How to Apply a Flat Roof Coating System

As a manufacturer of water based, eco-friendly elastomeric roof coatings we get asked often about the application processes on our products. These products are nonhazardous and user friendly with easy water cleanup after the job is complete. We are going to cover in the following blog the major steps to applying an elastomeric flat roof coating on your flat roof for the best results. For reference, here is a link to our most popular flat roof coating product - https://www.nationwidecoatings.com/pl/flat-roof-coating. We also offer PERMASIL PLUS™ Silicone Roof Coating https://www.nationwidecoatings.com/pl/best-silicone-roof-coating and it is available on Amazon Right Here!

Step 1: Visual Inspection and Replacement of Damaged Building Materials

 The substrate to be coated must be in SOUND condition. Physically inspect the surface area for missing or damaged building materials. Replace and/or repair all damaged areas back to sound and solid condition. This Application is not for metal roofs and will not seal rust, any rust must be treated before coating is applied, inquire about METAL-PRIME RED-OX™ Rust Treatment Process. Inspect for any existing leaks and be sure to repair leaks prior to the application of coating. You may use PERMAKOTE® on roofing surfaces having a slope greater than 1 inch per 24 inches or greater than a 4 degree angle, and that do not pond or hold any standing water at all. Only PERMAKOTE PLUS® Flat Roof Coating can be used on flat and level roofing surfaces, but the surface can not hold or have any more than ½” of standing water in any area of entire roofing surface (Please inquire for limitations). Fill in any low spots to achieve a level surface. Roof must completely drain; proper drainage is essential before any coating is applied. Make sure roof is adequately vented, or condensation leaking can occur. Check with a licensed roofing contractor if necessary.

Step 2: Pressure Cleaning

 High Pressure Clean entire roof surface with at least 2500 P.S.I. of pressure using a water and chlorine solution (approximately 2 quarts chlorine to 4½ gallons of water). Thoroughly remove all dirt, oil, grease, residues, mold, mildew, algae and any other surface contaminants. Severe mildew requires a stronger concentration of chlorine and scrubbing with a broom, roof brush or other agitating apparatus. When roof is completely cleaned, rinse with water only. Let roof surface dry at least 12 hours before continuing. The PERMAKOTE PLUS® flat roof coating system has excellent mildew resistance, but the system products WILL NOT KILL mildew already on the surface.

Step 3: Repair Surface and Patching Imperfections

After surface has thoroughly dried, Patch and Caulk all cracks, crevices, fractures, holes, valleys, vents, voids, etc., with PERMAPATCH™ elastomeric patching compound. Use a trowel or stiff brush to apply. Multiple coats are better than one thick coat if possible. The thicker PERMAPATCH™ is applied, the longer it will take to dry. Wait at least 4 hours before applying a second coat of PERMAPATCH™ and let final application dry at least 24 hours before continuing to next step. PERMAPATCH™ elastomeric patching compound dries from top to bottom, so be careful when working around a caulked area since it will be skin dry. There is no problem coating over PERMAPATCH™ even if it is not completely dry, since it is a high solids material.

PERMAPATCH™ has minimal shrinkage, but the thicker PERMAPATCH™ is applied the more chance it has to shrink, check after 24 hours and apply additional PERMAPATCH™ if necessary.

Step 4: Taping Seams (If Applicable, otherwise proceed to Step #5)

Tape all visible seams, valleys, large cracks & fractures prone to water intrusion on roof surface. Apply a liberal coat of PRIMER (PERMABOND™) at 12-16 mils wet film thickness, directly to the affected area using: 1- brush, 2- at least a one inch nap roller, or 3- at least a one gallon per minute piston type airless sprayer with a .021 minimum tip size. Remove all line filters and gun filters before spraying. Lay the PERMATAPE™ directly onto the WET PRIMER. Tape must be put down before PRIMER has had a chance to start drying (approximately 15 minutes). After all areas are taped let dry for 1 to 2 hours. Apply a second light coat of PRIMER at 6-8 mils wet over the top of the tape. Let dry for at least 2 hours before continuing. If a full PRIMER coat (Step#: 5) is applied the second light coat of PRIMER is recommended but not required.

Step 5: Primer Coat

Apply PRIMER (PERMABOND™) using: 1- brush, 2- at least a one inch nap roller, or 3- at least a one gallon per minute piston type airless sprayer with a .021 minimum tip size. Remove all line filters and gun filters before spraying.

The PRIMER must be applied perpendicular to the width of the roof. Example: If the width of the roof runs from North to South then the coating will be applied from East to West. This will be the start of a checkerboard application pattern. See diagram below. Apply the PRIMER at a rate of 100-150 square feet per gallon covering the entire roof surface. Wet film thickness of 12-16 mils resulting in a dry film thickness of 4-7 mils. Let PRIMER dry at least 4 hours before continuing. 

Step 6: First Coat of Flat Roof Coating

Be sure entire surface is clean and free of all moisture. Be sure the entire area to be coated is primed with a minimum dry film thickness of 4 mils. If not, then spot prime the deficient areas until the minimum dry film thickness is achieved.

Apply First Coat of Flat Roof Coating using: 1- brush, 2- at least a one inch nap roller, or 3- at least a one gallon per minute piston type airless sprayer with a .027 minimum tip size. Remove all line filters and gun filters before spraying.

The first coat must be applied perpendicular to the coat of PRIMER to continue the checkerboard pattern. See diagram below. Apply the first coat at a rate of 100-125 square feet per gallon per coat over the entire roof surface. Wet film thickness of 14-16 mils resulting in dry film thickness of 8-10 mils. Let dry at least 12 hours before continuing.

Step 7: Second Coat of Flat Roof Coating

Be sure entire surface is clean and free of all moisture. Be sure the entire area to be coated has a minimum dry film thickness of 12 mils (this includes 4 mils of PRIMER). If not, then spot coat the deficient areas until the minimum dry film thickness is achieved.

Apply Second Coat of Flat Roof Coating using: 1- brush, 2- at least a one inch nap roller, or 3- at least a one gallon per minute piston type airless sprayer with a .027 minimum tip size. Remove all line filters and gun filters before spraying.

The second coat must be applied perpendicular to the first coat of flat roof coating to complete the checkerboard pattern. See diagram below. Apply the second coat at a rate of 100-125 square feet per gallon per coat over the entire roof surface. Wet film thickness of 14-16 mils resulting in dry film thickness of 8-10 mils. Let dry at least 24 hours before Final Evaluation.

Step 8: Final Evaluation

At this time a detailed evaluation of the completed job will determine the quality of the workmanship and whether strict application specifications have been met. The entire roofing surface must be completely coated & sealed. Be sure to check that all roof areas are completely coated & sealed under permanently placed roof items such as roof top air conditioning units. Divide roof into 1,000 square feet sections and randomly check one spot in each section for a dry film thickness of all three coats of flat roof coating at least 20 mils. Remember to touch up the penetration made by the dry film thickness gauge. If specifications have not been met, recoat the entire roof or deficient areas. Repeat evaluation and recoating until the required minimum dry film thickness is achieved. 

Once the job is done clean-up is a breeze with soap and water. Any warranty paperwork should be completed and returned to Nationwide within 90 days of completing the flat roof coating project. Nationwide Protective Coatings warranties are renewable and transferable.

We also match competitors colors and custom colors! You can also review an Application Video for an Acrylic Flat Roof Coating System Here or Silicone Roof Coating System. 

Check us out on your next roof project and see how easy an elastomeric flat roof coating system can be applied to protect your roof for years to come.

When considering flat roof coating, it’s essential to choose the right materials to ensure durability and protection against the elements. Roof coatings for flat roofs serve multiple purposes, including waterproofing and UV protection, which are crucial for maintaining the integrity of your roof. Among the best flat roof coating materials, acrylic coatings stand out for their ease of application and excellent UV resistance. For those seeking superior flexibility and waterproofing, liquid rubber roof coatings and elastomeric coatings are often regarded as the best rubber roof coatings available. These coatings not only enhance the lifespan of your roof but also contribute to energy efficiency by reflecting heat. Brands like Nationwide Coatings offer a range of specialty coatings, including EPDM roof coatings and white roof coatings, which are designed to withstand harsh weather conditions. Proper application techniques, such as using a roof coating spray or roll-on roof sealant, can further enhance the effectiveness of these coatings, ensuring your flat roof remains sealed and protected for years to come.