Choosing Insulation for Hot Attics

In a hot climate, the attic is the battleground. On a sunny day an uninsulated attic can reach well over a hundred degrees, and that heat radiates down into your living space and overworks your air conditioning. The right insulation strategy keeps that heat from reaching your rooms.

For hot attics, the goal is both to slow conductive heat and, ideally, to reflect radiant heat before it builds up.

Blown-in fiberglass and cellulose both perform well on a hot attic floor, providing even coverage that slows heat moving down into the home. Spray foam at the roofline is another strong option, especially if the attic holds ductwork or HVAC equipment you want to keep cool.

Whatever the material, getting the R-value up to a solid level is the foundation — heat that can't get through the insulation can't reach your living space.

In hot, sunny climates, a radiant barrier really shines. Installed under the roof rafters, it reflects the sun's radiant heat away before it soaks into the attic, which can noticeably reduce attic temperatures and cooling costs when paired with good insulation.

Used together, a radiant barrier and proper insulation tackle both the radiant and conductive heat that make summer rooms uncomfortable.

Good attic ventilation lets built-up hot air escape rather than baking the insulation and roof deck. Combined with insulation and a radiant barrier, proper ventilation rounds out a hot-attic strategy.

A professional can assess your attic's heat load and recommend the right mix of insulation, reflective barrier, and ventilation for your home.