Roof Cleaning and Moss Removalin Covington

Roof cleaning, in our own words

Roof Cleaning: Removal of moss by brushing, the gutter cleaning and moss treatment

We remove the moss from the roof by brushing, not by pressure washing. The gutters are included as well as a pet and plant safe moss treatment.

Why brushing and not a pressure washer

An asphalt shingle is not a solid slab. It is a mat saturated with asphalt and then coated with a layer of mineral granules, and those granules are the part that takes the weather. They shield the asphalt from sunlight, they give the shingle its fire rating and its texture, and they are bonded to the surface rather than baked into it.

A pressure washer removes moss quickly because it removes everything quickly, granules included. You can watch them come down the roof and collect in the gutter, which is a fair description of a roof aging several years in an afternoon. High pressure also drives water sideways, up under the shingle courses, into the space the shingles are shaped to keep dry.

Brushing takes longer. It also takes the moss off and leaves the roof intact, which is the only version of this job worth paying for. That is the whole reason the method is stated plainly above rather than buried in fine print.

What moss actually does up there

Moss on a roof is not a stain. It is a living plant with a grip.

It starts in the seams, where two shingle edges meet and hold a little grit and moisture. From there it works under the bottom edge of the shingle above it and lifts. A lifted shingle has a broken seal, and a broken seal is an opening for wind to catch and for water to run backward. Multiply that across a slope and the roof stops behaving the way it was designed to.

The second problem is constant moisture. A mat of moss holds water against the surface long after the rain has stopped and the rest of the roof has dried. Anything that keeps a building material permanently damp is shortening its life, and in a climate that delivers rain most of the year, the moss never really gets the chance to dry out on its own.

Why South Sound roofs grow it so well

Moss needs three things: moisture, shade and something to hold onto. Homes here get all three delivered reliably.

Rain is the obvious one, but shade does more of the work than people expect. A north facing slope may not see direct sun for months at a stretch in the wet half of the year. Add a stand of firs or cedars on that side of the house and the slope simply never dries. That is why one side of a roof can be green to the ridge while the opposite side looks nearly new.

Tree cover contributes twice over. It blocks the sun, and it drops a steady supply of needles that collect in valleys and along shingle edges. That debris holds moisture and grit, which is the seed bed moss needs to get started.

Timing surprises people too. A roof can look dry and dead in late summer and be green again within weeks of the first sustained rain. The moss is not gone in the dry months, it is dormant. We wrote about that in roof moss is not dead in August, it is just waiting for rain.

What is included, and why it is bundled that way

Three things happen on this job, and they are bundled because doing one without the others wastes your money.

The moss comes off by brushing. That is the removal, done by hand, working with the lay of the shingles.

The gutters get cleaned. Everything brushed off a roof has to land somewhere, and a lot of it lands in the trough. Cleaning the gutters afterward is not an add on here, it is the second half of the same job. If you only want the gutters done, that is available on its own as gutter cleaning.

A pet and plant safe moss treatment goes on. Brushing takes the visible growth. The treatment deals with what is rooted in the seams and under the shingle edges where a brush cannot reach, and it slows the regrowth that would otherwise start with the next wet stretch.

What the roof looks like afterward

Expect a clear improvement the day of the work and a continuing one after it. The bulk of the moss leaves with the brushing. What stays is the rooted remainder in the seams, and that browns off and weathers away over the following weeks as rain and wind work on it.

That is the honest description of how roof moss behaves, and it is worth knowing before the work so the result matches what you are picturing. A roof that has been thickly covered for years also reveals whatever the moss was hiding, including uneven weathering and the odd damaged shingle. If we see something that looks like it needs a roofer rather than a cleaner, we will point it out. We clean roofs, we do not repair them.

When treatment on its own is enough

Not every roof needs the full job. If your roof is mostly clean, or it was cleaned recently and you want to keep it that way, a standalone moss treatment is the lighter and simpler option. Treatment kills and prevents. It does not remove anything, and it will not do much for a roof already carrying a thick mat.

It is also worth knowing what a soft wash is and is not. A soft wash removes dirt and grime that has built up over time. It does not remove moss growing on a roof. If the roof is green, brushing is the job.

Roof cleaning across the South Sound

We clean roofs for homes in Covington and across South King County, Pierce County and Thurston County, including Kent, Renton, Maple Valley, Auburn, Federal Way, Puyallup, Sammamish, Issaquah and Olympia. The full list is on our service areas page. We are residential only.

Book a roof cleaning online or get in touch and tell us which slopes are green and what is growing over the house.