How Much Does Roof Cleaning Cost In Snohomish & King County?

Joshua Darrow
Aug 26
4 min read

If you call Snohomish or King County home, you're probably all too familiar with the speed at which moss, algae, and debris treat your roof like a five-star resort. Thanks to our wet Pacific Northwest weather, these little green freeloaders have found the perfect paradise, and keeping your roof clean is more than just a beauty contest. It's about protecting one of the priciest parts of your humble abode.

Now, the burning question on every homeowner's mind is: "How much is this roof cleaning shindig going to set me back?" Well, my friend, that depends on a few crucial factors.

“Side-by-side comparison showing a residential roof before and after professional cleaning—left side with heavy black streaks and moss buildup, right side restored to a clean, like-new condition

What Affects the Price of Roof Cleaning?

Roof Size & Pitch A larger or steeper roof requires more time, safety precautions, and materials. A simple rambler will almost always be cheaper to clean than a tall multi-story home.
Condition of the Roof
Light debris? A basic blow-off and zinc treatment may be all you need.
- Heavy moss or black streaks? A soft wash treatment will be necessary, which takes more prep and specialized cleaning solution.
Type of Treatment
- Zinc treatment: Preventative, slows moss growth, and can kill light moss.
- Soft wash: Restorative, kills moss, algae, and black streaks at the root.
Accessibility
Homes with tight spaces, obstacles, or rooflines that require special safety setups may cost more.
Roof Material
Cement tile and metal roofs usually come at a higher cost because they require extra time, equipment, and safety precautions.

Average Roof Cleaning Costs In Snohomish & King County
while every home is different , we ran the data on over 1000 asphalt shingle roofs. Here's what you can expect:
- Zinc treatment (preventative/maintenance): $375 – $900
- Soft wash roof cleaning: $499 – $1,450+
- Roof care packages with warranties: $500 – $1,500+
Most standard residential homes fall between $500–$1,000 for a roof cleaning service, depending on treatment type and roof size.

Zinc vs Soft Washing What's the Difference?
A lot of homeowners wonder whether zinc or a full soft wash is the right choice. Here’s the honest breakdown:
- Zinc Treatment – Zinc is more of a preventative measure than a cure. When applied regularly, it helps slow down moss growth, but it won’t kill off heavy moss or black algae already on the roof.
- Soft Washing – This is a low-pressure treatment using a sodium hypochlorite algaecide solution. It eliminates moss, algae, lichen, and black streaks at the root level. It’s gentle on shingles and keeps your roof clean for much longer.

Here's a side by side comparison :

Factor	Zinc Treatment	Soft Washing (Sodium Hypochlorite Algaecide)
Purpose	Preventative — slows down moss growth	Restorative & preventative — kills moss, algae, and lichen at the root
Effectiveness	Minimal if moss is already present	Highly effective, clears stains and organic buildup
Longevity	Short-term unless reapplied regularly	Long-term results (often 2–4 years moss-free with proper care)
Best For	Light maintenance on relatively clean roofs	Heavier moss, black streaks, algae, or full roof restoration
Impact on Roof	Safe if applied correctly	Safe, low-pressure process designed for roof protection
Cost Range (Snohomish & King County)	$375 – $900	$499 – $1,450+ (cement tile and metal roofs can run significantly higher due to safety, time, and specialized methods)
Maintenance Needed	Must be reapplied regularly (every 6–12 months)	Re-treatment typically only every 2–4 years
Warranty/Guarantee	Rarely included	Often backed by warranties (e.g., 2-year no-moss-back with Mr. Pristine)

Which Option Is Right for Me?

If your roof is fairly clean with light moss growth, a zinc treatment can be a good maintenance tool — but it needs to be repeated regularly.
If your roof has noticeable moss, algae, or staining, or if you want longer-lasting protection, a soft wash is the better investment.
For cement tile or metal roofs, expect higher pricing Soft washing is the only option for these kind of roofs . These materials require more safety gear, special equipment, and careful handling.

Is the Cheapest Roof Cleaning Really the Best Option?

It’s tempting to shop for the lowest price, but when it comes to your roof, the cheapest option isn’t always the smartest choice.

Methods Matter Some companies cut costs by using high-pressure washing. This may blast away moss, but it also damages shingles and shortens roof life.
No Warranty, No Protection A cheap clean may look good at first, but without proper treatment, moss and algae will return quickly.
Hidden Costs If a contractor doesn’t carry proper insurance or licensing, you could be on the hook if something goes wrong.
Value vs. Price A professional company cleans, treats, and often warranties the work. That’s a very different service than a quick blow-off.

Bottom line: Paying a little more upfront for the right process and protection saves money (and stress) in the long run.

Final Thoughts

Roof cleaning isn’t one-size-fits-all, but now you have a clear picture of what it costs in Snohomish and King County, and why the cheapest option isn’t always the best.

At Mr. Pristine, we provide tailored estimates based on your home and back every service with our Pristine Promise Guarantee. Whether you’re looking for preventative zinc treatments or a full roof soft wash, our goal is to keep your roof pristine and protected for years to come.

Best regards,