Should insulation go in the floor or on the walls?

In a vented crawl space, insulation goes between the floor joists. In a sealed crawl space, insulating the foundation walls and rim joist instead brings the space inside the building envelope, which is generally the better performing arrangement in Georgia.

Why does my crawl space insulation keep falling down?

Fiberglass batts absorb moisture, gain weight and lose their grip. Repeated sagging is a moisture symptom, not a fastening problem — correcting humidity is what stops it.

Can wet insulation be dried and reused?

We do not reuse it. Batts that have been saturated hold contamination and rarely recover their original performance, and reinstalling them puts damp material right back against the sub-floor.

Will crawl space insulation lower my power bill?

It can reduce heat transfer through the floor and around ductwork, which helps. We describe the expected benefit honestly rather than promising a specific percentage, since results depend on the house.

Thermal envelope

Crawl Space Insulation in Georgia

Insulation hanging out of the joists is one of the most common sights under a Georgia home — and it is almost always a moisture story before it is an insulation story. We fix the cause, then rebuild the envelope correctly.

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Insulation installed between crawl space floor joists above a clean barrier

Why insulation fails under Georgia houses

Fiberglass in a vented crawl space sits in exactly the wrong conditions: humid air moving through it, cool sub-floor above it and damp soil below. It absorbs moisture, sags under the added weight and eventually drops out of the joist bays entirely.

Once it is damp, it does very little thermally and keeps moisture in contact with the wood it is pressed against. Replacing it without changing the environment simply resets the clock.

Two approaches, depending on the crawl space

Vented crawl space: insulation between the floor joists, supported properly, with the ground covered by a vapor barrier. Appropriate when the space will remain vented.
Sealed crawl space: insulation on the foundation walls and rim joist, with the floor left uninsulated so the crawl space is inside the conditioned envelope. This pairs with encapsulation and humidity control.

Sealed crawl space with insulated foundation walls and clean liner

How we approach an insulation project

1Assess humidity and identify why the existing insulation failed.
2Remove damaged, wet or fallen material and dispose of it.
3Correct the moisture source: drainage, barrier, sealing or a plumbing repair.
4Repair any sub-floor or framing damage found once the bays are open.
5Install insulation in the arrangement that matches the crawl space strategy.
6Air-seal the rim joist and access hatch to stop bypasses.

Insulation Falling Out of Your Joists?

That is a moisture signal. We check the humidity and the barrier before quoting replacement material.

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Comfort and duct performance

Cold floors in winter and warm floors above a hot crawl space are the comfort complaints homeowners raise most. Where supply ducts run through the crawl space, the temperature of that space affects the air delivered upstairs — one more reason a sealed, insulated crawl space usually outperforms a vented one in this climate.

Cost factors

Square footage of floor or linear feet of foundation wall to cover
Volume of old insulation requiring removal and disposal
Material type and R-value specified
Sub-floor or joist repairs uncovered during removal
Access and clearance in the crawl space

Crawl space insulation FAQs

Should insulation go in the floor or on the walls?: In a vented crawl space, insulation goes between the floor joists. In a sealed crawl space, insulating the foundation walls and rim joist instead brings the space inside the building envelope, which is generally the better performing arrangement in Georgia.
Why does my crawl space insulation keep falling down?: Fiberglass batts absorb moisture, gain weight and lose their grip. Repeated sagging is a moisture symptom, not a fastening problem — correcting humidity is what stops it.
Can wet insulation be dried and reused?: We do not reuse it. Batts that have been saturated hold contamination and rarely recover their original performance, and reinstalling them puts damp material right back against the sub-floor.
Will crawl space insulation lower my power bill?: It can reduce heat transfer through the floor and around ductwork, which helps. We describe the expected benefit honestly rather than promising a specific percentage, since results depend on the house.

Crawl Space Encapsulation →Sealing the space before re-insulating.Crawl Space Repair →Damage found once insulation comes down.High Humidity Crawl Space →The condition that ruins insulation.Moisture & Mold Conditions →What damp material means underneath.Crawl Spaces in Macon, GA →Middle Georgia homes and older insulation.Cost Guide →Where insulation fits in a full budget.

Free estimate

Tell us what's happening under your house

Crawl space pricing depends on square footage, access, moisture source and how much repair work the framing needs. We inspect first, then quote the scope that actually solves the problem — not a package chosen before anyone looked.

On-site inspection of drainage, grading, vapor barrier and framing
Humidity and moisture readings where they matter
Written scope showing what is required and what is optional