Wall Insulation Miami

Exterior wall insulation is a less common retrofit than attic insulation, but it matters significantly in Miami's high solar-gain environment. South-facing and west-facing concrete block walls in particular can absorb substantial solar radiation during afternoon hours, radiating that heat into the home long after the sun has moved. Properly insulated exterior walls reduce this heat transfer and can dramatically improve comfort in rooms that feel hot despite AC operation — a common complaint in Miami homes with uninsulated concrete block exterior walls.

The dominant exterior wall construction in Miami is concrete masonry unit (CMU) block — solid or hollow-core block that provides essentially no thermal resistance (R-1 to R-2). Standard new construction adds continuous rigid foam on the exterior or interior of the block, but retrofit insulation of existing CMU homes requires a different approach. Interior rigid foam board installation — applying 2-inch closed-cell rigid foam panels to the interior face of exterior block walls and covering with drywall — is the most effective retrofit, providing R-10 to R-13 without exterior modifications.

For wood-frame construction (common in Miami-Dade additions and upper stories), dense-pack blown-in insulation (see blown-in skill) or open-cell spray foam can be installed through small exterior holes into wall cavities without full renovation. This approach adds R-13 to R-20 to previously uninsulated stud cavities. We assess wall construction type and recommend the appropriate solution — there is no single right answer for all Miami wall configurations.