The three options
| Type | How long | Best for |
|---|---|---|
| Short term charcoal | 2 to 7 days | A first look, and real estate transactions where the clock is short |
| Long term alpha track | 90 days to a year | Knowing your real annual average, which is what your actual exposure is |
| Continuous monitor | 48 hours | Professional testing. Records hour by hour, so tampering and open windows show up in the data |
Where the detector goes, and why it matters
The test belongs in the lowest level of the home that is or could be lived in. In Spokane that is almost always the basement, whether or not it is finished right now, because a future owner may finish it.
Placement rules that change the result if you get them wrong:
- Between 20 inches and 6 feet off the floor.
- At least 3 feet from exterior walls, windows and doors.
- Away from drafts, heat, humidity and direct sun. Not on top of the dryer, not next to the sump pump lid, not on a windowsill.
- Not in a kitchen, bathroom or laundry room. The humidity throws off charcoal detectors.
Closed house conditions, in plain terms
For any test shorter than four days, the house has to be closed for twelve hours before the test starts and for the entire test.
- Windows and exterior doors shut. Normal in and out is fine.
- Whole house fans, window fans and evaporative coolers off. This matters here: swamp coolers are common in the region and they pull enormous amounts of outside air through the house.
- Heating and air conditioning run normally.
- Do not test during a storm with high winds, and be aware that big pressure swings can move results.
What makes a result invalid
Any of these and the test has to be repeated: the detector was moved, the house was aired out, the test ran shorter or much longer than its instructions, or it sat in a bathroom or near a heat source. A professional continuous monitor logs all of this, which is exactly why it is required in most real estate transactions.
What to have ready when you call
- Your ZIP code and whether the house has a basement, a crawl space, or sits on a slab.
- Whether this is for a sale, a purchase, or peace of mind.
- If there is a deadline, say so up front. Transaction testing gets scheduled differently.