In the case of bathrooms, kitchens and showers, having walls made of plasterboards or gypsum, high protection against moisture and water is required. Watertite WA12 is a composite waterproofing membrane and tile finish system, specially designed to provide such protection on flexible surfaces like gypsum or plasterboard walls, exposed to moderate water splashes.
A Step-by-step Guide
What you will need
Polyflex, Polybit CL 252, Polybit CM 11, Polybit CE 33
Step 1: Surface Preparation
The surface should be free of any cement laitance, oil, grease, curing compound and any other deleterious materials.
Light mechanical grinding / grit blasting / high pressure water jet may be used to clean the surface to be coated, based on the degree of contamination.
Nail heads and other protrusions that are likely to damage the coating must be removed or ground.
Structurally unsound and friable concrete must be removed and repaired. Honey combed or spalled concrete, surface irregularities, blow holes to be repaired with a suitable Polycrete concrete repair mortar.
Presence of organic growth should be physically removed and then treated chemically to restraint further growth. The surface should be thoroughly wetted with clean water and brought to a saturated surface dry condition (SSD) prior to the application of the coating.
Step 2: Mixing
Polythane P is a single component product but mixing the contents of the pail thoroughly prior to application is recommended.
This is required to remove any sedimentation and can be done with a slow speed drill fitted with amixing paddle to avoid formation of air bubbles.
Step 3: Priming
Polythane P does not require priming and hence can be directly applied onto the concrete surface.
For highly porous surface, a primer coat can be produced at site by mixing 1 part Polythane P with 1 part water.
Primer coat shall be applied at the rate of 5m2/L and allowed to dry.
Coating interval shall not exceed 24 hours.
Step 4: Corner detailing
Reinforce all corners with Ceresit CL 252 sealing strip. The sealing strip shall be embedded into the first coat whilst it is still wet and covered fully with the second coat.
Step 5: Application
1. The coating is normally applied in two or more coats. Apply the first coat of Polythane P by a brush or roller on the prepared damp surface.
2. The coating is to be applied on the cleaned surface at the rate of 0.8 L/m2. 1.5mm DFT in 3 coats and can be applied at approx. 0.8L/m2/coat.
3. Similarly apply one coat on all the fillets and edges, extending up to 50mm on either side.
4. After the application of the first coat and whilst the coating is still wet, embed Polybit CL252 fibre mesh at all corners and joints.
5. After the application of the first coat, apply the second coat at right angles to the first coat and only after the first coat has dried completely.
6. Clean all tools immediately with water after use. Hardened materials can be removed mechanically only.
Step 6: Surface Preparation
The surface should be dry, free of any cement laitance, oil, grease, curing compound and any other deleterious materials. New concrete moisture content on the surface should be less than 5%.
Step 7: Application
1. Pour Polybit CM 16 into the precisely measured amount of clean water (7.5L to 8.5L for 25kg bag) and mix with a drill and mixer until a homogenous mass without lumps is reached.
2. Leave the material for 2 minutes and then mix it again.
3. Apply the mortar with a suitable notched trowel.
4. For indoor use, the mortar coverage (wetting) on the tile backside must be at least 65%.
5. The floating-buttering method shall be used for larger tiles. (i.e. additionally a thin layer of the mortar should be spread on the tile’s backside, wetting equal or more than 90%).
6. Place the tiles only during the open time of the adhesive.
7. Do not lay tiles butt jointed. Fresh excess mortar can be removed with water, hardened material can only be removed.
8. Grouting on the wall can be done after 8 hours and after 24 hours in floor using Polybit grouts.
9. Walkability is reached after 24 hours.
10. Expansion joints, joints at the corners of walls and floor and around sanitary equipment shall be filled with silicone sealant.
Step 8: Surface Preparation
The surface and thin-bed mortar, dispersion adhesive or thick-bed mortar must have set sufficiently hard and dry.
Scraped joints must first be wetted. In case of tile coverings with a porous or non-scratchproof surface test suitability of CE 40 for grouting.
Step 9: Application
1. Measured quantity of Polybit CE 40 pour into the cold and clean water and mix with an electric mixer until you obtain a homogenous mixture, free of lumps.
2. 1.5 L of water are required for 5 kg of Polybit CE 40.Mix again after 3 minutes.
3. Apply the joint mortars using the slurry technique. Wipe over and clean freshly grouted tiles with a damp sponge.
4. Remove the dry film later with a soft cloth.
5. Dampen the freshly grouted joints after 24 hours to prevent surface moisture deficiency.
6. Floor tiles can be walked on after only 24 hours