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Using SmartFlash® ONE to Repair Roof Laps


By Joe Thompson on June 10th, 2022

I love to tell contractors about SmartFlash ONE because it’s an all-around champion product that can help cut down on labor time and provide building owners with a fast yet lasting repair. It has the resilience and stability of a two-part resin, but this ready-to-use solution can be applied without primer or A + B component mixing so contractors don’t have to worry about the product setting up too fast. Plus, any unused resin can be resealed and reused later, so it doesn’t go to waste.

One of the best features of SmartFlash ONE is how easy it is to apply. If you’ve ever painted a wall with a brush or roller, you already have the skills you need. And when it comes to repairing laps, this fast, easy application process can seriously boost labor and cost efficiency.    

Step-by-Step Lap Repair Using SmartFlash ONE

A one-part liquid-applied polyurethane bitumen waterproofing resin, SmartFlash ONE is designed for use on bituminous low-slope roof systems or asphalt shingles. It should not be used with single-ply membranes such as TPO, PVC, or EPDM.

Before you tackle your lap repair, make sure the area is dry and the temperature is 40°F and rising. If the weather is right, grab your brush or roller and get to work.

  • Step 1: Find the open seam(s) and prep the surface. Prepare the substrate to ensure the surface is free of debris, moisture, or contaminants. 
  • Step 2: Apply base coat. Wearing protective latex gloves, apply your waterproofing base coat of SmartFlash ONE. Apply resin at a rate of 30 wet mils extending about 1″ beyond where your SMARTFAB™ 500 polyester reinforcement fabric will be set in Step 3. Do not dilute or thin the resin. 
  • Step 3: Apply fabric reinforcement. Immediately embed SMARTFAB 500 into the wet resin, making sure there are no air pockets or wrinkles. This reinforcement should extend a minimum 3″ beyond deficiency in all directions. Saturate the polyester layer at a rate of 30 wet mils, ensuring that it is completely covered. Allow resin to dry.   
  • Step 4: Apply topcoat. Apply a waterproofing topcoat of SmartFlash ONE to the entire surface. 
  • Step 5 (Optional): Broadcast granules. If a granular aesthetic is desired, broadcast FlintRock™ Roofing Granules into the topcoat before it forms a skin. 
Guarantee Your Repairs with a Stand-Alone Warranty 

We’re so confident in the stress resilience and UV stability of the SmartFlash ONE formula that we back the product with up to 20 years of warranty coverage—comparable to the coverage usually provided for two-part solutions. To get the most out of our warranties, be sure to look carefully at the terms. It’s important to understand the differences in coverage for SmartFlash ONE when used as part of a CertainTeed roof system and when used as a stand-alone product:  

When used as a component of a CertainTeed asphaltic low-slope roof system, SmartFlash ONE flashing details assume the warranty duration and coverage of the overall roof system, up to 20 years. 
When used as a stand-alone product outside of a new asphaltic low-slope roof system, CertainTeed offers 10 years of limited warranty coverage. 

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About Joe Thompson

A key member of the CertainTeed Commercial Roofing Technical Services team, Joe Thompson has been assisting customers with low-slope roofing installations and inspections for nearly two decades. Not one to sit on his hard hat, he travels throughout the United States serving as lead instructor for CertainTeed’s popular Flintlastic® SA commercial roofing installer-training courses. An IIBEC member in good standing, Joe has attended so many roofing educational courses that he has lost count. 

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