Flat Roof Cleaning Advice




WASHING FOR LOW SLOPED ROOF MEMBRANES







Residential and commercial roofing washing services are available for low sloped or flat roofs in need of repairs and maintenance to protect the home or establishment.


All exterior flat or low slope roofing membranes become grimey over the life of the roof system from airborne dirt and pollutants.




The accumulation of dirt on a darker colored roof surface is less noticeable than on a light colored or white membrane. The type and amount of grime buildup is usually related to the location of the installed roofing system. Each type of “dirt” requires a slightly different level of effort and approach to remove from a roof surface.


Some of the first and 2nd generation of low-sloped roof houses and other buildings now  require roof maintenance due to water accumulation in some roof areas.  Also think about  many of the original roofing materials installed on these roofs have reached the 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 roof 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 initiatives, more and more architects are looking at eco- friendly roofing designs to reduce energy costs  which save natural resources.  Other considerations in dense areas is to reduce the effects that commercial roofs have on heat islands.


Flat and low slope roof membrane manufacturers exclude aesthetics from warranty coverage as an uncontrollable variable. If the building owner wishes to clean his roof to bring back the reflective qualities or aesthetic appearance of the covering, 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 abide by local and regional laws and codes with regards to acceptable cleaning soaps and correct disposal of cleaning water.


If you are not comfortable working at heights, it is advised to hire a professional roof cleaning company.


Needed equipment: soft bristle brooms, mops, and squeegees.


1. Broom clean the roofing surface. This will remove loose debris and dirt that might clog the drains or scratch the membrane surface during washing.


2. Wet the roofing surface and allow to “soak” for five minutes to soften any caked on dirt.


3. Loosen the dirt from the flat membrane surface by gently sweeping the wet surface with a soft bristle broom.


4. Rinse the area of membrane being worked on to assess the effectiveness of cleaning with water alone.


5. If there is still dirt on the roof membrane, re-wet the roof surface and allow to soak again for 5 minutes.


6. While soaking, apply a sprinkling of powdered floor cleaner or tri-sodium phosphate to the wet membrane.


7. Re-scrub the membrane with the soft bristle broom.


8. Thoroughly rinse with fresh water before the soap residue dries on the roof membrane.


9. The above steps will get rid of most forms of roof grime. If a single washing does not get rid of the dirt, you may have 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.