The reflective roof coating that keeps your buildings cool.

Two properties decide how well a reflective roof coating performs: solar reflectance and thermal emissivity.

Solar reflectance is how much sunlight a surface bounces back instead of soaking up. Ordinary white paint manages 70 to 80% when new, then fades fast as it gets dirty and chalks. A good reflective coating starts above 90% and stays there, thanks to its pigments and an anti-UV topcoat.

Thermal emissivity is how readily the surface sheds the little heat it does absorb, as infrared. The best coatings clear 0.90.

Put the two together and you get the SRI (Solar Reflectance Index) — the ASTM E1980 number the industry rates coatings by. CovaTherm 20 comes in at SRI 119 new, and 118 after accelerated aging in a QUV chamber. On a peak summer day a dark roof can hit 70 to 80 °C; a reflective one stays about ten degrees above the air temperature, so far less heat ever reaches the building.

Six benefits we can measure — in the research and on our own jobs:

• Cooler inside: 5 to 10 °C less under the roof, no AC needed. A warehouse that hits 45 °C at the summer peak settles back to 32–35 °C.
• Lower AC bills: field studies show 11 to 27% off peak demand, up to 40% on the hardest-working industrial roofs.
• Comfort and output: heat-stress research links a cooler floor to sharper focus and fewer heat-related stoppages.
• Longer-lasting waterproofing: a cooler surface expands and contracts less, which adds 8 to 10 years to bitumen, EPDM, or PVC membranes.
• Cooler cities: at scale, reflective roofs pull the surrounding air down by a few degrees and cut heat-wave deaths.
• More solar: a white roof adds about 10% summer output for monofacial panels, and 10–20% for bifacial ones, from the reflected light.

It's not a fix for everything. Three limits to know up front:

• It won't save failing waterproofing. Reflective coatings are watertight, but they're not a full waterproofing system. A roof that leaks all over still needs re-roofing. For the odd crack or blister, though, our 2-in-1 CovaSeal 20 does both — reflective finish and liquid waterproofing in one pass.
• It needs the right weather to go on. Water-based coatings can't be sprayed in damp or rain; the sweet spot is 17 to 30 °C, and wind gets in the way of spraying — so we time the job to the season.
• Standing water trips up some products. On low-slope roofs (under 3%), ponding can lift an ordinary reflective coating. That's why CovaSeal 20 uses an elastomeric resin built to sit under standing water.

Reflective coatings aren't all the same. Four things decide how one actually performs — and how long it lasts:

1. How much goes on. The thicker the build, the higher and longer-lasting the reflectance. Look for systems above 0.7 L/m².
2. The SRI. Insist on 100+ when new and 90+ once aged, measured after standardized accelerated aging. CovaTherm 20 holds 119/118.
3. The anti-UV topcoat. It stops the yellowing and chalking that kill reflectance in a couple of years. It's what separates a 5-year product from a 20-year one.
4. The real lifespan. Acrylic resin lasts 2–5 years, polyurethane 8–10, polyurethane plus topcoat up to 20. A 14-month payback only counts if you're not redoing the roof every five years.

A professional job runs in five steps, done by trained applicators:

1. Survey: the substrate's condition, moisture, repairs needed, and what the coating will bond to.
2. Pressure-wash: off comes the moss, dust, and grime.
3. Primer: the undercoat that makes the topcoats stick for the long haul.
4. Base coat: the reflective layer, sprayed in two cross passes from the ground. The rigs stay at the foot of the building; only the hoses go up. No load on the structure, no vibration, no risk to the existing waterproofing.
5. Topcoat (long-life systems): the anti-UV, anti-dirt finish that keeps the reflectance going for 20 years.

It all goes on in dry weather, 10 to 35 °C. A typical 1,000 m² roof takes 3 to 5 days, and your operation never stops. Crews are trained to work safely up top.

A reflective coating isn't the only way to cool a building. But it beats insulation and air-conditioning on three counts: cost, how fast it goes in, and payback.

A reflective coating pays back fastest, with nothing torn off and no downtime. For an industrial or commercial building over ten years old, it's the cheapest way to drop the indoor heat and buy the roof more years.

Beyond the building itself, a reflective roof feeds the bigger picture: less air-conditioning, lower cooling emissions, and a more comfortable place to work.

City-scale research all lands in the same place: cover enough industrial and commercial roofs and you offset a real share of urban warming, shave AC demand, and save lives in a heat wave. For one building, it's a smart investment. For a city, it's a public-health move.