How to Keep Your Basement and Crawlspace Dry

When basements leak, people panic. The good news about these unplanned indoor pools is this. While wet basements are often thought of as one of life’s biggest home repair headaches, basement water problems are generally easy and inexpensive to fix. Yes, that’s right–easy and inexpensive!

The basement is one of the greatest untapped spaces in any home. Think about it — if you have a basement, it’s like having an entire extra floor to do with what you wish. That is, however, unless it’s a swimming pool!

Damp, leaking, or flooded basements (or crawlspaces) can severely diminish the value of a house. They can lead to a host of associated problems like mold, rotted floor structures, insect infestations, and more. Worse yet, the cost of fixing a wet basement will generally be in the tens of thousands!

Well, let’s stop right there so I can let you in on a few facts about fixing floods:

• Most wet basements are blamed incorrectly on the home having a rising water table. This is usually not the case.
• The top cause of a wet basement or crawlspace is a lack of adequate roof and surface drainage. Clogged or misdirected gutters, along with grading that directs rainwater toward the house foundation, cause almost all below-grade water leakage.
• For years, so-called waterproofing companies have caused panic among homeowners by advising that a failure to install expensive sump pumps and drains will cause foundations to crack, and mold to take over. These high-pressure tactics could not be further from the truth and are simply an attempt to make a high-dollar sale on a system that’s rarely needed.
• And the best news? Most wet basements can be fixed in a weekend using a few hundred dollars’ worth of materials at most. I’ll show you how.

Where basement leaks wait to happen: Start outside

In the 20 years I spent as a professional home inspector, it wasn’t unusual for me to be asked to inspect a house that had a below-grade water problem. On one such occasion, a young couple had received five-figure estimates from multiple waterproofing companies along with a heaping helping of fear that the home would disintegrate if they didn’t hire them. They’d called me to help them decide which five-figure-estimating company to hire.

With that in mind, I walked up to the house, glanced up, and immediately saw a series of 1- to 3-foot trees growing out of their insanely clogged gutters! Problem solved. Mike drop. Tom out!

Designing and cleaning gutters to keep water away

The primary reason that basements or crawlspaces leak, flood, or just get damp, is that the home does not have a properly functioning gutter system. There are several common gutter failures that I see.

• Clogged gutters: The season is called Fall for a reason! Leaves, pine needles, and other tree droppings, along with the occasional tennis ball, regularly clog gutters. When that happens, gutters overflow, dumping all the rain that Mother Nature has to offer right along your foundation wall, where it has nowhere else to go but down and into your basement or crawlspace. (See Figure 4-6.)
• Too few downspouts: For standard five-inch gutters, a home needs one downspout for every 600 to 800 square feet of roof surface. Stand back and stare up at your roof and try to estimate if your home has this. Be sure to include any gutters on second-floor roofs that drain to first-floor roofs on their way to the downspout. If you are moving more water than that, you’ll need bigger gutters and spouts, or just more spouts.
• Downspouts discharging too close to the house: Gutter installers have a really bad habit I’d like to break. They typically extend the downspout discharge about a foot, and then into a splash block, which runs it out another foot. If you have any indication that there’s a water problem in your house, these need to be run out more like four to six feet.

Improving your gutters and site drainage are the two most effective ways to correct a leaking, damp, or musty basement. But of those two, gutter improvements are far and away much more important than grading improvements. In my 20 years as a professional home inspector diagnosing basement and crawlspace leaks, I’ve found that gutters cause 90 percent of the problem, with grading causing the rest. So, tackle your gutter fixes first. They are more likely to solve the problem (see Figure 4-7) and are actually a lot easier to do than hauling dirt to add around your foundation!

Making the grade to keep water away

After leaking gutters, the second reason basements flood is when the soil around the house settles and prevents water from draining away from the house. Here’s why that happens:

• When a home with a basement or crawlspace is built, excavators dig a deep hole to allow the masons to start building a foundation. This hole is wider than the house so that contractors can access all sides to build the foundation.
• As the home nears completion, the excavators return to backfill the soil around the house and — hopefully — grade it to slope away from the foundation walls.
• As time marches on, however, that soil starts to settle and compact. The grade that initially was pitched to run away from the house, goes to flat and ultimately reverses to run water toward the house.
• Once that happens, rainwater soaks into the soil around the foundation, and if it rains hard enough, it shows up in the basement as a leak or full-out flood.

Restoring a positive grade is not all that difficult. You’ll need to add soil along the foundation perimeter and grade it to slope downward about 6 inches over the first 4 feet away from the foundation. For this project, you’ll want to use clean fill dirt — not topsoil or mulch, which is too organic and will hold water instead of letting it drain.

Aside from maintaining a positive grade, be mindful of anything that traps water along the house, like brick, stone, or wood landscaping. If you are trying to fix a leak, you can’t afford to have anything holding water too close to your house.

Paths and patios should slope away from the foundation, too. A path or patio that slopes toward the home discharges water into the basement or crawlspace.

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