Rayson SealForce RC40 is a two-component, cold-applied aliphatic polyurea waterproofing membrane for exposed roofs — roller-, brush- or spray-applied, UV-stable and walkable, with certified cool-roof reflectance.
Best for exposed flat and pitched roofs that must stay UV-stable and reflective for decades — over concrete, screed, old membranes, metal, PU foam or bitumen.
SealForce RC40 is Rayson's cold-applied roof waterproofing membrane: a two-component, aliphatic (polyaspartic) polyurea that brushes, rolls or sprays onto a primed roof and cures to a seamless elastic film. Because the polymer is fully aliphatic, it holds its colour and gloss under direct sun where ordinary aromatic membranes darken.
The cured membrane bridges cracks, shrugs off ponding water with effectively zero uptake, and stays flexible from -35 °C to +80 °C, so it moves with the roof through daily thermal cycling instead of splitting. In its white shade it is a certified cool-roof surface — high solar reflectance that keeps the slab and the space below it cooler.
It bonds to concrete, cement tiles and screeds, metal, and directly over sound bitumen, PVC/TPO single-ply or older liquid membranes and PU-foam insulation, each with the appropriate primer. Corners, drains and cracks are reinforced with polyester fabric bedded wet-on-wet.
A standalone product performs its job in a single application rather than as one layer of a multi-coat system.
The figures below are a guide for planning. Site conditions and workmanship affect results — confirm the details for your project with our technical team.
| Coverage | 1–1.2 kg/m² total over two layers on cementitious surfaces |
|---|---|
| Mixing | Two parts mixed 13:8 (A:B) by weight; stir Part A ~1 minute, then combine and low-speed mix ~3 minutes until homogeneous; apply undiluted in at least two layers |
| Drying & curing | Touch/recoat ~18 h at 23 °C; resists early rain after 3 h; full hardening ~7 days |
| Pack sizes | Sets (A+B) of 21 kg and 5.25 kg |
Aliphatic (polyaspartic) polyurea keeps its colour and surface under ultraviolet light, where aromatic polyureas darken over time. On an exposed roof in Singapore sun, that UV stability keeps a cool-roof surface reflective and looking right for years.
No. Unlike hot-spray polyureas, RC40 is cold-applied by roller, brush or airless spray in at least two layers, so it suits ordinary roofing works and detail-heavy roofs without a heated plural-component rig.
Yes, over sound bitumen, PVC/TPO single-ply, PU-foam insulation or old liquid membranes, each with the correct primer and after proper preparation. A failing or debonding membrane must be dealt with first.
In the white shade it has a high solar reflectance and infrared emittance, reflecting sunlight instead of absorbing it. That lowers roof-surface and internal temperatures and can contribute to green-building credits.
It resists early rain about 3 hours after application, with full hardening in roughly 7 days. Timings lengthen in cool, humid conditions and shorten in heat.
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Answers from Rayson's own product information
Guidance only — confirm specifications with the Rayson technical team.