When moisture seeps into your basement, it can wreak havoc on your belongings. Appliances can rust, surfaces can warp, and mildew can damage and destroy. To protect your home, you need to take action to waterproof the basement. You can think of it in these terms: above and below, inside and outside, before and after.
If water is an issue below the ground, you first need to look above. Your home can take quite a beating out there from the rain, hail, sleet, and snow. So keep gutters clear of leaves, twigs, and debris. Ensure that drainage is unencumbered by installing leaf guards. Use downspout extensions to carry water at least 10 feet away from your home. Keep the system in good repair so that runoff isn’t concentrated around the edges and corners of the foundation.
Another above-ground method to waterproofing your basement is to re-grade your lawn so that its surface slopes away from the home’s foundation. Beginning at the edge of the house, the ground should slope at least six inches for every ten feet outward. If necessary, add soil and use a garden rake to increase the downward slope. Avoid planting trees with large, aggressive root systems within 20 feet of the foundation.
A below-ground option would be to set up a system where runoff collects in a catch basin and is piped to an underground drywell, a perforated plastic tank which allows water to gradually seep into the soil around it. Large concrete drywells are also available and can effectively handle significant volumes of water.
You can experiment to see if the moisture is coming from inside or outside. One way to do this is to attach a one square foot piece of aluminum foil to your basement wall. If, after 24 hours, moisture has condensed on the outside of the foil, a dehumidifier will probably solve the problem. However, if moisture has condensed on the side of the foil touching the wall, then you could be looking at dampness coming in from outside through cracks in the foundation or basement walls.
There are various products on the market designed to seal basement walls. You can consult professionals and read labels to decide which product will best meet your needs. Some are cement-like coatings, some are silicate-based sealers, and some are waterproofing paints, which can be applied with brushes, rollers, or sprayers. Another inside option would be the use of plastic sheets or panels, which channel water into a drain in the floor where it is carried out of the basement by a sump pump. Before applying any of those methods, you should seal any gaps in the wall with polyurethane caulk or epoxy filler.
A French drain is a trench which carries water away from the house, and it can be very useful both inside and outside. It is slightly sloped and is layered with gravel. As water flows through it by gravity or use of a sump pump, the water seeps through the gravel and into the ground. An outdoor French drain can divert water to a drainage ditch, curbside gutter, or drywell. An interior French drain collects water through perforated pipes and delivers it to an underground tank and it is pumped out of the house.
Of course, the most effective way of waterproofing your basement is a solid strategy implemented during construction. By planning beforehand, you can save yourself some headaches afterward. Preventive action is worth the expense, and it may save you thousands of dollars in repair costs after the damage has been done.