Spring Roof Inspection Checklist for Snohomish County After Rainstorms

By the end of April in Snohomish County, your roof has been through almost a full year of Pacific Northwest weather. Around 38 inches of average annual rainfall, most of it concentrated November through April, plus the wind events that come with it. Spring — before the dry summer locks in any damage — is the right window to walk around your house and look up. Below is the same checklist I run through on a free quote visit, simplified for homeowners.

Why Spring Is the Right Time to Look

In Western Washington, moss is at its most visible in March, April, and early May. The rhizoids — the little thread-like roots moss uses to anchor itself — have spent the wet months working into the seam between shingles. Once we hit June and the roof dries out, the moss above the surface looks gray and dormant, but the damage underneath continues. By August it can look like the moss is gone. It is not. It is just dehydrated. The first fall rain wakes it back up.

That is why the May window matters. The moss is visible, the rhizoids have not had a long dry spell to cement themselves in, and a soft-wash treatment now means you go into summer entertaining season with a clean roof rather than fighting it in October.

The 6-Point Spring Roof Check (From the Ground)

You do not need to climb on your roof for any of this. Most of it can be done with a pair of binoculars from your driveway and a 5-minute walk around the house. A phone camera with the zoom is fine too.

1. Visible moss patches. Look at the north and west-facing slopes — the ones that get less direct sun. Patches the size of a dinner plate or larger mean the rhizoids have been at it for more than one season.
2. Black streaks running down from ridges. Those streaks are gloeocapsa magma — an algae, not actually dirt. It does not damage the shingle the way moss does, but it spreads, and a soft-wash treatment removes it during the same visit as moss treatment.
3. Granules in your gutters and downspout splash zones. If you see what looks like coarse black sand collecting at the bottom of a downspout, those are asphalt shingle granules. Some granule loss is normal as a roof ages. A lot of it — enough that you can scoop a handful — means your shingles are losing their protective layer faster than they should.
4. Lifted or curling shingle edges. Look at the edges where shingles meet the gutter line and along the rake (the slope edges). Edges that point up or curl back are a sign that water has worked its way underneath, often because moss has lifted them.
5. Debris accumulation in valleys and at chimney bases. If you can see a buildup of fir needles, leaves, or small branches in the valleys, it is holding water against your roof every time it rains. Same goes for the bases of dormers, chimneys, and skylights.
6. Sagging or overflowing gutters. Look at the gutter line during the next rain. If water is sheeting over the front instead of going through the downspouts, the gutters need cleaning before the issue moves up to the fascia and roof deck.

What "Normal" Looks Like in the Pacific Northwest

A few things are common enough in our region that they are not emergencies. A faint green tinge on the north slope of an asphalt shingle roof, especially under fir or cedar canopy, is something almost every house in Snohomish County deals with at some point. So is a thin layer of fir needles in the gutter line every spring. The benchmark for "routine maintenance" rather than "urgent service" is whether the moss is still patchy and limited to one slope, and whether you can see individual shingles clearly through the growth.

When you cannot see the shingles anymore, when the moss is forming a continuous mat, or when the gutters cannot keep up with rain — that is when waiting another season starts to cost you in shingle life.

When to Bring in a Professional

The general rule I give homeowners: if you can see clear moss patches from the ground without binoculars, it is time to schedule a treatment. The Asphalt Roofing Manufacturers Association specifically recommends low-pressure (soft-wash) cleaning for asphalt shingle roofs. High-pressure washing strips the granules that protect the shingle from UV — that is the single most damaging thing you can do to a roof in the name of cleaning it.

A professional soft-wash roof cleaning applies a biodegradable solution at under 500 PSI (about garden-hose pressure) that kills moss, algae, and lichen at the root. The thick growth comes off in the first pass; the rest dies and washes away over the next few weeks of rain. Pair it with gutter cleaning the same visit and you are set up for the rest of the year.

A Recent Project Up in Stanwood

The cover photo on this post is from a job we wrapped earlier this season up in Stanwood. The homeowner had been holding off on roof cleaning for a couple of years and called in after seeing a streaky north slope after a particularly wet stretch. We did a full exterior pass — soft-wash on the roof, gutters cleaned and downspouts flushed, house wash to take the green off the siding. The whole thing was a single day of work. The before-and-after on properties like this is why I show up to the quote visit with a binoculars-and-a-phone walk-around rather than a big sales pitch: most homeowners can spot what needs attention themselves once they know what to look for.

How to Schedule

Summer slots fill up first for May and June visits — that window is when most homeowners realize they want the work done before the Fourth of July. If you would rather skip the back-and-forth, the instant quote tool gives you exact pricing in under two minutes based on your home's square footage. For homes with recurring conditions — a lot of tree canopy, regular moss issues — the Pristine Home Membership schedules everything automatically and locks in 2026 pricing through 2029.