9 Worst Problems To Have In Your Basement

Any basement–finished or unfinished–can have problems. Most basements experience at least one serious problem during their useful lifetime. Basement location–below grade, surrounded by moisture, and accessible to pests–makes it prone to problems not encountered in the rest of the house.

basement problems

Water Leaks

Water leaks–anywhere in the house–are every homeowner’s enemy. Almost all of the worst basement problems are water-related–directly or indirectly.

Leaking Walls and Floors

Water seeps into basements through cracked walls and floors, unsealed form-tie holes, poorly sealed windows, and wall penetrations for pipes and vents. Flooding and faulty sump pumps usually cause more serious amounts of water and damage.

White chalk-like stains called efflorescence (dried salt stains) on walls and floors are often mistaken for mold but are the first signs of a water leakage problem. Basement waterproofing is essential for a dry, comfortable, and safe house. Encapsulating a crawlspace keeps it dry and odor-free.

Plumbing Leaks

Unless water lines or drain pipes burst or are disconnected, plumbing leaks are often difficult to detect. Most leaks in drains, toilets, and pipes start small and end up collecting in the basement. Water damage to finished ceilings and walls or mold growth are the first signs of a problem.

Repairs often involve opening up walls and/or ceilings to find and fix the problem. They are time-consuming and expensive–especially when hiring professionals. Inspect the pipes and fixtures and surrounding areas once or twice a year. Early detection minimizes the problem and the costs.


Basement humidity levels need to be controlled to prevent condensation. Warm humid air contacting cool pipes or ducting or uninsulated concrete walls condenses into liquid. The result is rot, mold, and damage to walls, floors, and insulation. Humidity levels above 60% promote mold growth.

Most basements have humidity problems. Installing a dehumidifier, basement ventilation, and insulating the ductwork reduces humidity and condensation. Insulating basement walls with 2” rigid foam board insulation and rim joist insulation prevent condensation.


Mold spores are everywhere. Basement mold starts growing with the addition of moisture from high humidity or water leaks. It smells bad and causes health problems like asthma, headaches, and allergic reactions. Long-term mold infestations damage drywall, furnishings, and framing.

Mold continues to grow unless it is completely removed and the basement environment changes. The causes of mold in basements are always the same. Warmth, multiple food sources, and moisture. The easiest to control is moisture–condensation, humidity, and leaks.


Pests are attracted to dark places that provide food, moisture, and nesting sites. Ants, termites, mice, and rats among other insects and rodents infiltrate basements and crawl spaces. Most of them damage framing, furnishings, and drywall. Urine, feces, and dead pests make the basement stink.

Controlling humidity and eliminating leaks and standing water–along with sealing all holes to the exterior–reduces pest infestations. Inspecting the basement regularly–especially if it begins to smell–helps to spot problems early. Look for feces, discolorations, unexplained holes, and gnawing.

Wood Rot

Dry wood does not rot. High humidity, water leakage, mold, and pests start wood rot. Once rot starts, it is difficult to stop if the space remains damp or continuously gets wet. Damaged framing may have to be replaced to ensure the integrity and safety of the building envelope.

Rotting wood is difficult to spot in a finished basement. The first signs may be damp walls, ceilings, or floors. Mold growth is also a sign of hidden moisture accumulations.

Cracked Walls and Floors

Concrete and cement block foundations can crack if enough hydrostatic pressure builds up against the exterior. In northern climates, cold temperatures freeze the groundwater–expanding to create added pressure. Cracks can usually be repaired using hydraulic cement but bowed or bulging walls require professional assessment and remediation. Groundwater under the floor can wash away support soil and cause floors to sink, crack, and even cave in.

Cracked and broken walls and floors are not as common as most other basement problems. They are more serious because a compromised foundation creates dangerous conditions for the entire building.

Non-Water Related Basement Problems

Both of the following are more than problems. They can be deadly.

Radon Gas

Radon is a radioactive gas produced by decaying uranium contained in rock. It seeps into basements through cracks in floors and foundations. Radon exposure is the #1 cause of lung cancer in non-smokers and significantly increases the risk for smokers.

Radon test kits are available online or from home improvement outlets. Collections are sent to certified laboratories for analysis. Hiring a certified radon testing company is another option to help ensure home safety.

Carbon Monoxide

Carbon monoxide (CO) accumulates in basements when furnaces are faulty. Prolonged exposure symptoms include headache, dizziness, chest pain, and seizures among others. CO kills people and pets.

Install CO detectors for protection. Updated building codes in some jurisdictions make them mandatory in all new construction.