2 Ways to clean a roof – Mechanical & Chemical

Mechanical roof cleaning is the process of brushing, power washing and/or using a surface Professional Guildford roof cleaners cleaner (a large silver disk) that use pressure water to physically remove roof growth, Chemical roof cleaning uses chemicals such as CL (chlorine bleach), tsp, alcohol and other chemicals to kill everything on your roof.

What is mechanical roof cleaning?
Some roof cleaners only offer what we call “mechanical roof cleaning”, this is where they will brush and/or use a pressure-washer to clean the roof.

Power washing is a process that uses anywhere from 1000 – 3000 psi (that is 1000-3000 pounds per square inch of pressure of pressure) to physically remove growth from roofing materials. Power washing is a very effective way to remove anything on any surface but it comes with a price, the use of high pressure to clean asphalt shingles causes graduals that make up the shingles detach taking years off the life of the roof. With the use of high pressure, there is also a risk that major damage can occur as shingles can be broken and/or scared and water can be forced inside the house.
Another way is to gently brush or scrub the shingles, this can be a way to get moss and lichen from detaching but there is a very high chance that the shingle will be damaged in the process. Brushing can break shingles and forcing large amounts of granules to detach.

What is Chemical Roof Cleaning?
Chemical roof cleaning is the process of spraying the roof with chemicals designed to kill roof growth.

A common form of chemical roof cleaning is the use of a low concentration of chlorine bleach mixed with additives such as an enhancer, TSP, alcohol and surfactants (sticky stuff) that are sprayed onto the roof using a low-pressure pump (normally less than 100 psi). The primary concern with this form of roof cleaning is having flowers and grass die from the chemicals. A good roof cleaner using a chemical based cleaning system should ensure this will not happen by watering all plants and grass around the house before during and after they apply their chemicals to protect vegetation from being hurt. If done right bleach roof cleaning is a very safe, cost effective and guarantees all the things growing on a roof are actually killed.

Other Chemical ways to clean a roof – Zinc and Potassium:
The use of Zinc strips, Zinc Sulfate, Zinc Chloride, Copper Sulfate, and Potassium are other chemicals are widely used to clean roofs and keep them clean for many years. There are several different ways to apply the cleaning chemicals to the roof and each has their pro’s and con’s. There is a great write-up on the Oregon State University website that reviews each of these roof cleaning chemicals and how they can be applied. Click here to read a write up from OregonState.edu