Basement flooding: prevention can cost less than the cure

A flooded basement can be one of the worst calamities you face as a homeowner. A large percentage of basement floods occur when the soil is saturated from melting snow and springtime rains, so make sure you're inspecting and correcting the issues that cause basement water intrusion before they become expensive problems.

The cause of flooding is often simple

Don't assume that your basement is free from potential water damage just because you don't see any right now. (And if you do see damp spots, keep in mind that these may not only be signs of future flooding, but also of mold and mildew.) If any part of your basement is below grade, water is often in the soil just on the other side of the foundation walls and below the floor slab. If it doesn't drain away promptly or the foundation has a breech in its waterproofing system, it could find its way inside. Anthony Pack, Vice-president of "A Better Choice" Inc. in North Huntingdon, Pa., has been dealing with leaking basements for many years. In his opinion, the primary causes of lower level water intrusion are:

• Terrain - Any time the exterior grade slopes toward rather than away from the foundation, the odds of having a basement water leak increase.
• Water table - When the soil is saturated to its limit from rainfall or melting snow, deficiencies in a home's waterproofing system become evident.

Now that you know what can cause flooding, how can it be prevented?

Inspecting your home's foundation drainage system

Much of your home's basement drainage system is hidden below grade, but there are a few above ground components that can be inspected:

• Gutters and downspouts - The gutters and downspouts on your home are designed to channel roof water away from the foundation. If your gutters are blocked by leaves or other debris, water can overflow and drain into the ground right next to your basement walls. A loose or missing elbow or splash block at the bottom of a downspout can create a similar situation.
• Site grading - If areas of your lawn adjacent to the foundation appear to slope toward your home or there are low spots that could hold water, you may need to do some site grading. To achieve proper drainage around your foundation, a swale may need to be created or a below grade French drain might have to be installed. Consult with a landscape architect or site engineer to find the best solution for your lot.
• Foundation drains - Walkout or partially buried basements often have foundation drains day-lighted or exposed adjacent to the walkout section of the walls. These drains should be kept free of grass clippings and other debris that might interrupt the flow of water.
• Sump pump - Many below grade and partially buried foundations have a pit inside the basement that contains a sump pump. This pump drains water that may be building up below the slab before it has a chance to enter your home. Most pumps can be checked for proper operation by lifting the float; if the pump starts, it should be okay.

If all of these foundation drainage components pass inspection, your odds for keeping the basement dry are improved, but problems below grade should still be considered.

When your foundation is the problem

To guard against basement leaks, most builders use some form of exterior waterproofing on both poured concrete and masonry block foundation walls. Unfortunately, the waterproofing sometimes fails or another issue with the foundation allows water to enter. When that happens, it's time to call in a professional contractor. Here are three of the most common foundation fixes according to Pack:

• Crack repairs - A small crack in a poured concrete or masonry block wall can be repaired from the interior of the basement by applying epoxy. Costs can vary depending on the size and number of the cracks and whether the basement is finished.
• Interior French drains - If a basement is unfinished, many foundation leaks can be repaired by installing an interior French drain. Pack says these can cost from $38 to $60 per linear foot.
• Exterior waterproofing - It may be less expensive to repair a foundation leak in a finished basement by improving the exterior waterproofing. The downside: the foundation must be excavated down to the footer in the problem area. Pack says that $1.75 to $2.10 per square foot is a good figure to estimate additional exterior waterproofing.

Preventative measures required to keep your basement moisture-free can range in price, but they are almost always less costly than repairing flooding damage.