Crawl Space Dehumidifiers in Myrtle Beach & the Grand Strand

Sealing a crawl space removes the two biggest moisture sources: humid outdoor air coming through the vents, and evaporation from bare soil. But it does not remove all of the moisture. Water vapor still diffuses through the foundation and comes up from the living space, and in a Grand Strand summer, with dew points in the low 70s for weeks, that residual load is significant.

A dedicated crawl space dehumidifier is the most common way to keep a sealed crawl space dry. This page covers what the code requires, how units are sized, how they drain and are powered, and what conditions in Carolina Forest, Myrtle Beach, and North Myrtle Beach mean for the choice.

Why Does a Sealed Crawl Space Still Need Dehumidification?

Encapsulation turns the crawl space into a closed room under the house, and a closed room needs its humidity managed. Without some form of conditioning, moisture can build up inside the liner and recreate the conditions encapsulation was meant to address.

That is why South Carolina’s code does not allow a crawl space to simply be sealed and left alone. It requires an accepted method of conditioning the space. For the full system, see crawl space encapsulation.

Does South Carolina Code Require a Crawl Space Dehumidifier?

Not specifically a dehumidifier, but conditioning is required for any sealed crawl space. Under Section R408.3 of the residential code South Carolina builds on, an unvented crawl space needs a continuous sealed Class I vapor retarder plus one accepted conditioning method:

• Continuously operated mechanical exhaust
• A conditioned air supply
• Dehumidification

The dehumidification option is sized at a minimum of 70 pints of moisture removal per day for every 1,000 square feet of crawl space floor. Dehumidification is the most common choice along the Grand Strand because it conditions the crawl space independently, without drawing air from or exchanging air with the living space. For more, see SC building code R408.3 explained.

Signs Your Crawl Space Needs a Dehumidifier

• Crawl space humidity readings that stay above 60 percent through the summer
• Condensation on ductwork, pipes, or the underside of the subfloor
• A sealed crawl space that still smells musty or reads damp
• A lower floor that feels sticky even with the AC running (see why that happens)
• Surface growth returning on framing after cleaning
• A portable dehumidifier that fills constantly or can’t keep up

Crawl Space Dehumidifier vs. Portable Dehumidifier

Household portable dehumidifiers are built for basements and living spaces. They usually need their buckets emptied, they often aren’t designed to run continuously in a dusty, low-clearance space, and their capacity is rarely matched to a coastal crawl space.

Dedicated crawl space units are compact enough to sit or hang under the floor, drain continuously, run from a built-in humidistat, and are designed for that environment. In an unsealed crawl space, though, any dehumidifier is working against the outdoor air coming through the vents. That is why sealing comes first.

How Is a Crawl Space Dehumidifier Sized?

The code minimum is a starting point, not the whole answer. Sizing typically accounts for:

• The crawl space floor area and volume
• How well the space has been sealed
• The condition of the ground and walls
• How close the home sits to the water table, the marsh, or the ocean

An undersized unit runs nonstop without reaching its setpoint. A badly oversized one cycles on and off and costs more than it needs to. Manufacturers rate capacity under standardized test conditions, so ratings are worth comparing on the same basis rather than taking the largest number on the box.

Drainage, Power, and Placement

Three practical details decide how well a dehumidifier performs over the years:

• Drainage. A crawl space dehumidifier removes a lot of water during a Grand Strand summer. Condensate drains by gravity to the exterior, or to a condensate pump that discharges outside, and the line should never empty back toward the foundation.
• Power. Many units call for a dedicated circuit, and electrical work should be done by an appropriately licensed electrician.
• Placement. The unit should be accessible for filter changes. In flood zone homes, it should be mounted above the design flood elevation where possible.

A hygrometer or app-based monitor makes it easy to confirm the space is holding its target.

Crawl Space Dehumidifiers in Carolina Forest, Myrtle Beach, and North Myrtle Beach

Conditions under the house shift across short distances in Horry County, and that changes how a dehumidifier is specified.

Carolina Forest. Many subdivisions were built on graded and filled pine flatwoods, often near retention ponds. Sub-surface moisture there can run higher than the builders expected, so the ground and wall load on a sealed crawl space tends to be heavier.

Myrtle Beach. In established neighborhoods like Pine Lakes and Dunes Cove, older vented crawl spaces have often been cycling humid air for decades. Wood moisture is worth checking before the system is set up.

North Myrtle Beach. Beachside blocks in Cherry Grove, Windy Hill, and Ocean Drive sit over a very shallow water table. That makes both a well-sealed liner and adequate dehumidifier capacity important.

What Our Crawl Space Dehumidification Service Covers

• Crawl space humidity and wood moisture assessment
• Dehumidifier sizing based on floor area, volume, and local conditions
• Installation of a dedicated crawl space dehumidifier
• A continuous condensate drain line to an appropriate exterior discharge point
• Humidistat setup, typically targeting 50 to 55 percent relative humidity
• Coordination of any required electrical work with a licensed electrician
• Post-installation verification and humidity monitoring setup
• Documentation for home inspections and warranty records

What Affects the Cost of a Crawl Space Dehumidifier?

Several factors shape the scope of a dehumidifier installation:

• Unit capacity and features
• How condensate will be drained, whether by gravity or a pump
• Whether a new electrical circuit is needed
• Mounting and access
• Whether the crawl space is already sealed or is being encapsulated at the same time

Operating costs vary with how well the space is sealed and how hard the summer runs. A free inspection provides accurate pricing for your specific property.

What to Ask About a Crawl Space Dehumidifier

• How was this unit sized for my crawl space, and does it meet R408.3?
• Where will the condensate drain, and is a pump involved?
• Does it need a dedicated circuit, and who handles the electrical work?
• What humidity setpoint will be used, and how can I monitor it?
• What maintenance does the unit need, and what does the warranty cover?

Still deciding between equipment types? See dehumidifier, sump pump, or both, or browse all crawl space services.

Common Questions About Crawl Space Dehumidifiers