How to Cure a Wet Basement
How many times have you looked at your basement and thought how great it would be to have a playroom, a home office or a family room/entertainment center - if only it didn't get wet? Dampness is the leading reason that most people do not fully utilize their basement. Yet in many cases the causes of wetness can be eliminated or at least controlled. It is critical that you fix moisture problems before you tackle a basement remodeling job. What Causes Wet Basements? Wet basements are a common problem throughout much of the country. The reason is obvious - a basement is by definition an underground room. As the rainwater hits the ground around the house, gravity pulls it downward through the soil along the external walls of the basement. The water may then collect at the base of the foundation and find its way into the walls, or it may rise through the basement floor as the water table rises.
According to Tom Greiner, associate professor at Iowa State University Cooperative Extension Service, "Basements are not designed to be waterproof, only water-resistant. The most common place for water to enter basements is the joint where the wall and the floor meet. The water enters as a result of a force called hydrostatic pressure - the higher the level of water, the greater the pressure. Once the water enters the wall, particularly with block-wall construction, the concrete will absorb the water through capillary action, much like a sponge soaks up water. In addition, as the earth settles around your house over time, it may shift your foundation and basement walls, which in turn may cause the waterproofing material on the outside to crack and open. Water comes from various sources, including high water table, poor drainage, poor grading around the foundation, seepage from basement window wells, and clogged or incorrectly located gutters/downspouts (or no gutters at all). It can enter the basement through cracks in masonry or masonry joints, cracks in the foundation, and a broken or improperly located sump well/pump. Some of these sources are easy to identify and correct, while others may be almost impossible to address.
Why Should You Care?
Wet basements can not only make the area unusable due to standing water, but they can also cause a host of other problems. A damp or leaky basement can damage stored possessions, ruin washers, dryers and freezers, cause peeling paint or warped floor tiles, damage the heating plant, cause mold or dry rot in wood, and attract termites or carpenter ants. If severe, the water can also cause structural damage, such as enlarging existing cracks, buckling or collapsing basement walls, movement of the floor, and failure of structural supports. The wetness will also cause damp odors and excessive humidity. All in all, it can create a basement nightmare! How Do You Identify the Problem? While leaking water is the most obvious sign of a wet basement, the presence of efflorescence, a whitish mineral deposit on the basement wall, may be a more common indication. Other clues are dampness, rusty nails, rotted wood near the floor level, rusted metal feet on appliances, mold, mildew, lifted floor tiles and peeling paint. It is important to note that the simple presence of these signs is not an indicator of the severity of the problem. For instance, my own basement has efflorescence and some peeling paint, but it does not have leakage or long-term buildup of water in the walls. Nevertheless, these signs do indicate that there is an accumulation of water in the walls during the wet season. Before you do anything, check for water-supply-line leaks or breaks. Also check sinks and toilet drips or leaking plumbing. If you do not find any leaks, turn off all of the water in the house and take a reading of the water meter. Wait one to two hours and check if the meter changed while all water was turned off. If the meter did change, you may have a leak behind a wall and need to contact a licensed plumber to do repairs.
Also check for water leaks where pipes enter the basement. If a water leak exists around a pipe entering the basement (assuming the pipe itself is not leaking), chip away any loose or crumbly concrete and apply a waterproofing concrete patch. If there are no leaks, you need to make sure that the problem is due to water seepage, as opposed to condensation. In some houses, where there is an excess of moisture or inadequate insulation, moisture may simply be due to condensation. To test basement walls for seepage, tape a 12-inch-square piece of aluminum foil to the wall, making sure all sides are sealed airtight. Wait a few days, and check the foil. If moisture is on the side facing the room, it is condensation; if it is on the side facing the wall, it is seepage. Condensation is caused by excess moisture in the basement air, as opposed to leaking water. More often than not, condensation is a result of either inadequate ventilation or excess humidity from drying clothes or water pipes. Sunlight and air movement can dry out a basement quickly. During times of hot, humid weather or long rainy spells, keep your windows closed. The air outside will contain more moisture than the air inside the basement. Also, during warmer weather, the use of an air conditioner helps to cool and dehumidify the air. If you have a clothes dryer in the basement, make sure that the outside vent is not leaking. In addition, avoid drying clothes on hangers, or open the windows until they are dry. As a last step, insulate cold-water pipes.
WHAT CAN YOU DO TO CORRECT SEEPAGE?
Low-Cost External Solutions In most cases, basement leakage is caused by external conditions that can be corrected relatively inexpensively. "Poor surface drainage is usually the main cause of wet basements, Greiner says. Grading the land away from the house is very important. To move runoff away from the house, build up the soil around the foundation so that it slopes a minimum of six inches in the first 10 feet. Do not allow the soil to come in contact with the siding or go above the sill plate, as this may become a route for insects. Alternately, you may be able to lower the land away from the foundation to create the necessary slope. Extend the slope for at least 10 feet and seed it with a good lawn grass. If you have a large area of land that slopes toward the house, surface drainage may need to be intercepted and redirected some distance from the house. Dig a shallow, half-round drainage ditch or depression (referred to as a swale) to route the water around the house. Line the swale with stone or sod, or plant grass in it. Without proper grading and surface water control, all other efforts to prevent basement wetness will be futile. Gutters and downspouts can also be a significant source of water problems.
According to Dr. Bruce A. Tschantz, P.E., professor of civil engineering at the University of Tennessee, "A typical 2,000-square-foot roof can produce 1,300 gallons of water during just 1 inch of rainfall. If the rainfall is steady and prolonged, the opportunity for this roof water to soak into the ground next to the foundation wall is high. You need to make sure that the downspouts direct the water away from the house. To prevent buildup of water at the opening near the ground, use a concrete gutter or splash block to carry the water away at a slope of one inch per foot. Downspout ends should be at least five to 10 feet away from the foundation depending on the slope. If downspouts go underground, they should discharge at least 15 feet or more from the house. Underground downspouts often back up because they get clogged, or they leak because the joints are bad, cracked or separated, leading to water against the foundation. Regular cleaning of gutters is essential, especially in the fall after the trees shed their leaves. To prevent leaves and twigs from collecting, place screening across the length of the gutter or install a basket-shaped wire strainer over the downspout outlet. Some of the newer gutter systems enable leaves to pass over the gutter, while allowing rainwater to get in. Homeowners should also be sure to clean outside basement stairwells and window wells regularly.
If you don't have a drain in the bottom of the well, then install plastic dome covers. It is also important that your landscaping near the foundation not require irrigation. Irrigation will saturate the soil, preventing it from being able to absorb excess water in case of prolonged rains. Foundation perimeters are a good place for xeriscaping (natural landscaping that reduces the need for watering). Also verify that your grass, sidewalks and edging don't dam-up surface water near the foundation. Low-Cost Internal Solutions When external solutions fail, or are inadequate, you may need to consider internal solutions. Start with the easiest and least expensive - installing a sump pump and sealing cracks. If you already have a sump well, and it fills with water during part or all of the year, then purchase either a submersible or pedestal sump pump (cost - $100). The pump should be connected to PVC piping that discharges at least six feet away from the house into either a drainage swale or a dry well. Do not connect the sump pump to your wastewater plumbing. If your sump well is wet for more than two or three months, or if the basement floor gets wet without the sump pump, consider purchasing a battery-operated backup or an auxiliary gas-operated electric generator. If you do not have a sump well, dig a spot in a corner closest to where the water enters, (install a sump liner or concrete tile) and backfill with gravel. Check with your local building official and waterproofing contractors for the typical depth and size in your area. After installing the sump pump, seal all interior cracks with concrete sealer and coat the wall with a waterproofing paint.
Another idea is to buy one (or several) of the inexpensive devices that sound an alarm when they get wet. They are similar to battery-operated smoke detectors. Place them on the floor in areas prone to flooding. The early warning of water can save you a great deal of trouble. If you're going to be out of town during the rainy season, arrange to have a neighbor check on your basement in case of rain. If your leakage is due to cracks in the walls, you can try to seal the interior with a waterproof sealer or masonry patch. These products work well when the basement is not leaking at the time of repair. They range from mortar caulk to premixed mortar to hydraulic putty. Adding a latex bonding agent to a standard masonry mix will improve bonding. Hydraulic putty works well if you're repairing a continuously seeping hole. The product bonds extremely well and cures quickly, even when wet and under pressure. Urethane or epoxy injection repairs can be done from the interior on poured concrete walls only (cost - $400 to $600). If these measures don't solve the problem, then you need to identify if the leak is due to poor or cracked external waterproofing or to a high water table. If the leaks are due to poor waterproofing, you can try to construct a perimeter drain inside the basement. This involves digging a channel around the inside of the foundation and lining it with tiles or PVC pipe to carry the water to the sump well (cost - $2,000 to $4,000 by a professional). An alternative is to install a do-it-yourself baseboard system that directs the water along the base of the walls to a sump well without having to dig a channel (cost - $600 to $1,500).
Each method requires drilling holes in the lowest level of blocks to release the water. High-Cost External Solutions Costs escalate significantly if you have to resort to external measures. Sealing of external foundation cracks can be performed several ways, with varying costs of repairs. One option is the use of rubberized coatings containing portland cement. These products are expensive (more than $20 per gallon) and cover only 75 to 125 square feet per gallon. You need to identify the specific area so that you don't waste money coating sound masonry surfaces. Excavating, dampproofing and installing external drainage tiles should only be used as a last resort. Dampproofing involves putting a quarter-inch layer of mortar covered with a bituminous or plastic membrane on the outside wall. Drainage tile works like a perimeter drain except on the outside. Both methods require excavation, are very expensive (cost - $8,000 to $15,000) and may need to be redone over time.
High Water Table A sump pump is the only method to help alleviate a high water table. In some cases you may need multiple sump pumps. The best way to think of this situation is like trying to drain a pool with a straw. Since the water constantly flows, it is almost impossible to keep it from entering the basement. In many cases, a basement should not have been built in the first place. Where a sump pump helps, make sure that you have one of the backup methods discussed above. Foundation Problems In some rare cases, you may have structural damage as a result of water. There are many warning signs of a more serious problem:
. Doors that stick and squeak
. Separation of doorsills from frames
. Windows that stick
. Cracks in interior walls near corners of doors or windows
. Cracks in a brick fireplace wall
. Nails popping out of Sheetrock or gypsum board
. Wallpaper that curls and separates
. Curling and tearing of existing Sheetrock repairs
. Cracks in the exposed concrete grade beam of the house
. Caulking that pulls away from exterior surfaces
. Cracks and uneven elevations in structures attached to adjoining patios
. Cracks in the first-floor joists
While some of these signs may simply be due to a house settling over time, they may also point to a more significant problem. It is best to consult with a structural engineer or other professional. In most cases, water leaking into a basement can be eliminated or reduced for minimal expense. While you can handle most of the work yourself, some cases may require a professional. These actions must be taken before any finishing work is begun. You should also install a good-quality dehumidifier when you are finished to keep dampness to a minimum. Remember that you need to be able to drain the dehumidifier or it will add more moisture to the basement. With a little bit of effort, you can have a dry basement that will add much-appreciated living and recreational space to your home. Barry Chalofsky is an environmental land planner and the author of The Home and Land Buyer's Guide to the Environment. For more information, visit his website at www.erols.com/profed.