Measured against the Florida code
The attic numbers, not a brochure
The 2023 Florida Building Code, Energy Conservation, Table R402.1.2 sets a climate zone 1 ceiling at R-30 and a climate zone 2 ceiling at R-38. Cardinal installs R-38 and checks the inches. A Florida page that lists R-49 to R-60, or R-3.2 to R-3.8 per inch for both fiberglass and cellulose, is using a different book. Table R402.4.1.1 says air-permeable insulation shall not be used as the air seal.
Quotes are prepared by Russell Y, a building scientist, BPI certified, and certified to perform blower door testing. When the door is run, the result is air changes per hour at 50 pascals, the method in R402.4.1.2. That section limits new houses in climate zones 1 and 2 to 7 ACH50. An insulation job on an existing house is not automatically that test. We report the number only when we measured it.
Insulation numbers Cardinal uses against the Florida code| Item | Number | What it means |
|---|
| Zone 1 ceiling, Florida code | R-30 minimum | Palm Beach and Broward |
|---|
| Zone 2 ceiling, Florida code | R-38 minimum | Not R-49 and not R-60 |
|---|
| What Cardinal installs | R-38, depth checked | Above the zone 1 floor |
|---|
| New blown fiberglass | About R-2.5 per inch | Not R-3.2 to R-3.8 |
|---|
| Settled fiberglass | About R-2.2 per inch | 4 inches is about R-9 |
|---|
| New cellulose | About R-3.6 per inch | Denser. Still not an air seal |
|---|
| Open-cell foam | About R-3.6 per inch | A roof-deck product |
|---|
| Closed-cell foam | About R-6.5 per inch | 2 inches is about R-13 |
|---|
The attics on this page
Delray Beach is two attics split by I-95. East of the interstate, 33444 and 33483, Pineapple Grove, Lake Ida, and Tropic Isle are older houses. The hatch is small. The ceiling is often plaster. A few inches of original fiberglass is normal, and that few inches is closer to R-9 than to the R-30 the code asks for.
West of I-95, 33446, Kings Point and the Villages of Oriole still have 1970s and 1980s batts. A lot of those buildings are condominiums. A building with no scuttle is not a blown-in job. A villa with a vented ceiling is. 33445 is the band around the shop. 33484 runs toward the Boca line, and the tax bill decides which city the house is in.
The walk-in shop is 955 S Congress Ave, Delray Beach, FL 33445. Customers can walk in. The phone is (561) 654-7698, the same number as Boca. The work is the seal first, baffles in the soffit, then an even R-38. Wet fill and nests come out before any new insulation goes down, and that removal is its own price.
The code in Delray Beach
Delray Beach is in Palm Beach County. Table R301.1 of the 2023 Florida Building Code, Energy Conservation, lists Palm Beach County as climate zone 1A. Table R402.1.2 sets the zone 1 ceiling minimum at R-30. Delray Beach does not publish its own attic R-value. The city enforces the Florida Building Code.
Palm Beach County is not in the High-Velocity Hurricane Zone. That zone is only Miami-Dade and Broward. Parts of the Palm Beach coast are still a wind-borne debris region, which is an opening-protection rule from the wind map, not an insulation number. Section R806.2 of the 2023 Florida Building Code, Residential, sets the net free vent area at 1/150 of the attic. The exception is 1/300 only when 40 to 50 percent of that area is within 3 feet of the ridge and the rest is in the bottom third. Insulation cannot close the soffit. R806.3 requires at least 1 inch at the eave vent.
The county zone is Table R301.1. The Boca Raton worked example, including the vent math, is the building code page. Cardinal still installs a vented attic to R-38 and checks the depth.
Blown-in insulation, the full pageResidential insulationWhich insulation belongs in a Florida houseWho writes the quoteHow a South Florida attic actually works