How to map the smell
- Sketch the floor plan.Draw each floor roughly, with doors, windows, heating registers, the return grille and fireplaces.
- Set the conditions.Close exterior doors and windows, turn off the furnace fan and bath fans, and leave interior doors open for an hour.
- Rate each room.Walk slowly and write a number from 0 to 5 in each room, plus at specific walls, closets and corners.
- Change one thing.Close interior doors, or run the furnace fan, and rate again. Note what got stronger or weaker.
- Mark the hot spot.The highest-rated spot in the closed-door test is usually closest to the source.
Mapping sheet
- Room or spot
- Example: back bedroom, north wall
- Doors open
- 3
- Doors closed
- 5
- Furnace fan on
- 3
- Notes
- Strongest low on the wall near outlet
- Room or spot
- Doors open
- Doors closed
- Furnace fan on
- Notes
- Room or spot
- Doors open
- Doors closed
- Furnace fan on
- Notes
- Room or spot
- Doors open
- Doors closed
- Furnace fan on
- Notes
What the patterns mean
A smell that gets stronger when the door is closed is coming from inside that room's walls, floor or ceiling. A smell that spreads evenly when the furnace runs suggests the source is in or near the duct system. A smell strongest on an upper floor near the ceiling points to the attic, while one strongest near the floor of a ground-level room often points to a crawl space or basement below.
Animals usually die in sheltered spots: inside exterior walls, near plumbing penetrations, under bathtubs, behind kitchen appliances, above ceiling fixtures. Those are good places to focus once the map narrows the room.
Questions the map should answer
- Which room is strongest with interior doors closed?
- Is the smell higher near the ceiling or near the floor?
- Does running the furnace fan spread it evenly or make one register worse?
- Is the strongest spot on an exterior wall, near plumbing or near a fixture?
- Does the smell change on warm afternoons compared with cool mornings?
Common questions
Should I use a fan to help find it?
Not while mapping. Fans spread the smell evenly and make the source harder to find. Use them afterward to ventilate.
How long does mapping take?
About an hour of waiting with the house closed up, then fifteen minutes walking and writing.
What if two rooms rate the same?
Look at the wall they share, or the floor or ceiling between them; the source is often right on the boundary.
General information for Sloan's Lake, not a quote or professional advice. In an emergency, call 911.