All exposed low slope or flat roofing membranes get dirty throughout the life of the roofing system from airborne dirt and pollutants.
The accumulation of dirt on a dark shaded roof surface is not as noticeable on a light colored or white membrane. The type and amount of grime buildup is directly related to the location of the installed roofing system. Each type of “dirt” requires a bit different approach and level of effort to clean a roof surface.
Some of the first and 2nd generation of low-sloped roof houses and commercial buildings will now need roof maintenance due to water accumulation in some roof locations. Also consider that many of the original roof materials installed 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 scenarios when a lightly colored roofing system becomes dirty:
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 imperatives, an increasing number or designers are looking at eco- friendly roof designs to reduce energy expenses which conserve natural resources. Another consideration in dense areas is to lessen the effects that commercial roofs have on the natural weather patterns.
Flat and low slope roofing membrane manufacturers exclude appearance from warranty coverage as an uncontrollable variable. If the building owner wishes to clean his roof to bring back the reflective qualities or good appearance of the membrane, an equipment list and directions for DIY cleaning a warranted roofing system are listed below.
It is the owner’s duty to become familiar with and adhere to local and regional laws and codes with regards to approved cleaning soaps and correct disposal of cleaning 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.
Required equipment: soft bristle brooms, mops, and squeegees.
1. Broom clean the roof surface. This will remove loose debris and dirt that may clog the drains or abrade the membrane surface during washing.
2. Wet the roof surface and allow to soak in for five minutes to soften any dried dirt.
3. Loosen the dirt from the membrane surface by gently sweeping the wet surface with a soft bristle broom.
4. Thoroughly rinse the area of membrane being worked on to assess 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. While soaking, apply a generous amount of powdered floor cleaner or tri-sodium phosphate to the wet membrane.
7. Scrub the membrane again with the soft bristle broom.
8. Rinse with clean water before the soap residue dries on the roof membrane.
9. The above steps will remove most forms of roof grime. If one cleaning does not get rid of the dirt, you might need to repeat steps 1-8.
https://img.youtube.com/vi/cQhFf0gE4sc/0.jpg
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.
