Air sealing is a crucial part of building a healthy, energy-efficient home. Below is a checklist of items to use to ensure proper air sealing when building or renovating a conventional stick-frame home. A leaky home will decrease the R-value of your insulation, create unwanted drafts and comfort issues, and bring moisture and pollutants into the home. As the saying goes, “Seal it tight and insulate it right!”

Hidden air leaks in your home are like unseen holes in your wallet. image courtesy of Energy Star

• Seal around windows and exterior doors with backer rod, caulk or non-expanding spray foam.

• Seal all electrical, plumbing and HVAC penetrations between conditioned and unconditioned space with caulk or spray foam, or an approved putty material.

• Seal bottom plate and top plate of exterior walls and knee walls with caulk or sill seal.

• Seal band joists with caulk, spray foam or gasketing between top plate and band joist and between band joist and subfloor. Any penetrations in the band joist must be sealed with caulk or spray foam. Any joists or other cavities that span from conditioned to unconditioned spaces must be blocked off and air sealed.

• Block, cap and seal any chase ways that would allow unconditioned air to enter into the conditioned building envelope.

• Exterior walls behind tub and shower enclosures should be insulated. Prior to installing the tub or shower, a rigid, durable air barrier should be installed in direct contact with that insulation.

• Provide insulation wind baffle or other air barrier to block wind washing at all attic eave bays in roof assemblies with soffit vents.

• For cantilevered floor systems or floors above a garage, an air barrier must span the cantilever and any exposed edges of insulation.

• For fireplace cavities on exterior walls, a rigid air barrier must be fully aligned, with insulated framing in framed shaft behind fireplace and any gaps fully sealed with foam, caulk or tape.

• For porch roofs, a rigid air barrier must be installed at the intersection of the porch roof and exterior wall.

• For dropped ceilings, a rigid air barrier must be fully aligned with insulated framing, and any gaps fully sealed with caulk or foam.

• Recessed light fixtures (if installed in insulated cavities) should be rated IC (Insulation Contact) and airtight. Once installed, they should be sealed to the drywall with gasket, caulk or foam.

• All holes or penetrations in the building envelope should be sealed with a material capable of stopping airflow. Fibrous insulation does not stop airflow and will not be approved.

The finer points of air sealing. image courtesy of Southface

Sources for this checklist included Advanced Energy System Vision Guidelines, Southface Energy Institute Technical Bulletins, HealthyBuilt Homes program guidelines and Energy Star guidelines for homes and indoor quality.