The 30-Second Verdict
For Florida attics, spray foam on the roof deck (conditioned attic) is the premium upgrade that genuinely pays back over time — it keeps ducts in conditioned space and cuts AC bills. It costs $3,000–$6,000 more than fiberglass blown-in but reduces energy bills 15–25%. Fiberglass blown-in meets code and is the cost-effective standard. For walls, fiberglass is typically fine in Florida.
Head-to-Head Breakdown
Spray Foam Insulation
Pros
- Conditioned attic dramatically improves HVAC duct efficiency
- Air seals gaps while insulating — dual function
- Lifetime performance — doesn't settle or degrade
- Best moisture barrier option (closed-cell)
Cons
- 2–4× more expensive than fiberglass
- Requires professional installation
- Off-gassing during installation requires ventilation
Fiberglass Batt Insulation
Pros
- Much lower cost — meets FL energy code affordably
- DIY-friendly installation in accessible areas
- Easy to add more layers to increase R-value
Cons
- Poor air sealing — requires separate air sealing work
- Can absorb moisture in humid FL conditions if improperly installed
- Fiberglass in unconditioned attic leaves ducts in extreme heat
Side-by-Side Comparison
| Spray Foam Insulation | Fiberglass Batt Insulation | |
|---|---|---|
| Attic Application (FL) | Open-cell spray foam on roof deck creates conditioned attic — excellent for FL | Blown-in fiberglass on attic floor — common, lower cost, but leaves attic unconditioned |
| R-Value | Open-cell: ~R-3.7/inch; closed-cell: ~R-6.5/inch | R-2.9–3.8/inch; need R-38+ in Florida (10–13 inches) |
| Moisture Control | Closed-cell acts as vapor barrier; open-cell permits some moisture movement | Can absorb moisture if vapor barrier is improperly installed; mold risk in FL humidity |
| Air Sealing | Excellent — expands to fill gaps; dramatically reduces air infiltration | Poor standalone air sealing — requires separate air sealing work |
| HVAC Impact | Conditioned attic with spray foam can cut AC sizing by 20–30% | Unconditioned attic; HVAC ductwork in 140°F+ attic loses efficiency |
| Cost | Open-cell: $1.00–$1.50/sq ft; closed-cell: $1.50–$3.00/sq ft | $0.30–$0.70/sq ft installed (batts); $0.40–$0.80 blown-in |
| Longevity | Lifetime — does not settle, degrade, or lose R-value | Can settle 5–10% over time; may need top-off after 15–20 years |
| FL Code Compliance | Florida Energy Code compliant; conditioned attic pathway approved | Compliant at proper depth; standard approach for most FL builders |
Frequently Asked Questions
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Top-Rated Local Florida Insulation Alternatives
You don't have to pick a national brand. These Florida-based insulation companies have the highest real Google ratings in our directory — often at a fraction of the franchise price.
Typical insulation services: Attic insulation, Spray foam, Blown-in insulation, +2 more
Insulation Plus of Tampa
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I-Foam & Insulation Inc
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