Waterproofing a Swimming Pool with Polyurethane [DIY Step-by-Step Guide]

Do you want to coat your pool yourself with a modern, flexible waterproofing system? Then Impermax ST is an excellent choice. This liquid polyurethane coating is easy to apply, chlorine-resistant and completely seamless. In this article, we guide you step by step through waterproofing your pool with Impermax ST and Paintchlore 2K.

What is Impermax ST?

Impermax ST is a liquid, single-component polyurethane coating that cures into a strong, flexible, waterproof membrane. It is specially designed for use in swimming pools, ponds and pitched roofs. Its thixotropic properties also allow application on vertical surfaces without sagging.

Why choose Impermax ST?

• Seamless waterproofing.
• Resistant to chlorine, UV and wear.
• Easy to apply with a roller.
• Suitable for coating and tiling.

What do you need for this project?

• RESION Epoxy floor primer WB
• Impermax ST polyurethane coating
• Fibreglass chopped strand mat 150 g/m²
• Paintchlore 2K swimming pool coating
• Application tools like rollers, brushes, mixing cups and gloves

Step 1. Prepare the substrate

• Ensure the concrete is fully cured, clean, dry and stable.
• Round all internal and external corners with sand-cement.
• Repair cracks using epoxy resin + Stewathix thickener.
• Remove dust, debris and any loose material.

Step 2. Apply the epoxy primer 

• Add component A (plastic container) fully into component B (tin).
• Mix for 2 minutes with a drill and spiral mixer until homogeneous.
• Add 20–50% water gradually, making sure each addition is fully absorbed. 
• Apply with a roller and back-roll in cross directions. Avoid pooling.
• If the substrate is very porous, apply a second primer coat.
• Allow the primer to cure for approximately 6 hours, depending on temperature, humidity and substrate density.

Step 3. Reinforce vulnerable spots

• Cut fibreglass mat 150 g/m² to size.
• Apply the first coat of Impermax ST to corners, joints and pipe penetrations.
• Place the fibreglass mat directly into the wet coating.
• Fully saturate the mat with extra Impermax ST.

Step 4. Apply Impermax ST 

Apply 2 or 3 coats of Impermax ST, depending on the surface:

• Apply wet-on-wet where feasible, but ensure each coat cures adequately.
• Apply each coat in cross directions for an even finish.
• Use a medium-pile roller for best results.

Step 5. Finishing (paint or tiles)

5A. Coating the pool with Paintchlore 2K

• Mix Paintchlore 2K at 4:1 ratio (20 kg A + 5 kg B).
• Apply 2 coats, approx. 200 g/m² per coat.
• Minimum curing time: 8 hours between coats.
• Allow 7–10 days final cure before filling with water.

5B. Tiling the pool

• Broadcast dry quartz sand into the final wet Impermax ST coat.
• Allow to cure.
• Use a suitable C2 tile adhesive and a chlorine-resistant grout.

Need help with your pool project?

Do you have questions about products, quantities, or your specific situation? Feel free to contact our specialists — we’re happy to advise you by email or WhatsApp.