SMARTCOAT™ 301 Mastic is a 100% acrylic elastomeric, water-based, fiber-fortified roof 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 400/401 Acrylic Coatings. This product is suitable for application to metal, asphalt, modified bitumen, concrete and most single-ply roofs. While maintaining a high degree of elasticity, the addition of reinforcing fibers reinforces strength and delivers superior crack-bridging performance. SMARTCOAT 301 Mastic is UV-stable; coating is not required.

Technical Information






39 lbs.

Dry to Touch

4 – 8 hours


15 g/L

Volume by Solids


Weight by Solids


Cone Pen Viscosity

240 dmm

Tensile Strength

153 psi




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 with SMARTCOAT 100 Roof Wash. 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 should be applied 1/8" thick with a brush or trowel and extend two inches on either side of the fastener or split. For added strength, reinforce with polyester fabric and apply a second troweling of mastic. Apply only at temperatures above 50ºF and rising with no threat of rain for 48-72 hours.

5. Allow MASTIC to dry 4 to 8 hours prior to coating with SMARTCOAT 400/401 Acrylic Coatings; MASTIC cures by ultraviolet rays (UV); allow for sufficient daylight. MASTIC will lose its tack when it is suitable to be coated. Cure time is affected by environmental conditions.

6. Clean wet coating with soap and water. Dry coating may be removed with mineral spirits. Use care when handling solvents. For more information, see published SMARTCOAT specifications at

For Construction Details and Specs Click Here

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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