Over time, house roofs can accumulate all kinds of dirt and debris. Among them are leaves, twigs, branches, sticks, acorns, pine straw, and other detritus that are brought by the wind or by small animals like squirrels and birds. These debris can result in rain and melting snow water standing on the roof. Eventually, the water buildup can seep into the interior of the house and damage the roof decking, walls, floors, and so on.
Roof shingles can also have moss, lichens, and algae growing in the joints. All of this growth must be cleared regularly or they can eat into the organic content of the shingles and cause severe damage to it. Pressure cleaning is very effective in removing all this detritus and protecting the roof from damage. In addition, the clean roofs can add to the curb appeal of the house.
Understanding Different Roofing Materials
Before beginning with the pressure cleaning, you must take the time to study the kind of roofing material used and work out the cleaning methods accordingly. You might also want to have the roof examined by the roofing manufacturing company and request for an evaluation on whether the roof can be safely pressure cleaned. That’s because, roofs that are too old or in bad condition may not be able to sustain aggressive cleaning. If some roof tiles have severe granule loss, the manufacturing company might recommend that they should be replaced. Also, have the homeowner check for the warranty on the roofing. Many manufacturers may void the warranty if the roof is pressure cleaned.
- Cedar shingles and shakes: Cedar roofing material needs to be cleaned every 5 years. Post cleaning, it is advisable to oil the roofing. Oil is excellent for repelling water and can condition the wood. You can prevent the wood from splitting and cupping, and deter the future growth of moss.
- Tiles: Tiles must be lifted and their valleys cleaned regularly to make sure that any possibility of leakage is avoided. However, take care to ensure that the water does not reach the timbers and underfelt or it can damage the insulation and any electrical wiring and installations. In addition, using a high PSI can erode the smooth finish of the tiles. Without this smooth finish, the roughness of the tiles will make them more susceptible to the growth of moss and algae.
- Composition: Composition roofs have a coating of roof sand that is made of ceramic shavings. These shavings have the property of deflecting heat and keeping the interiors cool. Using a pressure washer or air compressor with a high PSI can result in the erosion of the shavings and exposing the house to the direct heat and harmful UV rays of the sun.
Equipment Needed
Choosing the right equipment can help you have the roof cleaned effectively and thoroughly.
- Pressure Washer: Choose a pressure washer that gives you a PSI or pounds per square inch force of around 1,500 with a water flow of 10 to 15 gallons per minute or GPM.
- Nozzles: Pick out nozzles that give you 35° to 40° angles. Never use smaller tips on roofs.
- Cleaning agents: Check with the supplier for eco-friendly agents that can kill moss, lichen, and algae, and prevent their future growth.
Prepping the Roof
Remove the excess loose trash from the roof with the help of a soft broom or brush. Take care not to use harsh scrubbing or you risk removing some of the roofing granules. You can also use an air blower to blast off debris like leaves, twigs, branches, and other windblown materials. Also, check the roof thoroughly for loose or missing shingles. Consider having them fixed securely or replacing them before beginning the pressure cleaning.
Dealing With Algae and Black Stains
When examining the roof before cleaning, you might notice that the roof has black spots. These black spots appear because of dead algae on the roof tiles. Since algae and moss grows and feeds off the roofing, it is very essential that you remove them. Choose an eco-friendly agent that does not contain any poisonous chemicals and will not kill vegetation and pollute the water drains. Thus, you can have the roof cleaned without damaging the surrounding environment and maintaining the integrity of the roof tiles at the same time.
Spread the cleaning solution of the roof tiles according to the instructions of the manufacturer and rinse. Once you remove the mold and moss, you can have the roof cleaned with pressure washing. To make sure that the cleaning solutions you’re using will not damage the roofing material, you can consider getting some spare tiles of similar types and trying the solution on them before cleaning the roof.
Pressure Washing Techniques
When pressure cleaning home roofs, take care to use a mild pressure similar to that exerted by rain so that is effective in removing the dirt but will not erode the protective granule layer of the tiles. Further, since pressure cleaning can dislodge the roots, spores, and microbes of lichens, algae, and moss, it can prove to be effective in preventing new growths of such vegetation for a long while. Here are some other tips to keep in mind.
- When pressure washing, take care not to let the water enter the skylights by spraying away from the edges. If you see moss or algae around the skylights, it is advisable to remove them by hand.
- Begin spraying from the ridge of the roof and work your way down to the eaves. This method will ensure that you don’t break any seals or lift any shingles and allow water to get under them.
- Using a detergent nozzle, apply the necessary soap and give it time to work.
- Spray clean water in even strokes without focusing on a particular area for too long. Use a 45° angle from the roof and take care to keep the tip of the nozzle at a distance of 8 inches to one foot from the surface.
- Having completed the pressure cleaning, you can take the necessary measures for preventing the future growth of algae and moss. Depending on the typical weather conditions of the area and the prevailing species of moss buildup, you can spread the appropriate chemical on the roof. Such treatments need to be repeated every six to twelve months to keep the roof clear of growth and possible damage.
Whether or not pressure washing can be used on roofs is an issue that has been widely debated. However, as against using chemicals and detergents for cleaning roofs, pressure cleaning can prove to an eco-friendly method that is also highly effective. It can help clean roofs so they remain energy efficient and protect the interiors of the house for many years to come.
References:
1.“All You Need to Know About Pressure Washing, Roofs & Moss.”Harbor Home Management. 8 May 2013. Web. 4 Sept. 2016.
2. Prisak, Sandy. “3 Roof-Cleaning Methods for Ugly Stains.”Angie’s List. 14 Dec. 2015. Web. 4 Sept. 2016.
3.“From New to Dirty & Dirty to Clean.”. Roofpedia. n.d. Web. 4 Sept. 2016.
4. Damon. “Pressure Washing Asphalt Shingles.”Element Smart Roofing. 10 Sept. 2012. Web. 4 Sept. 2016.