Problem: Difficulty in operating a door or window.
Cause: Warp or distortion of frame.
- Allow a minimum clearance of 1/8 inch (3 mm) between gypsum board (drywall) and the window and door frames to minimize pressures on the frames. Avoid cutting back board after installation as this may damage sheet air barriers.
- Avoid distortion caused by unequal pressure around the frame by using precut cedar-shingle shims rather than scrap lumber and by spacing shims evenly.
- When using expansive foam to air seal around the frame, do not overfill the gap as this could exert pressures on the frame. Use one-component foams. Remember that the warmer the temperature the greater the expansion.
- Units are less likely to warp after installation if they are stored in conditions similar to those in the building they will be installed in. Avoid exterior storage.
- Brick expands with moisture absorption while framing shrinks.& Leave a 1/8 inch (3 mm) gap at the sides of the frame 1/4 inch (6 mm) under the sill and 3/8 inch (10 mm) under second-storey sills. If a sloped brick sill is used, allow additional space under the window. Caulk all gaps and back caulking with a compressive foam gasket as shown in Figure 23.
Figure 23 - Detail Sealing At At Brick Veneer
- Exterior sheathing can expand or warp with exposure to rain and sun. Set sheathing back from the rough opening, flash openings properly.
- Use pre-finished windows or protect wood frames from absorbing moisture by painting or finishing them shortly after installing them.
- To prevent downward sagging of the window frame, align shims and cripple studs with the setting blocks, if possible. Setting blocks are usually located at the quarter points in fixed units, and below the junctions of multiple units as shown in Figure 24.
Figure 24 - Support Locations For A Large Fixed Window
- Where exterior rigid insulation is used, install furring strips the same thickness as the insulation around the perimeter of door and window frames to provide adequate surfaces for fastening as shown in Figure 25. This also provides better backing for caulking and flashing.