Metal Roof Coating Types and Prep Work
A coating job has two halves: the prep that makes the old roof tight, and the coat that goes over it. The 2018 IRC allows a new coating over existing metal panels without a tear-off. Which coating fits depends on how flat the roof is and whether water sits on it.
Silicone Coatings
One silicone maker calls it the most widely used coating in commercial roof restoration. It handles UV well and holds up under ponding water, meaning water that sits on the roof for more than 48 hours. The downsides, by that maker's own account, are that it picks up dirt within 6 to 12 months and is very slippery when wet. HomeAdvisor says high-end silicones can last 25 years or more.
- Installed cost: $1.50 to $2.50 per sq ft (HomeAdvisor)
- Primer: often sold as a complete system that needs none, though rusted areas still get a rust primer
- Best on: low-slope shop and warehouse roofs where water collects
Acrylic (Elastomeric) Coatings
Acrylic is the budget elastomeric coating. It's water-based, so it breaks down under standing water, and one maker recommends it only on steep metal roofs where water runs off. On a visible house roof, that same maker gives acrylic the edge for looks and for keeping its reflectivity, since it doesn't hold dirt the way silicone does.
- Installed cost: $0.65 to $1.75 per sq ft (HomeAdvisor)
- Recoat: every 10 years or sooner, by HomeAdvisor's estimate
- Best on: pitched house roofs that drain fast
Urethane Coatings
Urethane, listed by HomeAdvisor as polyurea or polyurethane, is the hardest-wearing of the three and the most expensive. It needs a primer and two coats. HomeAdvisor rates it for high-traffic roofs, such as a shop roof with equipment that gets serviced.
- Installed cost: $2 to $5 per sq ft (HomeAdvisor)
- Coats: primer plus two
Rust Treatment and Fastener/Seam Sealing
The prep comes before any coat goes on. One manufacturer's application guideline for silicone over metal lays out the steps:
- Wash: pressure-wash at 3,000 psi or more to strip dirt and loose old coatings
- Rust: prime every rusted area, at about a gallon per 100 to 200 sq ft depending on how bad it is
- Screws: retighten them all, swap stripped ones for larger-diameter screws, replace missing ones, then seal over every head
- Seams: seal horizontal seams with a 4 in strip and vertical seams with a 2 in strip
The same guideline warns that rust hidden between panels or on their underside can't be fixed by a coating. HomeAdvisor makes the same point more broadly: a coating doesn't replace mechanical repair. When the screws are the main problem, see screw replacement. For holes and failed flashing, see metal roof repair.
Repainting a Metal Roof
Repainting refreshes the color of a faded roof that doesn't leak, and HomeGuide prices it at $1.20 to $2.70 per sq ft. In one coating maker's guideline, factory-painted panels get primed and adhesion-tested before anything goes over them. HomeAdvisor also warns that different coatings don't always stick to each other, so ask what's on the roof now before choosing what goes over it.
Why Midland homeowners call Midland Metal Roofing
- Free quotes, no obligation to hire
- Panel, gauge and price in writing before any work
- Your request goes to one Midland roofer, not a call list
- Homeowners never pay us for the referral
Midland Heat and Cool-Roof Coatings
Midland's sun is what a coating fights. The Midland-Odessa airport station averages 115.2 days a year at 90°F or hotter and 23.8 days at 100°F or more, and the normal July high is 95.8°F (NOAA 1991-2020 normals). Midland County sits in climate zone 3B, the dry zone, under the 2015 IECC the City adopted.
The Cool Roof Rating Council describes a cool roof as one that reflects and gives off the sun's heat instead of passing it into the building, which cuts air-conditioning use at peak hours. Lighter colors usually reflect more, but the Council notes color isn't the only measure, so the published numbers matter more than the shade.
Ask for
the coating's CRRC-rated solar reflectance and thermal emittanceSkip
any "ENERGY STAR roof" claim, since EPA ended that roof program in June 2022Timing
one maker's guideline says not to apply within two hours of sunset, rain, fog or freezing weather
A coating suits a roof that's sound but worn. If the panels are rusted through or the deck is soft, price a metal roof replacement alongside it. For a mobile home, the coating option is covered on the mobile home metal roof page.