If your crawl space has standing water sometimes and often smells musty, you may be dealing with a couple of different issues. One might be water that drains in after a rain and another could be constant moisture from water vapor seeping up through the soil. There are different approaches for waterproofing a crawl space. Here are some options your contractor might suggest.
Repair the Drainage Problem
If water drains into the crawl space when it rains, try to figure out why. Maybe you've put in a driveway or plants near the foundation and water drains toward the house rather than away. There could also be problems with gutters dumping rain near your house rather than routing it away through the downspout. If you can fix these problems, water may drain away from the crawl space and put an end to puddles of water every time it rains.
If you can't seem to fix the problem, then putting in a French drain could be the answer. This type of drain is buried under the ground so water falls into it before reaching the crawl space. The drain can keep your crawl space dry since water will drain away before it has a chance to form puddles.
Put In a Sump Pump
It's not always practical to dig up your yard and bury a drain. If that's the case, then installing a sump pump in the crawl space might be the solution you need. A small pit is dug in the crawl space so water can drain into it. The contractor may need to bury a drain along the sides of the crawl space to catch the water and move it toward the pit. A sump pump is placed near the pit or inside it. When the water level is high enough, the pump kicks on and pushes the water out of the crawl space so the area is free of standing water.
Block Water Vapor With Barriers
Those crawl space waterproofing methods can keep rain from puddling on the floor, but they may not do much to control water vapor that wafts up through the soil. Your crawl space should be kept as dry as possible to protect your home above from excess humidity, mildew, musty odors, and water-loving bugs. When the crawl space is encapsulated, the contractor puts a thick water barrier over the soil to block the vapor.
The barrier may also be applied to the walls so condensation doesn't form and add to the humidity. This encapsulates the crawl space and separates it from all sources of water and moisture. The contractor may also recommend installing a dehumidifier in the space to make sure it stays dry.
Contact a contractor in your area to ask about crawl space waterproofing.