dips around bathtub

[dotto]

Hi again guys.I am doing mi bathroom and after removing the old tiles, i checked the two walls around the bathtub and at certain spots there are dips of about 1 inch. I want to try to make that surface as straight as possible before tiling and therefore my question is:
1) is it ok to use a quick set render to pack the wall up or, as i am using Mapei quick set as tile adhesive, it would be better to use the Mapei, although more expensive than render?
2) The walls in question are plastered, should i prime the walls with acrylic primer before making the walls straight regardless of what i use to straighten the walls, as Mapei quick set or render are both cement based and there could be a reaction with the plaster? Thanks ever so much.

 

[Karis]

1) is it ok to use a quick set render to pack the wall up or, as i am using Mapei quick set as tile adhesive, it would be better to use the Mapei, although more expensive than render?

You can use either but quickset render will be better if the holes are one inch deep! Do not use conventional sand/cement render or you’ll have to wait for it to fully cure which can take 4 weeks.

2) The walls in question are plastered, should i prime the walls with acrylic primer before making the walls straight regardless of what i use to straighten the walls, as Mapei quick set or render are both cement based and there could be a reaction with the plaster?

You need to acrylic prime plaster/plasterboard before using a cement based adhesive. But before you start in earnest, please remember what I said on your other thread;

If the original plaster is blown it should be removed. If your property is 1910 then the external walls will most likely be solid brick, can you confirm? If they are then it begs the question what is Bonding/finishing plaster (if that’s what you have) doing on your external walls! It’s not original, is completely unsuitable & is probably why it’s all now falling off. Solid external walls are prone to damp & sand/cement render & conventional modern plastering materials are not suitable. Duplex plaster board does have a foil backing but screwing any sort of plasterboard over the wall without curing damp or providing a vapour barrier & insulation will lead to cold spots, even more condensation & a festering mess behind the plasterboard. You need to prepare the wall correctly if your to avoid future problems.

 

[dotto]

Hi Karis thanks very much for your time. I will use quick set render where the dips are then. Regarding plaster blown off on external solid brick wall, i am still waiting for an answer in the "Plastering and Rendering" forum. Hopefully i will be able to sort it out without having to invest too much time, also the bathroom is really tiny, so create a stud wall is not really an option.