The short answer is Yes, kinda. Pressure washing your roof will remove granules and reduce the overall life of the roof, but the moss and algae you are removing also reduces the life of the roof as well so it is a decision that you as the homeowner will have to make to determine if the potential risk is worth having a clean roof.
How to Pressure Wash A Roof
Roofs get more than just rainwater on them. Depending on where you live, you may find moss and algae growing on your shingles especially if you do not have a shingle with Scotchgard like we install at D.K. Mason Roofing. Roofs with moss and algae growth need to be cleaned. Neglecting to remove the growth will only damage your roof further. However, there are some risks to consider.
You need to be careful to only step in dry areas of your roof, as wet algae is very slippery.
Start by Applying a Detergent
Before you begin pressure washing, consider using a good-quality biodegradable pressure washer-safe detergent. Applying some detergent first will help to loosen the algae, or moss so it’s easier to remove and doesn’t take as many granules with it. You won’t want to use a lot of pressure when you spray your shingles, as too much pressure can strip your shingles of their protective granules or even damage or remove the shingles themselves.
By applying detergent first, using a foamer or a soap shooter, you can gently loosen the unwanted growth from the shingles so you can use much less pressure to spray it away.
***Always Use Low Pressure to Spray it Clean and Use a Low-Pressure Spray Tip***
The power of a pressure washer can very easily damage the shingles on your roof, so it’s important that you select the proper spray tip. Start with a medium pressure spray pattern, and adjust from there accordingly. Always stand on a dry area of the roof, as wet shingles can be very slippery. Aim the pressure washer down the roof (toward the gutters), and keep the tip of the wand at least 18 inches away from the surface when starting.
NEVER aim your pressure washer up the roof, as it can push water under the shingles. Spraying water under your shingles can both tear off the shingles and force water under them and into your home. Cover a few shingles at a time, and move the wand slightly closer to the surface as more power is needed. It is very important that you constantly inspect for any damage you may be causing throughout your cleaning as it is very easy to use too much pressure and damage your shingles. Follow these steps and your roof will be looking great in no time. Don’t excessively clean your roof, as it’ll add more wear and tear. Only do this as needed.