Roof coating materials fall into four main chemistry families, acrylic, silicone, polyurethane, and asphalt based, plus the ancillary materials that turn a bucket of coating into a system: primer, reinforcing polyester fabric, mastic, and sometimes granules. The material you pick is driven less by price than by two things: the substrate it has to stick to, and whether the roof holds ponding water.
Pick the wrong chemistry for the deck and the coating peels, blisters, or washes off inside a season. This guide, part of our learn about roofing library, names every common coating material, shows which roof substrate each one bonds to, and lists the layers that make up a full coating system. For the cost-per-square-foot decision between the four mainstream options, see the roof coating types and cost breakdown; this page is the materials reference.
What are roof coating materials made of?
A roof coating is a liquid-applied, fluid membrane that cures into a continuous elastomeric film over an existing roof. Every coating is built from three parts: a resin or binder (the chemistry that gives it its name), a carrier (water or solvent that evaporates), and pigments plus fillers for color, reflectivity, and body. Solids content, the percentage left on the roof after the carrier flashes off, separates a durable material from a thin one.
Higher solids means more cured film per gallon and fewer coats to reach target thickness. Silicone runs roughly 90 percent or higher solids by volume, so it lays down thick fast. Water-based acrylics typically sit near 50 to 60 percent solids, meaning close to half of each gallon evaporates. That difference decides how many gallons a job actually needs.
The main roof coating material types
Four chemistries cover the large majority of coating work: acrylic, silicone, polyurethane, and asphalt based. A handful of specialty materials (butyl, SEBS, polyurea) fill niche substrates. The table below sorts them by base chemistry, carrier, and the roof each one fits best. The Roof Coatings Manufacturers Association (RCMA) publishes reference specs for most of these categories.
| Material | Base chemistry | Carrier | Best-fit substrate | Main limit |
|---|---|---|---|---|
| Acrylic | Water-based acrylic resin | Water | Metal, mod-bit, concrete, single-ply | Erodes under standing water |
| Silicone | Moisture-cure silicone | High solids, low solvent | SPF foam, ponding flat roofs, single-ply | Holds dirt, hard to recoat |
| Polyurethane | Aromatic base, aliphatic top | Solvent | SPF, decks with foot traffic | Higher cost, odor during cure |
| Asphalt emulsion | Asphalt in water | Water | Mod-bit, BUR, metal | Not for single-ply, dark unless top-coated |
| Asphalt cutback | Asphalt in solvent | Solvent | BUR, mod-bit | Strong odor, flammable wet |
| Aluminized asphalt | Asphalt plus aluminum flake | Solvent | Metal, mod-bit, BUR | Reflectivity fades as flake oxidizes |
| Butyl | Butyl rubber | Solvent | EPDM, single-ply | Limited color, niche supply |
| SEBS | Styrene block copolymer | Solvent | Metal roofs | Metal-focused, narrow use |
| Polyurea | Two-part spray polyurea | Plural-component | Concrete, plaza decks | Needs trained applicator and rig |
Acrylic coatings
Acrylic is the most widely used elastomeric roof coating material and the default for reflective, cool-roof work on sloped commercial metal and mod-bit roofs. It is water-based, low odor, and available in white and tints with high initial solar reflectance, often near 0.85 for bright white, a range covered in our cool roof energy savings report. Acrylic conforms to ASTM D6083. Its weakness is standing water: prolonged ponding softens and re-emulsifies the film, so acrylic belongs on roofs that drain.
Silicone coatings
Silicone is the ponding-water material. It cures by reacting with humidity, stays flexible for years, and erodes far slower than acrylic without turning brittle. High solids content lets a two-coat system reach 20 to 25 mils quickly, and ASTM D6694 covers silicone over spray polyurethane foam. The catch is recoating: almost nothing bonds to cured silicone except more silicone, so a future restoration is locked into the same chemistry or a full strip. See our deeper look at silicone roof coating.
Polyurethane coatings
Polyurethane coatings carry the best impact and foot-traffic resistance of the common materials, which is why they suit decks, walkways, and roofs that see service traffic. Systems usually pair an aromatic base coat for build and adhesion with an aliphatic top coat that resists UV yellowing. Moisture-cured polyurethane over foam follows ASTM D6947. The tradeoffs are solvent odor during cure and a higher material cost than acrylic.
Asphalt-based coatings
Asphalt coatings are the legacy material for asphalt roofs: modified bitumen, built-up (BUR), and metal. Asphalt emulsion is water-based and mixes asphalt with clay or bentonite; asphalt cutback thins asphalt with solvent for cold or wet adhesion. Both are dark and non-reflective unless finished with an aluminized or acrylic top coat. Asphalt coatings should not go over TPO, EPDM, or PVC single-ply, where the oils attack the membrane.
Which roof coating material bonds to which substrate?
Substrate compatibility is the single most common reason a coating fails early, and it is the detail most short guides skip. A material that grips bare metal may peel off cured silicone or dissolve an EPDM membrane. Use the matrix below as a first filter, then confirm against the specific manufacturer data sheet, because primers and formulations change the answer.
| Substrate | Acrylic | Silicone | Polyurethane | Asphalt-based |
|---|---|---|---|---|
| Metal (galvanized, Galvalume) | Yes, primer often needed | Yes, with primer | Yes | Yes (aluminized) |
| SPF (spray foam) | Yes | Yes (D6694) | Yes (D6947) | Not recommended |
| Modified bitumen / BUR | Yes | Yes, with primer | Yes | Yes |
| TPO | Limited, needs primer | Yes, with primer | Yes | No |
| EPDM | With butyl primer | Yes, with primer | Limited | No |
| PVC | Limited, needs primer | Yes, with primer | Yes | No |
| Concrete | Yes | Yes | Yes | Yes |
| Asphalt shingles | Rarely, warranty risk | Not recommended | No | Limited, bleed-through |
Coating asphalt shingles is a separate question with its own tradeoffs, and it voids many shingle warranties. Single-ply membranes (TPO, EPDM, PVC) can be coated to extend service life, but they almost always require a membrane-specific primer and a clean, sound surface first.
The full coating system: it is more than the bucket
A roof coating material rarely performs alone. A durable job is a layered system, and each layer is its own material with its own purpose. Skipping the primer or the reinforcing fabric at seams is where most coating warranties quietly fall apart. A typical restoration system stacks up in this order:
- Primer: a thin bonding layer matched to the substrate. Rusty metal, weathered single-ply, and cured silicone each need a different primer, or none, per the data sheet.
- Base coat: the first full-thickness pass that builds the membrane and carries most of the dry mils.
- Reinforcing fabric: polyester or fiberglass mesh embedded in wet coating over seams, penetrations, and flashings to bridge movement and add tensile strength.
- Mastic or sealant: a thick trowel-grade version of the coating used to detail drains, curbs, and fastener heads before the field coats go down.
- Top coat: the second full pass that reaches target thickness and delivers the final color and reflectivity.
- Granules (optional): broadcast into a wet top coat on walkways or for a granulated finish and added UV and foot-traffic protection.
How thick, how much: mils, coverage, and solids
Coating performance is measured in dry mils, the film thickness left after curing, not in gallons poured. Most manufacturer warranties tie their term directly to a minimum dry-mil thickness, so hitting the number is what protects the roof and the warranty. Restoration systems commonly target 20 to 30 dry mils total across base and top coats.
Coverage runs roughly 1 to 1.5 gallons per 100 square feet per coat for a mid-20s mil target, though it varies with surface texture and solids content. A porous, granulated mod-bit roof drinks more material than smooth metal. Because water-based acrylic loses close to half its volume to evaporation, it usually needs more gallons than high-solids silicone to reach the same dry thickness.
| Property | Acrylic | Silicone | Polyurethane |
|---|---|---|---|
| Solids by volume | ~50 to 60% | ~90%+ | ~65 to 90% |
| Ponding-water tolerance | Low | High | Moderate to high |
| Foot-traffic resistance | Moderate | Low (slick when wet) | High |
| Recoat friendliness | Easy | Hard (silicone only) | Moderate |
| Reference spec | ASTM D6083 | ASTM D6694 | ASTM D6947 |
How to choose the right roof coating material
Match the material to the roof’s biggest problem, then confirm substrate compatibility and cost. The priorities below sort the common decision cleanly, and most roofs point to one obvious answer once you name the constraint that matters most.
- Ponding or slow drainage: silicone, which shrugs off standing water where acrylic erodes.
- Reflectivity and energy savings: bright-white acrylic or silicone, both of which can carry a Cool Roof Rating Council rated reflectance near 0.85 when new.
- Foot traffic or impact: polyurethane, or a polyurethane top coat with broadcast granules.
- Asphalt roof on a budget: asphalt emulsion, ideally finished with a reflective top coat.
- Spray foam roof: silicone or polyurethane, the two chemistries written into the SPF coating standards.
Whatever the chemistry, the coating only performs if the roof underneath is sound and the drainage works. Coating is a restoration tool for a roof with life left, not a fix for a wet, failing deck. When more than a quarter of the membrane is saturated or the deck is compromised, replacement usually beats coating.
Frequently asked questions
What are the different types of roof coating materials?
The four main roof coating materials are acrylic (water-based, reflective, best for draining roofs), silicone (high solids, best for ponding water and spray foam), polyurethane (toughest against foot traffic), and asphalt based (emulsion or cutback for asphalt roofs). Specialty materials include butyl for EPDM, SEBS for metal, and two-part polyurea for concrete decks.
What roof coating material is best for a flat roof with ponding water?
Silicone is the standard choice for flat roofs that hold standing water. It cures by reacting with moisture, resists ponding without softening, and erodes far slower than acrylic, which re-emulsifies under prolonged water. The tradeoff is that cured silicone is slick when wet and can only be recoated with more silicone, so future restorations are locked to that chemistry.
Do roof coatings need a primer?
Often yes, depending on the substrate. Rusty or oily metal, weathered single-ply membranes like TPO and PVC, and cured silicone each require a substrate-specific primer for the coating to bond. Some clean, sound surfaces skip it. The manufacturer data sheet is the authority: applying the wrong primer, or none where one is required, is a leading cause of early peeling.
What is elastomeric roof coating made of?
Elastomeric simply means the cured film stretches and returns without cracking. Most elastomeric coatings are acrylic or silicone: a resin binder, a carrier (water or low solvent) that evaporates, and pigments plus fillers for color and reflectivity. The elastomeric property lets the membrane flex with a roof that expands and contracts through daily temperature swings.
Can you coat any type of roof?
Most low-slope commercial roofs can be coated: metal, modified bitumen, built-up, spray foam, concrete, and single-ply with the right primer. Asphalt shingles are the main exception, where coating risks bleed-through and voids many warranties. The roof must also be structurally sound and reasonably dry; coating a saturated or failing deck traps moisture rather than fixing the leak.
How many coats of roof coating do you need?
Most restoration systems use at least two coats, a base coat and a top coat, plus reinforcing fabric at seams and penetrations, to reach a target of roughly 20 to 30 dry mils. High-solids silicone can sometimes hit thickness in fewer passes than water-based acrylic. Warranty terms are tied to the final dry-mil thickness, not the number of coats.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.