Foundation cracks: what to check and who to call

A crack in a basement wall or a garage floor is scary, but not all cracks are alike. Some are small and never change; others let in water, dampness or a gas you can’t see. This guide is for you if you own your home and see cracks in the foundation, the floor or the walls, or if you live where sinkholes or earthquakes happen. It explains what the EPA, the U.S. Geological Survey (USGS) and some state laws say, and which programs help pay.

Radon level at which the EPA recommends fixing the home

4 pCi/L¹

How long a short-term radon test stays in the home

2 to 90 days¹

To dry wet materials and avoid mold, according to the EPA

24 to 48 hours³

What Earthquake Brace + Bolt offers in California

Up to $3,000⁶

Why cracks matter: water and radon

Foundation cracks are an open door. According to the EPA, radon is a radioactive gas that comes from the natural decay of uranium found in nearly all soils. It typically moves up through the ground and into the home through cracks and other holes in the foundation: cracks in solid floors, construction joints, cracks in walls, gaps in suspended floors and gaps around service pipes. Any home can have radonradonRadon is a natural radioactive gas that comes from the breakdown of uranium in soil, rock and water. You cannot see or smell it. It usually moves up from the ground into a home through cracks and other holes in the foundation, and the home can trap it inside. Any home can have it, new or old, with or without a basement, and it is a leading cause of lung cancer. Testing is the only way to know the level. If you are buying, EPA recommends asking the seller for test results or having the home tested, and high levels can be reduced.See the full definitionClose, new or old, with or without a basement.¹

Water is the other problem. The EPA recommends that the ground slope away from the foundation, so water doesn’t enter or collect around the house. It also says to fix leaks as soon as possible, and that if wet materials are dried within 24 to 48 hours, in most cases mold will not grow.³

If water already got into the basement

When water comes in through a crack, mold follows quickly. The EPA says absorbent materials such as ceiling tiles and carpet may have to be thrown away if they become moldy. If the moldy area is less than about 10 square feet, in most cases you can clean it yourself following its guidelines. And don’t paint or caulk a moldy surface: clean it and dry it first.³ The lead, mold and pests guide has more on mold at home.

What to check yourself

We found no official source with a measurement that says when a crack is serious in any home. What you can do is watch and document, so you can explain the problem well to a contractor and compare estimates.

Check your home step by step

1. 1. Photograph each crack

   Today

   With a ruler or a coin beside it and the date, to see whether it grows.⁷

2. 2. Watch where the water goes

   When it rains

   The ground should slope away from the foundation, according to the EPA.³

3. 3. Test for radon

   This week

   With a low-cost kit or a qualified tester.¹

4. 4. Get written estimates

   If the crack grows or water gets in

   From licensed and insured contractors; compare the work, materials, date and price.⁷

Write down what you see with the date: whether the crack grows from one month to the next, whether water gets in when it rains or whether you notice changes in doors and windows. Those notes help a contractor understand your case. If someone offers a free inspection and then scares you into buying an expensive repair today, be wary: the FTC says scammers knock on your door because they’re “in the area,” push you to decide immediately and ask for everything up front or only cash.⁷

The radon test

The EPA says you can’t see or smell radon, that testing is the only way to know your level, and that all homes should be tested.² There are low-cost do-it-yourself kits you can get by mail and in some hardware stores. If you’d rather have someone else do it, your state radon office has lists of qualified testers. Short-term tests stay in the home for two to 90 days, depending on the device.¹

Radon is measured in picocuries per liter of air (pCi/L). The EPA recommends fixing the home if the level is 4 pCi/L or higher.¹ The method mainly used is a vent pipe with a fan that pulls radon from beneath the house, and it doesn’t require major changes. Sealing foundation cracks and other openings makes that system more effective and cost-efficient.¹ In other words, if you’re going to fix the cracks, test for radon first.

One short-term test isn’t always enough. The EPA explains that radon varies from day to day and season to season, so a short-term test is less likely than a long-term one to show your year-round average. If you need results quickly, a short-term test followed by a second short-term test may be used to decide whether to fix your home.¹

Seal cracks or install a radon system

Helps

Seal the cracks

• Closes the way in for water and radon.¹
• Makes a radon system more effective.¹
• Not enough by itself if radon is 4 pCi/L or higher.¹

Most used

Radon system

• A pipe and fan pull radon from beneath the house.¹
• Doesn't require major changes to the home.¹
• Test before and after.¹

Test for radon before you decide.²

Sinkholes

In some areas the problem is under the house. According to the USGS, sinkholes are common where the rock below the surface is limestone, carbonate rock, salt beds or other rocks that groundwater can dissolve. The land can stay intact for a while, until the underground spaces get too big and the surface collapses suddenly. The most damage tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania.⁴

Insurance varies a lot by state. In Florida, section 627.706 of the Statutes says every property insurer must cover catastrophic ground cover collapse, and must make available, for an additional premium, coverage for sinkhole losses. The insurer may require an inspection first, and the policy may carry a sinkhole deductible of 1, 2, 5 or 10 percent of the dwelling limits.⁵ Read your policy and the home insurance guide to understand your deductibledeductibleA deductible is the part of an insurance claim you pay yourself. When you have a covered loss, the insurance company subtracts the deductible from the claim amount and pays you the rest. You may have a different deductible for each type of coverage. You will find it on the first page of your policy, called the declarations page, along with your coverages and limits. In taxes, the word "deductible" means something else: an expense that can lower the taxes you owe.See the full definitionClose.

Earthquakes: strengthening the foundation

In earthquake country, a wood house on a raised foundation can shift off its base. In California, Earthquake Brace + Bolt (EBB) helps strengthen it: the retrofit bolts the foundation to the frame of the house and, where there are cripple walls in the crawl space, braces them with plywood, to help keep the house from sliding or toppling off its foundation in an earthquake.⁶

EBB offers up to $3,000 for that retrofit, and income-eligible homeowners can apply for an additional grant of up to $7,000. It is only done on wood-framed homes built before 1980 on a raised foundation, and registration opens for a limited time each year.⁶ The earthquake and wildfire insurance guide covers the other half: insuring the home.

Example with real numbers

A basement crack that lets water in

An example in words of the order of the steps.

First

Dated photos of the crack with a ruler beside it

Outside

Check that the ground slopes away from the foundation

Test

Low-cost radon kit or qualified tester

Estimates

Two or more, in writing, from licensed contractors

If radon is 4 pCi/L or higher

Also ask for an estimate for a radon system

The steps come from the EPA and the FTC.³¹⁷ Plan the cost in your family budget.

Run it with your numbersFamily budget

How to choose who to hire

The Federal Trade Commission (FTC) recommends considering only licensed and insured contractors and confirming the license with your state or county government. Get multiple estimates: a written one should include a description of the work, the materials, the completion date and the price. Don’t automatically choose the lowest, and ask for an explanation if there’s a big difference among them.⁷ The guide to what a repair quote must include explains each part and where to look up a license in your state.

If this is you

You see a new crack in the basement floor

Photograph it with the date and test for radon before sealing it.¹¹

You have children and the house was never tested for radon

The EPA says all homes should be tested; there are low-cost kits.²¹

Someone offers you a free foundation inspection

Don't decide today or pay cash; get several written estimates.⁷⁷

You live in Florida and a hole opened near the house

Notify your insurer: Florida law requires coverage for catastrophic ground cover collapse.⁵

Costly mistakes

• Mistake: Painting over the crack and forgetting it.

  Instead: Photograph it with the date to see whether it grows, and test for radon; don't paint over mold.¹³

• Mistake: Letting rainwater fall right next to the house.

  Instead: Make the ground slope away from the foundation.³

• Mistake: Thinking a new house can't have radon.

  Instead: Any home can; get it tested.¹

• Mistake: Accepting the repair sold at your door.

  Instead: Get several written estimates from licensed contractors.⁷⁷

• Mistake: Assuming your insurance covers sinkholes.

  Instead: Check your policy; in Florida, sinkhole coverage is offered for an additional premium.⁵

What to do this week

1. Photograph each crack with a ruler beside it and the date.
2. Check that the ground and gutters carry water away from the foundation.³
3. Buy a radon test kit or ask your state radon office for its list of testers.¹
4. If the crack grows or water gets in, get two or more written estimates from licensed contractors.⁷
5. Read your policy to see what it says about sinkholes, earthquakes and floods; the flood insurance guide explains that coverage.⁵
6. Add the cost to your family budget.