Liquid Rubber — Application, Consumption & Comparison Guide
Liquid rubber (also sold as liquid plastic, liquid coating, fluid-applied membrane, or cold-applied waterproofing) is the modern alternative to traditional bitumen felt, EPDM membranes and built-up roofing. The cured film is a seamless, elastic, monolithic waterproof barrier — no joints, no overlap seams, no torch, no specialist gear. This page covers what liquid rubber is, how to apply it, how much you need, and how it compares with traditional options.
Shop: Liquid rubber paint — 14 RAL colours, 1.2 / 3.5 / 6 kg tubs →
What is liquid rubber?
Liquid rubber is a water-based acrylic-latex coating that's applied cold with brush, roller or airless spray. The cured film is a thin (200–400 µm) elastic membrane chemically similar to rubber. The technical name in standards-speak is "rubberised waterproof coating" or "elastic protective coating". In trade language it's also called liquid plastic, fluid-applied membrane, or simply rubber paint.
Compared to the old solvent-based 2-component PU systems, the modern water-based liquid rubber has:
- Single-component formulation — open the tub, stir, apply. No mixing, no pot life, no waste
- Water clean-up — tools rinse off with water, no white spirit
- Low odour, low VOC — safer for indoor application and around occupied spaces
- Cold application — no torch, no fire risk, suitable for warehouse roofs and inhabited buildings
Where liquid rubber excels
- Flat roof refurbishment over old bitumen felt — direct overlay, no strip-out
- Balcony waterproofing over existing tiles or screed
- Basement walls from inside (where exterior excavation isn't practical)
- Industrial roofs on corrugated iron, steel deck, asbestos-cement (encapsulation only)
- Concrete waterproofing — retaining walls, plinth, exposed concrete
- Pool linings — concrete, steel and polyester pools
Consumption per substrate
| Substrate | Per coat | Total (2 coats) |
|---|---|---|
| Bitumen felt (existing) | 120 g/m² | 0.24 kg/m² |
| Concrete (smooth) | 140 g/m² | 0.28 kg/m² |
| Concrete (rough) | 170 g/m² | 0.34 kg/m² |
| OSB / plywood / wood | 180 g/m² | 0.36 kg/m² |
For exact tub combinations, use the Material calculator.
Liquid rubber vs traditional alternatives
Compared to bitumen felt: cold application (no torch, no fire risk), no joints (seamless monolithic film), and much lower material cost (£3.50–£4.50/m² vs £7–£13/m²). Compared to EPDM membrane: also seamless, DIY-friendly, lower material cost, easier to apply to complex geometry. Compared to PU 2-component systems: simpler application, no mixing, no pot life, water clean-up, safer for occupied spaces.
For detailed cost analysis see How much does liquid rubber paint cost per m²?. For direct EPDM comparison see Liquid rubber vs EPDM.