Replacement Window Installation Methods

“The bitterness of poor quality remains long after the sweetness of a low price is forgotten” – Benjamin Franklin.

The quality of your window replacement installation is as important as the quality of the Vinyltek Replacement Windows. In our wet coastal climate, if your new vinyl windows are not installed properly, they could leak, create drafts, and you might even need to replace them again. We pride ourselves in having all of our crews registered and certified with the Window Wise National Program.

There are various methods of replacement window installation used in the Vancouver region, with differing levels of cost, quality and performance. Like many things, you most often get what you pay for.

Three of the most common window installation methods are: Piggy-Backing, Full Window Replacement Using a Rebate Flange and Full Replacement Using Nail Flange. Window installation contractors generally use some variation of these methods.

PiggyBacking Window Installation

This method is most typically used for replacing aluminum-framed windows. It involves removing the glass, the opening window, and any mullions (dividers), then placing the new window frame on top of the existing aluminum frame (hence the name piggybacking).

Once the window is in place, the installers caulk a rebate flange to the outside of the old frame to fit around the exterior of the window. They then screw the window into place through its frame and into the rough opening.  It’s important that they foam the interior around the gap between the new frame and the drywall and sills. The foamed gap will need to be covered with wood trim. Ideally a pan flashing will also be installed along the sill.

Installation Advantages

  • Quick and easy installation.
  • Doesn’t disturb the exterior stucco or siding.

Installation Disadvantages

  • Not as thermally efficient as other methods because a portion of the cold metal frame remains buried in the wall.
  • It’s difficult to properly support the weight of the new window.
  • New windows must be made smaller to fit over the existing frame.
  • Dependent on caulking for the water seal.
  • Does not meet The National Building Code standards.

Full Window Replacement Using a Rebate Flange

In this method the installers remove the entire metal frame except for the nail-flange, which is detached from the window without damaging the exterior siding or stucco. Prior to the installation of the new window the installers may add a pan-flashing on the sill. If the window is not directly protected by an overhang, they should also flash the head. Well-equipped installers will have a portable bending-machine to custom fabricate flashings.

They then install the new window and screw it into place through the frame. Usually, installers use special expanding foam to ensure the window is airtight in the rough opening. Alternatively, they may put a foam rod around the interior of the window to insulate and prevent drafts. Most installers use high quality caulking on the interior and exterior as a final step.

Installation Advantages

  • Relative ease of installation that doesn’t damage the exterior.
  • Allows for proper shimming and support of the new window.
  • Not dependent on caulking for water and air tightness.
  • Allows for installation of flashings.

Installation Disadvantages

  • New window will be slightly smaller than the previous window but larger than in the    piggybacking method.
  • Quality of flashing installation is dependent on the ability and equipment of the installer.
  • Installation requires more time and is therefore more costly.

Full Window Removal Using a Nail Flange

This installation practice is the most involved, but is also the closest to construction practices for a new window.

The installers cut the siding or stucco of the home back to allow for the removal of the entire window, including its nail-flange. They may also remove the interior drywall on the window jamb. They then install the new window, fasten it with a nail-flange, install flashing and seal it. They should use expanding foam to minimize air leakage. They will have to install exterior wood trims around the window, or the stucco will have to be patched. If they removed interior drywall, new wood sills, liners and casings will have to be installed. Some caulking will be required on the exterior.

Installation Advantages

  • Most likely to resist weather related problems.
  • The windows will be the same size as the existing windows.
  • Exterior and interior trims can enhance a home’s appearance.

Installation Disadvantages

  • It requires disturbing the exterior siding or stucco.
  • The installers need to be more highly qualified.
  • It’s the most time consuming and costly window replacement method.