Caulking air leaks AROUND WINDOWS AND DOORS

Gaps around window and door frames - namely between the frames and the rough openings - are a cause of significant drafts and air leaks, and should be properly caulked.

Note: Drafts in the movable parts of windows, doors and hatches should be weatherstripped (not caulked...).

Window Caulking vs Windows weatherstripping
Window weather-stripping involves the movable parts of the windows and materials like V-strips or adhesive backed tape. Caulking involves foams and several types of caulks and gaps in the rough opening and other spaces around the window structures.

Gaps in the windows rough opening

Air sealing and insulation do not coincide in their purposes... Insulation of the rough opening of the windows will not stop the air flow and air leaks.

There are very few insulation materials with good air leaking value. Common insulation materials - fiberglass and many others - will not stop air leakage (a problem demonstrated by well insulated attics without a proper air sealing).

Sealing the rough opening - or other gaps around the windows - demand air sealing materials (not insulation materials).

See: Weatherstripping windows and doors

Window and door rough openings

Rough openings (namely in windows) are typically 1,5 to 2'' larger than the window frame - to give the installer room to install, plumb and square the window. But that gap is often improperly sealed, and a cause of air leakage.

Contrary to common believe, many air leakage problems aren't in the windows but in the gap between the frames of the windows and their rough openings.

Sealing deep rough openings gaps

Rough Opening Around Windows and Drafts Wide gaps in the rough openings can be sealed with expanding-polyurethane foam. They are the best way to get an effective and long-life sealing in significant openings, rough surfaces and irregular cracks.

They will fill the whole gaps despite possible irregularities.

Since gaps are typically several inches deep, apply the foam in successive layers.

Caulking small window gaps

Small gaps (say, less than ½ inch wide) around the frames of windows and doors can be sealed with a good and flexible exterior-water-resistant caulk.

See: Air Sealing Products and Materials

Back rods

In deep gaps, use a backer rod between the joints: the roundness shape of the rod will create a thinner bead, giving flexibility and strength to the caulking.

Sealing loose panes of glass

Pay also attention to the glass panes issue. If they are loose in their frames, caulk them to avoid air leaking. In case of wood frames, there are many inexpensive putty compounds and glazing point solutions.

For metal and vinyl frames, use vinyl strips for a durable air sealing.

See: New efficient windows