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?
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.
Tip: the substrate may be slightly damp, but not wet.
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.
Note: this reinforcement is optional and only needed where extra strength is required.
Step 4. Apply Impermax ST
Apply 2 or 3 coats of Impermax ST, depending on the surface:
| Application |
Number of coats |
Consumption per coat |
Total thickness |
| Walls |
2 coats |
1 kg/m2 |
2.0 mm |
| Floor |
3 coats |
0.7 kg/m2 |
2.1 mm |
- 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.
Tip: apply Impermax ST between 10–30°C, on a dry substrate at least 3°C above dewpoint. Avoid hot surfaces and direct sunlight.
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.
Note: if tiling, PaintChlore is not required.
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.
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