Air Infiltration From Attic Through Ceiling

The easiest way to find air leaks is with a blower door.

Air infiltration from attic through ceiling.

Look for dirty insulation which is evidence that air is moving through it. Where walls inner and outer meet the attic floor dropped soffits dropped ceiling areas and behind or under attic kneewalls. A form of un controlled attic ventilation will also have an influence on the moisture balance. Fill ceiling box gaps with fire blocking foam invert the spray foam can and shove the tube up into the gap.

Spray foam also reduces infiltration through the ceiling. If you have an attic ac unit you should take this opportunity to check the air seals on the duct work. Consider swapping out or upgrading any duct work that is not insulated properly. Let it cure for about two hours.

During the summer standard ceiling insulation reduces the transfer of heat from the attic to the living space. As long as the roof isn t leaking the biggest wintertime source of attic moisture is air infiltration from the conditioned space through the attic floor air sealing the house at the attic floor basement band joist can do a lot for reducing 24 365 outdoor air infiltration which is the major driver of summertime indoor humidity levels. If you want to add insulation remember that air leaks have to be sealed first. In the day temperatures can get up to 140f in the attic.

It reduces energy consumption because the temperature in the attic is lower. The two control layers we re concerned about here are. Once this air sealing work is done you may want to add more insulation to your attic floor. This is building science 101.

Additionally the air tightness of the attic construction itself the un intentional air infiltration i e. One source is from outdoors through the attic ventilation and the other is from indoors through air leakage across the ceiling plane. Spray foam also reduces infiltration through the ceiling. During the summer standard ceiling insulation reduces the transfer of heat from the attic to the living space.

Then there are the control layers meant to control the flow of heat air and moisture across the building envelope. Once in the attic refer to your sketch to locate the areas where leakage is likely to be greatest. In the day temperatures can get up to 140f in the attic. Any ceiling vents need to be foamed and sealed where they meet the ceiling.

It reduces energy consumption because the temperature in the attic is lower. Most of the time houses are insulated with materials that do not stop air leakage. The opening around a furnace or water heater lue or chimney can be a major source of warm air moving in the attic. Because the pipe gets hot building codes usually require 1 inch of clearance from metal lues 2 inches from masonry chimneys to any combustible material including insulation.