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Roof Cleaning

How to Clean a Roof

If you have come to this page of our website it means that you are smart enough to do your home work before hiring a contractor to clean your roof. And, if you are smart enough to do your home work I can only assume you are smart enough to understand that not all pressure washing contractors are equipped to clean different roofing products. Yes, a roof can be damaged if the cleaning process is performed improperly. Yes, most if not all roof materials have exclusions in the manufacturers warranty for aggressive cleaning of the roof surface that may include low pressure washing and/or pressurized air cleans. Yes, I have witnessed first hand damage done to a roof because of poor pressure washing tactics. With that said when performed correctly a low pressure washing of a roof should produce no more granule loss than a normal rain cycle.

Stains and Dark Spots Removal

If your roof has a few dark stains, which is commonplace in the Greater Philadelphia area, you may not need to use any pressure at all. In some cases applying and rinsing the proper cleaning agent can do the trick. Keep in mind though those areas that were once darker than the rest of the roof may end up being lighter than the rest of your roof after cleaning, which is why we suggest cleaning the entire roof each time. 

Mold & Mildew Removal

If you are in an area in Pennsylvania or New Jersey that has tall trees, nearby vegetation, or a place in which a part or all of your roof does not see adequate sun exposure you will probably notice the accumulation of moss and/or mildew. Moss will start growing in the cracks between each shingle and at the overlapping sections from one row of shingles to the next. If left unattended, moss will keep growing over time. Should you allow the moss to continue to spread across the entire roof? Should you allow the moss to spread under the shingles and possible harm the underlayment, plywood and potentially the structural integrity of your roof? There is no simple way to answer this as it seems like a lose lose situation for the home owner. Should you hire a pressure washer to get rid of the moss and mildew, which could negate a manufacturers warranty or allow it to spread and potentially destroy your roof? For insurance reasons you can appreciate that we are not permitted to say certain things related to cleaning roofing products with regards to manufactures warranty. What I can say is that if there was moss and mold on my roof I would hire a professional pressure washing contractor to fix the situation, one that is experienced with cleaning roofs.

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Roof After

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Roof Cleaning & Repair in Winter

Before & After Pictures

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Choosing a Roof Cleaning Contractor

Just like you wouldn’t pick any stranger to babysit your children or you wouldn’t choose a college by picking out of a hat, do not pick a pressure washing contractor simply because they are local. Do some research and ask some questions. Be blunt about it. “Hi, I need my roof cleaned but I do not want to negate the warranty on my roof.” If the company in question does not answer you similarly to what is written above, move on to the next company. Any professional pressure washing contractor should know to spray at a 45 degree angle and remain at least 8″ away from shingles. They should know to never spray under flashing of skylights and always spray outward and away. In choosing your contractor make sure they have:

  • hot water commercial pressure washers
  • high volume machines that pump at least 6 gallons per minute
  • adjustable pressurized machines (as little pressure should be used)
  • multiple spray tips available

Roof Cleaning Agents

The alternative to pressure washing a roof is to apply chemicals that will kill the moss and mildew and eventually deteriorate once it dies. Keep in mind this will only take care of the moss and mildew growth, not any stains. While this takes a longer period of time certain chemical agents have been proven to work. Zinc Sulphate typically comes in powder form and can be either applied dry or diluted with water and sprayed on. Although it will be visible for a few weeks on your roof, the mold should start dying within a few days. Clean Brite costs more but is more environmentally friendly and generally performs just as well. We do not suggest sodium bicarbonate, which is basically baking soda, as it is not nearly as effective. We also do not recommend Copper Napthanate. Although is is extremely effective in killing moss and mildew, it is toxic to both people and plants.

J&J Power Wash offers residential and commercial patio pressure washing services. No matter how dirty your roof is and what product it is made of we can help. To set up a free estimate call us 215-703-8306 or fill out our online form. Click on the images below to enlarge them or visit our portfolio page for additional before and after pictures.

Serving the Greater Philadelphia and South Jersey Areas