Crystal Waterproofing Renovations

· 2 min read

Progress Update: Cavity Drain Membrane & Wykamol XPS Insulation in Clapham Common

Phase two of our Clapham Common basement waterproofing project is complete, featuring Wykamol cavity drain membrane and XPS Highload floor insulation.

Following on from our initial structural preparation, phase two of our basement waterproofing project in Clapham Common is now complete. We have fully wrapped the basement envelope with a robust Type C water management system and high-performance floor insulation.

Key Technical Milestones

Wykamol Cavity Drain Membrane: High-density dimpled membrane installed across internal walls and floor to safely manage water ingress and relieve hydrostatic pressure.

Wykamol XPS Highload Insulation: Heavy-duty, closed-cell extruded polystyrene boards laid directly over the subfloor, delivering exceptional compressive strength and thermal performance.

Sealed Perimeter & Joints: Perimeter channels and wall plugs sealed with specialist waterproof tape to form a continuous vapor barrier prior to floor screeding and wall framing.

Why This System Works

Combining a Type C cavity drain membrane with Wykamol XPS Highload insulation ensures a completely dry, energy-efficient basement. The membrane handles potential moisture penetration while the insulation eliminates thermal bridging from the slab, providing the ideal foundation for underfloor heating and final finishes.

What's Next?

With the membrane and insulation securely installed, our team is testing the drainage channels and sump pump system before laying the final floor screed and starting wall studwork. Stay tuned for the next update as this Clapham Common space transforms into a fully habitable living area!

Reading time is an estimate at 200 words a minute. Written up on 16 September 2026, last changed on 18 September 2026. Nothing here is a substitute for somebody looking at your own basement.

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