Questions to ask
1. Are you licensed for mold remediation in my state or city (if required), and can you show general liability insurance and workers’ compensation?
Why it matters: Some states require a mold remediation license or registration; others do not — but insurance still matters everywhere. Ask for a certificate of insurance with general liability limits, whether pollution or mold-related coverage is excluded, and workers’ comp for employees. Demolition, HEPA vacuums, and bagged debris create injury and property-damage risk. “We’ve never had a claim” is not a policy. Get carrier name, limits, and dates in writing before they open walls.
2. Are your project managers or technicians IICRC-certified (or similarly trained) in mold remediation or applied microbial remediation — and who will be on site each day?
Why it matters: IICRC mold remediation and related microbial credentials show training on containment, PPE, and removal standards many insurers and hygienists recognize. Ask which certifications are current and whether a trained lead stays on the job or only the sales visit. A polished estimator and an untrained demo crew is a common bait-and-switch. Prefer a named supervisor over “whoever is free.”
3. Have you identified and documented the moisture source — and will remediation include fixing that leak, humidity, or drainage problem (or coordinating with a plumber / HVAC / roofer)?
Why it matters: Mold returns if water keeps coming. Ask what they believe caused growth (roof leak, plumbing, condensation, flood category, poor ventilation) and whether their contract covers source repair or only removal. If someone else must fix the leak first, get that sequence in writing. Companies that sell remediation without discussing moisture are selling a temporary clean-looking surface.
4. What is your written scope — which rooms, materials to remove vs clean, square footage of affected area, and what stays protected?
Why it matters: Phone quotes based on “a little mold in the bathroom” hide wall cavities, insulation, flooring, and HVAC involvement. Ask for a written plan: containment boundaries, materials to remove (drywall, trim, carpet, pad), HEPA vacuuming and wipe protocols, drying equipment, and what is excluded. Clarify change-order triggers when hidden damage appears behind walls. The cheapest lump sum often grows once “extra demo” lines appear mid-job.
5. How will you contain the work area — plastic barriers, negative air machines with HEPA, and sealed HVAC returns — and how do you prevent cross-contamination?
Why it matters: Disturbing mold without containment can spread spores to clean rooms. Ask about critical barriers, negative pressure relative to clean areas, HEPA filtration, and whether supply/return vents in the work zone are sealed. Ask how debris is bagged and removed through the house. Vague “we’ll be careful” without naming equipment is a red flag for a wipe-down crew posing as remediators.
6. Do you recommend or require pre- and post-remediation testing — who chooses the independent hygienist, and who pays if clearance fails?
Why it matters: Clearance (post-remediation verification) is how you know the job met the agreed standard. Ask whether they require third-party testing, whether the tester is independent of the remediator, and what happens if results fail (re-clean at their cost vs yours). Be wary of companies that both sell expensive testing and remediation with no separation of roles — or that dismiss all testing as unnecessary while guaranteeing “safe” air. Get pass/fail criteria in writing before work starts.
7. Will you use biocides, fogging, or ozone — and when is removal of porous materials required instead of “killing” mold in place?
Why it matters: Industry practice generally emphasizes removing contaminated porous materials and cleaning non-porous surfaces, not relying on fog or ozone as a substitute for demolition. Ask when they recommend removal vs cleaning, what chemistry they use, and whether fogging is an add-on sold after a low base bid. Aggressive claims that spray alone makes a moldy wall “safe” without addressing moisture or material removal deserve skepticism. Ask how they protect occupants with asthma or chemical sensitivities.
8. How do you handle drying and moisture verification after demolition — meters, drying goals, and how long equipment stays on site?
Why it matters: Leaving cavities wet invites new growth. Ask about moisture meters or thermal imaging, target moisture levels before closing walls, and whether dehumidifiers and air movers are included in the price or rented daily as extras. Confirm who decides when rebuild can start. A crew that bags debris and leaves without documenting dry-out is incomplete.
9. What is included for disposal of contaminated materials, and do you follow local rules for bagging and hauling moldy debris?
Why it matters: Contaminated drywall and insulation must leave your home in sealed bags or containment, not tracked through living spaces. Ask who hauls debris, whether dump fees are included, and how they protect floors and clean exits. Unclear disposal often means debris sits in your garage or gets mixed with regular trash against local rules.
10. What warranty or re-service terms apply if visible mold returns in the same contained area within a defined window — and what voids that warranty?
Why it matters: Ask what is covered (same room / same cause), how long, and exclusions (new leaks, occupant humidity, unfinished source repair, HVAC contamination outside scope). Get it in writing. A “lifetime mold-free home” promise with fine print that voids for any moisture is marketing, not protection. Prefer clear re-service for the remediated area if source control was part of the agreed plan.
11. Can you provide recent local references for similar jobs, and will payment go through a business invoice with milestones rather than large cash-only up front?
Why it matters: References from homes with comparable scope (bathroom gut, basement, HVAC involvement) beat star ratings alone. Ask for two recent clients, how long the company has operated locally, and a payment schedule tied to containment setup, completion of removal, and clearance or final walkthrough. Large cash-only demands before work, or pressure to “sign today because mold is eating your house,” are classic high-pressure tactics. Legitimate firms can usually invoice under a business name and accept card or electronic payment.
Red flags
- No insurance proof, or refuses licensing info where your state requires mold remediation credentials.
- Guarantees to “kill all mold forever” with fogging or ozone alone — no containment, no material removal, no moisture fix.
- Scare tactics: same-day pressure, extreme health claims, or “your house will be condemned” without documentation.
- Cannot explain containment, negative air, or HEPA; “we’ll wipe it down” for widespread porous contamination.
- Sells both testing and remediation with no option for independent clearance — or dismisses all verification.
- Large cash-only deposit before work, no written scope, no receipt.
- Ignores the moisture source; remediation-only pitch with no plumber, roofer, or HVAC path.
Next-step checklist
- Photograph affected areas; note leaks, past floods, and HVAC symptoms before anyone opens walls.
- Confirm licensing (if required) and get written proof of liability insurance (and workers’ comp if they have employees).
- Compare at least two written scopes with the same rooms and materials list; note containment, disposal, and dry-out.
- Decide on independent pre/post testing and who pays if clearance fails — in writing before demo starts.
- Fix or schedule the moisture source (plumbing, roof, drainage, humidity) so remediation is not wasted.
- Hold final payment until the walkthrough (and clearance, if agreed) matches the written scope.