In most residential construction, window openings are already framed out with wood in order to use nails or screws to attach the window in place. If an adjustment to the opening is needed, keep it as close to the window size as possible. Allow about a 1/4 inch gap on all the sizes for adjusting. With log homes, the logs tend to settle or shrink over the years. Therefore a window jamb or a frame must be installed that won't shrink. Slides connect the sides of the frame to the log. In this way, the logs are able to move and shrink as they age without disturbing the window.
Windows should be installed from the outside in. Push the window inside until the band of flashing around the window is flush to the framing around the window opening. Once the window is placed in the opening, the person inside should check that it is plumb and level.
Flashing band should then be installed around the window on the outside. The flashing should be nailed into place. The person inside should then shim between the window and the framing to keep the window in place (Image 1, Image 2). Shims are used the level the window. Shims can be glued into place or tacked with a trim nail.
With the window shimmed, plumb and secure, it can be secured with nails from the outside (Image 1). The excess wood on the shims can be trimmed away using a flush-cut saw. Insulation should then be packed into the gaps between the window and frame. Fiberglass insulation (Image 2) works more efficiently for windows because it better helps prevent any air from escaping.