Bathroom Water Seepage Repair Guide

Who will do it?

Contrary to the popular believe this is not a plumber's job. This is a mason(Rajmistry)'s job. Plumbing part will be installed by the plumber but the waterproofing job needs an expert mason.

What treatments do you need for your bathroom renovation?

• The tiles need to be removed.
• The toilet needs to be removed too.
• The surface of the demolished place needs to be cleaned properly and should be left to dry for 24 hours.
• Use PMM (Polymer Modified Mortar) to seal the uneven surface. If the contractor skips this then ask him to do this without any neglect.

• We need to cover the splash area of bathroom using a waterproofing chemical.
• Then we need to lay tiles again and refit the toilet, shower and taps.

Popular choices for PMM (Polymer Modified Mortar)

SBR based products. My favorite is SikaLatex Power. (Product Expiry is 18 months after date of manufacturing.). It is a very expensive product yet yields very good results. 

Please consult your mason/ contractor/product site for better understandings.

Popular Choices for Waterproofing 

Don't use Dr Fixit Pidiproof 101 LW+. Cheap choice will be Dr Fixit 301 Pidicrete URP. SikaLatex SBR is also good. Don't use these things on inside of water tanks. It might cause cancer as these have carcinogen. 

If we are talking about more expensive solutions then there are many choices out there. Acrylic polymer cementitious coatings are the most popular ones. And these are food grade stuff. 

SikaTop 107 Seal IN(Safest as it is a Swiss company.), Dr Fixit 112 Pidifin 2k(Just ), Asian Paints Smart Care Damp Block 2K(It claims that it can withstand 5bar or equivalent ~ 50 mH2O of hydrostatic pressure. https://www.sensorsone.com/bar-to-mh2o-conversi... consult this for conversion referrence), Birla White Interior Surface (They say 3 bar. So, it stands between Pidifin and Damp Block 2k), Berger Paints Damp Stop etc.

I have experience with Sika and Asian Paints. 

Please ask the mason to follow the instruction properly. Don't add a single drop of water. It is a two wo/man job for creating the mixture. One will measure and pour fluid. Then s/he ll slowly add water. The other person will hold a cement mixer/ stir the solution slowly. Rest the solution for 5-6 min to allow the air bubbles to escape. Apply the mixer with help of a paintbrush in longitudinal manner. After 5-6 hrs of curing (Asian Paints) apply the second coat in horizontal manner. 

Then use PMM to lay the protective layer. And then use either tile adhesive/ PMM to affix tiles.

If the tile's gaps are extremely narrow then use cement based sandless grout. I suggest you to keep some gaps like 3-4mm using spacers. And use epoxy grout to seal those gaps. 

How to grout?

Even if you are using cement based grout then also don't use water. Use SBR solvents like SikaLatex SBR/ Dr Fixit Super Latex. If you are using epoxy based grout e.g. Roff then you have to be very very very careful while using it. Better leave it for the professional and remember not everyone can expertly lay epoxy grout. 

Don't forget to cure your tiles. After it you need to fill the gaps using epoxy. Epoxy are extremely heat/chemical/water resistant material. They will probably outlast the lives of your tiles and marbles.

Articles which inspired this post indian-vs-western-toilet by @flawlessking and Which dr fixit for seapage walls? Need to mix with putty by @Budhe-Baba