Crawl space insulation in Greensboro

Floor insulation versus wall insulation

North Carolina's closed crawl provisions allow insulation in the floor system or on the walls, and require wall insulation when the crawl is designed as a heated and cooled space. Where walls are insulated, the band joist area must be insulated too.

Why old batts fail in Triad crawls

Fiberglass batts between floor joists are common in Greensboro homes. In a humid vented crawl, they absorb moisture, sag, and fall. Wet batts lose much of their insulating value and hold moisture against the subfloor, which can lead to mold. Many crawls we see have batts hanging or lying on the ground.

Wall insulation options

• Rigid foam board on the inside of foundation walls.
• Closed-cell spray foam on walls and rim joists.
• Other approved materials as allowed by code.

NC code requires a 3- to 4-inch termite inspection gap between the top of foam wall insulation and the wood sill, and a gap between the bottom of foam insulation and the crawl floor. It also addresses fire safety: foam plastics in crawls must meet flame-spread and smoke ratings or be covered by an approved thermal barrier.

Source: NC closed crawl space provisions (R409.8), as published by Johnston County Building Inspections.

Rim joists

The rim joist, where the floor framing sits on the foundation, is a common source of air leaks and heat loss. Sealing and insulating it is often one of the most effective upgrades in a crawl.

Cost references

HomeGuide lists crawl insulation at roughly $1.00 to $4.50 per square foot, or about $500 to $3,700 total, depending on type and location. Removing old insulation adds about $1 to $2 per square foot. See our cost guide.

Order of work

Insulation comes after water and air are under control. Installing new insulation in a wet crawl repeats the old problem.

1. Fix water sources and drainage.
2. Remove wet or failed insulation.
3. Install the vapor retarder and seal the crawl.
4. Add drying.
5. Insulate the floor or walls as designed.

Energy and comfort

A properly sealed and insulated crawl can make floors feel warmer in winter and reduce the load on ducts that run under the house. HomeGuide notes energy bill reductions are possible; results depend on the house, the HVAC system, and how leaky the crawl was before.

For insulation work, see our crawl space encapsulation services in Greensboro. We serve High Point, Jamestown, Pleasant Garden, Stokesdale and nearby. Related: encapsulation overview and benefits.

Ducts in the crawl

Ductwork in a crawl should be sealed at joints with mastic or approved closure systems, as NC's closed crawl provisions require, and insulated as required. Leaky or uninsulated ducts in a humid crawl waste energy and can sweat in summer. Sealing ducts is often part of a crawl insulation project.

Pipes and freezing

Greensboro winters are mild, but cold snaps can freeze pipes in vented crawls with no insulation on the walls. Closing and insulating a crawl at the walls keeps it closer to house temperature, which reduces freeze risk. In a vented crawl with floor insulation, exposed pipes should be insulated.

Fire safety with foam

Foam insulation in crawls must meet flame-spread and smoke ratings under NC code or be covered by an approved thermal barrier. Foam in crawls used as conditioned space or plenums must be protected by a thermal barrier. Ask which product is used and how it complies.

Removing old insulation

Old fiberglass batts that are wet, moldy, sagging, or full of rodent nesting should be removed before encapsulation. HomeGuide lists old insulation removal at about $1 to $2 per square foot. Removal is dusty work; crews should bag material and wear protective gear.

Price source: HomeGuide, Crawl Space Encapsulation Cost.

Rim joists

The rim joist, the band of framing that sits on the foundation wall, is a common air leak and cold spot. Sealing and insulating it is often one of the most effective parts of crawl insulation.

Crawl insulation questions

Should I insulate the crawl floor or walls?

Floor insulation is common in vented crawls. Wall insulation fits closed crawls and is required when the crawl is designed as conditioned space.

Why does fiberglass insulation fall in crawl spaces?

In humid crawls it absorbs moisture, gets heavy, and sags or falls. Wet batts also lose insulating value.

What is the termite gap for foam insulation?

NC code requires a 3- to 4-inch inspection gap between the top of foam wall insulation and the wood sill.

Should insulation go in before drying the crawl?

No. Fix water and seal the crawl first, then insulate, or the new insulation can fail like the old.

How much does crawl insulation cost?

HomeGuide lists roughly $1.00 to $4.50 per square foot, or about $500 to $3,700 total, plus about $1 to $2 per square foot to remove old insulation.

Does closing the crawl help prevent frozen pipes?

Insulating a closed crawl at the walls keeps it closer to house temperature, which reduces freeze risk.

Is spray foam in a crawl a fire hazard?

Foam must meet NC flame-spread and smoke ratings or be covered by an approved thermal barrier. Ask how the product complies.

How much does it cost to remove old crawl insulation?

HomeGuide lists old insulation removal at about $1 to $2 per square foot.