What is a waterproofing membrane? The building’s invisible shield

A waterproofing membrane is a flexible, durable sheet or coating used to keep water out. It protects the structure against rain, damp and weather, and is what makes long service life possible.

What it provides

• Waterproofing: an effective barrier against rain, snow, groundwater and damp.
• Protection: extends the life of concrete, roofs, foundations, terraces and wet rooms.
• Heat and UV resistance: stands up to sunlight, temperature swings and chemicals.
• Flexibility: follows thermal movement and structural movement.

Types

• Bituminous: bitumen based, economical and widely used, torch applied.
• PVC: plastic based, flexible, light and chemically resistant.
• TPO: heat welded, high UV resistance and environmentally friendlier.
• Liquid applied: brushed or rolled on, giving a seamless surface around complex details.

Where it is used

• Roof waterproofing
• Foundation waterproofing
• Terraces and balconies
• Wet rooms — bathrooms and WCs
• Basement retaining walls

Rules for correct installation

• The substrate must be clean, dry and smooth, and always primed.
• Laps of at least 10 cm, fully bonded at every seam.
• Turn up vertical faces by at least 20 cm and terminate the top edge properly.
• Add reinforcement at drains, penetrations and corners.

Points to watch

• Do not work on a laid membrane with sharp tools or materials.
• Never cover the membrane before a flood test.
• The wrong membrane type tears within a season — the substrate and the use decide the choice.