Due to the tech advances in roofing materials, it is now up to the owner if he wants to call a roof cleaning contractor to perform flat roof cleaning or if he wants to carry out roof repairs as a DIY project.
All exterior low slope or flat roofing membranes become grimey throughout the life of the roof system from airborne dirt and pollutants.
The buildup of grime on a darker colored roof surface is less noticeable than on a white or light colored membrane. The type and amount of dirt buildup is directly related to the location of the installed roofing system. Each type of “dirt” requires a bit different level of effort and approach to clean a roof surface.
Some of the 1st and second generation of flat roof houses and other buildings will now need roof maintenance due to water pooling in some roof areas. Also consider that many of the original roofing materials used on these roofs have arrived at end of their useful life.
When repairing, the owner must keep in mind that flat roofs are extremely sensitive to human traffic.
There are two possible issues when a lightly colored roofing system becomes grimey:
1. Aesthetically, a clean roof looks better and helps with curb appeal and property values.
2. Practically, a clean roof will be more energy efficient.
With current design initiatives, an increasing number or designers are looking toward environmentally friendly roof designs to lessen energy costs which save natural resources. Other considerations in dense areas is to lessen the effects that commercial roofs have on the natural weather patterns.
Low slope and flat roofing covering makers exclude appearance from warranty coverage as an uncontrollable condition. If the building owner wishes to clean his roof to bring back the reflectivity or aesthetic appearance of the membrane, a materials list and directions for cleaning a warranted roofing system are listed below.
It is the building owner’s duty to become familiar with and abide by local and regional laws and codes with regards to approved cleaning soaps and proper disposal of dirty water.
It is advised to hire a professional roof cleaning company to do this job because of the chemical solutions involved and the hazards involved working at heights.
Needed materials: soft bristle brooms, mops, and squeegees.
1. Broom off the roof surface. This will remove loose dirt and debris that might clog the drains or scratch the membrane surface during washing.
2. Wet the roof surface and allow to soak in for five minutes to soften any dried dirt.
3. Dislodge the dirt from the membrane surface by gently sweeping the wet surface with a soft bristle broom.
4. Thoroughly rinse the area of membrane that is being worked on to determine the effectiveness of cleaning with water alone.
5. If there is still grime on the membrane, re-wet the roof surface and allow to soak again for five minutes.
6. When soaking, apply a sprinkling of Spic and Span® or tri-sodium phosphate to the wetted membrane.
7. Re-scrub the membrane with the soft bristle broom.
8. Thoroughly rinse with clean water before the soap residue dries on the roofing membrane.
9. The above steps will get rid of most forms of dirt. If a single cleaning does not get rid of the dirt, you may need to repeat steps 1-8.
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Cautions and Warnings:
Damage to the roof during washing operations is not covered under the warranty. If damage occurs during washing, it is the responsibility of the owner to repair.
Source for the following: genflex.com/wp-content/uploads/2013/04/Design-Criteria1.pdf
Do not abrade the surface of the roof membrane. Seams are typically laid shingle fashion towards the roof drain or gutter. Do not agitate, power wash or scrub against the seam. Go over the top or parallel to it.
A commercial roofing system is a major investment for a property owner. It is important to protect the roof system from accidental damage during cleaning.
Before hiring the project out to a local contractor, there are a few things to consider.
1. Building owner assumes all risk for damage to the roofing membrane during the cleaning process. Use extreme caution in performing the work yourself or hiring the job out.
2. The roofing manufacturer is available for assistance in writing the scope of work.
3. Many installers also offer roof cleaning services.
4. Perform a visual inspection of the roof system before and after cleaning the roofing membrane to identify any pre-existing roof damage and to verify the effectiveness of the cleaning process. It may prove beneficial to take photographs of the roof system before cleaning begins.
5. Do not use, or allow anyone else to use, a floor scrubber on the membrane.
6. Pressure washing equipment can severely damage a roofing membrane if not used by a professional with membrane roof cleaning experience. If a pressure washer is used in cleaning the roofing membrane, please keep the following items in mind:
a. Do not use any pressure washer tip less than a 30° arc. Tips with a concentration angle smaller than 30° will damage the roofing membrane.
b. Do not use a rotating tip apparatus.
c. Maintain a minimum of 24” (60 cm) between the pressure washer nozzle tip and the roofing membrane.
d. Do not use a pressure washer rated higher than 2500 psi (17 MPa).
7. Always get current certificates of liability insurance from the contractor performing the work with your company listed as an additional insured party.
8. If you suspect the warranted roof system may have been damaged during the cleaning process, contact the manufacturer immediately.
