Types of Window Installation

There are two types of installation for replacement windows and doors:


Retrofit involves the installation of a new window into the frame of the window that is being replaced. It is usually less expensive and minimizes the disturbance to the surrounding wall and trim. It can also reduce the glass area of a window by about 20 percent. Such an installation is possible only if the existing frame, framing, siding and drywall have no deterioration and are properly sealed and insulated.


Two types:

  • a) reno/stucco flange – old frame is cut out leaving the original nailing flange. (Building envelope is cut.) New window is slipped in.
  • b) “piggy back” – perimeter of old frame is left in place (glass & centre bar are removed). New window is mounted inside the old frame (reduces glass size the most)

Pros – faster & cheaper installation (requires less skilled workers)

Cons – easily recognizable as retrofit windows, smaller window sizes, rely on caulking for weather seal (not properly connected to the building envelope). Mold, mildew or even rot may still exist undiscovered on old window frames and inside the framing of the structure. Not approved for new construction or renovation/replacements requiring a permit.

Complete tear out:

This involves removal of the old window including the frame. Because the installer can create a completely airtight insulated seal between the product and the rough opening, this type of installation is recommended (by architects, inspectors & professional contractors).


Pros – windows look like they belong inside and out, original / large window sizes, “peace of mind” (rot/mold/mildew issues can be resolved), building envelope can be maintained & improved (the most important barrier against water/air leakage), windows be fully insulated to allow for maximum window performance in all seasons. Approved for all applications whether permitted or not.

Cons – slower and more expensive (requires experienced / professional installers)

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