There are several reasons why your basement may develop a leak, and you must determine the cause before an effective waterproofing solution can be determined. The following are the most common reasons why you are finding moisture in your basement.
Moisture doesn't always invade the basement from outside, sometimes the problem is right inside your doors. Moisture and condensation that builds up on the basement walls and ceiling is a result of condensation, likely due to poor ventilation. Installing a dehumidifier in the basement and making sure moisture sources, like clothes dryers, are vented outside will help overcome condensation issues.
High groundwater levels can put hydrostatic pressure on basement walls. Not only will moisture leak through the somewhat porous concrete foundation, but the basement walls may also bow under the pressure. Groundwater issues tend to worsen during times of rain and snowmelt simply because the water levels are higher. This issue may require the installation of external drainage systems along with a waterproofing treatment on the walls themselves.
The ground around your home should be graded so that moisture flows away from the foundation. If the ground is poorly graded so that it is nearly flat, or worse, slopes toward your home, you will likely have basement leaks since moisture will flow toward and collect against the foundation walls. Re-grading the yard often helps, but you may also need to install a drain system or waterproof the basement walls.
The most common drainage issue that leads to a basement leak is guttering issues. Your house should be equipped with working gutters and the downspouts should empty out well away from your foundation. If they don't, then the drain water can collect against your foundation walls and cause leaks. A combination of French drains installed around the perimeter of your home and a well-planned gutter system should solve basement moisture issues.
Any damage to the foundation can lead to water leaks, especially when the ground is wet. Wide cracks, those that stair-step up the walls, or cracks that branch diagonally from a corner are the most common. Cracks can also form around basement windows, leading to gaps in the framing. Cracks need to be repaired and the cause of the crack may need to be addressed so it doesn't occur again. Once cracks are repaired, a waterproofing treatment on the walls can prevent moisture issues.
Contact a basement waterproofing service like J.A. Kilby Enterprises Inc. for more help.