A true vapor barrier is more than just plastic thrown on the ground. A proper installation includes:

• fastening to the foundation wall

• sealing seams with approved tape

• overlapping material correctly

• wrapping piers

• blocking ground moisture migration

A Class 1 vapor barrier significantly reduces humidity by stopping moisture vapor from rising through the soil.

Closed-cell spray foam creates an air, moisture, and thermal barrier on the foundation walls. This provides:

• sealed exterior boundary

• reduced condensation

• increased energy efficiency

• more stable crawlspace temperatures

It forms a monolithic shell around the crawlspace perimeter, helping maintain an indirectly conditioned environment.

(Stop Letting Contractors Install These!)

With an encapsulated crawlspace, there is no reason to have any ventilation to the outside. That means all the original vents are sealed and there definitely aren’t any positive or negative pressure fans installed to intensionally connect the crawlspace with the outside.

With a sealed or encapsulated crawlspace:

• vents are obsolete

• vents bring in humidity

• vents hurt energy efficiency

• vents contribute to mold growth

Every vent should be:

• blocked from the interior

• sealed

• insulated

One exception: homes located in FEMA-designated flood zones, where flood vents are required. These homes will have FEMA “Smart-Vents” installed in the foundation.

Even the most energy efficient new construction home’s need dehumidifier’s. Moisture doesn’t just come from the outdoors. We produce it by breathing, cooking, showering and living within our homes.

Even with a sealed crawlspace, spray foam insulation, or an HVAC supply:

👉 You still need a dehumidifier.
(Especially in airtight modern homes.)

HVAC systems are NOT designed to dehumidify your crawlspace on their own. During spring and fall (shoulder seasons), temperatures are mild but humidity is high — meaning your HVAC won’t run long enough to pull moisture from the air.

At FLC Energy, we recommend at minimum:
AprilAire E070 for most crawlspaces on Delmarva.

If the crawlspace is designed to be conditioned, connecting it to the home’s HVAC system can further stabilize temperature and humidity.In this case, it’s certainly not a bad idea to heat and cool it! If you want to be technical, not directly supplying hot or cold air to your conditioned crawlspace means its an “indirectly conditioned” space.

It isn’t always possible to heat and cool your crawlspace though. If you have duct-work in your attic, or between your first and second floor, supplying air to this space isn’t an option. In that case, we would recommend a standard encapsulation of the space, rather than fully conditioning the area.

Standing water is a serious issue that impacts:

• humidity
• HVAC performance
• indoor air quality
• structural integrity

Solutions include:

• French drains
• sump pumps
• downspout extensions
• regrading
• gutter improvements

But beware:
A sump pump alone will NOT solve standing water.
It may prevent flooding, but it does not remove groundwater intrusion from outside – only a french drain can do that.