Blown-in is the workhorse of attic insulation, and for most Central Florida homes it is the right answer — not because it is the cheapest, but because an attic floor is exactly the kind of irregular, obstacle-filled surface that loose fill covers properly and batts never do. What decides whether the job actually works is not the material. It is what happens in the hour before the hose comes out.
Air sealing first, insulation second
This is the part most quotes leave out, and it is the difference between a job that works and one that just looks thicker.
Insulation slows heat moving through a surface. It does almost nothing about air moving around it. A typical ceiling is punctured dozens of times — around the top plates of every interior wall, at plumbing and wiring penetrations, around bath fans and recessed lights, and at the attic hatch. Those gaps let conditioned air out and 130°F attic air in, and blowing two feet of fluff on top of an unsealed ceiling does not close a single one of them.
Sealing those penetrations before the insulation goes down costs a fraction of the insulation itself and it is where a meaningful share of the comfort improvement actually comes from. Any quote that does not mention it is quoting a thinner job than it appears.
How much you actually need
Most of Central Florida — Polk, Hillsborough, Pinellas, Manatee — sits in climate zone 2. The Florida Building Code's energy provisions set a minimum ceiling value of R-38 for new construction in that zone, with an allowance down to R-30 where the insulation extends fully over the wall top plate at the eaves. South Florida, zone 1, is R-30.
Existing homes are frequently nowhere near that. It is common to find R-11 to R-19 in a house built in the seventies or eighties, sometimes less where it has been walked on or disturbed by trades working in the attic. Getting from R-19 to R-38 is the single most cost-effective envelope improvement available to most homeowners here.
One thing to be clear about: depth is not R-value. Different materials at the same depth give very different numbers, and settled depth is not installed depth. We mark the depth on the rafters and verify coverage across the whole attic rather than eyeballing the pile near the hatch.
Fiberglass or cellulose — the honest comparison
Both work. They fail differently, and that is what should decide it.
- Blown fiberglass — glass fibres, so it does not absorb water and does not feed mould. It settles very little over time, which matters because settled insulation is thinner insulation. It is lighter, so it is the safer choice over a ceiling that has already been loaded up or where the framing is marginal. It is also less prone to the dust issue described below.
- Cellulose — recycled paper treated with borate for fire and pest resistance. It packs into odd cavities more densely than fiberglass, which makes it good in walls and around awkward framing, and the borate treatment genuinely discourages insects. Its weaknesses are that it is heavier, it settles more, and it is organic — if it gets wet it mats down, loses its loft permanently and has to come out.
In a humid climate with a real risk of roof leaks and wind-driven rain, that last point carries weight. We lean fiberglass for open attic floors in Central Florida and reach for cellulose where dense packing into a cavity is the actual requirement. If someone is pushing one material for every situation, they are selling what is on the truck.
When blown-in is NOT the right spend
If your air conditioning ductwork runs through the attic — which it does in a great many homes here — adding depth at the ceiling leaves those ducts sitting in an attic that still reaches 30 to 50°F above the outdoor air. The air inside them warms before it ever reaches the room. In that situation, sealing at the roofline with spray foam brings the attic inside the conditioned envelope and does something loose fill cannot.
It is also the wrong spend if what is up there needs to come out first — wet material, rodent contamination, or fill that has been packed flat. Adding new insulation on top of that just buries the problem under something you paid for.
And if the attic has never been air sealed, sealing plus a modest top-up will usually outperform a deep blow with no sealing at all, for less money.
Do you have to remove the old insulation first?
Usually not. If the existing material is dry, clean and simply thin, new fill goes straight over the top and both layers count toward the total. Removal adds real cost, and we will tell you when it is unnecessary.
It becomes necessary when the material is wet or has been wet, when there is rodent contamination or an odour that traces back to the attic, when it has been compressed flat, or after smoke exposure. In those cases it comes out first — see insulation removal.
The details that get missed
- Soffit baffles. Loose fill blown toward the eaves will block the soffit vents if nothing stops it, and a blocked soffit vent takes out the attic ventilation the roof depends on. Baffles go in first.
- Recessed lights. Fixtures that are not rated for insulation contact need clearance maintained around them. Burying a non-IC-rated can light is a fire risk, not a detail.
- The attic hatch. An uninsulated, unweatherstripped hatch is a hole in an otherwise good ceiling, and it is skipped constantly.
- Bath and kitchen fans. They should be ducted to the outside, not simply dumping humid air into the attic. We flag it when we find it.
- Walkways and storage. If you store things in the attic, that has to be planned for — insulation crushed under plywood is insulation you are not getting the benefit of.
Rebates worth claiming
Lakeland Electric offers a $300 rebate on attic insulation where the existing insulation measures R-19 or less, and a pre-inspection has to happen before the work — claim it afterwards and it is gone. Duke Energy, TECO and FPL run their own separate programmes with their own rules and amounts. Programmes change, so we check what is current for your utility rather than quoting a figure from memory, and we handle the paperwork.
What install day looks like
Most attic-only jobs finish in a single day. We lay protection on floors and stairs, run the hose from the truck, seal the ceiling penetrations, fit baffles and any required light barriers, then blow to the specified depth and verify it across the whole attic — not just where it is easy to reach. The material stays in the attic; your living space does not become a work site. We take the depth readings and leave a record of what was installed.
What drives the price
Square footage and the R-value you are targeting are the obvious ones. Beyond that: how much air sealing the ceiling needs, whether old material has to be removed first, attic access and headroom — a low-pitch roof where the crew works on their stomachs costs more than a walk-around attic — the number of obstructions such as ductwork, wiring and can lights, whether baffles and light barriers are required, and how much of the attic is used for storage. We look before we quote.
Common questions
Can I just add new insulation on top of what is already there?
In most cases yes. If the existing material is dry, clean and undisturbed, new fill goes straight over it and the R-values add together. Removal is only necessary when the old material is wet, contaminated, odorous or packed flat — and we would rather tell you it is unnecessary than sell you a removal you do not need.
Does blown-in insulation settle?
Cellulose settles noticeably; fiberglass settles very little. This is why installed depth and settled depth are different numbers, and why the material is blown to a marked depth that accounts for it rather than to whatever looks right on the day.
Is cellulose or fiberglass better in Florida?
For an open attic floor here, fiberglass usually has the edge — it does not absorb water, does not feed mould, is lighter on the ceiling, and settles less. Cellulose earns its place where material needs to be dense-packed into a cavity. Anyone who says one is always right is not thinking about your house.
How long does it take and how disruptive is it?
A typical attic is a one-day job. The hose runs from the truck to the attic, and the work stays up there — we protect the route in and clean up behind us. You do not need to leave the house.