Blog > Category > Posted: 2023-Nov-16, Updated: 2024-Mar-13

Installation - Full-Frame Window vs Pocket Replacement Window

When considering window replacement, there are various options to explore. This article aims to delve into the distinctions between full-frame window installation and pocket window installation.

Full-frame window installation

A full-frame window replacement involves the complete removal of the existing window and frames, down to the studs. This comprehensive approach, widely adopted by window replacement services, ensures the revelation of any hidden issues or subpar installation practices. The process entails replacing the entire frame and window, offering a thorough solution that minimizes potential negative impacts on your home for years to come.

Pocket replacement window installation

In contrast, a pocket replacement window installation, also sometimes known as:

  • pocket insert installation
  • retrofit window installation
  • sash-only replacement
  • snap-in window replacement
  • insert window replacement

This replacement method retains the existing window frame and sills. It involves inserting a full window/sash and window frame into the opening. While this method may provide cost savings in some cases, it is typically reserved for situations where preserving the existing outside/inside window frame, trim, or siding is crucial for maintaining the home's styling character and aesthetics.

To execute a pocket replacement, the window sash (including panes), tracks, and stops must be removed, down to the window frame. The success of this installation method relies on ensuring that the existing window frame is square, plumb, level, free of rot, and in good condition. Special installation steps are necessary to meet current standards.


When replacing existing windows, it is crucial to consider issues beneath the surface that may not be immediately visible. A window may appear functional, but underlying problems such as a deteriorating or rotten frame, lack of insulation, trapped moisture, mould, or insect infiltration could exist. Windows, exposed to internal and external elements, may suffer from deficiencies impacting their integrity, performance, and durability.

Balancing insulation is essential, as excessive insulation can impede natural expansion and contraction during extreme temperatures, leading to warping, misalignment, and operational issues. Conversely, inadequate insulation may result in condensation, moisture buildups, cracked caulking, and drafts.

Characteristics of a pocket replacement window:

  1. Preservation of Existing Frame:
    The existing window frame and surrounding trim are not removed. They are retained, and the new window unit is inserted into the space.
  2. Condition Requirements:
    For a successful pocket replacement, the existing window frame should be in good condition, square, plumb, and level. It should also be free of rot or other significant damage.
  3. Aesthetic Considerations:
    This method is often chosen when the existing outside/inside window frame, trim, or siding is unique or integral to the home's character, and replacing it would negatively impact aesthetics.
  4. Cost Savings:
    Pocket replacement windows can be a cost-effective option compared to full-frame replacements since there is less labour involved in preserving the existing structure.
  5. Procedure:
    The window sash (including panes), tracks, and stops are typically removed, leaving the original frame intact. The new window unit, including the frame and sash, is then installed within the existing opening.

A word of caution

In most cases, a full-frame installation is deemed the optimal solution for window replacement. While pocket replacement windows have their advantages, it's important to note that they may not be suitable for all situations. The decision between pocket and full-frame replacement often depends on factors such as the condition of the existing frame, aesthetic considerations, and the desire for energy efficiency. It's recommended to consult with a professional window installer to determine the most appropriate solution for your specific needs.

Related topics

Diagram - Anatomy of a window (interior view)

e-book - Almost everything to know about windows

Diagram - Anatomy of a window (exterior view)

The ins and outs of window grills

How to ensure a successful window purchase

Infographic - Window installation - What to expect

Need more information?

If you would like to know more about whether full-frame or pocket window replacement is right for you, give us a call or send us a request for more information. We’d be happy to address all of your questions or concerns.

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