Weatherization/Installing or replacing doors and windows

Installing or replacing doors and windows
When choosing new doors and windows:
 * Replace solid core external doors with metal-clad, foam-core doors or fiberglass doors.
 * Replace drafty single-glazed windows with efficient, low-E, double-glazed, insulated windows. Krypton is more insulating than argon, but windows with krypton cost more.
 * Avoid metal-framed windows. Replace steel or aluminum windows with a wood, vinyl, or fiberglass windows.  If you must buy a metal-framed window for some specific reason, make sure that there is a thermal break separating the inner half from the outer half.
 * If you can't afford new double-glazed windows, keep your existing windows, and install year-round storm windows on the outside. You can open them and insert a bug screen in the warmer months.  Alternatively, you can shrink-wrap polyethylene on the windows in the colder months with a hair dryer to trap air, you can install low-E film on the window panes, or you can install an "interior insulating window".
 * In the attic, install double-glazed windows with built-in venting around the frame, so that you can close the windows in cold weather without stopping air from flowing through the attic.

When installing new doors and windows:
 * Seal the gap between the window casing or nailing flange and the sheathing by applying a bead of exterior-grade caulk before attaching the window to the framing studs.
 * Seal the gap between the window or door framing and the framing studs (the rough opening).
 * Make sure new windows and doors have drip caps (flashing) above them to keep water away. If there are no drip caps, install them while installing the windows or doors.
 * Be aware that all multi-pane windows will eventually lose their air-tight seal. Fog that appears on the interior of the window (between the layers of glazing) is an indication of leakage.