Inspecting a Home with New Replacement Windows?

Be Sure to Take a Very Close Look

by Greg White June 1, 2017

In the spring of 2016, a homeowner contacted me to inspect a replacement window installation in her home and provide my professional opinion. She was dissatisfied with the installation, stating that her new vinyl window installations were being held together by “just a few screws and some caulking.”

Windows and doors are the main penetrations in any building envelope system. As such, they usually are key contributors to water intrusion and invisible underlying structural damage in the home because the installations may have failed or may not have been installed incorrectly (that is, not “up to code”) in the first place.

As a main facet of construction, window fenestrations are so important that the International Energy Conservation Code (IECC), the International Residential Code (IRC), the International Building Code (IBC), the American Society for Testing and Materials (ASTM) and the American Architectural Manufacturers Association (AAMA) all have regulations regarding their system designs and installations. However, the way in which people interpret these specifications can vary greatly.

ASTM and AAMA are two organizations that determine the window industry standards, but they are not responsible for enforcing them. Enforcement is the responsibility of the local building official. Sometimes the lengthy proposed specifications end with a statement defining “approval” as follows: “Should the manufacturer’s installation instructions (provided with the product) conflict with the requirements of this practice, the manufacturer’s instructions shall prevail.” This type of general statement leaves one to wonder whether industry standards can be enforced legally and, if so, what recourse a homeowner would have if the window installations fail.

To address my client’s situation, I looked up the manufacturer’s installation specifications for the new windows that she’d had installed, along with pertinent regulations from ASTM, AAMA, IBC and IRC.

Here’s what I found:

  • Section R612.1 of the 2012 IRC requires that “windows and doors be installed in accordance with the fenestration manufacturers’ installation instructions and flashed in accordance with Section R703.8.”
  • Section 1405.4 of the 2012 IBC requires window openings to be flashed “in such a manner as to prevent moisture from entering the wall or to redirect it to the exterior.”
  • Section R703.8 of the 2012 IRC gives more specific provisions for the installation of flashing around the window. It
  • requires that flashing be installed in shingle fashion, in such a manner as to prevent the entry of water into the wall cavity or penetration of water to the building structural framing components, and that the flashing is to extend to the surface of the exterior wall finish or to the water-resistive barrier for subsequent drainage.
  • Both the 2012 IECC and 2012 IRC require that replacement windows comply with the regulations.
  • Definition AC148 (IBC) defines flashing as follows: “1.3.1 Flashing: Sheet material, integrated with the water-resistive barrier that bridges and protects the joint (gap) between the window or door frame members and the adjacent construction for the purpose of preventing water penetration by draining water away from the window or door.”

I noticed that, unfortunately, very little emphasis is given to “non-flanged” windows, which are becoming the prevalent choice for vinyl window replacements. There are numerous flashing specifications regarding flanged windows (that is, the kind with nailing fins) to ensure that water intrusion will not occur after their installation, but little to no specifications are available when it comes to the non-flanged replacement windows that are not from the original manufacturer (for which, according to ASTM and AAMA, manufacturer’s specs take precedence).

For the windows that my client had installed, the manufacturer’s specifications started with this statement: “Follow your local building codes, customs and building practices for additional installation requirements. The manufacturer will accept no responsibility for air or water leakage above, under or around the window unit. These instructions are general in nature.”

The specifications also described a requirement to use four screws (one at each corner) for fastening. There was no guideline for any flashing at the perimeter or sill. There was, however, a note regarding spacing measurements, which this window exceeded.

These are the types of “manufacturer specifications” that would take precedence over those established by the industry’s standard councils and committees that have been authorized to set the standards for the
interests of the owner or the purchaser, without enforcement.

Home Inspectors Can Provide Clarity
As home inspectors, we can be a great asset to our clients by applying extra focus on window types, life expectancies and installations. We also can point out potential ways that replacement windows could fail in our reports. For example, home inspectors should identify “sill pan flashing” installations—specifically, whether they exist or not. Having this type of flashing alone (assuming that it is installed properly) can ensure that water intrusion is directed to the exterior.

Because purchasing and installing new windows is a tremendous expense, our clients will appreciate having our expertise and our ability to address their interests.

The owner provided me with Photo 1, which she took when the windows were being installed. The installer used a reciprocating saw to cut around the window frame, separating the old window from the nailing fin, and from the substrate and the existing weather-resistive barrier and the flashing system. Then the installer set the new, non-flanged window on the raw framing of the opening and attached it with two screws: one placed at the upper left jamb and one placed in the head frame of the window, using small blocks of wood for spacers. The installer then “caulked” the ½-inch to ¾-inch space at the perimeter with silicone without using a backer rod to support the sealant and without adding any additional fasteners.

Doing the Research on Window Installation and Pan Flashing Regulations
To become more familiar with my client’s situation, I reviewed the regulations to become familiar with the following important points:

  • With the front flange turned down, the leg can be placed over the sheathing and the weather-resistive barrier, but more effectively, it can extend out and lap the exterior siding or veneer. The rear vertical leg (or back damn) is typically visible at the interior, extending past the back edge of the window frame. Installers often will replace end damns (side damns) with a bead of sealant that is not long-lasting, allowing water migration into wall cavities.
  • ASTM E2112-07 defines pan flashing and recommends its use “under all windows and doors, except where wall construction details incorporating fenestration drainage systems are provided by the building designer, or where wall construction details are specifically provided by fenestration manufacturers’ installation instructions.”
  • 3.2.91 pan flashing, n—a type of flashing used at the base of a rough opening to divert incidental water to the exterior or to the exterior surface of a concealed WRB. Note: Pan flashings have upturned legs at the interior edge and at the ends of the rough opening to form a three-sided pan. They are intended to collect and drain water toward the exterior, including water that may enter through the window unit (for example, between the jambs and sill) or around the window (between the rough opening and the fenestration). The pan flashing must be integrated with other flashings and the window assembly to capture water that may otherwise penetrate to the sill framing and allow it to freely drain to the exterior. The window, flashings and pan are to be sealed in a manner that reliably inhibits air and moisture flow to the interior.
  • 5.16.3 Use of Pan Flashings—This practice recommends that pan flashings be used under all windows and doors, except in situations for which wall construction details incorporating fenestration drainage systems are provided by the building designer, or for which wall construction details are specifically provided by the fenestration manufacturers’ installation instructions. Where used, pan flashings shall be integrated with the wall’s weather-resistive barrier in shingle-lap fashion. The pan flashing shall be continuously sealed to the weather-resistive barrier. Note: Pan flashings may not be applicable for certain installations (for example, surface barrier systems, window receptors or pre-existing installations).
  • ASTM defers to the manufacturer in case of conflict: 1.5. This practice provides minimum requirements that will help to accomplish the installation of fenestration products in an effective manner. Actual conditions in buildings vary greatly, and in some cases, substantial additional precautions may be required. In the event that the manufacturer’s installation instructions (provided with the product) conflict with requirements of this practice, the manufacturer’s instructions shall prevail. This practice is not intended to limit or exclude other new procedures that may refine or further improve the effectiveness of the fenestration installation.

Taking a Close Look at the Client’s Window
Usually, by taking a close look at the window sill-jamb interface at the interior (photos 2-4), I will get some insight as to whether a sill pan flashing was installed. A properly installed sill pan flashing’s upturned leg should be visible at the bottom of the interior window frame and should be caulked to prevent water intrusion to the interior. When I took a close look at the replacement window in my client’s home, I noticed that it was set on the wood framing of the raw opening with a piece of wood trim placed against the window sill and then caulked where the wood met the vinyl frame. In other words, there was no sill flashing.

As I inspected the outside of the window sill-jamb interface, I could see that the siding trim, both jamb and sill members, had been incorporated within the window installation. I performed an AAMA 511 sill damn water field test to see if either the sill or jamb interfaces leaked. Both the left and the right sides leaked water. Oftentimes, window-sensitive “welded” (or fastened and sealed with sealant or gasket) sill-jamb or head-jamb interfaces become damaged when products are shipped from the manufacturer to the window company or during delivery from the window company to the job site (or even during the installation itself).

A worker hired by the homeowner removed the window I was inspecting so that I could verify and document the poor attachment and lack of flashing. At removal, it was visible to me that no flashing had been incorporated with the install (nor did the manufacturer’s specifications require it). Water leaking at the sill-jamb interfaces, which was apparent from the results of the sill damn testing, easily entered the structural framed wall interior through a cracked sill that was damp and water-stained. This window installation depended entirely on the added, failing sealants to prevent water intrusion and, most likely, it would not have passed a wind load ICC spec test because it was held together with only two screws.

Sharing the Report with the Client
It was apparent that water easily could enter the interior wall under these circumstances, which then would lead to structural damage, interior cosmetic damage to drywall and paint, plus possibly create a health hazard related to mold growth. This window installation relied on its sealant application, which was, at a minimum, lacking good adhesion properties and supportive backer rods. In addition, there was no apparent flashing integration between the weather-resistive barrier or the sill pan flashing installation.

From everything I had learned about window installation, it seemed that the degree of fault for this failure that could be placed on the window company or the installer was marginal, because of the ordained committee and council regulations that refer back to the precedence of the manufacturer’s installation guidelines, which, in this case, obviously lacked the inclusion of industry standard requirements, leading to confusion about liability issues.

I explained all of this to the homeowner, who was in disbelief and appalled at the lack of protection offered by the regulating agencies. Performing this inspection made it clear to me that I should look closely at all new replacement window installations in every home that I inspect. Also, this case confirmed my certainty that I should report all findings (good or bad) to the owner or prospective new owner to protect their interests and provide much-needed information regarding how to prevent potential water damage.

As I reviewed information related to this case, I also uncovered this conclusion made by the U.S. Department of Housing and Urban Development in the results of a study published in 2006: “The risk of water intrusion can be reduced by using durable pan flashing/sill protection products, in conjunction with other water management techniques. In addition, the first cost of pan flashing/sill protection installation is worthy of consideration given the potential costs of structural damage, mold growth, remediation work and litigation. An estimated average first cost for a home with 15 windows is $150 for materials and $175 for labor, for a total of $325, or $21.67 per window.”

Because the expense is minimal for sill pan installation, it seems as though it should be incorporated into every window and door install specification.

I also learned about a 2015 class action lawsuit brought by a group of homeowners against a window company in South
Carolina. The plaintiffs’ experts alleged that the windows relied on other sealant materials in or over sill joints to prevent the intrusion of water—the resulting joints were incapable of preventing water intrusion over the long term. Because investigators found mold growth owing to water intrusion, the decision was made that the cumulative defects impaired the effectiveness and performance of the windows, rendering them unsuitable for the purposes for which they were sold and warranted.

Replacement windows are expensive, averaging $450 to $1000 each, including labor and materials. This can easily add up to $10,000 to $25,000 for an average home, without adding the possibility of costs needed to address a health risk and its adverse effects, as well as the potential added expense of containment and removal.

Greg White began his career as a residential contractor for 15 years, then worked in commercial construction, which led him to become part of a specialized team of engineers who investigated and tested materials. He and his colleagues were at the forefront of the discovery of window design failures that affected exterior building envelopes and water intrusion. Their work in the field of water-testing methods eventually assisted in the development of guidelines acknowledging the need for adding sill pan flashings to specified window installation details. White resides in northwest Arkansas, where he works as a building envelope consultant, a certified commercial building inspector and a property condition assessor. Visit his website at www.gregwhiteconstruction.com/.

Sound Advice for Home Inspectors
If you are not already placing extra focus on building envelope fenestrations (windows and doors, primarily), I hope that reading about this case will increase your awareness. By pointing out issues related to window installations, you can help save your clients money and build their confidence in your ability and expertise. Poor window and door installations mean water intrusion and, quite possibly, costly structural damage, as well as consequential health hazards related to mold growth in walls, interiors or both. 

In the consulting world, we have a saying, “There are only two kinds of windows—those that leak from the beginning or those that leak later.” Placing a simple sill pan flashing under windows and doors can make any installation complete. 

 


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