Roof Cleaning - A Home Owners Guide - The Do's And Don'ts

Your roof is dirty, you see black spots, moss, lichen or maybe some other kind of fungus. Now the question is, "How can I clean it?"

You are not alone, as I am sure you have noticed the same problem on other roofs in your neighbourhood. If you have done some research, you will have found that the problem occurs in every city and state.

Is it damaging my roof? Yes, I have seen moss eat its way through two layers of shingles and into the wood underlayment. Black algae feed on the surface and eat the shingle granules as it spreads across the roof. Just look in your gutter on the infested side, I guarantee it will be full of discarded shingle granules. Yes, it can shorten the life expectancy of a 40-year-old roof shingle by half or more.

What can I do about it? There are 3 options: clean it yourself, hire a professional roof cleaning company, or replace the roof. Let's take a look at these three options.

Replace - If you have that kind of money, great! Here's the bad news: even though the new shingles on the market are algae-resistant, beware! Read the warranty they only provide for an average of 10 years. If you have the money and want to afford a clean roof for 10 years, you should do it.

Hire a roof cleaning company - a good choice, but who? They exist, usually listed in the Yellow Pages under "roof cleaning" or "pressure washing." What to look for in a roof cleaning company is very important. 1. references 2. specific insurance coverage, painters, carpenters or builders liability insurance will not cover roof cleaning, check this 3. ask about the cleaning products, there are many products that will clean a roof, but if they are heavily chemical they will dry out the roof shingles to the point that after a few months on a windy day piece of shingle will be flying around. 

These products will also stain your home's siding and kill plants and grass. You want them to use something "environmentally safe" not just "biodegradable" which just means it will eventually disappear, there are biodegradable plastics but you don't want them sitting on your lawn for the next 20 years, do you? So make sure the product is environmentally friendly. 

4. portfolio: they should have before and after pictures of work they've done, and you should take the time to drive by one of the houses and make sure they didn't just download pictures from the internet. 5. do they have a home improvement license? they should. If they don't have these 5 things, go to the nearest business.

Clean it yourself - dangerous work! but doable if you consider yourself a "handyman", and the cheapest solution. The trick is to buy the right product. Don't even consider bleach, which is a disaster waiting to happen, but buy a product specifically designed for roof cleaning. 

Don't fall for the sales pitch of "just spray it on and nature will clean it", that's bullshit, it might work but it would take years to clean and you would have to keep reapplying it. 

No, there is only one way: get up there, but the roof securely on the underside, even if it is walkable, the roof will be incredibly slippery, spray the product on, usually with a "garden-style" sprayer, take a medium bristle brush and scrub the infested area, keeping it wet, and then take a regular garden hose and wash it off.