Roof coatings are one of the most misunderstood products in the roofing industry. Marketing materials promise miracles: "Never replace your roof again!" "100% waterproof!" Reality is more nuanced. Coatings are a legitimate, cost-effective maintenance and restoration strategy for specific roof types in specific conditions. They are NOT a substitute for structural repair or a failing roof system.
Roof Coating Types Compared
| Coating Type | Best For | Ponding Water | UV Resistance | Cost/sq ft | FL Lifespan |
|---|---|---|---|---|---|
| Silicone | Flat/low-slope, any substrate | Excellent | Excellent | $3.00-5.00 | 15-20 years |
| Acrylic | Metal roofs, steep slope | Poor (re-emulsifies) | Good | $2.00-3.50 | 10-15 years |
| Polyurethane | High-traffic areas, abuse resistance | Good | Fair (needs topcoat) | $3.50-6.00 | 15-20 years |
| Elastomeric | Concrete, stucco, masonry walls/roofs | Moderate | Good | $2.50-4.50 | 10-15 years |
| Asphaltic/Aluminum | Built-up roofs (BUR), temporary | Poor | Fair | $1.50-3.00 | 5-10 years |
Silicone Coatings (Recommended for Florida)
Silicone is the premium choice for Florida flat roofs. Its chemistry makes it uniquely suited to our climate:
- Ponding water tolerance: Silicone does not absorb water or re-emulsify. It can sit under standing water indefinitely without degrading. In Florida, where afternoon thunderstorms dump inches of rain on flat roofs that may drain slowly, this is critical.
- UV stability: Silicone maintains its properties under intense UV exposure without becoming brittle or chalking significantly.
- Single-coat application: Many silicone systems achieve full warranty protection in a single coat at 20-25 mils DFT (dry film thickness), reducing labor costs.
- Reflectivity: White silicone coatings achieve 0.85+ solar reflectance, qualifying as cool roofs and reducing building cooling costs by 15-25%.
- Limitations: Silicone attracts dirt more than acrylic (reduces reflectivity over time without cleaning). It's also slippery when wet, requiring caution for maintenance access.
Acrylic Coatings
- Water-based, easy application, lowest cost
- Excellent adhesion to metal roofs (re-coating aging metal is acrylic's sweet spot)
- Critical FL limitation: Acrylic re-emulsifies in ponding water. If water sits on an acrylic-coated roof for more than 48 hours, the coating softens and can wash away. This makes acrylic inappropriate for dead-flat roofs in Florida's rainy season.
- Best application: Metal roofs with adequate slope (2:12 or greater), where water drains quickly
When Coating Makes Sense
- Existing roof membrane is structurally sound but approaching end of warranty
- No active leaks (or leaks are isolated and repairable before coating)
- Insulation is dry (moisture scan shows less than 15% of insulation area is saturated)
- Decking is solid (no soft spots, no structural concerns)
- Budget favors $2-6/sq ft coating over $8-15/sq ft full replacement
- Building will not undergo major renovations (HVAC, structural) in the next 10 years
- Roof age is 10-20 years (old enough to benefit, young enough to have remaining structural life)
When Coating Does NOT Work
- Multiple active leaks: Coating over a leaking roof is painting over water damage. Fix the leaks properly first, or replace.
- Saturated insulation: If moisture scans show significant wet insulation, coating traps the moisture. The insulation must be cut out and replaced, which often means full replacement is more economical.
- Structural damage: Rotted decking, sagging areas, or compromised structural members require repair or replacement, not coating.
- Asphalt shingles: Coatings on steep-slope asphalt shingles are generally not recommended by any major manufacturer. They can trap moisture between the coating and shingle, accelerating deterioration. Roof Maxx is a different product category (rejuvenator, not coating) designed specifically for asphalt shingles.
- Over 25 years old: A roof system past its expected lifespan needs replacement, not a temporary patch.
The Coating Process
- Moisture survey: Infrared or nuclear moisture scan to identify wet insulation. Cost: $500-1,500.
- Repair: Fix all identified issues. Replace wet insulation sections, repair flashing, seal penetrations.
- Cleaning: Pressure wash entire roof surface. Coating will not adhere to dirty, oxidized, or chalked surfaces.
- Priming: Some substrates require primer for adhesion (especially over aged single-ply membranes).
- Application: Spray, roll, or brush coating to manufacturer's specified thickness (typically 20-30 mils wet).
- Reinforcement: Fabric reinforcement embedded in coating at seams, penetrations, and transitions.
- Final inspection: Thickness verification (wet mil gauge during application, DFT gauge after cure).
Coating Costs in Pinellas County
| Roof Size | Acrylic | Silicone | Full Replacement |
|---|---|---|---|
| 2,000 sq ft | $4,000-7,000 | $6,000-10,000 | $16,000-30,000 |
| 5,000 sq ft | $10,000-17,500 | $15,000-25,000 | $40,000-75,000 |
| 10,000 sq ft | $20,000-35,000 | $30,000-50,000 | $80,000-150,000 |
| 25,000 sq ft | $50,000-87,500 | $75,000-125,000 | $200,000-375,000 |
The economics are clear: coating a structurally sound roof costs 30-50% of full replacement while extending the roof's useful life by 10-20 years.
Get a Roof Coating Assessment
Not every roof is a coating candidate. We provide free assessments including moisture scanning to determine if your commercial or flat roof qualifies for coating restoration. Schedule a freeroof inspection. ServingSt. Petersburg, Clearwater, and all of Pinellas County.