Top causes of basement moisture and how to fix the issue

Posted Mar 31, 2021 in Foundation Crack Repair, Waterproofing, Sump Pump Solutions

Wet basement

Do you have a wet base­ment? Base­ment mois­ture is not an uncom­mon prob­lem. In fact, base­ments are noto­ri­ous­ly dark and damp places. Yet how­ev­er com­mon it may be, mois­ture in your base­ment can be bad news. Unfor­tu­nate­ly for home­own­ers, a lit­tle bit of mois­ture can turn into a big prob­lem. From struc­tur­al dam­age to tox­ic mold that is haz­ardous to your health, base­ment mois­ture can cause major issues for your home. So what exact­ly are the caus­es of base­ment mois­ture? And more impor­tant­ly, what can you do to fix it?

Let’s start at the begin­ning. First of all, how do you know if you have mois­ture in your base­ment? It is impor­tant to be able to iden­ti­fy the warn­ing signs and symp­toms. The signs of base­ment mois­ture may not be as obvi­ous as a pud­dle of water on the floor. In fact, there are numer­ous ways in which mois­ture can present itself in your base­ment. Here’s a quick list of a few things to look for:

  • Water Trick­ling Out of the Walls
  • Sat­u­rat­ed Base of Con­crete Walls (a ring of dampness)
  • Con­den­sa­tion on the Walls and Floor
  • Stained or Blis­ter­ing Walls
  • Damp, Humid Air
  • Stand­ing Water on the Floor
  • Dete­ri­o­rat­ing Car­pet or Wood
  • Rot­ting Columns, Head­ers, and Joists
  • The odor of Mold or Mildew

If you see any of these signs, you are expe­ri­enc­ing mois­ture in your base­ment. Now that you know there is mois­ture, let’s find out where it is com­ing from.

Base­ment mois­ture typ­i­cal­ly comes from one of three sources:

Rain or groundwater

Sim­ply put, this is out­side water that makes its way inside. As lit­tle as 1 inch of rain can bring 1,250 gal­lons of water pour­ing down onto a 2,000 sq. ft. home. With­out prop­er grad­ing, down­spouts, and gut­ters, that water might find its way into your basement.

Inte­ri­or mois­ture sources

Some­times the water in our base­ments orig­i­nat­ed or was cre­at­ed there. Such sources can include dry­ers, show­ers, cook­ing, humid­i­fiers, and even the mois­ture from new­ly-con­struct­ed concrete.

Ven­ti­la­tion with humid, out­side air

In warmer weath­er, we often open our base­ment win­dows to help ven­ti­late the space. How­ev­er, when we let humid, out­side air into our cool base­ments, it can con­dense on the walls and floors.

Now that we know the pos­si­ble sources of the water, we can deter­mine the cause of the mois­ture, and ulti­mate­ly what to do to fix the prob­lem. Check out our list of:

Six com­mon caus­es of base­ment mois­ture and how to fix them

1. An Inte­ri­or Water Leak

This may seem like a no-brain­er, but you should always check for inside leaks first when try­ing to iden­ti­fy the cause of mois­ture in your base­ment. A water leak can come from numer­ous places: a show­er, a sink, a toi­let, a wash­ing machine, a dish­wash­er, a bad pipe, just to name a few. Some­times, if the mois­ture in your base­ment is locat­ed on the ceil­ing or walls beneath a bath­room or kitchen, an inte­ri­or water leak is to blame. Find where the mois­ture is locat­ed and deter­mine if some­thing in that area is leaking.

How to Fix It: An inte­ri­or leak is typ­i­cal­ly one of the eas­i­est prob­lems to solve. Sim­ply repair the leak (or have a plumber take care of it for you) and with any luck, that was the cause of the mois­ture, and it will be gone for good.

2. Inef­fec­tive Grading

Rain or ground­wa­ter often makes its way into base­ments due to poor grad­ing. The ground around your foun­da­tion should slope away from the house, not towards it. If drain­ing in the wrong direc­tion, water will accu­mu­late against your foun­da­tion and even­tu­al­ly make its way inside. This often hap­pens when fill dirt around your foun­da­tion isn’t prop­er­ly com­pact­ed. As the dirt set­tles, the slope changes and water flows toward your house rather than away from it.

How to Fix It: Build up the dirt around your foun­da­tion, cre­at­ing a slope aim­ing away from the house. This should be a min­i­mum of one inch per foot, for at least 6 feet.

3. Miss­ing or Defec­tive Gut­ters and Downspouts

The pur­pose of gut­ters and down­spouts is to direct rain­wa­ter away from the foun­da­tion of your home. If those gut­ters and down­spouts are miss­ing, or not func­tion­ing prop­er­ly, rain­wa­ter is often direct­ed towards your foun­da­tion. As water drains toward your house, it can accu­mu­late in the soil around it. If water accu­mu­lates around your foun­da­tion, chances are, it will make its way inside into your basement.

How to Fix It: Con­sid­er adding gut­ters if there are none already in place. A min­i­mum of 1 down­spout should be placed per every 50 ft. of the roof eave. Exten­ders should be placed on all down­spouts, dis­pers­ing water at least 4 ft. away from the foun­da­tion. Exist­ing gut­ters should be cleaned reg­u­lar­ly to ensure they are func­tion­ing properly.

4. Cracks in Your Foundation

If you have cracks in your foun­da­tion, you can be sure that water will find them and make its way into your base­ment. In fact, some­times the water is even the cause of the cracks them­selves. If floor joists are not prop­er­ly con­nect­ed to the foun­da­tion walls, it can allow the walls to move, and in turn, cracks are formed. Water can actu­al­ly cause cracks in the foun­da­tion as well due to poor drainage in the soil.

If water is not direct­ed away from your foun­da­tion and accu­mu­lates against the foun­da­tion walls, and that pres­sure (hydro­sta­t­ic pres­sure) can force the water into the walls, cre­at­ing cracks. No mat­ter how the cracks formed, if they exist, water can enter your base­ment through them.

How To Fix It: Depend­ing on the cause of the cracks, your solu­tions will vary. If hydro­sta­t­ic pres­sure (due to water accu­mu­lat­ing around the foun­da­tion) is the cause of the cracks, repair­ing your exte­ri­or drainage should help to solve the prob­lem. The cracks will still need to be repaired, but the cause should have been repaired. If struc­tur­al prob­lems caused the cracks, prop­er foot­ing and con­nec­tions (straps or anchor bolts) should be put into place to seal the gaps.

5. Poor (or Miss­ing) Drain Tile and Sump Pit

Many hous­es do not have a sub­sur­face drainage sys­tem. Base­ments in old­er homes often were not intend­ed to be hab­it­able spaces, thus an under-the-floor drainage sys­tem wasn’t nec­es­sary. More mod­ern homes that do have a drainage sys­tem often expe­ri­ence prob­lems with their sys­tem. This can range from a clogged pipe, bro­ken con­nec­tion, or a bro­ken sump pump.

How To Fix It: Unfor­tu­nate­ly, prob­lems with your sub­sur­face drainage sys­tem, or adding one where there wasn’t one, are a much more seri­ous project than some of the afore­men­tioned solu­tions. If you think this is where your prob­lem lies, its best to call in the pro­fes­sion­als. It involves dig­ging up your floor­ing and adding a drain sys­tem, which leads to a pump that will expel any mois­ture. Build­ing or repair­ing a drainage sys­tem is a com­plex task, best left to experts with tools and knowl­edge to get the job done right the first time. Click here to get help with your drainage problems.

6. Con­den­sa­tion

Base­ment con­den­sa­tion occurs when warm, moist air comes in con­tact with your cool base­ment walls and floor. As the walls cool the warm air, mois­ture is cre­at­ed, just like con­den­sa­tion on a cold beer on a hot sum­mer day. You’re in luck if the mois­ture in your base­ment is com­ing from con­den­sa­tion, rather than a leak or drainage prob­lem, as these issues are typ­i­cal­ly much eas­i­er and less expen­sive to resolve.

How To Fix It: There are a few ways to deal with con­den­sa­tion in your base­ment. First off, check the exhaust of your dry­er and drain the cen­tral air con­di­tion­er. Ensure they are not clogged and are flow­ing prop­er­ly. Both can cause a sur­pris­ing amount of mois­ture to be put into the air. Next, con­sid­er one of the fol­low­ing options:

Base­ment Exhaust Fan: If you have a bath­room or kitchen in your base­ment, be sure to install (and use) an exhaust fan. Steam from hot show­ers and cook­ing cre­ates lots of mois­ture than if trapped, can cre­ate con­den­sa­tion. Be sure to use the exhaust fan any­time a show­er is tak­en or the stove is used.

Increase Air Cir­cu­la­tion: If you only have a minor amount of con­den­sa­tion, increas­ing your air cir­cu­la­tion could resolve the issue. If your base­ment does not have air con­di­tion­ing vents, con­sid­er adding some. It is typ­i­cal­ly a rel­a­tive­ly easy project. Make sure to keep vents open to keep air flow­ing. If you don’t have AC, adding a fan, and run­ning it a few hours a day, can help to dis­trib­ute mois­ture. If your base­ment is clut­tered, elim­i­nat­ing some of the junk will help air to flow more freely as well.

Insu­late Your Base­ment: Insu­lat­ing the places where con­den­sa­tion builds up can also help to elim­i­nate mois­ture. Cov­er­ing those places, such as walls, pipes, and ducts, with insu­la­tion, will help keep warm air from com­ing in con­tact with the cool sur­faces, thus pre­vent­ing condensation.

Mois­ture warn­ing signs:

If you see signs of mois­ture in your base­ment, don’t wait to do some­thing about it. The longer the prob­lem per­sists, the big­ger and more cost­ly the repairs will be. For more tips or help with your wet base­ment, reach out our team at Fam­i­ly Water­proof­ing Solu­tions today at (708) 330‑4466 or sched­ule a free esti­mate.

About the Author

Maria Kirchner, founder of Family Waterproofing, is a waterproofing expert with extensive hands-on experience in basement waterproofing, concrete raising, and moisture prevention. Passionate about staying ahead through annual training, she shares practical tips on her blog to empower homeowners—like tackling sinking slabs with polyurethane foam for quick, cost-effective fixes. Her customer-first approach has earned hundreds of 5-star reviews, helping families protect their homes with confidence. Connect with Maria for personalised advice: Contact Us.

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