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Contractor’s Corner

Roofing, painting, siding and window tips and tricks from Rocky Mountain Roofing & Exteriors
How to Clean a Roof

How to Clean a Roof

NEVER power wash your roof.

We’ll say that a few more times just in case. Just remember, whatever you end up doing, if you power wash your roof, you lose at roof cleaning.

Now that we’ve established that, maybe let’s talk about how TO clean a roof, yes? Roof cleaning isn’t the best DIY project, especially if your roof has a lot of surfaces, but it can be done. Let’s get into how to clean a roof.

How to Clean a Roof: Getting Started

Firstly, roof cleaning goes best when it’s done on a dry but overcast day. If it rains, your efforts will be washed away. If the sun comes out, your efforts will evaporate.

So. On your dry but overcast day, load up your favorite garden sprayer with equal parts laundry-strength or stronger chlorine bleach and water. If you use bleach that’s stronger than laundry-strength, you just stand a slightly better chance of getting the whole job done in one pass.

Now that your favorite garden sprayer is loaded up with equal parts bleach and water on a decidedly dry but overcast day, spray the roof with the sprayer which is full of the aforementioned bleach and water. You might need a ladder (be careful!), you might not. If you find that you actually have to walk around on your roof to hit everything, consider calling your friendly, local roofing contractors in Denver, CO to come take care of this slippery, high-off-the-ground job for you.

But, if it’s full DIY speed ahead, once the roof is sprayed with bleach and water via your favorite garden sprayer on a dry but overcast day, let it sit there for 15-20 minutes. This is the part of the process that gets jeopardized by rain and sun.

After, say, 20 minutes, come back around with a gentle garden hose–do not power wash your roof–and rinse your bleach water, along with the moss that it’s soaked into, off that roof.

Once you’ve rinsed without power washing, feel free to repeat if not everything came off.


Importance of Roof Cleaning

Roof cleaning is important because moss is like roof cancer. Whereas algae just kind of exists and looks gross, moss does that and gets down under and between shingles, encouraging them to curl up and flake right off.

Algae looks like black streaks down your roof. Homeowners often get spooked when they see these streaks because they’ve heard of the damage moss can do. But don’t fret–black streaks don’t cause leaks.

Moss, however, looks like moss. You know, the green stuff that grows on wet things, especially in the forest. If it’s moss, you’re going to have to show it who’s boss.

To reiterate, black streaks don’t cause leaks. But green moss must be shown who’s boss. Or it will wear your roof down and absolutely cause leaks.

But don’t power wash. Power washing is not how to clean a roof. If you do it, you could send your shingles flying. You’re bound to at least loosen them.

And while we’re on the subject, don’t scrub your roof either, for the same reasons.

Best Roof Cleaner Products

Beware! Most products that are called “roof cleaners” aren’t for use on moss. Just algae and other superficial pests. Moss products usually have the word “moss” in their names.

If you’d like to use a moss killer on your roof instead of bleach and water, just make sure to find one that’s intended for roofs. Patios and lawns also grow the stuff and it can be easy to accidentally take home a product that’s meant for those areas instead.

Something that purpose-made moss killers have over the bleach/water solution is that if you follow their instructions correctly, they can actually prevent moss for a few months after application.

Professional Roof Cleaning Costs

Again, roof cleaning isn’t the best DIY project, simply because it’s high off the ground and slippery. If you do get a contractor out to do it for you (solid choice), average roof cleaning costs are usually between $200 and $350. Of course, it depends on how much roof you have and how much moss you have, which in turn combine to determine how long the job will take.

The important thing is to get this done one way or another because whatever roof cleaning costs you incur will be far lower than replacing your roof, which you’ll have to do much sooner than you planned if you don’t get that moss off your roof.

Get that moss off your roof! But don’t power wash it. Even just real quick.

Need Help with Your Colorado Roof?

You know what? Rocky Mountain Roofing & Exteriors could just take care of it for you. We’ve done well over 3,000 jobs in the Denver area including tearing off and replacing roofs, so for us, a good moss cleaning is a breeze. We have all the gear and the training to make this task as safe as it can be, which is reason number one. But also, we won’t just get most of the moss off–we’ll clean that thing and have it looking pretty again, just like the day it was installed.

If you’re on the proverbial fence about whether to take this on yourself or have a professional do it for you, getting a free estimate is your next logical step. Let’s see what kinds of numbers you’re looking at, right? Then you can make a really well-informed decision.

It only makes sense to trust your Colorado roof to the best Colorado roofing company. Give us a call at (303) 377-2801 to find out what’s what. Talk to you soon!

But don’t power wash your roof. Seriously, you’ll break it.