Blown-In Insulation
Everything a South Florida homeowner needs to know about blown-in insulation — the science, the materials, the R-values, the cost, and exactly how Cardinal installs it to Florida code with FLIR proof.
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What is blown-in insulation?
Blown-in insulation — also called loose-fill insulation — is shredded fiberglass or cellulose material blown through a hose into your attic floor or wall cavities. Instead of pre-cut batts that leave gaps at every joist, wire, and penetration, loose-fill settles into a continuous blanket that fills every void and irregular space.
The result is a uniform thermal layer with no compression, no gaps, and no thermal bridges — the three things that destroy the R-value of batt insulation. It's the fastest, lowest-cost way to bring an under-insulated attic up to Florida code R-30 or Cardinal's recommended R-38.
Cardinal blows both fiberglass loose-fill and cellulose loose-fill, spec'd to your home after a free FLIR thermal inspection. Most attics are completed in a single day.
The science, simply
Heat moves three ways: conduction (through materials), convection (through moving air), and radiation (from a hot surface). Insulation fights conduction by trapping millions of tiny pockets of still air — and still air is one of the worst heat conductors there is.
Blown fiberglass and cellulose are made almost entirely of trapped air held between fine fibers. The thicker the blanket, the more air pockets, the more heat it resists. That resistance is measured as R-value — higher R means slower heat flow and a cooler home below.
Fiberglass vs. cellulose — the honest comparison.
Both are proven loose-fill materials. The right choice depends on your climate, your assembly, and your existing insulation. Here's how Cardinal specs it — no upsell.
Blown fiberglass
R-2.2 / in- Moisture-resistant — won't hold water
- Minimal settling (<2%)
- Non-combustible
- Lighter weight on ceiling
- – Lower R-per-inch than cellulose
- – Can be airborne during install if uncontained
South Florida attics — Cardinal's default for humid climates
Blown cellulose
R-3.2 / in- Higher R-per-inch — less depth needed
- Dense pack stops air movement
- Treated borate fire retardant
- Made from recycled paper
- – Can hold moisture if wetted
- – Settles up to 20% over time
- – Heavier when dense-packed
Dense-pack wall retrofits and dry attic floors
How deep is deep enough?
R-value is additive — more inches means more R. Here's the installed depth Cardinal blows to hit each target R-value, and what each level means for your home.
| Target R-Value | Blown Fiberglass | Blown Cellulose | What it means |
|---|---|---|---|
| R-30 | 14" | 9" | Florida Building Code minimum (ceiling/attic) |
| R-38 | 17" | 11" | Cardinal recommended for South Florida cooling load |
| R-49 | 22" | 14" | High-efficiency / new construction |
Depths are approximate installed thicknesses based on manufacturer coverage labels. Cardinal verifies actual installed depth at multiple points and documents it with a FLIR thermal scan before you pay the balance.
Six signs your attic needs blown-in.
Rising FPL bills
Cooling costs climbing with no rate change — your attic R-value has degraded or was never to code.
Hot second-floor rooms
Upstairs stays 5–10° warmer than downstairs — radiant heat from an under-insulated attic.
Drafty, uneven temps
Rooms feel different temperatures — gaps and voids in existing batt insulation leak conditioned air.
High indoor humidity
AC runs constantly but humidity stays above 55% — the thermal envelope is leaking.
Home is 15+ years old
Pre-2010 Florida homes were built to R-19 or R-30 — below today's R-38 recommendation.
Insulation below the joists
You can see the tops of your ceiling joists in the attic — you're well under R-30.
How Cardinal blows in your insulation.
FLIR attic scan
We map every void, gap, and compressed batt in infrared before we touch a thing — so we blow only where it actually helps.
Prep & air seal
We seal penetrations, mask fixtures, and protect the living space. A clean, prepped attic floor is ready for a uniform depth blow.
Blow to R-38
Fiberglass or cellulose blown to a uniform R-38 depth across the attic floor, filling every gap batts miss. Most homes done in a single day.
Depth + FLIR proof
We measure depth at multiple points and re-scan in infrared to confirm coverage. You get a proof report before you pay the balance.
Blown-in vs. spray foam vs. batts.
Each insulation type has a job it does best. Here's the honest head-to-head so you know where blown-in wins — and where it doesn't.
| Feature | Blown-In | Spray Foam | Batts |
|---|---|---|---|
| Installed cost | $1,500–$4,000 | $3,500–$9,500 | $1,000–$3,000 |
| R-value per inch | R-2.2–3.2 | R-3.8–6.5 | R-3.1–3.8 |
| Air sealing | Low (fills gaps, doesn't seal) | Excellent (airtight) | Poor (gaps at edges) |
| Moisture resistance | Good (fiberglass) | Excellent (closed-cell) | Fair |
| Speed of install | Single day | 1–2 days + cure | 1–2 days |
| Best use | Attic floor top-up | Roof deck / whole attic | Open wall cavities |
The takeaway: blown-in is the value champion for attic floor top-ups. Spray foam wins for roof decks and whole-attic air sealing. Batts make sense for open wall cavities during a remodel. Cardinal installs all three — we recommend what your home actually needs.
Why blown-in behaves differently in Florida.
South Florida's climate is dominated by cooling load, not heating — heat moves down through your ceiling into your living space for most of the year. That flips the logic northern homeowners are used to: here, the attic is the single biggest source of heat gain, and the attic floor is where blown-in does its heaviest lifting.
Humidity is the second factor. Cellulose can hold moisture; fiberglass won't. In a climate where attic dew points regularly exceed 70°F, Cardinal defaults to blown fiberglass for attic floors to avoid any risk of moisture retention, mold, or settled R-value.
Florida Building Code requires R-30 minimum in ceilings. Cardinal recommends R-38 for the cooling load — and we install to that depth, verified with a ruler and a FLIR scan.
The Cardinal standard
- Blown to R-38 — above Florida code R-30
- Fiberglass default for humid-climate moisture safety
- Depth measured at multiple points, documented
- Before & after FLIR thermal proof
- Lifetime workmanship warranty
- Local crew — no subs, no shortcuts
Cardinal Insulation — your blown-in authority.
- 4263 NW 1st Ave, Boca Raton, FL 33431
- (561) 654-7698
- Open 24 hours · 7 days a week
- 5.0 stars on Google
A different category
of contractor.
We don't compete on price. We compete on the 15-point standard the industry skips — from FLIR thermal imaging to Building Scientist verification. Here's where the barrier falls.
No competitor named. The standards speak for themselves.
We put the risk on us, not you.
The barrier between you and comfort shouldn't be money or trust. We remove both — with financing, a lifetime warranty, and proof you can see.
Lifetime Workmanship Warranty
Every seal we install is guaranteed for the life of the home. If it ever fails, we fix it free — no fine print.
Flexible Financing
Spread the cost over 12–60 months with low-interest options. Most homeowners pay less per month than they save on cooling.
Same-Week Inspection
Quote today, FLIR inspection this week. We don't make you wait to start saving.
Documented Savings
Before-and-after infrared proof. You see the sealed shield in thermal imaging before you ever pay the balance.
Ready to remove the barrier?
60-second quote. No call required. No obligation.
Air leaks, noise, and energy bills.
The three questions every South Florida homeowner asks before investing in blown-in attic insulation — answered straight, with the science behind each.
Blown-in insulation resists air movement but does not fully stop it — it filters air, it doesn't seal it. That's why Cardinal air-seals every top plate, wiring penetration, and plumbing chase with foam before any insulation goes in. Skipping that step (which cheap quotes do) lets conditioned air leak past the insulation and wastes the R-value you just paid for. In South Florida's humid climate, unsealed air leaks also carry moisture into the attic, which can compress insulation and grow mold. Our free FLIR inspection maps every leak before we blow a single bag.
Blown-in attic insulation noticeably reduces exterior and between-floor noise — typically 5–8 decibels of airborne sound transmission, which the ear perceives as roughly half as loud. Cellulose outperforms fiberglass here because its higher density absorbs more sound energy. South Florida homeowners near I-95, Federal Highway, or flight paths report a clear difference after a blown-in top-up. It won't eliminate impact noise (footsteps, slamming doors) — that requires wall cavity insulation — but it meaningfully quiets road traffic, lawn equipment, and neighbor activity.
Topping an under-insulated attic to R-38 typically cuts cooling costs 15–25% in South Florida homes. The exact savings depend on your attic's current R-value, A/C efficiency, and duct location. If your ducts run through the attic (common in South Florida homes built 1970–2010), the savings can be higher because the ducts now sit in a cooler space. We document the expected savings in your itemized quote and verify the install with a post-install FLIR scan so you can see the thermal difference before you pay the balance.
South Florida's climate means your A/C runs 8–10 months a year, pulling conditioned air up into the attic through every unsealed gap. Insulation without air sealing is like wearing a sweater with the zipper open — it slows heat but doesn't stop the air carrying it. In South Florida's humidity, those same air leaks carry water vapor that can condense in the attic, wet the insulation, and grow mold. Cardinal seals every penetration first, then blows — the order matters, and it's the step that makes the R-value actually perform.
Yes, indirectly. The added density in the attic dampens low-frequency exterior noise — wind-driven rain on the roof, thunder, and distant storm activity all register quieter after a blown-in top-up. It does not structurally reinforce the roof (only closed-cell spray foam does that), but the sound-dampening effect is a consistent benefit South Florida homeowners mention after installation. If storm resilience is a priority, ask about pairing blown-in with a radiant barrier or spray foam on the roof deck.
South Florida homes lose the most cooling energy through the attic — the sun bakes the roof deck to 150°F+, and that heat radiates into your living space. Blown-in R-38 insulation creates a thick thermal blanket on the attic floor that slows that heat transfer, so your A/C runs less, cycles shorter, and lasts longer. The Department of Energy estimates proper attic insulation saves 15–30% on cooling costs in hot-humid climates like South Florida. We verify the improvement with before-and-after FLIR thermal imaging on every install.
The questions Boca, Delray & Boynton actually ask.
Blown-in (loose-fill) insulation is shredded fiberglass or cellulose blown through a hose into your attic floor or wall cavities. It settles into a uniform blanket that fills every gap, void, and irregular space that batt insulation can't reach. It's the fastest, lowest-cost way to add R-value to an existing attic without demolition.
Insulation resists heat transfer by trapping millions of tiny air pockets in a low-conductivity material. Blown-in fiberglass and cellulose trap still air between their fibers — still air is a poor conductor, so the layer slows heat from moving through your ceiling. The thicker the layer, the more air pockets, the higher the R-value.
Florida Building Code requires R-30 minimum in ceilings, but Cardinal recommends R-38 for South Florida's extreme cooling load. That's roughly 17 inches of blown fiberglass or 11 inches of blown cellulose. We verify installed depth at multiple points and document it with a FLIR thermal scan.
Fiberglass is Cardinal's default for South Florida: it's moisture-resistant, settles less than 2%, and won't hold water in our humid climate. Cellulose has a higher R-per-inch and is excellent for dense-pack wall retrofits, but it can hold moisture and settle up to 20% over time. We recommend per home after a free FLIR inspection.
Blown-in attic insulation runs $1,500–$4,000 for a typical South Florida home, or $1.50–$4.00 per square foot installed. Price depends on attic size, target R-value, and material (fiberglass vs cellulose). It's the lowest installed cost per R-value of any insulation type. Get an instant itemized quote by ZIP code.
Properly installed blown fiberglass lasts 80+ years with minimal settling. Cellulose can settle 15–20% over a decade and may need a top-up. Cardinal over-specs depth to account for any settling, so your R-value stays at code for the life of the home — backed by a lifetime workmanship warranty.
Yes — if the existing material is clean, dry, and uncompressed. Blown-in is the ideal top-up method because it fills the voids and gaps in older batt or loose-fill insulation. We inspect with FLIR first and recommend removal only if the existing insulation is water-damaged, moldy, or rodent-contaminated.
Yes. Topping an under-insulated attic from R-19 to R-38 typically cuts cooling costs 15–25%. Pair it with a radiant barrier for layered defense and savings up to 40%. Most South Florida homeowners recover the cost in 3–5 cooling seasons on FPL savings alone.
Serving the Boca–Delray–Boynton corridor.
From the Boca inlet to Boynton's western estates — every hot zone below is a home we sealed this year. This is our local service area.
