The findings that show up again and again on Seattle & Eastside home inspections aren't random — they follow the region's wet climate and its housing stock's age. Expect crawlspace moisture and roof moss on almost any home, and — depending on when it was built — knob-and-tube or aluminum wiring, polybutylene or galvanized pipe, or a buried heating oil tank. None of these automatically kill a deal, but each one changes what you should ask for, budget for, or walk away from.
Why Pacific Northwest homes have their own pattern of findings
Two things drive what an inspector finds here more than anywhere else: rain and age. Western Washington gets moisture for months at a stretch, so anything related to drainage, crawlspaces, and roofing shows up constantly — it's less about a particular home being poorly maintained and more about the climate working on every house, every year. Layer on the fact that Redmond, Bellevue, Kirkland, and Seattle all have large pockets of homes built before 1980, and you get a second, predictable set of findings tied to the materials and methods that were standard decades ago. A newer home in Sammamish or Issaquah will mostly dodge the second category; a mid-century home in north Seattle or Kenmore usually won't.
Moisture and crawlspace issues — the most common finding of all
If your inspector finds only one thing, odds are it's related to moisture. Common versions include:
- Missing or damaged vapor barriers in the crawlspace, letting ground moisture rise into the floor framing.
- Standing water or damp soil under the house, often tied to poor site grading or a downspout discharging right next to the foundation instead of away from it.
- Dry rot or fungal growth on sill plates, joists, or sub-flooring where moisture has been sitting for a while.
- Undersized or disconnected crawlspace ventilation, which traps humidity instead of letting it escape.
Most of these are fixable — regrading, extending downspouts, adding or replacing a vapor barrier, installing a sump pump or French drain — but cost varies enormously depending on severity, so get a specialist's bid (not just the inspector's estimate) before you decide whether to ask for a credit or walk.
Roof moss and gutters
Moss on the roof is close to universal in this climate and isn't automatically a problem, but a heavily moss-covered roof holds moisture against the shingles and shortens their remaining life, and clogged or undersized gutters compound the crawlspace and foundation issues above by dumping water exactly where you don't want it. Ask the inspector (or a roofer, for anything beyond cosmetic moss) how many years of life the roof realistically has left — in a region where roofs work harder than in drier climates, "how old" matters less than "how worn."
Electrical: knob-and-tube and aluminum wiring
Homes built before roughly the 1950s sometimes still have original knob-and-tube wiring — ungrounded, insulated with cloth that degrades over time, and identifiable by ceramic knobs and tubes visible in the attic or basement. Homes built in the 1960s-70s sometimes used aluminum branch-circuit wiring instead of copper, which can loosen at connections and overheat if it wasn't installed with the right connectors.
Both matter beyond safety: they can affect your homeowners insurance. Many carriers decline to write a policy on a home with active knob-and-tube wiring, or require an electrical inspection first; aluminum wiring is generally easier to insure but still draws scrutiny from some insurers. Get an insurance quote during your inspection or financing contingency period — not after you're already past your deadlines — so a coverage problem doesn't surprise you at closing.
Plumbing: polybutylene and galvanized pipe
Two older plumbing materials turn up often enough to know by sight:
- Polybutylene pipe — gray plastic tubing used roughly from the 1970s through the 1990s — has a well-documented history of failing at its fittings over time and is generally considered a full re-pipe candidate rather than a spot repair.
- Galvanized steel pipe, common in homes built before the 1960s, corrodes from the inside over decades, which shows up as low water pressure, rust-colored water, or reduced pipe diameter — and it's not a problem a plumber can inspect from the outside; the usual way to assess it is by cutting into a section or scoping it.
Either one is a legitimate repair-cost or price-negotiation item, not a reason to panic — but budget a full re-pipe (tens of thousands on a larger home) into your decision if either is present and extensive.
Heating oil tanks and Washington's decommissioning rules
Older Eastside and Seattle homes sometimes still have a heating oil tank — buried, or in a basement — left over from before gas or electric heat took over. If you find one, or evidence one used to be there, a few Washington-specific rules apply:
- Decommissioning is required once a tank sits unused for a year or more. Washington's fire code (adopted locally as WAC 51-44, based on the International Fire Code) requires the tank to be decommissioned — either by removing it from the ground or by cleaning it and filling it with an approved inert material (abandonment in place).
- Most cities require a permit and a certified contractor. Seattle, for example, requires a permit before work starts and requires the contractor to use an ICC-certified Underground Storage Tank Decommissioner. Rules and fire-code editions vary by city, so check with the local fire or building department.
- A suspected leak gets reported fast. Seattle's guidance is to report a suspected leak within 24 hours to the Washington Department of Ecology's spill line, 1-800-OILS-911, and to stop any automatic oil deliveries immediately.
- Sellers disclose tanks on Form 17 — including ones that were already decommissioned — and should hand over any decommissioning certificate they have. "Don't know" is a permitted answer, so a tank can still turn up as a surprise; a sweep with a metal detector or utility locator is cheap insurance if the lot or basement makes you suspicious.
- Washington's old tank-insurance program is closed to new registrations (since July 2020) and has shifted toward a state loan-and-grant program to help with decommissioning or cleanup costs. If you inherit a tank issue, check current eligibility directly with the Pollution Liability Insurance Agency (PLIA) rather than relying on older program details.
None of this means avoid a home with a known tank — many have already been properly decommissioned — but get the paperwork, not just a verbal assurance, and price in decommissioning cost if it hasn't happened yet.
Heat pumps and furnaces
Heat pumps have become the default heating-and-cooling system in much of the Eastside's newer construction, and they're increasingly retrofitted into older homes too. A standard home inspection checks that the system runs and looks for visible defects, but it isn't a full HVAC evaluation — it won't open up the unit, check refrigerant charge, or estimate remaining compressor life. If the system is older, undersized for the home's square footage, or you've noticed in listing photos that the outdoor unit looks worn, a separate HVAC contractor evaluation during your inspection period is worth the cost, especially since summers here increasingly make the cooling side matter as much as heating.
Foundation, drainage, and the sewer line
Foundation cracks, settling, and drainage problems often trace back to the same moisture issues covered above, just further along. And a home's inspection doesn't typically include its sewer connection — that's a separate line item you choose on the inspection contingency form. See our sewer scope guide for why older clay or Orangeburg pipe fails and how to order one, and our guide to septic and well inspections if the home isn't on city sewer and water at all.
How findings fit into your inspection contingency
None of the items above automatically mean "walk away" — they're exactly what the NWMLS Form 35 inspection contingency is designed to let you respond to. Once you have your inspector's report (and any specialist follow-up reports), you typically have a set number of days to request repairs, a price reduction, a credit, or to cancel the agreement, depending on what your contract specifies. See our full guide on the home inspection contingency in Washington, including when waiving it is and isn't a reasonable risk.
Your due-diligence checklist
- Read the crawlspace and roof sections of the report closely — these are the findings most likely to appear on any home, regardless of age.
- Identify the home's wiring and plumbing era from the inspection report, and get a licensed electrician's or plumber's bid if knob-and-tube, aluminum wiring, polybutylene, or galvanized pipe is present.
- Get a homeowners insurance quote early if older wiring is present, before your contingency deadlines pass.
- Ask directly about any oil tank, current or former, and request decommissioning documentation if one existed.
- Consider a separate HVAC evaluation if the heating/cooling system is older or looks worn in listing photos.
- Budget for the sewer line and (if applicable) septic/well as their own line items, separate from the general inspection.
Where a flat fee agent helps
A thorough inspection on an older Eastside home can surface five or six separate findings worth following up on — wiring, plumbing, roofing, an oil tank, the sewer line — each needing its own specialist and its own deadline inside your contingency window. A traditional buyer's agent charging roughly 2.5% commission on a $1.1M home costs about $27,500. A flat $2,999 buyer's agent handles the same coordination — lining up specialists, tracking every deadline, and negotiating what the inspection turns up — while leaving tens of thousands of dollars for whatever repairs or credits you end up needing. See flat fee vs. a traditional buyer's agent and who pays the buyer's agent in Washington.
General information, not a substitute for a licensed home inspector, electrician, plumber, HVAC contractor, or environmental professional. Decommissioning rules, permit requirements, insurance availability, and program details change over time and vary by city and carrier — confirm current requirements with your local fire or building department, the Washington Department of Ecology, the Pollution Liability Insurance Agency (plia.wa.gov), and your own insurance agent before relying on any detail above. Shi Hao Liu is a licensed WA real estate broker (License #26003789) with Kelly Right Real Estate, not an inspector or contractor. Verify any WA broker at the WA Department of Licensing.