Cardinal Insulation, 4263 NW 1st Ave, Boca Raton, FL 33431. Blown-in insulation is the first service. Batt insulation is the job we do when the bay is still open, and the job we refuse when someone wants a second batt laid on top of a slumped attic.
Where a batt works
A fiberglass batt that fills a stud bay, cut to the bay and not stuffed past its thickness, does the job it was made for. That is a wall or a floor while the cavity is open: new work, an addition, a garage ceiling that is still down to the joists. A wood-frame wall in this climate is often R-13 in the cavity. The batt has to touch all six sides. A gap at the side is a stripe of missing insulation, and compressing a batt to make it fit lowers the R-value you paid for.
Where a batt fails
An attic full of batts from the year the house was built has slumped, pulled off the plates, and left the wires proud. Laying a new batt on top does not fill those gaps. If the old batts are dry, we seal the leaks and blow over them to R-38. If they are wet or full of nests, they come out. We do not sell a batt top-up as the attic job.
The usual Boca attic is still blown-in insulation. The choice between a batt, a blow, and foam is on which insulation belongs in a Florida house. A roof that should be inside the house is spray foam, not a batt tucked between rafters and left vented.