Weatherstrip windows around the sash to reduce air leakage. If the windows do not have to be opened and do not serve as emergency exits, they can be locked and caulked. Where storm windows are installed, seal the inside window more tightly than the outside window to reduce condensation problems.

TECHNICAL NOTE

Building codes require that every bedroom have at least one window that opens from the inside to allow escape in case of emergency. Be mindful of this requirement before deciding to seal shut certain windows."

Many types of weatherstripping are available. Table 3-4 lists some of the more common varieties of weatherstripping, though it is certainly not an exhaustive list. Try to visit a window and door supplier that stocks a wide variety of original manufacturer products. For newer windows with built-in weatherstripping that has lost its effectiveness over time, pry out a sample and take it to the window manufacturer or supplier for replacement with the same type. Cheaper products are usually less durable and less effective, so do not choose merely on the basis of cost.

Preparation and installation are important and typically involve the following steps:

• Try to adjust and square windows that are out of alignment.
• Remove old weatherstripping, caulking and blobs of paint from contact surfaces. If the surface is very uneven, apply a bead of caulking under the weatherstripping or fill, sand and paint the surface to make it smooth.
• Clean the surface with a clean cloth and fast-drying mineral spirits or MEK (methyl ethyl ketone).
• Apply the weatherstripping. With doors and windows that are used often, you may want to reinforce the adhesive types with staples.
• Check the window for smooth operation and ensure all hinges, slides and hardware operate freely and correctly.
• Periodically check the weatherstripping for wear.

i) Double-hung and single-hung windows

Double-hung and single-hung windows should be weatherstripped on the sides, top and bottom of the moving sash, as shown in Figure 8-5. Caulk air leaks around the fixed portion of the window.

Sides

The thin plastic V-type weatherstripping is a good choice. Open the window and slip the stripping up the crack between the sash and the frame, with the mouth of the V facing the exterior. It need only extend to 25 mm (1 in.) above the top of the closed window. You can do a better job if you first remove the stop and the bottom sash.

Top

Weatherstrip the space where the two sashes meet by removing the lower sash and applying V-type weatherstripping to the upper window from the inside.

Bottom

Apply V-type or compression-type neoprene rubber to the windowsill where the closed window will sit or to the bottom of the moving window sash itself.

ii) Sliding windows

Sliding windows with sashes typically use brush weatherstripping that will require removing the sash and pulling the old weatherstripping out of its slot. Cut the new material to the length required and snap or slide it into the slot. Tack, staple or glue each end of the brush material to ensure that the weatherstripping stays in place before reinstalling the sash.

Sashless sliders - panes of glass not encased in a frame - are inefficient. At the very least they should be supplemented with interior storm windows. Better yet, replace them with energy-efficient units.

iii) Swing-type (hinged) windows

Swing-type (hinged) windows are treated like doors. Apply weatherstripping to the frame so it meets the edge of the sash or place it on the stop where it will meet the face of the sash. The force of a closed window against the weatherstripping makes a pressure seal. Hinged windows usually require a combination of V-strip and compression-type weatherstripping. Hinges and locking hardware may complicate the job. Sometimes, more than one weatherstrip will therefore be needed in those areas.