Checking mold risk before signing a lease
How to check mold risk before signing a lease: score the address, walk the unit for the four things photographs hide, and get any observation into writing before you sign.
Step by step
Score the address before the viewing
It costs nothing, needs no permission and takes seconds. What it gives you is not a verdict but a shape: whether the weight sits in the region, the ground, the building's era, or something documented. That decides what you look for when you get there.
Walk the lowest level first
Below-grade space is where concealed growth most often is, and finishing a basement is the improvement most likely to hide it. Look for a tide line at a consistent height on the wall, efflorescence on masonry, a section of flooring newer than the rest, or a room that smells different with the door closed.
Check the four things photographs never show
Which way the ground slopes at the building. Where downspouts discharge. Whether bathroom and kitchen extraction goes outside or into a loft. And whether any window in the unit shows condensation staining at the frame. All four are free to check and none appear in a listing.
Ask the questions the score raised
If the drivers name a construction era or cladding, ask when the building was last worked on. If they name terrain, ask whether the lower units have ever taken water. A letting agent who does not know is a normal answer; one who changes the subject is a different one.
Put observations in writing before you sign
Email, not conversation. "Noted damp staining under the bathroom window and a musty smell in the rear bedroom — could you confirm whether these have been looked at?" Sent before signing, that email is the record that a condition pre-existed your tenancy, and it is the single most useful thing a tenant can do in this whole process.
Photograph everything at move-in
Date-stamped, including the places you expect to have an argument about later: behind furniture positions, under sinks, window frames, the base of exterior walls. Deposit disputes and habitability disputes both turn on what the unit looked like on day one.
What the data actually changes for a tenant
It changes where you look, and it changes what you ask. It does not change your rights, and it will not be accepted as evidence by anyone — a modelled estimate is not an inspection finding and should not be presented as one.
The disclosure module is generally inert for rentals, because no transaction generates a statutory form. That means a rental score rests on climate, terrain and building data, and is a weaker instrument than the same score on a purchase. Worth knowing before you weight it heavily.
Where it earns its seconds is the era and cladding signal. A building from the model's worst decade, with cladding that traps water, is one you inspect differently — and that is knowable before you have booked a viewing.
What to do about it once you are in
Hold indoor humidity between 30% and 50%. A hygrometer costs very little and it is the only instrument that catches a developing problem before anything is visible.
Run extraction past the end of the shower, not for its duration. Most bathroom moisture leaves in the ten minutes after, and most extraction stops before then.
Report anything in writing, every time, and keep the thread. Landlord obligations vary by state and by lease, but every version of them turns on notice — and a phone call is not notice you can produce later.
Cost
For a tenant checking one unit, the free check is the whole answer. Paid tiers add disclosure parsing, and rentals generally have no disclosure to parse.
For a landlord or agent screening units before letting them, the same per-property pricing applies: free, $29, and $79 where a form exists. Volume arrangements for portfolios are agreed directly rather than published as a self-serve tier.
Questions people ask
- Is it worth getting a mold risk score before renting?
- Worth the seconds the free check takes, yes — it tells you what to look at during the viewing. The paid tiers add disclosure analysis, and rentals rarely have a disclosure, so they add little here.
- How do I check a mold risk score before renting an apartment?
- Score the building's address. It works on any US address without permission. For an apartment specifically, remember the score describes the building, not your unit — a top-floor flat and a garden-level one in the same building face different conditions.
- Can I refuse to sign because of a score?
- You can decline any lease for any lawful reason. What a score cannot do is compel a landlord to act — it is an estimate, not a finding, and it carries no weight in a dispute.
- What if I find mold after moving in?
- Report it in writing immediately and keep the thread. Your rights depend on your state and your lease, and every version of them starts from documented notice.