Should I buy a house with mold in the attic?

Is mold in the attic a deal breaker?

It depends on two prices you can get before your deadline: removing the mold and fixing the water that feeds it. With written bids in hand, ask the seller to fix both or credit you for both, or walk if the numbers are too big. The Environmental Protection Agency (EPA) says that if you clean up mold but leave the water problem, the mold will most likely come back.

Key takeaways

• The water source decides how big this is: a bath fan duct venting into the attic is a defined fix, while a roof leak or soft sheathing needs a roofer's bid first.
• This Old House puts attic mold removal at $1,000 to $4,000, and moldy insulation adds to it; the duct or roof fix is a separate bid.
• Before your deadline, get written bids from a mold remediation contractor (and a roofer, if it's a leak), then ask for the work with receipts or a matching credit.

What causes mold in an attic?

Mold needs water. EPA says none of the many types of mold will grow without it. In an attic, the International Association of Certified Home Inspectors (InterNACHI) points to two sources.

• A bathroom fan duct that ends in the attic. InterNACHI calls improper duct termination the most common bathroom ventilation defect. Warm, moist bathroom air condenses on cold framing and insulation.
• A roof leak. InterNACHI says a roof leak can feed mold colonies in the attic that grow unnoticed. Chimneys, plumbing vents and skylights are common leak points.

Your report may call it "appears to be microbial growth" rather than mold. InterNACHI tells inspectors to use that wording, since only a lab can confirm mold. If the report doesn't name the moisture source, ask your inspector, then have the roofer or contractor confirm it on site.

How serious is mold in the attic?

Fix it before you move in. InterNACHI's duct guide says: "Inhaling mold spores can cause health problems in those with asthma or allergies, and can cause serious or fatal fungal infections in those with lung disease or compromised immune systems." EPA adds that molds "have the potential to cause health problems," and that exposure "may cause allergic reactions in sensitive individuals."

Attic mold can reach the rooms you live in. InterNACHI notes that "mold spores can be sucked into the living areas of a residence by low air pressure," the kind bath fans, dryers and kitchen fans create.

The wood is the second concern. InterNACHI calls attic mold "a clear indication of improper ventilation that must be corrected" to avoid structural decay and respiratory problems. It also warns that "by the time decay becomes visible, affected wood may have lost up to 50% of its strength." If the report notes an active roof leak or soft, stained sheathing, have a roofer look before your deadline.

How much does it cost to remove mold from an attic?

Size and access drive the spread. This Old House puts the low end on a small spot in an easy attic and the high end on extensive mold in a cramped one. Mold inside the insulation adds removal cost.

Say your report finds mold in a medium attic, fed by a bath fan duct that vents into it. The Boise company puts correcting that duct at $2,000 to $4,000, so its medium-attic cleanup plus the duct comes to $4,000 to $9,000 in Boise. That still leaves out insulation replacement, which the same company prices separately.

Those ranges assume a minor, easy-to-reach moisture source. The same company warns that a hidden roof leak can add thousands. Only a roofer's written bid closes that gap.

Who should I call before my deadline?

Call a mold remediation contractor for the cleanup. EPA says to pick one with experience cleaning up mold, check references, and ask them to follow EPA's or another professional body's remediation guidelines. The Boise company lists cleanup at 1 to 4 days, depending on attic size.

The water fix depends on the cause. A duct that ends in the attic has to be rerouted to the outdoors, so ask for that as its own line in the remediation proposal. A roof leak needs a separate written bid from a roofer. How to get repair estimates during the inspection period covers other ways to get a figure while your window is open.

What should I ask the seller for?

Write it as one line, with scope, trade and the bid behind it:

• Attic mold: remove mold from the roof sheathing and framing, reroute the bath fan duct to the outdoors, mold remediation contractor, amount per the contractor's written bid.

Ask for the work done with receipts, or a credit sized to the bid. If the seller does the work, ask for a written scope that shows the water problem was fixed first. EPA says a cleanup is done only when the moisture problem is fixed and visible mold and moldy odors are gone.

Kept prices every line of an inspection report for $79, usually under 4 hours, so your bids can go to the mold and the water behind it. What to ask for after a home inspection shows how the line fits with the rest of your list. The buyer repair request letter template has the wording around it.

What if the seller says no?

You can accept it, ask for a credit or price cut instead, or walk away. Make that call once the remediation bid, and the roofer's if there's a leak, is in hand. When to walk away after a home inspection walks through that call. Your contract sets the deadline and your options if the seller refuses, so confirm them with your agent.

Will insurance pay for mold in the attic?

Don't count on it. Progressive says homeowners insurance doesn't usually cover mold unless a covered peril, like a burst pipe, caused it. If the mold has been around for weeks or longer, it says a policy likely won't pay. The mold on your report is already there, so don't plan on a claim to cover it. Ask your own insurance agent how your policy treats mold.

Is black mold in the attic worse?

Color won't tell you. EPA notes that molds come in many colors. EPA also says that when mold is visible, sampling is in most cases unnecessary: the job is the same cleanup and water fix either way.

Once the remediation bid is in, upload your inspection report to Kept: most of your other findings come back priced, with labor, materials and tax shown, so the mold bid sits beside real numbers for the rest of your request. $79 per memo, usually under 4 hours.

Sources

• EPA, A Brief Guide to Mold, Moisture and Your Home
• InterNACHI, Bathroom Ventilation Ducts and Fans
• InterNACHI, Moisture Intrusion
• This Old House, How Much Does Mold Remediation Cost?
• ATI Restoration, How Much Does Mold Remediation Cost?
• BUK Restoration, Attic Mold Remediation Pricing Guide
• Progressive, Does Homeowners Insurance Cover Mold?