Crawl Space Insulation
Proper crawl space insulation keeps floors warmer, reduces energy bills, and improves comfort. Costs range from $1,000–$4,000 depending on size and insulation type.
Insulation Types & Costs
Fiberglass Batt (Floor Joists)
$1.00–$1.50/sq ftR-Value: R-11 to R-30
Pros: Lowest cost, widely available
Cons: Absorbs moisture, falls down over time in crawl spaces
Rigid Foam Board (Walls)
$1.50–$2.50/sq ftR-Value: R-10 to R-25
Pros: Moisture resistant, durable, seals air gaps
Cons: Labor intensive to install around obstacles
Spray Foam (Walls/Floor)
$2.50–$5.00/sq ftR-Value: R-6 to R-7 per inch
Pros: Best air seal, fills every gap, moisture resistant
Cons: Most expensive option
Where to Insulate: Floor vs. Walls
Vented Crawl Space → Insulate the Floor
In a vented crawl space, insulate between the floor joists (the subfloor). Use fiberglass batts or rigid foam boards. The crawl space itself remains unconditioned.
Sealed Crawl Space → Insulate the Walls
In a sealed/encapsulated crawl space, insulate the foundation walls instead. This conditions the entire crawl space and is more energy-efficient overall.
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