Crawl space moisture control in Tupelo
Water reaches a Tupelo crawl space as rain, as groundwater in slow-draining clay, and as humid air. A good plan deals with all three, in order.
Most wet crawl spaces have more than one cause. A crawl space company should figure out which ones apply to your house and fix them in the right sequence: stop liquid water first, then bring down the humidity.
Where does the moisture come from?
- Rain and roof runoff. Overflowing gutters, short downspouts and yards that slope toward the foundation.
- Wet clay. Black Belt soils hold a lot of water, according to Mississippi State University, so the ground under a house can stay saturated for days.
- Humid air. Summer air drifting in through vents condenses on ducts, pipes and framing.
- Leaks. Supply and drain lines, a water heater relief line or a clogged air conditioner condensate drain.
Getting the water out
- Gutters and downspout extensions that carry roof water well away from the foundation
- Regrading so the soil falls away from the walls
- An interior perimeter drain feeding a sealed sump basin and pump for crawl spaces that still collect water
The code also has something to say here: when groundwater can rise to within 6 inches of the finished floor, or surface water doesn't drain well, IRC R408 expects the under-floor grade to match the outside grade unless an approved drainage system is installed. Ask where a sump will discharge, whether it has a high-water alarm and what happens during a power outage.
Bringing the humidity down
In a sealed crawl space, a dehumidifier controlled by a humidistat is the most common choice. The IRC's unvented crawl space section lists dehumidification at 70 pints a day per 1,000 square feet as one approved option, along with continuous exhaust or a supply of conditioned air. Units built for crawl spaces fit low clearances and drain on their own, unlike a portable bucket unit set on the liner.
Signs the system isn't keeping up
- The musty smell returns every July and August
- The dehumidifier runs constantly but readings stay high
- Water on the liner near the walls, the sump or the unit
- A sump pump that cycles nonstop or never runs
Upkeep
- Clean or replace the dehumidifier filter as the maker recommends
- Check the condensate line and sump outlet after heavy rain
- Keep gutters clear, especially in the fall
Every price comes from the crawl space company, after someone has actually been under your house. We don't quote prices, and any number you hear over the phone before an inspection is a rough guess at best.
Where we connect you with help
Common questions
Should I open my crawl space vents in summer?
In a humid place like north Mississippi that often adds moisture. DOE research notes that humid outdoor air can be wetter than crawl space air.
Does every crawl space need a sump pump?
No. A sump is for crawl spaces that still collect water after gutters and grading are fixed. A company can tell after seeing the space, ideally soon after a heavy rain.
Related services
More background: Tupelo crawl space guide.
Musty air, a bouncy floor or water under the house?
Call and we'll connect you with a crawl space company that works in Lee County.