HireContractor
ElectricianPlumberHVAC ContractorRoofing ContractorPainting ContractorWater Damage RestorationFoundation RepairConcrete ContractorFence ContractorFlooring ContractorLandscaping ContractorSolar InstallerSiding ContractorWindow ContractorMold RemediationGarage Door ContractorAll 42 Trades →

Mold Remediation: What to Ask Before Hiring a Company

Mold remediation is an industry where fear sells. Some companies exaggerate the danger to justify inflated prices, while others do the bare minimum and leave hidden mold behind walls. The key to navigating this is understanding that mold remediation should be based on testing data, industry protocols (IICRC S520), and measurable outcomes -- not scare tactics. An independent mold inspector who does not also do remediation is your most important ally.

10 QuestionsPrintable ChecklistAvg Cost: $1,500 - $6,000 per job

Questions to Ask

1Should I hire an independent mold inspector before you begin, or do you provide testing?

Why It Matters

A company that both tests and remediates has a financial incentive to find problems. An independent inspector provides unbiased assessment and can verify the remediation was successful through post-clearance testing.

Red Flag

They strongly discourage independent testing, or they say their own testing is sufficient and no third-party verification is needed.

Pro Tip

Best practice is three-party process: independent inspector tests and creates a scope of work, remediation company executes, independent inspector performs post-clearance testing to verify success.

2What containment procedures do you use to prevent mold spores from spreading to unaffected areas?

Why It Matters

Mold remediation disturbs colonies and releases massive quantities of spores. Without proper containment, remediation makes the contamination worse by spreading spores throughout the house.

Red Flag

They don't use containment barriers, or they use simple plastic sheeting without negative air pressure.

Pro Tip

Proper containment includes: polyethylene barriers sealed with tape, negative air pressure (HEPA-filtered air scrubbers exhausting to the outside), and decontamination chambers at entry points.

3Do you follow the IICRC S520 standard for mold remediation?

Why It Matters

The IICRC S520 is the industry standard reference for professional mold remediation. It establishes protocols for assessment, containment, removal, and verification that the work was done correctly.

Red Flag

They're unfamiliar with S520, or they claim their own proprietary methods are superior to industry standards.

Pro Tip

Ask specifically about their adherence to S520 Condition 1, 2, and 3 classification. A company following S520 should be able to explain which condition your mold growth falls under and what the remediation protocol requires.

4What protective equipment do your workers use, and what precautions should my family take?

Why It Matters

Mold remediation workers should wear full PPE including N95 or P100 respirators, Tyvek suits, and gloves. If workers aren't protecting themselves, they're not following safety protocols.

Red Flag

Workers arrive without respirators or protective equipment, or they say the mold isn't dangerous enough to require PPE.

Pro Tip

Your family should not be in the containment area during remediation. Ask about HVAC system isolation to prevent spores from circulating through ductwork during the project.

5Will you address the moisture source that caused the mold, or only remove the mold itself?

Why It Matters

Mold cannot grow without moisture. Removing mold without fixing the water source guarantees recurrence. The moisture source might be a plumbing leak, condensation, poor ventilation, or water intrusion from outside.

Red Flag

They focus entirely on mold removal without investigating or addressing the moisture source.

Pro Tip

A thorough remediation company will identify the moisture source as part of their assessment and either fix it or recommend a specialist (plumber, waterproofing contractor) to address it.

6What materials will you remove versus clean, and how do you make that determination?

Why It Matters

Porous materials (drywall, insulation, carpet) that are contaminated usually must be removed. Non-porous and semi-porous materials (wood framing, concrete) can often be cleaned with appropriate methods.

Red Flag

They remove everything without regard to material type, or they try to clean porous materials that should be removed.

Pro Tip

The decision should follow IICRC S520 guidelines based on material porosity and contamination level. Wood framing is typically cleaned with wire brushing, HEPA vacuuming, and antimicrobial treatment. Drywall with visible mold growth is typically removed.

7Will you HEPA vacuum all surfaces in the containment area before removing barriers?

Why It Matters

Settled mold spores on surfaces within the containment area become airborne again when disturbed. HEPA vacuuming before removing containment barriers captures settled spores and prevents recontamination.

Red Flag

They plan to tear down containment immediately after removing moldy materials without cleaning settled spores from remaining surfaces.

Pro Tip

The cleaning sequence should be: remove contaminated materials, apply antimicrobial, allow to dry, HEPA vacuum all surfaces (including ceilings, walls, and floors), then wipe surfaces, then remove containment.

8Do you perform or arrange post-remediation verification testing?

Why It Matters

Post-remediation testing (clearance testing) compares indoor spore counts to outdoor levels to verify that the remediation was successful. Without it, you have no objective proof the work achieved the goal.

Red Flag

They say clearance testing isn't necessary, or they perform their own post-testing rather than using an independent party.

Pro Tip

Independent post-remediation testing should show indoor spore counts at or below outdoor levels, with no elevated counts of the specific mold species that was being remediated.

9What is your warranty, and what happens if mold returns in the same area?

Why It Matters

If mold returns in the same location within a short time, either the moisture source wasn't addressed or the remediation was incomplete.

Red Flag

No warranty at all, or a warranty that excludes the same mold species returning in the same location.

Pro Tip

A reasonable warranty covers mold recurrence in remediated areas for 1-3 years, provided the moisture source has been addressed. The warranty should specify that the company will return and re-remediate at no additional cost.

10How much will this cost, and can you provide a detailed written estimate?

Why It Matters

Mold remediation costs vary widely ($1,500 to $30,000+) depending on the extent of contamination. A written estimate with line items prevents surprise charges.

Red Flag

They give a verbal ballpark number without inspecting, or they cannot provide a written estimate with a scope of work.

Pro Tip

The estimate should detail: containment setup, material removal (by area/type), cleaning methods, antimicrobial treatment, HEPA vacuuming, air scrubbing, and disposal. Compare scope, not just price, across bids.

Bonus Tips for Hiring a Mold Remediation

  • Hire an independent mold inspector (not affiliated with a remediation company) to assess the situation and create a scope of work before getting remediation bids. This costs $300-$600 and saves you from unnecessary work.
  • Understand that small areas of mold (under 10 square feet on a single surface) can often be handled by homeowners with proper precautions, according to the EPA. You don't always need professional remediation.
  • Ask your insurance company about coverage before starting. Standard homeowner's policies vary widely on mold coverage. Some have specific mold exclusions, others cover mold resulting from a covered peril (like a burst pipe).
  • Be wary of companies that use scare tactics about toxic black mold. While Stachybotrys (black mold) can cause health problems, many types of mold appear black, and professional assessment should determine the actual species and risk level.

Find Licensed Mold Remediation Companies Near You

Browse verified mold remediation contractors in your area. Listings include license numbers and customer reviews where available.

Search Mold Remediation CompaniesMold Remediation Directory

More Mold Remediation Resources

Mold Remediation DirectoryBrowse all mold remediation contractorsMold Remediation Cost GuideAverage pricing: $1,500 - $6,000 per jobAll Hiring GuidesChecklists for all 42 trades

Related Trade Guides

Water Damage RestorationWaterproofing ContractorInsulation Contractor
Get Free Quotes