A Dehumidifier for Your Crawl Space in Murfreesboro
In a sealed crawl, the dehumidifier does the work the vents used to do badly. Here's how to tell a good setup from one that just runs.
A dehumidifier for a crawl space typically costs $800–$2,000 installed with its wiring (This Old House, 2026); Fixr lists $750–$1,700. It belongs in a crawl that is already lined and closed, drains by hose or pump, and should hold the air below about 60% relative humidity through a humid Middle Tennessee summer.
When does a Murfreesboro crawl need one?
Once the vents are closed, moisture still comes in: through the liner seams, from the foundation walls, from the house above. Something has to remove it. In summer, outdoor dew points at Nashville International Airport average 68.0°F in July and 66.6°F in August (NOAA hourly normals). Any of that air that leaks in carries a lot of water. A dedicated dehumidifier is the usual answer. Some homes instead supply a small amount of conditioned air from the HVAC system, which an HVAC contractor should design.
What makes a crawl space unit different?
- Built for cool air. Household units lose much of their output below room temperature; crawl units are rated for it.
- Low and tough. They hang from joists or sit on a stand and tolerate dust.
- No bucket. Water leaves by hose, so nobody has to crawl in to empty anything.
- Ducting options. Larger or chopped-up crawls may need short ducts to move dry air into far corners.
How is the size chosen?
By the volume of air and how leaky the space is after sealing. The installer measures floor area and height, notes any water sources, and checks how tight the vents and rim joists are. A well-sealed crawl needs a much smaller unit than a drafty one, which is why sizing comes after the liner plan, not before. Too big and it short-cycles; too small and it runs nonstop in July and still loses ground.
Where does the water go, and how do you check it?
Ask for one of three drain routes: a hose sloping downhill to the outside, a line into the sump, or a little condensate pump that lifts the water out. Then ask for a way to read the humidity without crawling under the house, such as a remote sensor or a display upstairs. A reading you can glance at in August tells you more than any brochure. For what the liner and vent sealing add on top, see the crawl space encapsulation cost ranges.
Questions homeowners ask
Will a dehumidifier work if my crawl is still vented?
Poorly. With vents open it keeps drying fresh humid air that flows straight in, runs almost constantly and wears out early. Seal the vents and cover the soil first.
How often does it need attention?
Clean or change the filter a few times a year, check that the drain line flows, and glance at the humidity reading during summer. Ask the installer what the unit's warranty covers.
Get the crawl space under your Murfreesboro home looked at
A few taps tells the specialist what you're dealing with: a smell, a sweating duct, water after storms, or a plan to seal it up. The Murfreesboro crawl space specialist calls you to talk it through.