Liquid Plastic — Application, Consumption & Comparison
Liquid plastic (also called 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 plastic is, how to apply it, how much you need, and how it compares with traditional options.
What is liquid plastic?
Liquid plastic 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 rubber, fluid-applied membrane, or simply rubber paint.
Compared to the old solvent-based 2-component PU systems, the modern water-based liquid plastic 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 plastic 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 plastic 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.