Should a Musty or Wet Basement Stop You From Buying an Older Home?

By Aubre J. Stacknick, Global Real Estate Advisor, Piatt Sotheby's International Realty. Originally published on aubrestacknick.com.

Not by itself. A damp basement is a clue, not a verdict: what matters is where the water comes from, how long it has been happening, and whether the fix is a gutter or a foundation.

A musty basement scares buyers faster than almost anything else in an older Pittsburgh house. Some walk out the door. Others wave it off because the kitchen is beautiful.

Both reactions skip the useful question. What is the water doing, and what will it take to stop it?

Aubre J. Stacknick is a Global Real Estate Advisor with Piatt Sotheby's International Realty in Pittsburgh, PA, helping buyers and sellers across Western Pennsylvania see a home through a builder's eyes. Basements are where that background pays off, because the house tells you its history down there.

What does a musty smell in a basement actually mean?

A musty smell means moisture is present and has been for a while. Mold and mildew need moisture to grow, and the smell is what they leave behind. The U.S. Environmental Protection Agency's guide to mold, moisture, and your home is blunt about it: control the moisture and you control the mold.

The smell does not tell you how big the problem is. It can come from a damp corner that has never been fixed, a dryer vented into the basement, or a foundation that leaks every spring. Same smell, very different price tags.

Here is how I sort them.

Where is the water coming from?

There are four common sources in older western Pennsylvania homes, and they have very different fixes.

• Surface water. Downspouts that empty beside the foundation, gutters that overflow, or soil that slopes toward the house. This is the cheapest and most common cause. The fix is often outside the house.
• Groundwater. Water that rises through the floor or seeps through the wall where it meets the slab, especially after long rain or snow melt. Houses on hillsides see this a lot. The fix may be interior drainage and a sump pump.
• Plumbing. A leaking supply line, a drain that weeps at a joint, or a washing machine hose. Easy to find, easy to fix, easy to miss.
• Humidity. A basement that is simply too damp in summer, with no leak at all. Cool walls meet warm air and sweat. A dehumidifier and better airflow often handle it.

The EPA recommends keeping indoor humidity below 60 percent, ideally between 30 and 50 percent. A small, inexpensive humidity meter tells you where a basement sits. Ask the sellers whether a dehumidifier runs down there, and whether it runs all summer.

What should you look for during a showing?

You do not need tools for the first pass. You need to slow down and look at the edges.

• The bottom of the walls. Peeling paint, white chalky deposits, or dark staining low on the wall point to repeated moisture.
• The floor where it meets the wall. Cracks that run along the joint, or a floor that looks patched in one strip, can mean someone has already tried to fix something.
• The bottom of anything stored or built down there. Swollen baseboards, warped paneling, rusted metal feet on a furnace or water heater.
• The ceiling joists and subfloor above. Dark spots or soft wood under a bathroom or kitchen can mean a plumbing leak, not a foundation problem.
• Fresh paint in one spot. A single recently painted wall in an otherwise tired basement deserves a question.
• A sump pit or drain. Look inside. A dry, clean pit with a pump that is plugged in tells a very different story from a pit with a ring of mineral crust.

None of these is a diagnosis. Each one tells you what to ask next.

Do cracks in the basement wall mean the foundation is failing?

Not usually. Hairline vertical cracks are common in poured and block foundations and often come from the concrete curing and settling. They are worth noting and watching.

The cracks that need a specialist are different. Horizontal cracks, wide cracks, walls that bow inward, and stair-step cracks in block that grow over time can point to pressure from soil and water outside the wall. If you see any of those, bring in a structural engineer before you go further. A foundation contractor is not the right first call, because that person also sells the repair.

What should you ask the seller?

Three questions cover most of it.

• Has water ever come into the basement, and when was the last time?
• What has been done about it, by whom, and is there paperwork?
• Is there a transferable warranty on any waterproofing or drainage work?

Pennsylvania sellers generally complete a written property disclosure, and it asks about water problems. A vague or blank answer is itself information. Read the disclosure before you read the listing photos, then compare it to what you see.

What inspections should you add?

A general home inspection is the starting point, and it should happen after you have chosen the house and before you are locked in. In a house with a damp basement I often suggest adding:

• A structural engineer, if you see horizontal cracking, bowing, or a wall that has been patched
• A sewer scope, if the floor drain backs up or the house is older and the main line has never been replaced
• A radon test, because testing is the only way to know the radon level in a particular house, according to the EPA, and radon enters through the foundation
• A moisture check by a qualified inspector, if the basement is finished and you cannot see the walls

Radon is a separate issue from water, but the same basement visit is the right moment to ask about it.

What does a finished basement change?

A finished basement hides the evidence. Drywall, paneling, and carpet cover the very surfaces you would read for clues. If the basement was finished, I want to know when, who did it, and whether the water was solved first.

A basement finished before the water was fixed can trap moisture behind new walls. Signs include a dehumidifier running hard, a closed-in musty smell, carpet that is damp at the edges, and baseboards that are swollen at the bottom. Ask what is behind the finish, and ask for permits on any plumbing or electrical that went in down there.

So should it stop you from buying?

Sort the problem into one of four buckets.

• Walk away, when the cause is structural and the seller will not let you investigate.
• Bring in a specialist, when you cannot tell the cause and need a real answer before you decide.
• Negotiate, when the cause is known, the fix is priced, and you are comfortable with it.
• Move forward, when it is humidity or a simple drainage fix that you understand.

A good number of damp basements land in the last two buckets. The fix is a grading change, a downspout extension, or a dehumidifier. Many buyers lose a good house to a fear that a ten-minute explanation would have settled.

The common mistakes buyers make with basements

• Judging the house by the kitchen and never going downstairs with a flashlight
• Treating a musty smell as normal for an older house
• Taking "it has always been that way" as an answer
• Skipping the sump pit and the drain
• Paying a dry-basement price for a basement that is dry only because the weather has been

For more on spotting expensive problems early, read How Can I Tell if a House Has Expensive Problems Before I Buy It?. If the house is older, What Should I Look For When Buying an Older Pittsburgh Home? covers the other systems worth checking. And if a finished basement is part of a renovation, How Can You Tell If a Renovation Was Done Right Before You Buy? shows how I read the seams.

Common questions

If you are looking at an older house and want a second set of eyes on the basement before you write an offer, book a 30-minute call. Bring the address.