The Guide identifies five key installation objectives that every installation must meet. The Guide does not advocate a single installation method. Instead, it provides example installation details that satisfy these installation objectives for a variety of wall types, existing window frame types, replacement frame types, and exposure conditions.

1 Determine Rain Exposure Conditions

The Guide shows how to identify which windows and doors are most vulnerable to exposure from driving rain and therefore require more robust water penetration control, based on the extent of overhang protection, the location of the building, and the surrounding terrain.

2 Develop an Effective Water Penetration Control Strategy

The basic objective of every replacement installation is to make the installation at least as good as the existing situation, and if possible, to improve on deficiencies in the existing situation. The Guide shows how the sound principles of a first and second plane of protection, required by the building code, can be achieved in every installation.

3 Ensure Air Barrier Continuity

Airtightness is not only important for energy efficiency and comfort - it is essential for effective water penetration control. Ensuring air barrier continuity between the existing wall assembly and the new window or door is a key aspect of all installation details.

4 Minimize Condensation Risk

Most non-metal replacement windows have significantly greater condensation resistance than the windows they are replacing. Detailing that minimizes thermal bridging and air leakage, and locating windows closer to the interior wall surface are among the measures that mitigate condensation risk.

5 Provide Structural Anchoring and Support

The appropriate anchoring and shimming of windows can be product-specific and are therefore dependent on the manufacturer's recommendations. The Guide addresses the general principles, but does not provide details for all conditions.