A Wet Basement Is a Real Problem
If you have a wet basement, you’re probably concerned and rightly so. Something as simple as condensation can warp hardwood floors overhead and promote the growth of toxic mold. If the cellar contains actual living space, you may be looking at ruined drywall, framing, or carpet.
Regrettably, a wet basement is a common problem. The American Society of Home Inspectors estimates that 60% of American homes have a wet basement problem and 38% are at risk of developing basement mold.
A wet basement often results from rainfall and melting snow, and it doesn’t take a downpour. A house with a 1500 square foot roof sheds 1000 gallons of water for every inch of rain that falls on it.
The problem can also be rising groundwater, sometimes produced by an underground spring. The water works its way through porous material, joins, and cracks in the foundation to produce a wet basement floor and damp basement walls.
Once a problem gets out of hand, wet basement solutions provided by a professional can cost several hundred to several thousand dollars. So it’s a good idea for your bank balance as well as your health and the safety of your possessions to address the issue as soon as possible.
Finding wet basement solutions starts with determining whether the underlying problem is one of condensation, runoff, or subsurface seepage. Each requires a somewhat different approach.
A Wet Basement: Condensation
Condensation, also known as sweating, happens when warm air comes into contact with cooler foundation walls or cold-water pipes that lack adequate insulation. I can result in wet carpets, rusted appliances, and a cellar that feels clammy. Inside a crawlspace, condensation can promote wood rot and insect infestation and buckle and delaminate plywood.
To tell if condensation is the real problem, tape foil over wet spots and check it a day later. If you find moisture on the outer foil face, you have condensation. If the moisture’s on the inner face, you’ve got runoff or seepage.
To fix a wet basement that suffering from condensation, air it out with open windows and fans. Install a dehumidifier near a spot that affords easy drainage.
When it’s cold out, turn up the heat in the basement, make sure all the cold-water pipes are protected by foam insulation, and check to see that the clothes dryer vents to the outside with no duct leaks. Don’t dry clothing on a line in the basement or store wet firewood there.
You can also damp-proof walls with a waterproof coating.
If you only have a crawlspace as opposed to a complete basement, cover the ground in the space with plastic sheeting. 6-mil polyethylene is a good choice. It’s sturdy and does a good job of overlapping seams. You can also provide additional foundation vents to enhance the air circulation that carries dampness away.
Note that if you continue to have wet basement problems even after taking all these measures, then your problem isn’t condensation, or not solely condensation, after all.
A Wet Basement: Runoff
You have a runoff problem if rainwater or melted snow isn’t being directed away from the house. It enters the basement through cracks or gaps in walls and floors either due to hydrostatic or capillary action.
You likely have a runoff problem is you have a wet basement floor or wet basement walls immediately after a storm or a thaw.
If that’s the case, figure out how the water is getting in. The ground outside should slope away from the house by at least one vertical inch per one foot of horizontal distance. Make sure gutters and downspouts aren’t clogged or making puddles near the foundation and that the downspouts don’t leak. If the downspouts were installed seams out, it won’t be difficult to check.
Also make sure driveway curbs are channeling water into the street and that you don’t have unsealed cracks in the surface of the driveway. If the house is on a hill and has a swale, a trench to catch runoff, check that it isn’t clogged.
In addition to attending to the above, keep runoff out of your basement by patching cracks in the foundation and sealing the walls. Polyurethane masonry caulk should handle smaller cracks. For bigger ones, use a hydraulic cement that expands as it dries.
You can patch cracks in a driveway with cold-mix asphalt patching compound. Ordinary cement will do for a concrete driveway or sidewalk.
You can choose an interior gutter system to channel water to a sump pump or floor drain. Epoxy will seal it to the floor.
If your house has an underground drainage system, call in a professional to check it and clear the lines if necessary. If the system has deteriorated to the point where it can no longer serve its purpose, seal it off at the surface and arrange for rainwater to drain into a dry well instead.
Grass alongside the house can also absorb excess water.
If none of these measures prevents a wet basement due to runoff, it’s time to call a professional.
A Wet Basement: Subsurface Seepage
If your wet basement problems resemble problems due to runoff but happen all the time, you’re probably dealing with subsurface seepage. People from your local government can probably tell you if your area has high groundwater or underground springs.
You will likely need a professional to deal with this particular wet basement problem. Make sure the contractor is licensed is going to guarantee the work, get a firm not-to-exceed price with detailed specifications, and check the contractor’s references with three former customers.
The contractor’s wet basement solutions may involve injecting absorbent clay into soil and urethane caulk into cracks, installing a sump pump, and/or installing perimeter drains. Or, an exterior system may be required. The price of the work varies considerably depending on which of these measures is appropriate and sufficient.
A Wet Basement: Special Drying Considerations
Finally, whatever the cause of your wet basement, be aware that particularly if it’s well and truly flooded, wet basement drying and repair may require special processes and equipment. You or the professionals may need to attend to the following:
- Supplemental heat can speed up the drying of a cold basement.
- Supplemental ventilation in the form of industrial fans and other air-moving devices can speed drying by improving air circulation.
- Utilitiesworkers from your gas or electric company may need to enter the wet basement to deal with problems that would otherwise make a flooded area too hazardous to dry.
- Did you store potentially dangerous substances like pesticides, solvent, or paints in the basement? If so, flooding could have damaged the containers, and someone will have to deal with that before drying begins.
- Ground soil vapor barriers keep moisture from entering the basement through crawlspaces and dirt floors.It may be necessary to install or restore such barriers.
- Air pressure during drying must be properly managed to prevent condensation and secondary damage.
- Structural damage. If there’s any reason at all to suspect the wet basement has produced structural damage to the house, an engineering evaluation must assess the possibility.