Dry Rot Repair in Seattle, WA: Common Causes and Fixes
Seattle’s climate is kind to evergreens and hard on houses. Months of mist, wind-driven rain, a short dry summer, and wide temperature swings put wood under constant stress. If moisture lingers in the wrong places, fungi find a foothold and the quiet work of decay begins. By the time paint bubbles or trim softens under a thumb, the damage is often broader than it looks at first glance. Dry rot, despite the name, is a moisture problem with a fungal culprit. Getting ahead of it takes disciplined inspection, good details, and repairs that do not just patch the surface.
I have cut out more rot around Seattle than I care to count, from Queen Anne eaves to West Seattle decks to Beacon Hill basements. The patterns repeat. Corners fail first, horizontal surfaces soak up splashback, and any break in paint or caulk becomes a wick. What follows is a field guide to how dry rot starts here, how to spot it early, and how a professional handles the fix so you are not back in the same place two winters later.
What “dry rot” really means in our climate
The term gets used loosely. True dry rot refers to specific fungi that can move moisture through wood fibers and spread aggressively. In the Puget Sound area, most decay we see is common brown rot or white rot that thrives in damp, poorly ventilated assemblies. The fungi digest cellulose and hemicellulose, leaving wood brittle, crumbly, sometimes with a cubed pattern. It does not happen without moisture. That is the keystone insight for every dry rot repair in Seattle: stop the water first, treat the fungus second, rebuild last.
Here, the drivers are predictable. Wind can push rain up under laps and into window perimeters. Marine air raises ambient humidity, so wet assemblies dry slowly. Sun is a limited partner at best, especially on north and east faces. Add a failed piece of flashing or a missing drip cap and rot is a matter of time.
Where Seattle homes tend to rot first
Different neighborhoods show different stories. On older Craftsman and Tudor homes, we often see decay in bargeboards, rafter tails, and window stools. In postwar bungalows and midcentury homes with minimal overhangs, siding bottoms and corner boards are frequent casualties. Townhomes from the 1990s and early 2000s can struggle at deck ledgers, parapet caps, and the complex seams around multi-part windows.
Siding species matters. Original cedar holds up better to intermittent wetting than finger-jointed primed pine, but even cedar loses the fight if water is trapped behind it. Engineered wood and fiber cement behave differently: they do not rot, but the trim and sheathing behind them still can if water intrudes. I have torn off fiber cement that looked perfect while the OSB sheathing behind it had turned to oatmeal at the bottom two feet.
If you catch rot in trim early, exterior trim repair is straightforward and contained. Let it run, and it migrates into framing and sheathing, raising costs and complicating replacements. Seattle trim repair jobs often reveal hidden failures: a missing head flashing over a window, a badly integrated WRB, or a deck ledger bolted through clapboard without adequate flashing. A conscientious dry rot repair contractor does not just replace what you can see, but also tracks water back to its source.
Early signs worth acting on
Homeowners often call after paint starts to bubble or when a corner board gets spongy. Before that, there are subtle signals. A thin hairline crack at the top of a window head with a faint watermark down the siding. A stubbornly dark band at the bottom course after rain, long after other surfaces have dried. Caulk that pulls away repeatedly in the same place. On the interior, a musty smell near a baseboard on an exterior wall, or a temperature difference you can feel with the back of your hand.
If you suspect trouble, a Seattle dry rot inspection should involve more than a glance. Pros carry moisture meters, pry bars, and the willingness to gently open a small section to see what lies behind. Thermal imaging has its place, but it is not a magic wand. The simplest test is still a firm push with an awl or screwdriver into suspect trim and siding, especially at horizontal transitions and penetrations.
Why water gets in: the usual suspects
In the field, nine times out of ten the decay traces to one or more of these conditions.
Missing or misaligned flashings at heads, sills, and horizontal breaks. Drip caps over windows and doors are cheap insurance, but they only work if properly integrated with the weather resistive barrier.
Failed sealant joints around penetrations. Caulk is a maintenance item, not a structural water barrier. If joint sizes are too large or the backing is wrong, sealant fails early.
Splashback and ground clearance issues. Siding installed too close to grade or hardscapes gets hammered by rain rebound. The bottom edge stays wet, fungi thrive, and paint fails.
Roof and gutter problems. Overflows, missing kickout flashings where rooflines meet walls, or short downspouts dump water where siding and trim cannot cope.
Ventilation and vapor management. On the shaded sides of homes, trapped moisture behind siding never gets a chance to evaporate, especially if assemblies are too airtight without drainage planes.
Those five points cover most of the real-world drivers I see in siding repair Seattle projects. The lesson is not to rely on paint and caulk to make a bad detail work. You want gravity doing most of the work for you, and a clear path for water to drain and air to circulate.
How a thorough inspection unfolds
A good inspection moves from the general to the specific. Stand back and scan the wall planes. Look for subtle waves in the siding or irregular shadow lines that hint at swelling sheathing. Note roof-to-wall intersections and any exterior features that concentrate water, such as belly bands and decorative trim. Then step in closer. Probe suspect spots gently. Check the underside of window stools and horizontal trim. If the moisture meter reads high in a cluster, pick a spot and remove a small piece of trim to see the WRB and sheathing condition.
On older houses, expect a mix of past repairs. Not every old fix is bad, but a patchwork of materials with mismatched expansion rates creates its own problems. Photograph as you go. When I prepare a seattle dry rot repair estimate, I include pictures of each area with notes on probable cause and recommended corrective measures. Homeowners appreciate transparency, and it sets the stage for scope decisions if hidden damage appears during demolition.
Repair philosophy: remove, remediate, rebuild, redirect
If you take away nothing else, remember this sequence. Remove all compromised wood back to sound material. Remediate remaining wood and surrounding areas to halt fungal activity. Rebuild with appropriate materials and joinery. Redirect water so the repaired area stays dry in future storms.
For small areas, house trim repair can be as simple as custom-milling a new sill or scarfing in a new section of corner board with a proper scarf joint and epoxy consolidant at the cut. For widespread damage, siding replacement services Seattle WA homeowners request often make more sense than piecemeal patches. The choice depends on the age and condition of the cladding, the extent of sheathing damage, and the budget.
When repairs extend to framing, take the time to restore the wall assembly correctly. That means WRB continuity, flashings shingled in the right direction, and back-ventilation or rainscreen details where feasible. In our climate, a 3/8 to 3/4 inch rainscreen gap behind lap siding gives assemblies room to breathe. It adds labor and materials, but it pays for itself in durability.
Material choices that stand up in Seattle
There is no single right answer, but there are wrong ones. Finger-jointed primed trim can work on protected facades, yet it is not my first pick for windy corners that get sideways rain. Clear vertical grain cedar, back-primed and sealed on all six sides, remains a strong performer for exterior trim. If clients prefer low maintenance, cellular PVC trim has earned its place. It does not rot, though it moves differently with temperature and needs proper fastening to avoid warping. For paint, I favor high-quality acrylics and a build of at least two topcoats over a bonding primer.
On the siding front, fiber cement is popular for a reason. It resists rot and holds paint well. Even so, the trim, flashings, and penetrations drive the durability story. Cedar beveled siding has classic charm and can last decades if detailed with a rainscreen and kept painted. Engineered wood siding has improved, but edge sealing is critical and cut ends must be guarded with care. Metal or high-pressure laminate panels solve some problems while introducing others at joints and fasteners. Choose based on the house style, exposure, and your tolerance for maintenance.
The anatomy of a proper window repair
Windows are frequent leak points. A quick cosmetic fix just buys time. A durable repair follows a sequence. First, remove the exterior casing and any damaged sill, then assess the condition of the sheathing and framing. If the rough opening is wet or rotted, open it up, replace compromised studs, and let the cavity dry if readings are high. Next, integrate a flexible sill pan or form one from peel-and-stick flashing that rises up the jambs a few inches. Reinstall or replace the unit, then layer head flashings and WRB so water always has a shingled path out. Set new trim with proper gapping at joints, prime all cuts, and caulk only where it stops wind and water without trapping moisture. On heavily exposed faces, add a small drip kerf under projecting trim to break surface tension.
When done properly, exterior trim repair around windows is often the single most valuable investment in the envelope. It not only stops current leaks but also prevents the kind of hidden saturation that leads to expensive interior drywall and flooring damage.
Costs, contingencies, and timelines
Homeowners often ask, how much will this cost, and how long will it take. For trim and siding repair, I give ranges and build in contingencies. A small isolated rot pocket at a corner board might run a few hundred dollars if access is simple. A window with a failed head flashing and damaged sill plus surrounding sheathing can climb into the low thousands. Larger seattle dry rot repair projects that include multiple elevations, rainscreen upgrades, and siding replacement can move into five figures. Elevation, scaffolding needs, and lead-safe practices on pre-1978 homes affect the number.
Time depends on drying phases and weather. In a wet week, we tent areas and run heaters to bring moisture content down before closing walls. Rushing this step is one of the fastest ways to guarantee future problems. A single window repair can be done in a day or two if materials are on hand. A full façade tear-off and rebuild might take two to three weeks with a well-coordinated crew. Good siding contractors in Seattle will sequence work to keep your home protected every evening, even mid-project.
When to repair and when to replace
I often talk clients through a fork in the road. If more than a quarter of a façade shows decay, or if the design has systemic flaws like missing head flashings across multiple openings, you may be throwing good money after bad with spot repairs. That is when siding replacement services Seattle WA homeowners request become cost effective. You get a clean slate to improve the WRB, add a rainscreen, install proper metal flashings, and reset all penetrations. The long-term maintenance burden falls dramatically.
Conversely, if the house has good bones and the water intrusion comes from a handful of discrete points, a targeted repair is smart. Address the source, upgrade the details at those points, and keep a calendar for maintenance. I have homes on service plans where we do a spring and fall walkthrough, touch up caulk where appropriate, clear weep paths, and wash shaded faces to keep mildew off paint films. That small investment wards off big repairs.
Working with a contractor: what to ask and expect
Dry rot work straddles carpentry and building science. When you interview a dry rot repair contractor, ask about their approach to water management. You want clear answers on WRB integration, flashing types, and how they handle transitions from old to new. Request a written scope that includes demolition expectations, disposal, temporary weather protection, and allowances for hidden damage with unit prices for additional framing or sheathing.
Ask to see examples of their trim and siding details. Photos of past projects tell a story: how they end-trim bottoms https://www.seattletrimrepair.com/about/ above hardscapes, how they cap parapets, whether they use kickout flashings where a rake meets a wall. Licensing, bonding, and insurance are givens. For older homes, confirm lead-safe certification. Reliable siding contractors Seattle WA homeowners trust will also pull permits when required and coordinate inspections if structural work is involved.
Practical maintenance that pays off
Seattle’s rains are not negotiable, but the home’s response is. Small habits prevent most rot. Keep gutters clear before the first big fall storm. Check downspouts and splash blocks to make sure water moves away from the foundation. Trim back plants that press against siding and trap moisture. Maintain ground clearance: siding should stay several inches above soil and at least an inch above concrete. Inspect caulked joints annually, especially at dissimilar materials like trim to masonry or metal. Repaint on schedule. High-quality exterior paint is not just cosmetic, it is a moisture control layer, and when it fails, wood drinks.
A final tip from the field: look up. Many of the worst wall failures start with roof water that has nowhere to go. Kickout flashings, properly sized gutters, and longer downspout extensions cost little compared to sheathing replacement.
Case notes from around town
A Ballard bungalow had peeling paint at a front window and a soft exterior sill. The owners expected a quick patch. Behind the sill, the sheathing was damp to the touch, and moisture readings hit the high teens. Removing two courses of lap siding revealed a missing head flashing. The repair team installed a flexible sill pan, new cedar casing with a drip kerf, and a bent metal head flashing tucked behind the WRB. The wall was dried to under 12 percent before closing, and the painted finish still looks crisp four years later.
On Capitol Hill, a rowhouse with modern fiber cement panels showed staining along the horizontal joint at the second floor. The panels were fine, but the Z-flashing was too short and lacked end dams, letting water track behind. Replacing panels would not solve it. The fix involved removing a panel row, upgrading the flashings with proper end dams, and resetting the rainscreen gap with new furring to keep the drainage plane continuous. No decay recurred after two wet seasons.
A West Seattle deck ledger was bolted directly over lap siding with no flashing. Inside, the drywall corner downstairs showed a faint brown arc after storms. Opening the exterior revealed rotten sheathing and a ledger that had started to eat itself. The cure required full removal of siding in that bay, new sheathing, a ledger mounted over proper flashing and spacers to allow drainage, and new siding. Insurance covered part of it because the leak caused interior damage, but the owner would have preferred a $40 piece of flashing and an extra hour during the original build.
A note on permits, codes, and best practice
While most trim and siding repair does not trigger a structural permit, be mindful of thresholds. If you replace sheathing over large areas, alter framing, or change window sizes, the city may require permits and inspections. Seattle’s energy code can also apply when replacing windows or re-cladding significant portions of an exterior. Code is the floor. Best practice is the aim. Rainscreen assemblies, high-quality flashings, and six-side sealing of wood trim are not always mandated, but they are prudent in our climate.
Choosing details that keep water moving
Everything on an exterior should either shed water or stand off the surface to let it dry. Sills and head flashings need positive slope. Belly bands should be treated like mini roofs with metal caps and kickouts at ends. Horizontal trims should be rare and well protected. Where you cannot avoid them, give water an escape path and a break in surface tension. The small act of back-priming cut ends and sealing fastener penetrations with a dab of high-quality sealant extends service life by years. I insist that crews precoat cedar siding on all sides before installation. It takes time. It saves callbacks.
How to prepare your home and yourself for the work
Expect noise, dust, and a few days of disrupted access near work areas. Move vehicles, patio furniture, and plan for pets. A considerate crew will lay protective coverings, set dust barriers where interior access is needed, and keep the site tidy. For older homes, lead-safe work practices mean more containment and cleaning steps, which adds time but protects your family and the crew. Agree on daily start and stop times and a communication rhythm. The best siding contractors in Seattle provide a daily update, even when weather causes a pause.
The role of documentation
I keep a photo log of every step: conditions found, layers removed, moisture readings, and details installed. It is not just for the file. It gives homeowners confidence that hidden work was done right. If you sell, that documentation can reassure buyers and their inspectors. When you work with a contractor, ask for these records. Good companies already do it because it reduces disputes and demonstrates value.
When replacement beats repair for siding
There is a point where trim and siding repair stop making financial sense. If you see repeating failures across elevations, if the cladding is nearing end of life, or if underlying design flaws cannot be economically corrected piecemeal, a planned re-siding project is smarter. During siding replacement services Seattle WA projects, we have the chance to straighten wall planes, improve insulation in accessible cavities, replace corroded flashings, and add a continuous rainscreen. Homeowners often pair this with window replacements for comprehensive envelope upgrades. The upfront cost is higher, but the power of doing it once, correctly, with a unified system shows in lower maintenance and improved comfort.
Final thoughts from the ladder
Dry rot is patient and unsentimental. It exploits small weaknesses, then waits for time and weather to do the rest. The fix is not magic. It is a method. Keep water out with thoughtful details. Give stray moisture a path to escape. Use materials that match the exposure and assemble them with care. Maintain the finish. When damage appears, move decisively and ask the next question: not just what rotted, but why.
If you are vetting siding contractors in Seattle, ask to walk a current job. Watch how they flash a head, how they handle cut ends, how they talk about water. That will tell you more than a brochure. And if you are just starting to see small blisters in the paint or feel a soft edge on a window stool, do not wait for summer. A prompt Seattle dry rot inspection now can turn a weekend fix into a lasting repair instead of a wall-wide replacement later.
Seattle Trim Repair 8338 20th Ave NW, Seattle, WA 98117 (425) 517-1751