Roof Talk-101 Roof Cleaning Guidelines

Roof Talk-101 ROOF CLEANING GUIDELINES

 

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All exposed low slope roofing membranes get dirty over the life of the roof system from

airborne pollutants and dirt. The accumulation of dirt on a dark colored roof surface is

less noticeable than on a light colored or white membrane. The amount and type of

accumulation is related to the location of the installed roof system. Each type of “dirt”

requires a slightly different approach and level of effort to remove from a roof surface.

There are two possible issues when a light colored roof system becomes dirty:

 

1. Aesthetics: If the roof surface is visible from the road or adjacent

buildings, it may be preferential to maintain a decorative appearance

versus utilitarian.

2. The second issue is energy efficiency. With current design initiatives,

more and more designers are looking toward environmentally friendly roof

designs to reduce energy costs which save natural resources, and to

reduce the effects that commercial roofs have on the natural weather

patterns (heat island).

 

 

Low slope roofing membrane manufacturers exclude aesthetics from warranty coverage

as an uncontrollable variable.

Should the building owner wish to clean his roof to restore the reflectivity or aesthetic

appearance of the membrane, an equipment list and directions for cleaning a warranted

roof system are below. It is the owner’s responsibility to become familiar with, and abide

by, local and regional codes and laws regarding acceptable cleaning soaps and proper

disposal of cleaning water.

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

 

1. Broom clean the roof surface. This will remove loose dirt and debris that

might clog the drains or abrade the membrane surface during washing.

2. Wet the roof surface and allow to “soak” for five minutes to soften any

dried dirt.

3. Loosen the dirt from the membrane surface by 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 membrane, re-wet the roof surface and allow to

soak for five minutes.

6. While soaking, apply a sprinkling of Spic and Span® or tri-sodium

phosphate (available at most paint stores) to the wetted membrane.

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

8. Rinse with clean water before the soap residue has a chance to dry on the

roofing membrane.

9. The above steps will remove most forms of dirt. If one washing does not

remove the dirt, you may need to repeat steps 1-8.

 

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. 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.