Acrylic and silicone are two of the most common liquid roof coating chemistries used on roofs across Ireland and Northern Ireland. They look similar in the tin, cost broadly similar per litre, and both get applied with a roller or airless spray. But their long-term performance is very different — especially under Ireland’s frequent rain. This article explains, honestly, when to choose each — and why the cheaper option can end up more expensive over a building’s lifecycle.
The chemistry in plain English
Acrylic coatings (examples: Cromapol, Acrypol Plus, Aquaseal) are water-based or solvent-based polymer emulsions, usually with chopped polyester or glass fibre reinforcement. They dry by evaporation. They cure to a flexible but hydrophilic film — it will absorb moisture over time.
Silicone coatings (examples: GacoFlex S42, Cromar Hydrosil, Liquasil) are single-component elastomers that cure by reaction with atmospheric moisture. They form a hydrophobic film that is chemically unaffected by standing water.
This single difference — water-permeable vs water-repellent — drives almost every downstream performance characteristic.
Where acrylic shines
Acrylic coatings are genuinely useful products. They:
- Are widely available in small pack sizes at accessible prices
- Are DIY-friendly — can be applied by non-specialists
- Work well for short-term patch repairs and minor leak sealing
- Come in a wider colour range than silicones
- Have lower entry cost per m²
For a small domestic porch roof or a one-off repair, acrylic often makes commercial sense. We’re not going to tell you otherwise.
Where silicone dominates
For commercial, industrial and public-sector roofs, silicone wins on every long-term performance metric:
| Property | Acrylic | Silicone |
|---|---|---|
| Ponding water | Softens, absorbs moisture | Unaffected indefinitely |
| UV stability | Gradual chalking, colour fade | Stable, no chalk |
| Service life | 5–10 years | 15–25 years |
| Recoat interval | Every 5–8 years | Every 15–20 years |
| Typical warranty | Product-only, short | Up to 20 years (system) |
| Class A fire | Rarely | GacoFlex S42: Yes |
| Low VOC | Variable | Available below 50 g/L |
The total cost of ownership question
Acrylic wins on initial cost per m². Silicone wins on lifecycle cost per m². Picture a 1,000 m² commercial flat roof over 20 years:
- Acrylic route: a lower installed cost on day one, but a recoat roughly every 7 years — typically two additional recoats over 20 years, each with its own access, preparation and labour costs.
- Silicone route (GacoFlex S42, 20-yr warranty): a higher installed cost on day one, with no recoat needed during the warranty period.
Once the repeat recoats are added in, the silicone route typically costs less over the asset lifecycle — plus you get 20 years without disruption, scaffold costs, access hires and the operational headache of managing repeat refurbishments. Every roof is priced per project, so ask for a fixed quote for both routes after a free site survey.
How to choose
Use this simple decision framework:
- Short-term, small, low-stakes? → Acrylic (Cromapol, Acrypol)
- Commercial, long hold, tender spec, occupied? → Silicone (GacoFlex S42, Liquasil, Hydrosil)
- Heavy ponding water issue? → Silicone, always
- BER upgrade or BREEAM project? → Silicone with cool-roof cert
- Asbestos cement roof encapsulation? → Silicone, always
Still unsure which chemistry fits your roof? Email info@duratite.ie or see our full silicone roof coating guide. Free written advice, no obligation.