Should I buy a house with water in the basement?

Is it worth buying a house with water damage in the basement?

You can buy a house with water in the basement once you know where the water comes from and what stopping it costs. Your report says water is getting in, not why or what the fix is. Before your deadline, have a basement waterproofing contractor find the source and price the fix in writing, then ask the seller for that number. If a wall is also cracked or bowing, book a structural engineer first.

Key takeaways

• Fixes run from waterproof paint at $1 to $8 per square foot to $8,000 to $18,000 for inside and outside work together.
• White chalky powder on the wall can be cosmetic, but it points to a potential moisture problem.
• Most waterproofing crews book at least three months out, so ask for a credit, not a repair finished before closing.

Is water in the basement bad?

Treat water in the basement as a repair item, not a quirk. The International Association of Certified Home Inspectors (InterNACHI) Standards of Practice tell inspectors to report "observed indications of active water penetration" as "in need of correction."

The bigger risk is what the water feeds. The Environmental Protection Agency (EPA) says "the key to mold control is moisture control." Mold usually isn't a problem indoors unless spores land on a wet spot and start growing. Once they do, EPA says molds "have the potential to cause health problems," from allergic reactions "in sensitive individuals" to asthma attacks "in people with asthma who are allergic to mold."

Your inspector isn't required to determine whether mold is present under InterNACHI's standards, and an inspection won't find hidden defects behind finished walls. Ask the contractor who looks at the water to check. If they find it, removal is a job for a mold remediation specialist.

What if the report shows old water damage?

Water that was dried fast is a smaller question than water coming in today. EPA says that if wet materials are dried 24 to 48 hours after a leak, "in most cases mold will not grow."

Ask the seller, through your agent, when the water came in and for any invoice showing how it was dried and repaired. Waterproofing pros typically back their work with a warranty, so ask for that paper too. If nobody can say, treat it as active until the contractor tells you otherwise. Water damage repairs can run $1,360 to $6,290, on top of stopping the water.

What does it cost to fix water in a basement?

It depends on the fix, and the fix depends on the source. Interior methods handle water that's already inside. Exterior methods stop it before it reaches the wall. They cost more up front, but This Old House says they give decades of protection with little upkeep. Most homeowners spend $2,461 to $8,202 in total, per HomeAdvisor. The outside work in the table below runs higher.

Within a row, the price moves with a few things:

• Foundation type. Block foundations cost more to fix than poured concrete.
• Basement size. A bigger basement needs more material and labor.
• Soil and permits. Clay soil makes digging harder, and some cities charge $75 to $500 for an excavation permit.

Interior drain tile means jackhammering the basement floor. Ask whether the bid covers patching the floor and containing the dust.

Who finds the source before your deadline?

A basement waterproofing contractor finds the source. Ask for four things in writing: where the water comes from, the fix, the length of wall it covers, and whether the pump is in the price. This Old House recommends quotes from at least three contractors.

With a cracked or bowing wall, the engineer goes before any waterproofing company, so the scope isn't written by the company selling the fix. See bowing basement wall on inspection report.

Get the bid inside your window. The work itself takes longer to schedule: This Old House says most crews book at least three months out. How to get repair estimates during the inspection period covers getting contractors out in time.

What should you ask the seller for?

Ask for the contractor's number, not a round one. Given the booking wait, a credit or a price reduction fits your timeline better than a repair the seller has to finish before closing.

Say the contractor finds water coming through one 40-foot wall and specifies interior drain tile with a new sump pump. The drain tile costs 40 × $60 = $2,400 to 40 × $120 = $4,800. Add the pump and the total is $2,400 + $1,200 = $3,600 to $4,800 + $2,500 = $7,300. If your city requires a permit for the digging, add $75 to $500. If the contractor also finds mold, add removal. With both: $3,600 + $75 + $500 = $4,175 to $7,300 + $500 + $3,500 = $11,300.

Put the written bid behind the request, not this example. A line can be as short as this:

Seller to credit buyer the amount of the attached waterproofing bid: interior drain tile and sump pump along the north basement wall.

What to ask for after a home inspection covers how this 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?

If the seller says no, you still have choices:

• Ask for part of it. Tie a smaller credit to one line, like the sump pump.
• Switch to a price reduction if the seller won't write a credit.
• Walk away if the source is still unknown or the fix costs more than the house is worth to you. Your contract's inspection contingency, if you have one, sets whether and when you can cancel, so confirm with your agent.

When to walk away after a home inspection helps you make that call.

Is efflorescence in a basement a problem?

On its own, efflorescence isn't a major problem, but the water behind it can be. InterNACHI says this white chalky powder on concrete or brick "can be a cosmetic issue, or it can be an indication of moisture intrusion that could lead to major structural and indoor air quality issues."

To tell it from mold, pinch it. Efflorescence turns to powder and dissolves in water. Mold does neither, and anything purple, pink or black isn't efflorescence. A stiff brush removes it, but washing it off can make it come back. Ask the contractor whether the wall behind it is wet.

How do I know what the rest of my list is worth?

Price the rest of your list the way you priced the basement: a bid for the big items, a range for the small ones. Kept prices every line of an inspection report for $79, usually under 4 hours, and marks regrading and drainage correction as needing a professional quote (how Kept prices). That tells you which bids to chase first.

While the contractor works out where the water comes from, upload your inspection report to Kept and get the rest of your request priced before your deadline.

Sources

• InterNACHI, Home Inspection Standards of Practice
• InterNACHI, Efflorescence for Inspectors
• EPA, A Brief Guide to Mold, Moisture, and Your Home
• This Old House, How Much Does Basement Waterproofing Cost?
• HomeAdvisor, How Much Does It Cost to Waterproof a Basement?
• Bob Vila, Basement Waterproofing: Costs and Key Considerations, Explained