Factors to Evaluate
Basement moisture can be the result of condensation, seepage or leaks. Condensation, which is caused by poor ventilation, results in damp walls and pipes. Seepage, due to insufficient outside drainage, can range from damp areas to significant water puddling, depending on the amount of rainfall or water saturating the soil. Leaks resulting from cracks in the floor or foundation walls also lead to puddles or standing water after rainfall.
A poorly ventilated basement will benefit from heat and air conditioning, if it isn't already accessible in the lower level. Insulating water pipes and running a heavy-duty dehumidifier will further reduce dampness. Cost in 2009: $50 to $300 (for pipe insulation and a quality dehumidifier; costs will be significantly higher if heating and air conditioning work must be done).
If your water problem is caused by insufficient outside drainage, waterproofing may not even be necessary. Check your gutters and downspouts and make sure they're free of debris and draining at least 10 feet away from the house. Also, be sure the ground slopes away from the house at the foundation. Cost in 2009: $0 to $200 or more (to replace any missing or damaged gutters and downspouts). If slope near the foundation needs to be increased, costs will be higher for rock or fill dirt.
Resolving basement leaks is the most expensive issue for homeowners and is a problem that should be addressed by professionals. A basement waterproofing expert will help you determine the appropriate solution, whether it involves minor leak repair and sealing basement walls (2009 cost: $350 and up) or installing drains and sump pumps to consistently eliminate outside water before it can enter the house (cost: $1,000 to 2,500). Serious water problems may require an extensive exterior drainage system and foundation repair (cost: $2,500 to $12,000).
Because basement water problems can run the gamut from mild moisture to major flooding, it is important to find the cause of the problem before attempting any solution. If professional help is necessary, get several quotes and, if possible, referrals from friends or relatives before hiring a contractor. Also call several of contractor's references from the past year.