Insulation in Jacksonville & Northeast Florida

Published 2026 cost guides put crawl space insulation at $1–$4.50 per square foot installed, with most crawlspaces between $500 and $3,700. Fiberglass batts between the joists sit at the low end and foam board or closed-cell spray foam at the high end. Taking out old, wet or fallen insulation first adds about $1–$2 per square foot.

It depends on whether the crawlspace is vented. In a vented crawlspace the insulation goes under the floor, between the joists. In a sealed crawlspace it moves to the foundation walls and rim joists, because the space under the floor is now part of the house, and Florida’s code ties insulated perimeter walls to some of the ways a sealed crawlspace can be conditioned (section R408.3).

Moisture, mostly. Fiberglass batts in a humid crawlspace soak up water, get heavy and sag until they drop, and animals pull down what is left for nesting. Once it is wet it holds that moisture against the subfloor, so fallen insulation is both a symptom and part of the problem.

Wet, moldy, fallen or animal-soiled insulation does. Covering it or adding more on top traps the problem in place. Removal typically adds $1–$2 per square foot, and it is priced on its own line so you can see it.

Yes, mainly for cooling and comfort. Walls and attics are insulated but the underside of the house is often neglected, so the floor over a hot, muggy crawlspace becomes a large uninsulated surface the air conditioning has to fight. Moisture-resistant insulation that stays dry keeps doing that job.