EPDM rubber membrane was a popular flat-roof system through the 1990s and 2000s. A lot of it is now 20+ years old, chalking, shrinking at laps and leaking at upstands after years of Irish rain and wind. Strip-and-replace is disruptive and expensive. Silicone overcoat bonds directly to sound EPDM and resets the warranty clock for another 15-20 years. Here’s how.
Typical failing EPDM symptoms
- Surface chalking, colour loss, UV-bleaching
- Lap joints lifting or peeling
- Pinhole leaks around mechanical fixings
- Ponding water causing localised membrane softening
- Upstands and penetrations leaking despite patching
- Overall brittleness — membrane no longer flexes with deck movement
Why silicone overcoat works
Silicone bonds directly to clean, sound EPDM without a primer. The membrane forms a seamless hydrophobic layer over the entire roof — new laps, new penetrations, new ponding resistance, all in one application. Existing laps, detail work and fasteners are covered and sealed by the coating.
Critically: silicone flexes with EPDM. Both are elastomers. There’s no compatibility issue, no thermal expansion mismatch, no risk of the overcoat cracking while the EPDM continues to move.
When EPDM overcoat is right
- Membrane is 15–25 years old but fundamentally sound
- No large sections of substrate damage
- Insulation below is dry (saturated insulation needs replacing first)
- Budget doesn’t stretch to full strip-and-replace
- Operational disruption needs to be minimised
When strip-and-replace is better
- Large sections of membrane are failed or missing
- Insulation below is saturated
- Structural deck problems (rot, corrosion)
- Full re-insulation is planned as part of the works
Typical project
- Survey: Free Duratite survey identifies condition and suitability
- Repair: Any major defects patched with EPDM primer + patch
- Clean: Pressure wash with biocidal cleaner, remove debris, let dry
- Detail: SF42 fibre-reinforced silicone over laps, upstands, penetrations
- Topcoat: GacoFlex S42 at 1.0 L/m² in single pass
- Cure: 8–12 hours, warranty issue
Cost
A silicone overcoat on EPDM is priced per project, with a fixed quote after a free site survey for either the 15-year or the 20-year premium warranty tier. Compared with strip-and-replace (new EPDM, new insulation, disposal), silicone typically saves 40–50% on total cost and removes 90% of the operational disruption.
Weathered EPDM? Email info@duratite.ie for a free survey, or see our silicone guide.