How To Clean Roofing Shingles | Timberline/GAF Roof Cleaning Instructions

By Ed Thompson

How To Clean Roofing Shingles

You may have found this page while searching for the right contractor for your roof cleaning project.   You can find many conflicting points of view on the subject.  Some companies pressure wash while others use a bleach-like solution.  It is important not to choose a method that may potentially void your roof warranty.

Black staining on a roof is a bacteria called Gloeocapsa Magma.  There is no rhyme or reason as to why it forms on roofs.  The spores travel by air.  They land everywhere on a roof, they do not choose where to land, but it seems to grow more visibly on the north sides of the roof where there is less sunlight.  Shady sides of a roof retain more moisture which allows the stain to fester more predominantly.

The most popular brand of roof shingles is a GAF Timberline roof.  GAF has put out a bulletin that acknowledges the stain and offers a suggested method of stain removal.

We are a roof cleaning company in New Jersey.  Regardless of where you live in the USA, the stains are the same as well as the cleaning procedure.  They clearly warn against pressure washing and suggest the use of bleach and TSP (trisodium phosphate).  Our company chooses not to use trisodium phosphates since it is not an environmentally friendly product.  Phosphates promote algae growth in lakes.  This is why it suggested to keep certain lawn fertilizers from reaching the storm drains.  Trisodium phosphates increase the ph level in sodium hypochlorite.  Here in the northeast we get fresh shipments of sodium hypochlorite.  There is no reason to have to increase the ph levels in order for us to clean roofs.

Moss and lichens are also pests that deteriorates roofing shingle.  These organisms are easy to kill, but not always quick to remove.  These growths form a root system in the shingle just like a plant.  If you force these items from the roof you can potentially take the roofing granules off also and leave scars on the roof.  To remove these items safely is to treat and kill the growths then let them decompose and dry out.  The rains will slowly wash away the decaying growths.  This is not a quick process and can take up to 90 days.  This is the least aggressive way to clean the roof of moss and lichens.

This method of chemical cleaning is what we call “soft-washing”.  It is safe to use sodium hypochlorite.  Local municipalities are the largest purchasers of sodium hypochlorite that is used to sterilize our drinking water.  This product does have the ability to adversely effect surrounding landscape.  Be sure to ask you roof cleaning contractor how they plan to contain the runoff and protect the landscape.  Sodium hypochlorite is non-carcinagenic and certainly is a less aggressive cleaning compared to “roof pressure washing”.  High pressure water does nothing to kill the mold spores.  Using this method will insure the staining to return rather soon.

This article was written for those searching well informed answers.  You can read more about roof cleaning by visiting our sister website at http://www.powerwashing-newjersey.com/non-pressure-roof-washing/ or call us anywhere in the United States @ (877) 420-WASH.  We’d be more than glad to help you find the right soft-wash contractor.