The house in this example

Home
Small 1950s brick ranch near West Colfax over a dirt-floor crawl space.
Heating
Forced air with ducts running through the crawl space.
First sign
A rotten smell at the floor registers, strongest in the hallway.
Season
Late October, a few weeks after nights turned cold.

Following the smell down

Illustrative example. Not a real job or customer.

Illustrative example, not a real job or household. The homeowner notices the smell strongest at the hallway floor register and at the crawl space hatch in a closet. Nothing is visible in the rooms.

  1. They pull the hallway register and see nothing in the boot, so they check the crawl space from the hatch with a bright light.
  2. About eight feet in, near a heating duct, there is a dead rat on torn plastic and bare soil.
  3. Rather than crawl in without gear, they hire a wildlife and cleanup provider.
  4. The provider bags the rat, removes the stained soil under it, replaces a torn section of vapor barrier and seals a gap around a sewer pipe at the foundation.
  5. The homeowner changes the furnace filter and runs the fan with windows open.

The smell faded over a few days. The sealed pipe gap and repaired vapor barrier made a repeat less likely.

Why it smelled through the vents

Ducts in a crawl space are never perfectly sealed. The furnace pulls a little crawl space air in through joints, and floor registers above the crawl space let odor rise. That is why the smell appeared at the registers first.

Bare soil absorbs fluids, so removing the stained soil mattered as much as removing the rat.

Questions this raises

  1. Is your crawl space vapor barrier intact, or torn and patchy?
  2. Are there gaps around pipes and cables where they pass through the foundation?
  3. Are the crawl space vents screened?
  4. When were the ducts in the crawl space last inspected for gaps?

What the household changed afterward

Beyond the repair, the homeowner screened the two foundation vents with metal hardware cloth, moved the woodpile away from the house, and started checking the crawl space from the hatch each fall. The provider also pointed out a few gaps in the duct joints, which were sealed so the furnace would not pull crawl space air into the house in future.

Common questions

Is it safe to go into a crawl space with a dead rat?

With gloves, a respirator, eye protection and care around droppings, a short look can be reasonable. Removal and soil cleanup are better left to someone equipped for it.

General information for Sloan's Lake, not a quote or professional advice. In an emergency, call 911.