Waterpoofing is a good idea for basements that are prone to moisture buildup or leaks. Moisture in a basement can stem from a variety of issues, such as poor drainage on the exterior of the home, groundwater seeping up and in from a water table below the foundation, condensation forming, or actual leaks in the foundation. Visible signs of a moisture problem include condensation forming on the walls, water pooling or ongoing musty odors. Leaks and cracks only get worse over time and can lead to mold in the home as well as expensive damage to the foundation. Several factors affect the cost of waterproofing a basement.
Humidifier and sump pump
The first step in waterproofing a basement is for a professional to identify where the source of the problem is—or to identify potential problem sites when doing preventative waterproofing work. John Wernsdorfer of John W Property in Portsmouth, New Hampshire, says that during an initial site visit, he inspects the basement and finds out why the client wants to stop the water. If it’s just to preserve the home and prevent minor moisture issues, a dehumidifier (at approximately $400) and a sump pump might solve the problem. Depending on the region in the country, the additional load on utility bills to run a humidifier 24 hours a day could cost around $10 per month.
To make sure that a basement stays bone dry at all times, it’s a good idea to look at the bigger picture and take measures to prevent moisture buildup in the first place rather than just treating the moisture after the fact. Prevention can require addressing landscaping issues. For example, is snow or rain runoff being properly directed away from the home?. Other preventative measures include installation of more effective gutters and a new drainage system to keep the water from pressing through the walls or floor. Costs for these measures can range widely, depending on how extensive the work to be done is. Chris Levins of CLC Contractors in Morrisville, Pennsylvania, says that the starting cost to install french drains on the exterior of a home is $25 per linear foot, but installing them into a basement costs around $45 per linear foot because of the increased labor and access difficulty.
Another option—and one that can work in tandem with the first two solutions—is sealing the floor with a liquid rubber compound, says Wernsdorfer of John W Property. These compounds typically cost about $100 per gallon. That’s for materials alone, not including the labor costs of application or preparing and cleaning the floor. The sealant can be painted for added appeal after application, says Wernsdorfer.
Wernsdorfer of John W Property says he can’t estimate an average price per square foot for waterproofing basements because each home or commercial property has such different needs. Here are some examples of residential and commercial property waterproofing jobs and their costs from John W Property:
400-square-foot residential basement
"Water was leaking water through the walls and floor in a newly purchased home after rain storms. The water seeping in from underground turned out to be a function of bad drainage off the roof. We fixed the roof drainage and made minor gutter additions. We also installed a dehumidifier as a backup, stationed above the potential flood level to run 24 hours a day and drain automatically into the sump. The wetness was completely stopped."
Total project cost: $500
Cost of materials: $120
Cost of labor: $380
- The job took one day of work to complete.
600-square-foot residential basement
"Water from an underground shallow water table was seeping into the basement. We sealed the floor and walls as best as possible and slowed the seepage, but it’s not always possible to stop it completely. We then had a dehumidifier installed as a backup, stationed above the potential flood level to run 24 hours a day and drain automatically into the sump."
Total project cost: $1,200
Cost of materials: $400
Cost of labor: $800
- The job took two days of work to complete.
1,500-square-foot commercial basement
"Water was leaking through the walls and floor in the furniture storage area of a new furniture store. Water was seeping in through draining cracks off the parking lot. We sealed the interior floor and walls, then filled the many cracks and tar holes in the parking lot draining water toward the basement. We also repaired a pooling water location near the basement entrance. This work slowed the seepage. We installed a dehumidifier as a backup, stationed above the potential flood level to run 24 hours a day and drain automatically into the sump. The water leakage was stopped almost entirely. Fully repairing the parking lot would have ended the problem, but the cost to repair and repave the lot was well above the client’s budget, so waterproofing provided an effective alternative."
Total project cost: $3,500
Cost of materials: $2,000
Cost of labor: $1,500
- The job took three days to complete work.