Requirements for the Building Thermal Envelope

Insulation and fenestration criteria.

The building thermal envelope shall meet the insulation requirements of Table R402.1.1. Note that Climate Zone 1 refers to Dade and Broward counties and Climate Zone 2 includes all other Florida counties

Access hatches and doors

Access doors from conditioned spaces to unconditioned spaces (e.g., attics and crawl spaces) shall be weather-stripped and insulated to a level equivalent to the insulation on the surrounding surfaces. Access shall be provided to all equipment that prevents damaging or compressing the insulation. A wood framed or equivalent baffle or retainer is required to be provided when loose fill insulation is installed, the purpose of which is to prevent the loose fill insulation from spilling into the living space when the attic access is opened, and to provide a permanent means of maintaining the installed R-value of the loose fill insulation.

Floors

Floor insulation shall be installed to maintain permanent contact with the underside of the subfloor decking.

Basement walls

Walls associated with conditioned basements shall be insulated from the top of the basement wall down to 10 feet below grade or to the basement floor, whichever is less.

Slab-on-grade floors

Slab-on-grade floors are not required to be insulated in Florida’s Climate Zones, as indicated in Table 402.1.1.

Crawl space walls

As an alternative to insulating floors over crawl spaces, crawl space walls shall be permitted to be insulated when the crawl space is not vented to the outside. Crawl space wall insulation shall be permanently fastened to the wall and extend downward from the floor to the finished grade level and then vertically and/or horizontally for at least an additional 24 inches (610 mm). Exposed earth in unvented crawl space foundations shall be covered with a continuous Class I vapor retarder in accordance with the Florida Building Code, Building or Florida Building Code, Residential, as applicable.

Sunroom insulation

All sunrooms enclosing conditioned spaces shall meet the insulation requirements of the Code.

Air leakage

The building thermal envelope shall be constructed to limit air leakage in accordance the Code.