Wet basements in Chattanooga
A damp basement in Chattanooga usually has one of three causes: rain running toward the house, groundwater pushing up after storms, or humid summer air condensing on cool walls. They look alike from the inside, a damp wall, a musty smell, a water line on the floor, but they call for different fixes. The first job of any honest contractor is to tell you which one you have.
The license that fits your job
Waterproofing an existing home in Chattanooga is residential repair work, and Tennessee's rules depend on the price.
- For residential remodeling or repair work on an existing home costing more than $3,000 and less than $25,000, Tennessee requires a Home Improvement Contractor's license in Hamilton County.
- In Tennessee, a state contractor's license is required for a construction project totaling $25,000 or more, including materials, labor and profit, and the license must be in place before a price is bid or offered.
Many waterproofing jobs land in the first band. Ask which license the company holds, look it up on the state's Commerce and Insurance lookup, and keep the number with your contract.
Storm water comes first
NOAA's engineering weather data for Chattanooga lists a 100-year rainfall rate of 3.4 inches per hour. In a storm like that, every gutter, downspout and grading flaw sends water toward the foundation. Before paying for anything inside, walk the outside in a heavy rain and look for:
- gutters that overflow or downspouts that empty against the wall;
- soil, mulch or pavement that slopes toward the house;
- window wells that fill;
- a driveway or patio that drains to the foundation.
Fixing these is often the cheapest waterproofing there is, and a good contractor will point them out before quoting interior work.
Humid air on cool walls
Chattanooga's summers are humid. NOAA counts about 894 hours a year with the wet-bulb temperature at 73°F or higher, and a summer design point of 92°F with a 75°F wet-bulb. When that air reaches a cool basement wall, moisture condenses on it. That isn't a leak, and a drainage system won't stop it. A dehumidifier sized for the space, closed windows in muggy weather and insulated cold-water pipes will.
A quick test tells you which you have: tape a square of plastic sheeting to the wall for a couple of days. Water under the plastic is coming through the wall. Water on top is condensation.
Freeze, thaw and cracks
NOAA lists about 48 freeze-thaw cycles in an average year in Chattanooga and a 50-year frost depth of 9 inches. Repeated freezing of wet soil against a wall can widen small cracks over the years. Ask whether a crack is a shrinkage crack that only needs sealing or one that shows movement, which needs a structural look before it's waterproofed.
Inside or outside
Interior systems collect water that gets in and pump it out: a perimeter drain under the floor edge, a sump and a pump. Exterior work stops water before it reaches the wall: excavation, a membrane and a footing drain. Interior systems usually cost less and disturb the yard less; exterior work deals with the cause. Ask each company why it recommends one over the other for your house.
Comparing quotes
- the cause the company found, and how it found it;
- outside fixes it recommends first;
- the system it proposes, with the length of drain, the sump and the pump;
- whether a battery backup pump is included;
- the license held and the job total;
- the warranty, what it covers and whether it transfers to a buyer.