This page provides general information about various roof coatings. Most of the information was compiled from a wide assortment of manufacturers’ technical data sheets or material safety data sheets for actual coating products, and should be considered to be representative but not definitive. This information should not be used if precise values are needed for critical design calculations. When precision is necessary, always refer to the data sheets of the actual, specific product you intend to use, or contact the technical department of the coating manufacturer.

For information regarding coating application instructions (like whether reinforcement fabric is needed and coverage rate, etc.), the legality of use of the material in your jurisdiction, and especially safety information, see the manufacturer’s technical data sheet and material safety data sheet for the actual product you are considering using.

When applying roof coatings, remember that virtually all surfaces to be coated must be clean, dry, and free of contaminants such as dirt, oil, grease, old loose coatings, and other debris. Some of these coatings are extremely toxic during application and all manufacturer’s safety guidelines must be followed.

General Terms for Roof Coatings

  • Bituminous Roof Coatings

Bituminous coatings use asphalt or coal tar pitch as their main waterproofing component.

  • Cool Roof Coatings

A cool roof coating is any coating that reduces the amount of heat the roof absorbs from the sun by reflecting a higher proportion of sunlight and increasing thermal emittance as compared to traditional coating materials. White roof coatings and coatings formulated with other reflective pigments are considered “cool”.

 

  • Elastomeric Roof Coatings

Elastomeric coatings have elastic properties which allow them to stretch and return to their original dimensions without being damaged. This allows them to accommodate building movement and particularly the thermal expansion and contraction of the roof membrane on which they are applied. Most non-bituminous roof coatings are elastomeric. Non-elastomeric coatings must have similar expansion/contraction rates as the roofing material they are applied to (an asphalt coating on an asphalt roof, for example).   

 

  • Fibered (Fibrated) Roof Coatings

Fibered coatings are formulated with cellulose or fiberglass fibers. The fibers are typically between ¼ inch and 1 inch long. The fibers in a roof coating increase tear resistance in the cured coating and resistance to flow during application (improving its performance when applied to steep slopes or flashings) Generally, only non-elastomeric coatings will be fibered, as the fibers reduce the elasticity of the material.

 

  • Polymer-Modified Roof Coatings

A polymer-modified coating is a bituminous coating that has been formulated with the addition of a bitumen-compatible polymer such as styrene-butadiene-styrene to improve its performance. A polymer-modified coating will typically be more flexible, longer-lasting, and more expensive than unmodified coatings. Often referred to as “rubberized”.  

 

  • Polymer Roof Coatings

Polymeric coatings are made using any of various synthetic resins (polymers) as the primary waterproofing component. The most commonly seen polymeric coatings are based on acrylics, silicones, or polyurethanes, but there are several other polymer-based coatings.

 

  • Reflective Roof Coatings

A reflective coating is any roof coating formulated to be highly reflective of the sun’s rays. Typical reflective coatings are white, aluminized, or include special reflective pigments in other colors. Reflective coatings produce a “cool roof” effect. In the case of a black EPDM roof, for instance, a reflective coating can reduce the normal afternoon temperature of the roof by up to 60°F (34°C).

 

  • Rubberized Roof Coatings

A “rubberized” coating is a bituminous coating that contains a synthetic rubber. See “Polymer-Modified Roof Coatings”.

 

  • White Roof Coatings

A white coating is simply a coating that is white. White coatings are generally considered “cool” or “reflective”. Most polymeric coatings are available in white. Titanium dioxide is the most commonly used pigment in white roof coatings.

 

Types of Roof Coatings by Material 

  • Acrylic Coatings

Main Components: (Example, formulations vary) water, calcium carbonate (or other extender pigment) acrylic polymer resin, titanium dioxide (or other prime pigment)

Acceptable Substrates: Acrylic coatings are available in a wide variety of formulations for application on almost every type of substrate. Individual coating products are not applicable to all substrates. It is important to check the product data sheet of the actual product before selecting an acrylic coating.

Unacceptable Substrates: Existing silicone coatings, gravel-surfaced built-up roofs

Colors: White, tan, gray, various other colors

Elastomeric: Yes

Chemical Resistance: Poor

Handles Ponded Water: Poor

Handles Foot Traffic: Poor (some formulations perform better)

Application Method: Brush, roller, or spray

Application Temperature: Above 50°F (10°C)

Notes: Water-based. One of the most inexpensive types of coating. Easy to apply. Low VOC. Low toxicity.

 

  • Aluminum (Aluminized) Coatings

Main Components: Mineral spirits (or other solvent), asphalt, aluminum powder/flakes (up to 30%), perlite (or other filler)

Acceptable Substrates: Smooth-surfaced asphalt built-up roofing, modified bitumen, metal, existing asphalt coatings

Unacceptable Substrates: Coal-tar, single-ply membranes, Kynar®- or Hylar®-coated metal, spray polyurethane foam, gravel-surfacing, existing non-asphalt coatings

Colors: Silver

Elastomeric: No

Chemical Resistance: Poor

Handles Ponded Water: Poor

Handles Foot Traffic: Fair

Application Method: Brush or spray

Application Temperature: Above 40°F (4°C)

Notes: Available fibered or non-fibered. Gives asphalt roofing a reflective surface.

 

  • Asphalt Cutback (Solvent-Based) Coatings

Main Components: Asphalt, mineral spirits

Acceptable Substrates: Smooth-surfaced asphalt built-up roofing, modified bitumen, metal, existing asphalt coatings

Unacceptable Substrates: Coal tar pitch roofing, single-ply membranes, Kynar®- or Hylar®-coated metal, spray polyurethane foam, gravel-surfacing, existing non-asphalt coatings

Colors: Black

Elastomeric: No

Chemical Resistance: Poor

Handles Ponded Water: Poor

Handles Foot Traffic: Fair

Application Method: Brush or squeegee

Application Temperature: Above 40°F (4°C)

Notes: Available fibered or non-fibered. Used to re-coat and extend the life of asphalt roofs. Can be thinned to use as a primer. Can be used to bond asphalt-impregnated felts together when making repairs. Can be used to adhere roll roofing/modified bitumen cap sheets when making repairs. Can be used when re-applying gravel to bare spots on gravel-surfaced roofs.  

 

  • Asphalt Emulsion – (Water-Based) Coatings

Main Components: Water, asphalt, bentonite clay (or other stabilizer)

Acceptable Substrates: Smooth-surfaced asphalt built-up roofing, modified bitumen, metal, existing asphalt coatings

Unacceptable Substrates: Coal-tar, single-ply membranes, Kynar®- or Hylar®-coated metal, spray polyurethane foam, gravel-surfacing, existing non-asphalt coatings

Colors: Black, brown

Elastomeric: No

Chemical Resistance: Poor

Handles Ponded Water: Poor

Handles Foot Traffic: Fair

Application Method: Brush, roller, or spray

Application Temperature: Above 50°F (10°C)

Notes: Available fibered or non-fibered. Only used in surface applications or as a base-coat for another asphalt-compatible coating. Used to re-coat and extend the life of asphalt roofs.

 

  • Butyl Coatings

Main Components: (Example, formulations vary) aliphatic hydrocarbon, petroleum resin, polybutene, titanium dioxide, styrene, butadiene, xylene

Acceptable Substrates: Metal, spray polyurethane foam, smooth-surfaced built-up roofing, modified bitumen, EPDM, PVC, TPO

Unacceptable Substrates: Gravel-surfaced roofing, existing silicone coatings. Always check specific product data sheets for material compatibility.

Colors: White, gray, custom colors available

Elastomeric: Yes

Chemical Resistance: Fair

Handles Ponded Water: Excellent

Handles Foot Traffic: Fair

Application Method: Brush, roller, spray

Application Temperature: Above 40°F (4°C)

Notes: Polymeric coating. Solvent based. High VOC. Relatively expensive. Highly elastomeric. Can qualify as a vapor barrier.

 

  • Coal Tar Pitch-Based Coatings

Main Components: Refined coal tar pitch, aromatic solvent, Fuller’s earth (or other stabilizer)

Acceptable Substrates: Smooth-surfaced coal tar pitch built-up roofing, concrete

Unacceptable Substrates: Asphalt roofing, single-ply membranes, spray polyurethane foam, existing non-coal tar pitch coatings

Colors: Black

Elastomeric: No

Chemical Resistance: Good

Handles Ponded Water: Good

Handles Foot Traffic: Fair

Application Method: Brush or squeegee

Application Temperature: Above 40°F (4°C)

Notes: May be hard to find. Used to re-coat and extend the life of coal tar pitch roofs.

 

  • Polyurea Coatings

Main Components: An isocyanate component is combined with an amine resin blend component at the time of application.

Acceptable Substrates: Concrete, spray polyurethane foam, metal, built-up roofing, modified bitumen, EPDM, PVC, TPO single-ply membranes

Unacceptable Substrates: Gravel-surfaced roofing, existing silicone coatings

Colors: Many colors available

Elastomeric: Yes

Chemical Resistance: Excellent

Handles Ponding Water: Excellent

Handles Foot Traffic: Excellent

Application Method: Spray

Application Temperature: 5°F (3°C) above the dew point and rising

Notes: Cures in seconds, requires special equipment and training to apply. Relatively expensive.

 

  • Polyurethane (Aliphatic) Coatings

Main Components: (Example, formulations vary) polyoxypropylene glycol, cyclohexane, aliphatic hydrocarbon, titanium dioxide (or other prime pigment), hexamethylene diisocyanate, xylene, ethyl benzene 

Acceptable Substrates: Spray polyurethane foam, EPDM, Hypalon, PVC, TPO, smooth-surfaced built-up roofing, metal, modified bitumen, concrete

Unacceptable Substrates: Gravel-surfaced roofing, existing silicone coatings

Colors: White, gray, various other colors

Elastomeric: Yes

Chemical Resistance: Good

Handles Ponded Water: Fair

Handles Foot Traffic: Excellent

Application Method: Brush, roller, spreader, or sprayer

Application Temperature: Above 40°F (4.45°C), below 100°F (38°C), and more than 5°F (3°C) above the dew point and rising

Notes: Solvent-based. Very UV stable, often used as a top coat over an aromatic polyurethane coating. More expensive than aromatic polyurethane. Has a strong odor during application.

 

  • Polyurethane (Aromatic) Coatings

Main Components: (Example, formulations vary) diphenylmethane diisocyanate, methylene bisphenyl isocyanate, trimethylbenzene, aromatic hydrocarbons, calcium carbonate (or other extender pigment), xylene

Acceptable Substrates: Spray polyurethane foam, EPDM, Hypalon, PVC, TPO, smooth-surfaced built-up roofing, metal, modified bitumen, concrete

Unacceptable Substrates: Gravel-surfaced roofing, existing silicone coatings

Colors: Gray

Elastomeric: Yes

Chemical Resistance: Good

Handles Ponded Water: Fair

Handles Foot Traffic: Excellent

Application Method: Brush, roller, spreader, or sprayer

Application Temperature: Above 40°F (4.45°C), below 100°F (38°C), and more than 5°F (3°C) above the dew point and rising

Notes: Susceptible to UV degradation, is not acceptable as a surface coating. Used as a base coat beneath an aliphatic polyurethane or other compatible UV-resistant coating. Less expensive than aliphatic polyurethane. Has a strong odor during application.

 

  • PUMA Coatings (Polyurethane Modified Acrylic)

Main Components: (Example, formulations vary) methyl methacrylate, 2-propenoic acid, 2-ethylhexyl ester, titanium dioxide (or other prime pigment), barium sulfate

Acceptable Substrates: Concrete, spray polyurethane foam, metal

Unacceptable Substrates: Consult manufacturer’s technical department.

Colors: White

Elastomeric: Yes

Chemical Resistance: Good

Handles Ponded Water: Poor

Handles Foot Traffic: Good

Application Method: Brush, roller, spray

Application Temperature: Above 40°F (4.45°C), below 100°F (38°C), and more than 5°F (3°C) above the dew point and rising

Notes: Lasts longer than typical acrylic coatings. A mixture of polyurethane and acrylic coating chemistry.

 

  • PVDF Coatings (Polyvinylidene Fluoride)

Main Components: (Example, formulations vary) water, N-methyl-2-pyrrolidone, polyvinylidene fluoride resin, acrylic modifier, pigments

Acceptable Substrates: Metal. Other substrates require the application of a compatible base coating.

Unacceptable Substrates: Consult manufacturer’s technical department.

Colors: Various colors available

Elastomeric: Yes

Chemical Resistance: Excellent

Handles Ponded Water: Good

Handles Foot Traffic: Excellent

Application Method: Spray

Application Temperature: Above 60°F (15°C)

Notes: Based on formulation known as Kynar 500. Very long lasting.

 

  • SEBS Coatings (styrene ethylene butadiene styrene)

Main Components: (Example, formulations vary) Calcium carbonate, mineral spirits, hydrocarbon resin, styrene/butadiene copolymer

Acceptable Substrates: Hypalon, metal, TPO, other substrates with application of compatible base coat

Unacceptable Substrates: EPDM, KEE, PVC

Colors: White, black, gray, various other colors

Elastomeric: Yes

Chemical Resistance: Fair

Handles Ponded Water: Good

Handles Foot Traffic: Good

Application Method: Brush, roller, spray

Application Temperature: Above 40°F (4.45°C), and more than 5°F (3°C) above the dew point and rising

Notes: Solvent-based. Strong odor during application. Particularly compatible with steel roofing.

 

  • Silicone Coatings

Main Components: (Example, formulations vary) crystalline silica, titanium dioxide (or other prime pigment), petroleum hydrocarbon distillates, methyl oximino silane

Acceptable Substrates: Metal, EPDM, Hypalon, PVC, TPO, existing roof coatings, spray polyurethane foam

Unacceptable Substrates: Asphalt or coal tar pitch roofing (may be possible with appropriate primer), gravel-surfaced roofing

Colors: White, tan, gray, various other colors

Elastomeric: Yes

Chemical Resistance: Good

Handles Ponded Water: Good

Handles Foot Traffic: Poor

Application Method: Brush, roller, spray

Application Temperature: 35°F (1.7°C) and rising

Notes: Hard to adhere to. Restricts re-coating options, generally old silicone coatings must either be removed or re-coated with another silicone coating. Relatively expensive. Reinforcement fabric recommended for many applications. Almost all substrates require thorough priming. Application to concrete and existing silicone coatings can generally be done without priming.

 

  • Soy-Based Coatings

Main Components: Some soy-derived polymers, other components depend on the primary chemistry of the coating, typically polyurethanes or acrylics

Acceptable Substrates: Varies according to the primary chemistry

Colors: White, various other colors

Elastomeric: Usually

Chemical Resistance: Varies

Handles Ponding Water: Varies

Handles Foot Traffic: Varies

Application Method: Brush, roller, spray

Application Temperature: Varies

Notes: Soy-based roof coatings are kind of like salad dressings that are advertised as being made with olive oil, but when you read the ingredients, you find out that half the dressing consists of canola oil and the olive oil is only 5%. It’s important to check what the chemistry of the actual product is before selecting a soy-based coating. The attraction of soy-based coatings is that a renewable resource is used to produce a portion of the material, rather than petroleum.