What a silicone coating does and doesn't do
Silicone cures into a seamless, rubbery membrane over the existing roof. It's highly resistant to UV and, unlike acrylic coatings, holds up under ponding water without breaking down. A bright white finish reflects most of the sun that hits it, lowering surface temperatures sharply on a South Texas afternoon.
What it can't do is dry out a wet roof or hold together a membrane that's coming apart. If the insulation underneath is soaked, coating over it traps the moisture and the roof keeps rotting from inside. A coating is a restoration for a roof that's still structurally sound, not a fix for one that's already failed.
Is your roof a good candidate for coating?
The strongest candidates are TPO, modified bitumen, built-up and metal roofs that are aging but mostly dry, with seams that can be repaired and decks that feel firm. Coating works well when the main problems are weathering, small cracks and heat, not widespread leaks.
We confirm that with a moisture survey across the roof and cores in suspect spots. As a rough guide, if more than a small share of the roof is wet, replacement usually makes more sense. Wet sections can sometimes be cut out and replaced before coating, which keeps restoration on the table for roofs that are mostly sound.
- Good candidate: dry insulation across nearly all of the roof.
- Good candidate: weathered surface with fine cracks but intact seams or seams that can be repaired.
- Good candidate: metal roofs with surface rust but solid panels.
- Poor candidate: wet insulation spread across large areas.
- Poor candidate: decking that flexes or has rotted through.
Adhesion testing: the step that decides success
A coating is only as good as its bond to the roof. Before quoting a full job, we clean small test patches, apply the specified primer and coating, let them cure, and pull them to measure adhesion. Some old surfaces, like chalky TPO or certain granulated cap sheets, need a specific primer or more cleaning to bond well.
Skipping this step is how coatings peel off in sheets a couple of years later. The test costs a little time but tells us exactly which prep and primer your roof needs, and sometimes that the roof isn't a good candidate at all.
Prep and repairs before the coating goes on
Coating goes on last. First, we pressure wash the roof to remove dirt, chalk, pollen and oak debris, and let it dry fully. Then we repair everything: open seams get reinforced with fabric and mastic, blisters are cut and patched, wet areas are replaced, and loose flashing is secured.
On metal roofs, we tighten or replace backed-out screws, treat rust and seal laps and fasteners before the main coat. Our metal roof repair work covers those fixes in detail. For flat roofs with open leaks, repairing the leaking areas is the first stage of any restoration.
How the coating goes on and how thick it needs to be
Silicone is sprayed or rolled on in one or two coats, measured in dry mils, the actual thickness once cured. We set the target thickness from the manufacturer's spec and check it with a wet-mil gauge as we go. Thin spots wear through first, so consistent coverage matters more than how the roof looks from the ground.
Silicone cures with moisture in the air, and it should go on when no rain is expected for several hours. Afterward, the surface is slick when wet and collects dirt more readily than other coatings, so it should be walked carefully. If the coating is worn years later, it can usually be cleaned and recoated with more silicone.
Coating versus replacing a low-slope roof
Restoration generally costs less than a new roof, avoids tear-off debris and lets building use continue with little disruption. For small commercial owners, that cost difference can be significant, which is why we often discuss it on commercial projects. A new TPO system makes more sense when insulation is wet, decking is damaged or you need added insulation underneath.
We'll lay out both options with numbers so you can compare. Phone (210) 750-1898 if you'd like us to test your roof before deciding.
