Home / Moss Removal & Gutter Care / Gutters, Downspouts & Drainage
A roof's job is to shed water. A gutter's job is to catch that water at the edge and move it somewhere harmless. When the roof fails, you get a stain on the ceiling and you notice. When the gutter system fails, the water does not disappear — it redirects, and every redirection path damages something that is not the roof: fascia, soffit, siding, foundation, basement, or the framing at the eave.
That indirection is why gutter problems run for years unaddressed. Nobody connects a damp basement corner in February to a downspout discharging six feet away, or connects a gutter sagging at one end to the rot that will eventually pull it off the house during a windstorm.
In Seattle the stakes are higher than the national average for a specific reason. Our rainfall is not intense, it is persistent. A gutter here does not have to survive a violent cloudburst; it has to keep working, continuously, for eight months, under a canopy that drops debris into it the entire time. The failure mode that matters locally is not overwhelming volume. It is blockage, and everything that follows from it.
Gutter failure in this region follows a predictable sequence, and knowing it lets you intervene early.
Step one: debris accumulates. Under bigleaf maple, Douglas fir, and western red cedar, this is continuous rather than seasonal. Conifer needles are the harder problem — they pack into a dense felted mat that sheds water rather than passing it, and they arrive year-round rather than in one autumn drop you can plan around.
Step two: water goes over the front edge. A blocked or overloaded gutter overflows at the outer lip, and that sheet of water falls directly along the fascia line.
Step three: water gets behind the gutter. This is the more damaging path and it is worse where drip edge is missing. Without a drip edge to carry water off the roof edge and into the gutter, surface tension pulls water back underneath the shingle edge and against the fascia board.
Step four: fascia rot. The fascia is now wet for most of the year. In a climate that keeps wood above the moisture content where decay fungi thrive for eight months at a stretch, it softens and rots. Rot spreads into the soffit and, at the worst end, into the rafter tails — which is structural work.
Step five: the gutter falls off. Gutters are fastened to the fascia. When the fascia loses integrity, it stops holding fasteners. The gutter, loaded with wet debris and water and hit by a winter windstorm, pulls away and takes trim with it. Homeowners experience this as storm damage. It was actually five years of drainage failure with a storm as the final step.
The whole cascade is preventable at step one, cheaply, and gets expensive fast after step four.
Five-inch K-style is the residential default and is adequate for most Seattle homes, because our rain intensity is modest. Six-inch is worth the upgrade in specific cases: large roof areas draining to few outlets, steep pitches that deliver water to the gutter fast, long runs, and homes under heavy conifer canopy — because the larger channel tolerates partial blockage before it overflows. Under trees, capacity is really debris tolerance.
The most common under-specification is too few downspouts. A general rule is one downspout for roughly every 30 to 40 feet of gutter run, and more where a large roof area drains to a single point. Doubling downspout count does more for real-world performance than upsizing the gutter, because it reduces the distance water must travel through a channel that may be partly blocked.
Gutters must fall toward the outlets, conventionally around a sixteenth of an inch per foot. Too little and water stands in the trough, which accelerates corrosion and gives debris a place to settle and mat. Too much and the gutter looks visibly crooked from the street. Standing water in a gutter after rain has stopped is a clear sign the slope is wrong.
Hidden hangers screwed into solid fascia, spaced roughly every 24 inches and closer under heavy canopy where debris loading is high. Spike-and-ferrule attachment, common on older homes, works loose over time as the wood cycles wet and dry. If your gutters are held by nails driven through the front lip, they are on borrowed time.
Seamless aluminium is the regional standard, formed on site so there are no joints along the run to leak. Gauge matters more than people think: heavier aluminium resists denting from ladders and falling limbs. Steel is stronger but corrodes at cut edges. Copper is exceptional, lasts generations, and has the incidental benefit of shedding trace ions that suppress moss on surfaces below it.
The gutter must sit low enough that water shedding off the shingles lands inside it, and close enough that it does not miss on the way past. A gutter mounted too low catches nothing in heavy rain; one mounted too high can let water run behind. This is set by the fascia and the drip edge working together.
Drip edge is an inexpensive metal angle installed along the eaves and rakes, beneath the roofing at the edge, that carries water clear of the fascia and directs it into the gutter. It is code-required, and it is left off with some regularity, particularly on older homes and budget re-roofs.
Its absence is the reason many gutter systems fail even when the gutters themselves are fine. Water leaving a shingle edge without drip edge does not fall cleanly. Surface tension curls it back around the edge, behind the gutter, and onto the fascia — the exact path that produces rot. You can install a perfect gutter system on a house with no drip edge and still rot the fascia it is screwed to.
Checking for it is easy: look along the eave from a ladder or with binoculars. You should see a thin line of metal running the length of the edge, tucked under the shingles and lapping over the back of the gutter. If you can see raw sheathing edge or shingles overhanging with nothing beneath them, it is missing. Adding it later means lifting the shingle edge, so the sensible moment is during a re-roof — another reason to confirm it appears explicitly in a roofing quote.
A gutter system that collects water beautifully and discharges it against the foundation has relocated the problem from the roof to the basement. This is the half of the system almost nobody inspects.
Water needs to leave meaningfully away from the foundation — several feet at minimum, further on clay soils that drain slowly. A splash block directly at the base of the downspout spreads the water but does not move it. Extensions, buried drain lines, or a tightline carrying water to an appropriate discharge point are what actually solve it.
The ground should fall away from the house. Seattle's topography means many homes sit on sloped lots where one side of the house is uphill, and a downspout discharging on that uphill side is sending its water toward the foundation regardless of how far the extension runs. On sloped lots, downspout placement is a design decision, not a default.
An inch of rain on 1,000 square feet of roof is roughly 600 gallons of water. A Seattle winter delivers that repeatedly. Every one of those gallons arrives at a small number of discharge points, and if those points are next to the foundation, that is the volume being introduced there.
Seattle regulates stormwater management, and how roof runoff is handled on a property can be subject to code, particularly on new construction, significant remodels, and where connection to the public drainage system is involved. Options include dispersion into vegetated areas, infiltration systems, and connection to an approved drainage line. Homeowners planning drainage work should confirm requirements rather than assuming any discharge arrangement is acceptable, and connections to a side sewer in particular should never be improvised.
Gutter guards are marketed aggressively in this region, and the marketing claim — never clean your gutters again — is not true under a Pacific Northwest conifer canopy. Here is the fair version.
What they do well: keep out leaves, twigs, and the larger debris that causes outright blockage, meaningfully reducing cleaning frequency on many homes.
Where they struggle here: fine conifer needles. Needles pass through or lodge in mesh apertures, and on surface-tension and reverse-curve designs they accumulate on top of the cover itself, forming a mat that water sheets over rather than entering the gutter. The result is a gutter that is clean inside and completely non-functional. Fine-mesh stainless designs handle needles best; open foam inserts tend to become saturated debris beds and are a poor match for our conditions.
The honest recommendation: guards are worth it where access is genuinely difficult or dangerous — tall homes, steep lots, roofs that require a long ladder set on a slope — because they convert several cleanings a year into one inspection. On a single-storey home with easy ladder access, the money is usually better spent on twice-yearly cleaning and on trimming back the limbs producing the debris. And regardless of product, they need to be inspected annually, because a guard that has failed silently is worse than no guard at all: it hides the blockage.
Late autumn, after deciduous drop. The essential clearing. Everything from maple, birch, and other broadleaf trees comes down over a few weeks, and clearing it before the heaviest rain arrives is the single most valuable maintenance action of the year.
Spring, after conifer shed. Firs and cedars drop needles through the year with a heavier flush in spring. This clearing also lets you see what winter did — loose hangers, separated seams, sections pulling away from fascia.
More often under heavy canopy. Homes directly under mature conifers may need three or four clearings a year, and pretending otherwise is how the cascade above gets started.
What to check while you are there. Run water through with a hose and watch: does it flow to the outlets or stand in sections, indicating slope problems? Do the downspouts run freely, or does water back up, indicating a blockage in the vertical? Are seams and end caps leaking? Is the fascia behind the gutter sound, or soft when pressed? Where does the water actually go once it leaves the downspout?
That last question is the one most worth answering, because it is the one nobody checks and the one that determines whether your roof drainage is protecting the house or quietly undermining it.
Twice a year minimum: late autumn after deciduous leaf drop, and spring after conifer shed. Homes directly under mature firs or cedars often need three or four clearings, because needle drop is continuous rather than seasonal and needles pack into a mat that sheds water.
Usually missing drip edge. Without it, water leaving the shingle edge curls back underneath by surface tension and runs onto the fascia rather than into the gutter. You can install a perfect gutter system on a house with no drip edge and still rot the board it is fastened to.
Five-inch K-style suits most Seattle homes since our rain intensity is modest. Six-inch is worth it for large roof areas draining to few outlets, steep pitches, long runs, and homes under heavy conifer canopy — where the larger channel tolerates partial blockage before overflowing.
Roughly one for every 30 to 40 feet of gutter run, and more where a large roof area drains to one point. Adding downspouts improves real-world performance more than upsizing the gutter, because it shortens the distance water travels through a channel that may be partly blocked.
They reduce cleaning frequency but do not eliminate it, and the never-clean-again claim is not true under a conifer canopy. Fine needles pass through or mat on top of the cover so water sheets over it. They make the most sense where access is genuinely difficult or dangerous, and they still need annual inspection.
Several feet from the foundation at minimum, further on slow-draining clay soils, and always downhill of the structure. An inch of rain on 1,000 square feet of roof is roughly 600 gallons, all arriving at a few points. Seattle also regulates stormwater, so drainage work should be confirmed against current requirements.
We measure by hand, assess the decking and ventilation from below, and put a fixed number in writing before anything starts. Free estimates across Seattle and the greater Puget Sound region.
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