Gaco Roof Application Guide

Just some tips and tricks on applying GacoRoof. And maybe some Frequently Asked Questions. And a video or two. And flyers. Wow. This post really has it all, eh?

It is extremely important to get the roof clean and dry. First remove heavy deposits of dirt, leaves and other debris from the roof using broom or air broomer, then inspect the entire roof surface and flashings for any open seams, tears, cuts, etc. Repair these flaws so water is not blown in under membrane during the cleaning process. Pressure wash roof with water and allow to dry completely.


For general cleaning, apply GacoWash Concentrated Cleaner according to label instructions. On all single-ply membrane roofs, after application of cleaner, power scrub the roof surface until clean and then power wash to remove debris and continue rinsing until all suds are gone. 

Biological Control: Areas of algae, mildew or fungus on the roof membrane or the existing coating should be treated with a solution of 1 part household bleach and 3 parts water,

followed by a power washer rinse using clear water. Drying: After cleaning and rinsing the roof, ensure no dirt or debris is present. Allow surfaces to thoroughly dry to prevent blistering. Examine roof, paying particular attention to areas of physical damage to determine that residual water has in fact dried before applying coating. NOTE: Drying time depends on weather conditions such as temperature, humidity and air movement.

Bonds to Most Surfaces (including but not limited to):
  • Aged Asphalt*
  • Aged EPDM and TPO/CPA
  • Built-Up
  • Cap Sheet
  • Composite
  • Concrete
  • Fiberglass
  • Metal
  • Modified Bitumen
  • Torchdown
  • Most existing coatings
  • Sprayed Polyurethane Foam
  • Low-Pitched Roofs
  • Flat Roofs
  • Mobile Homes
  • RV’s & Campers

*Not for use on 3-tab asphalt or architectural shingles.

May require multiple coats to create a seamless membrane.

If the roof has been patched with any asphalt or black tar-like products within the last 12 months, applying a coat of GacoFlex E5320 2-Part Epoxy Primer/Filler may help prevent bleed-through staining on the final coats. GacoRoof will adhere to most surfaces without a primer; however, some substrates may require a primer for optimal adhesion. To verify adhesion, use the GacoRoof Adhesion Test Kit, which provides results in just 24 hours. If the test reflects poor adhesion, prime all surfaces with GacoFlex E5320 according to label directions.

A minimum of two coats are required; Recommended final film build is a minimum of 22 dry

Appl2mils. To help ensure complete coverage during application of the final coat, it is recommended to use a different GacoRoof color for the first coat to create a color contrast. Mix before application to ensure uniform color and consistency. Product should not be thinned.

Flat roofs (less than 1:12 pitch/5°): Use a solvent-resistant ¾” or 1” nap roller cover and depending on type of roof, dip roller directly into pail and apply, or pour product onto flat roof surface and roll out evenly, or for very smooth surfaces, pour out product and spread with an 1/8” notched squeegee then immediately back roll for a smooth, even finish.

Pitched roofs (greater than 1:12 pitch/5°): Use extreme caution when on a pitched roof. Follow all safety guidelines to avoid injury. Use a solvent-resistant ¾” or 1” nap roller cover, dip roller directly into pail, and apply. A roof pitch greater than 4:12/19° is not considered walkable; Additional reach equipment may be needed to properly apply the product safely and effectively.

Allow the first coat to dry for 3 to 12 hours. Apply second coat as soon as the first coat can be safely walked on. The coverage rate of GacoRoof is 100 sq. ft. per gallon in each coat on a smooth surface; coverage rate may decrease on textured surfaces, and more coating will likely be used on first coat than on additional coats. Smooth roofs can be completed in 2 coats, lightly textured surfaces often require 3 coats, and heavily textured surfaces may require 4 coats to achieve a final 22 dry mil film build.

Do not apply in temperatures below freezing, above 120°F (49°C) or if rain is expected within 2 hours. Do not walk on GacoRoof other than for periodic maintenance; for areas of light foot traffic, create a walking path by applying a coat of LiquidRoofTape according to label instructions.

Independent contractors who are utilizing an airless sprayer should consult our GacoRoof Silicone Spray Guide and Safety and Storage Guide.

Application tools and equipment can be cleaned with GacoFlex Silicone Solvent or 100% Pure Mineral Spirits. DO NOT USE WATER OR RECLAIMED SOLVENTS. Once a container of GacoRoof is opened, the curing process has started. Use the entire product on your project if possible. Allow any remaining product in the container to solidify and dispose of in the proper manner.

Roof structures may settle over time. A periodic inspection of your roof, which includes transition areas, flashing, vents and skylights, is recommended. Keep drains cleared at all times. Roofs become slippery when wet. Use extreme caution. Do not recoat GacoRoof with acrylic, urethane or Hypalon® coatings. Recoat cleaned GacoRoof only with more GacoRoof.

CAUTION: An old, neglected, or failing roof does not have the resilience to withstand the rigors of weather. GacoRoof may not be suitable for such a roof. If you are in doubt about the condition of your roof, consult a qualified roof inspector.


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