Window Installation Process

When installing or upgrading your windows you have two common installation methods to choose from, Nail-On, also known as New Construction, and Retro-fit. If you aren’t sure which method is right for you don’t worry, at SCCCI we will help you to determine the best option for your home.

Nail-On or New Construction

Retrofit window installationThis has become much less popular for all homeowners who desire a quick, damage free, dust, dirt and debris free installation. Nail-On windows require the pulling of or removal of the existing frame in its entirety. This requires interior drywall/plaster damage as well as exterior siding/stucco demolition. Furthermore, it results in the existing moisture barrier being removed and subsequently replaced. For newly constructed homes or homes in the process of being built this installation method is highly recommended. You may ask, Why? The exterior and interior finishes are not typically completed until after the windows are installed, moisture barrier is completed and the city has signed off the permits (required whenever doing a new moisture barrier). Therefore, there is no damage done to the exterior or interior. In addition, as far as mess and debris, we all know that it is common with new construction and building. It is important to note that a Nail-On type of install will ultimately give you more actual glass vs. frame. Others say a benefit to this type of install is you don’t have the replacement flange or the frame piece that covers the gap of a Retro-fit Installation.

Summary of Nail-On/New Construction : Unless you are building a new structure and/or are okay with excessive dust, dirt, debris and interior/exterior damage and a more drawn out installation, this method should not be your choice.


Retro-fit Window Installation diagram

Retro-fit Window Installation diagram

Windows are installed into existing openings using existing moisture barriers and the existing structural ‘header’. This method seems to be the predominant installation method being chosen by most homeowners as well as contractors. The Retro-fit method is quick (typically up to 8 openings in a single day) and hassle free in that it does not require exposing the existing 2” x 4” structural framing thus, not requiring a city inspection because the moisture barrier has not been disturbed. Best of all, since it doesn’t require the breaking out of interior plaster or exterior stucco/siding you do not have to redo your blinds, shutters, painting, wallpaper, etc. Essentially, the window is measured to fit perfectly square into your existing opening. *This does result in approximately 3” all the way around the window of less glass space, since the window and frame are being custom manufactured to fit into the existing frame. The window unit is leveled square into the opening and secured into the frame. All gaps should be insulated and make sure the finish moldings (both interior and exterior) are included.

Common Problems you can run into:

  • Windows are measured improperly resulting in too large or small of a window, which means having to make it fit via enlarging the opening or reducing the size of the window. Both are not efficient or recommended. Typically if too large, the window may bow or bend making it difficult to open or close and in some cases glass may crack or the locking mechanisms may not engage properly. If too small, you lose even more glass space and gaps are too large to efficiently insulate resulting in these areas becoming common drafty areas. The best windows can become inefficient if no measured properly.
  • Windows are secured into the opening improperly resulting in the window being too loose. If you don’t use enough screws (typically one every 18”) the window will rattle, appear loose in the opening and/or become prematurely damaged.
    Note: It is typical to have a small (¼“ – ¾“) gap between the frame of the Retro-fit unit and the frame of the old existing window being retrofitted. A common short cut is to not shim that gap allowing the screw to be in a space with no grab vs. using a shim or block to have grab all the way through to the 2” x 4” framing.
  • Many installers believe it is best to tighten the screws all the way, this is not proper. You must ‘back off’ the screw to eliminate the frame from bowing (if tightened all the way). When a frame bows the window becomes more difficult to open and close and more difficult to lock and unlock. In addition, ‘backing off’ a screw allows for normal expansion and contraction within the opening allowing for a window to last a lot longer.
  • Use of substandard or improperly installed caulkings that perform inadequately; they dry out, crack and simply put they don’t perform as is needed and designed. On a Retro-fit window with a replacement flange caulking should be applied in an ‘S’ shape on all 4 sides of the flange (top, bottom*, left and right). Note: Space caulking is mandatory, not recommended it’s required. In addition a full bead of caulking should be applied as a finish bead along the edge (between the existing stucco/siding wall and the window replacement flange).
  • *Space Caulking – A gap approximately 3” in width should be left at each and every weep hole in the window. At the bottom of the window, weep holes allow the water runoff to exit the track. If a window has had caulking applied with no spacing or gaps at these weep holes it could, and usually does, trap moisture which can then lead to stucco problems, rotting siding, decaying or interior damage to paint, plaster or wallpaper. Even worse it is even a breeding ground for moss, mildew, fungus and mold.
    This is a mistake made from a lack of knowledge and/or training not normally done to save the few pennies that you will save if done initially.

SCCCI has 25+ years in business as a Los Angeles exterior painter, window installer, insulation contractor and vinyl fence installer. We are based in Chatsworth, CA and serve the Greater Los Angeles Area including the San Fernando Valley, Simi Valley and Ventura County.
We have earned many credentials from highly valued services including the Better Business Bureau, League of California Homeowners, and more. Our company has been under the same license number (#492512) for our entire existence as a company under the Contractors State License Board. View our license info here. Click to view our proof of insurance. Read more about our credentials here.
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SCCCI - S. CA. Construction Consultants, Inc.
9960 Canoga Ave. Suite D1
Chatsworth, CA 91311
Local: (818) 534-0600
Toll-Free: (800) 413-3333
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