sealing exterior walls

It's important to seal all air leaks in the exterior walls, including openings associate to plumbing pipes, HAVC equipment or electrical conduits and fixtures... Sealing the gaps and holes in the exterior walls is crucial for energy savings.

Fiberglass and other common insulation materials do not stop air leaking in exterior walls. The exterior walls should benefit from appropriate sealing... That includes structural air sealing based on air barriers (and vapor barriers or retarders in wood and steel frame homes in freezing climates) and also adequate caulking of the several small openings and holes...

Types of gaps and holes in exterior walls

Your outside walls may have an unexpected number of holes. Check the walls for holes associated to....

- plumbing pipes and vents;
- electrical conduits, fixtures and wires;
- dryer ducts;
- exhaust fans;
- trims of windows
- heating and cooling equipment...

Sealing Dryer Vent with a foam (Dow)

Holes may have been drilled through the top and bottom plates and are in this case difficult to access.

But their sealing is of paramount importance. Since many holes and gaps in top and bottom plates areas (of wood frame construction) are very difficult to access, the ideal time to carry out the sealing is during the replacement of the floor covering or during the painting of the walls... See: Sealing Sill Plates and Rim joints

Sealing Exterior Wall Penetrations

Sealing Exterior Walls from both inside and outside

Sealing an exterior wall with a foam from Dow

Caulking penetrations through the exterior walls - associated to plumbing pipes, electrical fixtures or conduits... - should be done from both the exterior and interior.

Use proper caulks: flexible and water resistant when applying the caulk from the exterior.

sealing exterior walls around windows

Gaps in the exterior walls can also be associated to windows; in that case, you should remove the interior trim and fill the rough opening with a non-expanding foam. Alternatively, use a backer rod and a good exterior-flexible and fire-rated caulk.

sealing connections in common walls

Common exterior walls between apartments, townhouses and duplexes should be air-tightly sealed and shouldn't be a source of air leakage as it happens so many times. The assembly should be air sealed at all boundaries.

To seal the connection between wood frame walls use spray foams. Masonry block walls are often sealed with two-component spray urethane foam. Both foams should be fire-rated.

This is often a technical work, that should be performed by experienced professionals, paying attention to local codes.

Structural sealing

The exterior walls of frame wood construction should be protected from the wind, the chimney effect or the pressure of the HVAC/ventilation equipment... Sealing penetrations and gaps is not sufficient per si. The walls will not withstand the pressures of the elements without structural air sealing. Insulation materials will not prevent air leakage through home cavities... Only air barriers can prevent it... Air barriers are, in wood and steel frame homes, a key element of exterior wall sealing.