How To Choose Your Window Installation Company

The most under-appreciated drivers of comfort, energy efficiency, and longevity when replacing windows, is the installation method and expertise of the installer. Improper window installation robs homeowners of the performance their products should deliver and that they paid for. A nationwide single and multi-family building inspector estimated that 80% of problems with windows are associated with the installation.

Notwithstanding the horror stories that are all too easy to find, we as homeowners tend to focus on what replacement window to buy but take for granted that the windows will be installed the right way. Or we close the sales with the in-home sales person and never see the installation crew until the old windows are being removed. Immediately after the installation, a poor job could be “invisible”.

In short order, the caulk used for your replacement windows will open gaps and allow moisture to attack the foam and other materials used to “seal” the window. Depending on the installation, moisture can infiltrate the wall and cause significant damage to the framing and drywall that will be discovered only after the damage is done and expensive to repair.

Protecting yourself is not hard. The most widely known and trusted certification for window installers is InstallationMasters™ founded by the American Architectural Manufacturers Association. The course takes one and one-half days and cost just $350-400. Once certified, the installer is given a card to prove their competency. Given the low cost and minimal time commitment, we strongly recommend you demand to see this certification and accept nothing less when choosing an installer for your replacement windows.

Part of the InstallationMasters™ certification specifies the use of nailing fins, in addition to through jamb connection to the house framing, whenever possible. In addition to another point of attachment to the home, the nailing fin provides a surface for protective flashing to be applied to the window, directing moisture away from the interior. There are replacement windows that are manufactured without nailing fins. It takes significantly more time to attach a window and properly seal it (the InstallationMasters™ approach) than to slide one into the opening, screw it in place, and use foam and caulk as the only lines of air and water defense. Since time is money, fast beats quality, particularly if homeowners are not aware of the inherent compromise.

Proven Expertise

In addition to certification, experience is key. Checking references is a must and relying on the aforementioned InstallationMasters™ certification will help. Beyond that, ask if the installation crew has a current job underway. If so take the time to visit the job and talk to the owner. Trust your eyes. Is the work neat and organized? Are the home’s furnishings well protected? Would you feel comfortable with the installers in your home? Lastly ask for proof of general liability and workman’s compensation insurance. There are smaller, high quality installation companies that do not have workman’s compensation but don’t allow anyone to work on your home who does not have general liability insurance.


Window companies fall into one of two warranty approaches. The large replacement window companies and most of the vinyl world offer a lifetime, sometimes transferable, warranty on the product and labor. Since lifetime is a theoretical target and not a statement of true product life cycles, these warranties are written with the support of actuarial experts who calculate the frequency of validated warranty claims to determine their level of acceptable warranty exposure.

The other approach is ten years on product and twenty years on glass seal failures. This approach has its roots in the large window manufacturers who built their businesses serving contractors and their new construction and remodel projects.

Which warranty, depends on how you look at the difference between lifetime and life cycle. As a practical matter, we don’t believe there is a big difference at the product level and, if the installation is of high quality, the labor warranty term will be less important.

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