Ten to twenty years depending on the chemistry, the film thickness applied and the exposure. Acrylic on a well-drained metal roof and silicone on a ponding EPDM roof both reach the upper end when applied at the specified mil thickness. Thin applications fail early, which is why the warranty term is tied to thickness rather than to the product name.
Get My Free Estimate →A roof coating is a fluid-applied membrane rolled or sprayed over an existing low-slope roof, restoring the waterproofing layer and adding reflectivity without a tear-off. On the right roof it buys ten to twenty more years at a fraction of replacement cost.
On the wrong roof it seals moisture inside the assembly and hides a problem that gets worse and more expensive. Which one you have is a question of substrate condition, not of preference, and it is answered by a survey rather than a sales visit.
We work on the small commercial buildings across the Madison suburbs, the strip retail, contractor shops, clinics, self-storage and light industrial in Sun Prairie, Cottage Grove, DeForest and Stoughton.
Which roofs can be coated
Coatings work over most low-slope substrates when the assembly beneath is dry.
Aged EPDM takes a coating well, and it is the most common candidate here, because the black membranes installed through the 1990s and 2000s are now chalking and shrinking at the details.
Modified bitumen and built-up roofs coat well and gain the most from reflectivity, since dark asphalt surfaces run hot enough to accelerate their own aging.
TPO and PVC can be coated, though adhesion is fussier and the manufacturer will specify a primer and a cleaning regime that must actually be followed.
Metal roofs are strong candidates, where the real work is treating the fasteners and seams before any coating goes down.
Acrylic coatings
Acrylic is the water-based, lowest-cost option, and it is the right default on a sloped metal roof or a modified bitumen roof that drains properly.
It reflects well, it recoats easily at end of life, and it is the most forgiving to apply. Its weakness is standing water, which softens and eventually re-emulsifies the film.
Application temperature governs the schedule. Acrylic needs conditions above roughly 50 degrees and a clear drying window, which in Wisconsin means a season running from late spring into early autumn, not a warm week in November.
Silicone coatings
Silicone is the answer where water ponds, which describes a great many of the low-slope roofs we survey in Dane County.
It cures through moisture rather than evaporation, holds up under standing water indefinitely, and tolerates a wider application window than acrylic. It is more expensive per square foot.
Two tradeoffs are worth knowing before you choose it. Silicone attracts and holds dirt, so reflectivity drops over the first few years. Recoating silicone requires either a silicone-compatible product or a specific surface preparation, which narrows your options a decade from now.
Polyurethane coatings
Polyurethane is the toughest of the three and the one to specify where the roof takes foot traffic, around rooftop equipment, service walkways and clinic mechanical decks.
Aromatic polyurethane is used as a base coat and degrades in sunlight. Aliphatic goes on top and holds colour and gloss. A correct polyurethane system uses both, which is part of why it costs more than acrylic.
It also handles impact better than either alternative, which matters on a hail-exposed roof.
When a coating is the wrong answer
Say no to a coating in four situations, and be suspicious of any contractor who does not raise them.
Wet insulation is the first and the most important. If moisture has entered the assembly, a coating traps it, the insulation stays saturated, the deck corrodes or rots underneath, and the failure resurfaces later as a much larger job.
Substrate failure is the second. Membrane that has lost its reinforcement, seams that have failed across large areas, or a deck that flexes underfoot needs replacement, not a topcoat.
A roof at the end of its structural life is the third. Coating a 30-year-old assembly with brittle insulation postpones a decision you will still have to make.
Unresolved drainage is the fourth. Silicone tolerates ponding, but ponding usually signals a slope or drain problem that a coating does not fix.
If you suspect any of these, say so when you call. We would rather tell you the roof needs replacing than sell you a coating that fails.
Want a straight answer on your roof?
We'll inspect it, document everything, and tell you honestly what you're looking at, even if the answer is patch it for now. No pressure.
The survey that has to happen first
A defensible coating recommendation starts with an infrared or capacitance moisture scan and, where the scan flags an area, a core cut through to the deck.
The core answers what the scan cannot. How many layers are up there, what the insulation is, whether it is wet, and what the deck is made of.
Manufacturers require this documentation before issuing a restoration warranty, which is a useful test of the contractor in front of you. Anyone offering a warranted coating without a moisture survey is not going to get you the warranty.
Call (608) 909-9109 to arrange a survey on your building, or send us the address and roof age and we will come out and scan it.
What coatings cost around Madison
Installed cost varies with the chemistry, the number of coats, the condition of the details and how much preparation the roof needs.
Acrylic systems sit at the low end, silicone in the middle to upper range, and polyurethane systems highest. Preparation is the variable that moves a quote most, because a roof needing seam reinforcement, flashing repair and extensive cleaning can carry as much labour as the coating itself.
Against that, a full tear-off and replacement of the same roof typically costs several times the coating figure, and takes the building out of normal operation for longer.
Your accountant is worth a call before you decide, because maintenance work and capital improvements are treated differently for tax purposes and the comparison sometimes changes the answer.
Warranty terms to read closely
Manufacturer restoration warranties commonly run ten, fifteen or twenty years, and the term depends on the coating thickness applied, measured in mils of dry film.
Read whether the warranty covers material only or material and labour, and whether it is prorated. A twenty-year prorated material-only warranty and a fifteen-year non-prorated system warranty are not comparable products.
Ask who inspects the finished work. The stronger warranties require a manufacturer inspection, which is the same mechanism that makes residential system warranties worth having.
Get a straight answer on your Madison roof
Wisconsin storm season and insurance non-renewal letters do not wait. Get a free, no-obligation inspection and an honest assessment of exactly what your roof needs, even if the answer is to wait.