Attic Insulation Not Deep Enough

Many homes are leaky and have insufficient insulation in the attic.

Attic insulation not deep enough.

Fiberglass and cellulose insulation have r values of 2 9 to 3 8 per inch while sprayed foam insulation can go as high as 8 0 per inch. Hot air fills the attic and raises the temperature. For instance in some places like las vegas the sun tends to set on the roof causing the attic to be warm. Warm spaces have less condensation risk than colder space so when you add insulation to the attic floor you re intentionally blocking some of that heat from keeping the attic warm.

Once you know total depth you can estimate the r value if the insulation. Department of energy it s recommended that attics have an r 38 to r 49 or about 12 to 15 of fiberglass or cellulose insulation. Your attic should have a certain amount of insulation in it and the recommended level of insulation for your attic is dependent on where you live. From flat to cathedral in fhb 192.

Generally heat rises and cool air falls. For fiberglass and cellulose insulation you can estimate about r 3 per inch. Mark the desired level on different roof trusses around the attic before you start photo 4. Inspecting your attic insulation first things first you need to go up into your attic inspect the condition of the insulation and calculate the current level of insulation.

The recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type. According to the u s. For houses with 2 6 rafters it s necessary to increase rafter depth to make room for enough insulation to meet code minimums. If the rafters are deep enough it may be possible to use rigid foam as the ventilation baffles sealing along the perimeter of each piece to create an air barrier then filling the rest of the cavity with batts or blown insulation see ceiling remodel.

Always cover the tops of the ceiling joists to make sure the insulation is deep enough to reach your target r value and to prevent thermal bridging the heat loss that occurs through the wood framing. If you can t see the joists because the insulation is above them then you should measure the insulation depth with a ruler to see if you have enough. But in homes that do not have proper attic insulation or ventilation heat tends to migrate. Add the right kind of insulation when adding additional insulation you do not have to use the same type of insulation that currently exists in your attic.

This allows a lot of heat up to the attic.