Why Regular Roof and Gutter Cleaning Matters

The Math That Makes This Worth Reading

A roof cleaning with moss treatment runs $850 to $1,200 for most asphalt roofs around here (more with heavy moss), and on our schedule that's an every-2-to-4-years expense. A roof replacement runs $10,000-$30,000. Moss and clogged gutters are the two things that quietly move that replacement date up by years. A well-maintained roof commonly lasts 10-15 years longer than a neglected one. Nothing else in home maintenance has a spread like that.

What clogged gutters actually do

A clogged gutter doesn't just overflow. It dumps every storm's water in a sheet right at your foundation line, and it holds standing water against the fascia boards until they rot. By the time you notice a sagging gutter or a damp basement corner, the water has been doing this for months. Twice-a-year cleaning (spring and fall, after the big leaf drop) is the whole fix.

What moss actually does

Moss is a sponge that lives on your roof. It holds water against the shingles for weeks after rain, works under the shingle edges and lifts them, and opens paths for leaks. There's also a newer cost: insurance carriers now review aerial imagery, and a visibly mossy roof can trigger a fix-it notice or even non-renewal. A meaningful share of our calls start with one of those letters.

The curb appeal part is real too

If you're selling, a green-streaked roof reads as "deferred maintenance" to every buyer and inspector who sees it, and it's one of the cheapest big-visual-impact fixes a house can get. Most of our pre-listing customers say the roof looks like it was replaced.

Recommended Maintenance Schedule

For Pacific Northwest homes, Seattle ProWash recommends:

• Full roof cleaning every 2-4 years to remove moss, algae, and debris (sooner under heavy tree cover)
• Annual moss treatment between cleanings to keep growth from coming back
• Gutter cleaning twice a year (spring and fall) to prevent clogs

Professional vs. DIY

Ground-floor gutters on a one-story home are a fair DIY job. We wrote a whole guide on doing it safely. The roof itself is different: moss treatment needs the right product at the right concentration to kill growth at the root without harming shingles or landscaping, and walking a wet Seattle roof without fall protection is a genuinely bad idea. That's the part worth paying for, along with the 12-month moss-free guarantee that comes with it, and a set of before/after photos so you can see exactly what was done.