Ask somebody in Ohio where a dead animal ends up and they will say the basement. Ask in Arizona and they will say the attic. In Washington the answer is usually neither, and the reason is a construction decision made decades before anyone bought the house.
Washington builds over a vented void
Across much of western Washington the standard residential foundation is a timber floor over a vented crawl space. Not a slab, not a full basement, but a shallow void two to four feet deep with a ground sheet over the dirt, insulation between the joists overhead, and openings cut through the foundation wall on every side.
Those openings are not a defect. They are the design. The space is meant to breathe, because a sealed void under a timber floor in a wet climate is a rot problem waiting to happen. So the builder puts vents in, screens them, and moves on.
A vent that lets air through is a vent that lets a rat through. Screens tear, a service pipe gets replaced and the gap around it never gets sealed, an access panel stops seating properly after somebody works down there. Over twenty or thirty years a house accumulates openings, and each one is an invitation into a dark, dry, sheltered space directly underneath the floor you are standing on.
Why the foundation type changes the job
The reason this is worth knowing is that it changes three things at once.
Where the animal goes to die. An animal that is sick, injured or poisoned looks for somewhere dark and enclosed. In a house with a crawl space, that is the most available such place, and it is the one a homeowner is least likely to check.
Where the smell appears. Air does not stay in a crawl space. It moves upward through gaps around pipework, ducting and the subfloor, which is why a carcass below the floor produces a smell that seems to come from everywhere and nowhere. People describe it as being strongest in a hallway or a closet, which is usually just where the biggest gap is.
Whether anyone can reach it. This is the part that decides whether there is a job. A crawl space with a working hatch and two feet of clearance is enterable. The same space with eighteen inches of clearance, a collapsed vapor barrier and ducting running the length of it may not be, and no amount of wanting to help changes that.
The step most people skip
Washington adds something here that most states do not. Under WAC 220-400-040 it is unlawful to possess wildlife found dead, with a specific permission for removing wildlife found dead on property you own or control. That permission comes with a condition: before you remove it, you have to telephone the Department of Fish and Wildlife or the Washington State Patrol and give your name, address, telephone number and a description of the animal and where it is. The rule also provides that the animal remains the property of the state.
It is a phone call rather than a permit application, and it takes a minute. But it is a legal step and it comes before you pick anything up.
There is a carve-out worth knowing, because it covers the most common case. Washington's statutory definition of wildlife, at RCW 77.08.010, excludes old world rats and house mice of the family Muridae, along with feral domestic animals. So a dead Norway rat under your floor is outside that rule entirely. A dead squirrel in the same space is not.
What to establish before you call anyone
Three things make the conversation useful, and you can work all of them out without going anywhere near the animal.
- Where your access is. Usually an exterior panel on the foundation wall, sometimes a floor hatch in a closet or hallway. Which one you have changes how the job is approached.
- Roughly how much clearance there is. Can a person move through on their elbows, or is it a space you could only reach into? This is the single biggest factor in whether the recovery is possible at all.
- Where the smell is strongest, and when. If it rises and falls with the heating or ventilation running, that points at air being moved from the void into the house, which is useful rather than mysterious.
Where the honest limit sits
A crawl space is reachable more often than people fear, and that is the good news. The bad news is the part that gets glossed over on sites like this one, so here it is plainly: if the animal is inside a sealed wall cavity above the floor rather than in the void below it, most operators will not cut into drywall or a finished ceiling to get it, and this site will not promise that on anyone's behalf. That becomes a construction decision rather than a removal visit.
And nobody can tell you how long a smell will last. No Washington agency publishes a decomposition or odor timeline, the measured research that exists was done outdoors in other climates, and a number invented to sound reassuring is worth nothing to you.
This article describes a common Washington construction type and the state rule that applies before you handle wildlife found dead on your own property. It is general information for Washingtonians, not advice about a specific building, and nothing here is a statement that any operator is available for your address.