Sealing rough stone wall with lime mortar inside shower cubicle Fillers, sealants and adhesives for all types of DIY work. Help, advice and information on all aspects of this subject

[TimandCaro]

I am installing a shower tray and cubicle up against a bare, rough stone wall mortared with lime. On the other side of the wall is a roof void. I would like to retain the rough stone look but coated in a white coating. I understand that stone and mortar need to breath but I feel that in this context some sort of sealant needs to be applied? Would PVA followed by a scrubbable white paint do? Thanks.

[stoneyboy]

Hi timandcaro
A very unusual installation and unlikely to be successful. You could try using waterproof PVA and then paint on top but I suspect you will be doing regular patch repairs.
Regards S

[TimandCaro]

Thanks for your thoughts, stoneyboy. Any further ideas or advice will be gratefully received
I wonder if zinsser Watertite Might be more durable? Someone has suggested fibreglass mesh and gel layer but that seems a bit over the top? I’m not really sure whether a breathable coating is necessary?

[stoneyboy]

Hi timandcaro
If you want to retain the rough stone look you should not use mesh and gel.
Since the other side of the wall is not an exposed face you will probably have most success with a solvent based paint for the base rather than water based pva. The Zinsser product should be ok but start by liberally coating the lime mortar joins first. Once you have Zinssered the whole wall you must check that subsequent overpainting is done with compatible paint.
Regards S