Metal roof restoration is the alternative to tearing off and re-panelling a commercial metal roof. The panels stay; the weak points get fixed. Rust is treated, loose and missing fasteners are replaced, seams, laps and penetrations are sealed and reinforced, and then the whole roof is coated with a GAF silicone or acrylic system.
Exposed-fastener metal roofs on warehouses, shops, churches and metal buildings tend to fail the same ways: thousands of screws whose washers have dried out, end laps that open up with every heat cycle, and rust where water sits. A restoration addresses all of it in one project, starting at $2.50 per square foot, typically about a third of the cost of a new roof.
Signs a Metal Roof Needs Restoring
- Rust spots on panels, at end laps or around fasteners
- Screws that have backed out, or washers that have cracked and shrunk
- Leaks at laps, ridges, gutters or around rooftop units and pipes
- Old sealant that has split or pulled away
- Faded, chalky paint that no longer reflects the sun
None of these on its own means the roof is finished. The question is whether the metal is still sound. That's what the survey answers.
Rust: What Can Be Coated
The Roof Coatings Manufacturers Association's guidance is practical. White rust on galvanized or aluminum-zinc coated metal can be coated after cleaning. Red rust has to be removed or treated with a corrosion-inhibiting primer first. Rusted fasteners have to be treated or replaced. GAF's metal steps match: rusty areas get GAF Metal Roof Primer before the coating system goes on.
When restoration is the wrong answer: if the panels are rusted through across large areas, or the structure under them is damaged, no coating will hold them together. We'll tell you that after the survey, before you spend money on a coating.
How We Restore a Metal Roof
We follow GAF's published steps for restoring metal roofs:
- Qualify the roof. The roof has to be clean, dry and tight, and adhesion tests confirm the coating will bond to your panels.
- Repair and clean. Damaged sheet metal is repaired, every loose or missing fastener is secured or replaced, and the roof is power washed with GAF Cleaning Concentrate. Where water collects behind rooftop units, sheet metal crickets go in.
- Treat seams and fasteners. Ridges, rake edges and horizontal laps are reinforced with GAF Premium Fabric embedded in mastic or flashing. Vertical seams are sealed, and every exposed fastener is encapsulated. GAF notes that typical standing seam profiles do not need seam treatment.
- Detail penetrations. Curbs, pipes and drains are sealed with mastic and 12-inch GAF Premium Fabric.
- Coat the roof. A GAF silicone or acrylic system goes on to the rate specified for the warranty term, with the wet thickness checked as the crew works.
Silicone or Acrylic on a Metal Roof?
Both work on metal, and we install GAF's system for each:
- GAF silicone over metal, specified for 10, 15 or 20-year terms. The usual pick for low-slope metal that holds water at laps or behind equipment. More on silicone roof coating.
- GAF Premium Acrylic HydroStop, a fully fabric-reinforced acrylic system that GAF describes as "an affordable solution to extend the life of structurally sound metal roofs," also specified for 10, 15 or 20-year terms. Suits sloped metal that sheds water. More on acrylic roof coating.
The warranty term is set by how thick the coating goes on, and the proposal states it. See how the GAF coating warranty works.
What Restoration Saves on a Metal Building
Re-panelling a metal building means removing the old panels, often replacing fasteners into the purlins and working over an open structure. A restoration keeps the panels in place, so there's no open roof over the building's contents and far less disruption to the business underneath. Run your square footage through the roof coating cost calculator to see the difference.
Sources: GAF silicone over metal · GAF HydroStop system · Roof Coatings Manufacturers Association FAQs.
Metal Roof Restoration FAQ
Metal roof restoration in Houston typically falls within our coating range of about $2.50 to $4.50 per square foot, compared with $8 to $16 per square foot to replace a commercial roof. The amount of rust treatment, the number of fasteners to replace and seal, the seam work and the warranty term decide where a roof lands.
Usually, if the metal is still sound. The Roof Coatings Manufacturers Association says white rust can be coated after cleaning, while red rust must be removed or treated with a corrosion-inhibiting primer and rusted fasteners treated or replaced. Panels that are rusted through across large areas need replacing instead.
Loose and missing fasteners are secured or replaced as part of GAF's preparation steps, and then every exposed fastener is encapsulated so the coating system covers it.
Both have GAF metal systems specified for up to 20 years. Silicone is the usual choice where water sits on low-slope metal. Acrylic, in GAF's fabric-reinforced HydroStop system, suits sloped metal roofs and costs less per square foot.
Yes. GAF notes that typical standing seam profiles do not need the seam treatment that exposed-fastener panels do, so the work focuses on cleaning, adhesion testing, penetrations and the coating itself.
Have a metal building with rust or leaking laps? Call (832) 224-3435 or request a free roof survey.