used in the manufacture of the board.
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