How to Clean a TPO or PVC Roof

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A building owner invests a great deal into a low-slope roof, but the job doesn’t end after installation. It’s important for contractors to explain the value of maintenance — and that includes cleaning as well. There are several reasons routine cleaning should be included in normal roofing system maintenance, including:

  • Keeping the surface white so it can provide maximum reflectivity and its associated energy conservation benefits
  • Preventing the accumulation of dirt and debris, which can act as a nutrient source for algae and other plant growth
  • Preventing the accumulation of food sources for birds and other pests
  • Preventing the accumulation of chemical contaminants on the roof surface that may harm the membrane and reduce its performance life

Because of safety concerns and potential for roof membrane damage, GAF recommends you take these precautions:

  • First, only trained professionals should be allowed on the roof to avoid any damage to the integrity of the roofing system.
  • Fall safety requirements must be followed—a wet, single-ply membrane is slippery. Use caution and follow all fall safety requirements.
  • Avoid walking on surfaces where the cleaning solution has not been rinsed away.
  • Where the run-off may come in contact with exterior facades, test a small area to make sure there are no deleterious effects to the façade from the cleaning solution.
  • Be sure to make accommodations for the run-off cleaning solution to avoid damage to plants and contamination of ground water. Always comply with all local, state, and federal requirements for water run-off.

So, how often should a low-slope roof be cleaned? It depends on several factors such as the severity of environmental contaminants, the frequency of rainfall, the propensity for dirt and dust accumulation, and the roof slope and drainage characteristics.

Note: Some roof surfaces may not require routine cleaning and others may require cleaning on a frequent basis.

When cleaning EverGuard® TPO and PVC membranes, contractors should follow these tips:

1. Protect any low curbs, base flashings, or other points where water could enter from the use of a pressure washer.

2. Protect plants, shrubbery, and exterior facades from run-off of cleaning solution.

3. Use a low-pressure power washer (2,000 psi or lower) to clean and rinse off the top layer of dust and dirt.

4. Use a soft-bristled, long-handled brush or floor broom with a cleaning solution consisting of a mild, non-abrasive household detergent and water to clean the surface of the roof membrane, taking care to not damage the top surface of the membrane.

5. Rinse the roof completely with the low-pressure power washer to rinse the cleaning solution off the roof.

6. Inspect the membrane and ensure no damage has occurred; repair any incidental damage per GAF guidelines.

Proper maintenance and cleaning should be offered to a building owner after every installation to help extend the life of their investment.

Related articles:
PVC vs. TPO: Is the Debate Over?
The History of TPO

There are 6 comments

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  1. George Clarke

    1. We blow off the roof. 2. We use a 1000 psi to pre-rinse. 3. Apply solution agitate with a soft brush and rinse with 1000 psi. 4. Repeat number 3 if needed. Always use care where you send the runoff. It should be absorbed into a grassy area where it won’t go into any waterways. if you use something that can kill plants, then you should act responsibly.

    • Thomas J Taylor, PhD

      Thanks for comments. Sounds like you do a good job. We recommend using Simple Green as the cleaner, diluted per their directions. Nothing harsher should be used. I agree that people need to be aware of the run-off.

  2. Paul Watson

    Mr. Curtis,
    Great information. Do you recommend the same cleaning method in the case of rust stains? Other trades left clips of nails on our membrane, leaving rust stains. Will these stains be harmful to TPO membrane?

  3. Gerald B. Curtis

    As a Roofing Specialist Consultant, functioning frequently as a Quality Assurance Observer as a roof is installed, I have often run into the question of needed cleaning after installation of TPO (primarily in my cases) Membranes because of installer carelessness or preventive disinterest on the part of other trades that traverse the completed roof, or both. A dusty construction site can also contribute to the loss of albedo.

    With concurring input from a major manufacturer, I have found that the use of a floor buffer run on LOW speed with a non-abrasive pad (There are some pads that incorporate abrasives, so be very careful.), using any mild liquid dish detergent and COPIOUS quantities of water, the ability to restore the initial manufacturer-delivered membrane albedo is high, easily accomplished, and faster than using a broom that the article describes.

    In my opinion, using a pressure washer is risky, and not as effective as mechanical dirt-lifting abrasion.

    Care must be taken to prevent the wearing of the pad to the point that the pad-grabbing teeth of the buffer disk engage the membrane, thus gouging it. Cleaning performed by an experienced operator will avoid such a concern.

      • Thomas J Taylor, PhD

        Wendy – there are different types of membrane used on camper roofs. My answer is the same as for any roof membrane – reach out to the manufacturer and/or supplier to find out what should be used to clean it. The wrong choice could damage the membrane.

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