SMARTCOAT™ 350 Silicone Mastic is a professional grade high performing silicone mastic intended to seal leaking seams, fasteners, penetrations and/or any splits, tears or deficiencies in the roof’s surface prior to coating with SMARTCOAT 450 High Solids Silicone Coating. This product is suitable for application to metal, asphalt, modified bitumen, concrete and most single-ply roofs. Upon cure, SMARTCOAT 350 forms a durable, breathable and water-resistant barrier that is resistant to degradation from UV and natural weathering; coating is not required.

Technical Information



Tack-Free Cure

2 hours

Dry to Touch

6 hours




25 lbs.



Tensile Strength

305 ± 10 psi @ 73˚F


60% ± @ 10 73˚F

Tear Resistance

25 ± 5 lbf/in @ 73˚F

Solids by Volume

91% ± 2

Solids by Weight

97% ± 2

Shelf Life

18 months (un-opened containers, stored between 35°-75°F)


Coverage: Approximately 12-13 sq.ft. per gallon applied 1/8" thick; additional material may be required when 3-coursing to saturate and encapsulate polyester fabric.

1. Clean roof surface thoroughly using SMARTCOAT 100 Roof Wash as needed. Surface must be free of dirt, dust, oil, grease, wax, rust, chalky or loose paint, mildew and any other surface contamination that may inhibit adhesion.

2. If adhesion test indicates primer is required, prime surface with SMARTCOAT 210 Universal Primer. When applying on a smooth or granulated modified bitumen or built-up-roof, though most granulated surfaces do not require primer for adhesion, SMARTCOAT 200 Asphalt Bleed Blocker will serve prevent top-surface yellowing from migrating bituminous oils.

3. Inspect all fasteners; replace loose, broken or missing ones.

4. Material shall be applied between 1/8"-1/4" thick with a brush, trowel or gloved hand and extend two inches on either side of the fastener or split. SMARTCOAT 350 is typically applied in one application. If applying in multiple applications, allow adequate time between each application for the mastic to cure before applying additional material. Details or repairs with a high potential for movement may require polyester reinforcement and/or the use of a sacrificial release tape. When reinforcing with polyester, thickness shall be sufficient to saturate and encapsulate polyester reinforcement. Refer to SMARTCOAT construction details for guidance. Tack free in 2 hours. Dry to touch in 6 hours. Drying time is dependent on temperature, humidity and film thickness. Final cured thicknesses must be free of voids, pinholes, cracks or blisters.

5. Allow MASTIC to dry approximately 6 hours, depending on temperature and humidity, prior to coating with SMARTCOAT 450 High Solids Silicone Coating.

6. Clean equipment containing uncured material may be accomplished by cleaning with mineral spirits, toluene, or alcohol based solvents. DO NOT USE water.

For more information, see published SMARTCOAT specifications at

Warranty Details

CertainTeed offers three asphaltic low-slope roof system warranty options: Limited Warranty on Materials, Integrity Roof System Limited Warranty, and Integrity Roof System No Dollar Limit (NDL) Limited Warranty. CertainTeed warranty durations are based on a combination of system specification and product selection. Please download an overview of these warranty options for details. Consult with your contractor or CertainTeed Territory Manager to determine which warranty is best for your project.     

CertainTeed offers standard asphaltic low-slope roof system warranty durations between ten and twenty-five years. Additionally, Gold Star Contractors can increase warranty durations by 25% by engaging in an Integrity Maintenance Agreement with their client.

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