Forensic Engineers and Consultants

Archive: Water Damage

Construction Techniques to Prevent Water Penetration at Windows

Windows, and their interface with the exterior walls, are an important part of a building’s envelope that resists the intrusion of water. Most builders take many precautions to protect a house from water damage. One of the most important factors in keeping the water out is the installation of window flashing, a thin material that prevents water from seeping in around a window. Over time, even a tiny gap around a window that allows water to enter can result in fungal growth, wood decay, and structural damage that can end up requiring costly repairs.

Expensive water leaks correlated with windows can often occur between the window units and their frames, but the most predominant leakage paths appear to be based on poor construction and installation techniques of the window and wall interfaces. Water infiltrating through these paths can cause considerable amounts of damage to the wooden framing which often is concealed until the water damage has become widespread. The water management components for windows include the following:

  • Sills and thresholds
  • Water-resistive barriers
  • Flashings
  • Caulking
  • Proper integration with the wall’s water-resistive system
  • Continuous drainage paths

The American Society for Testing and Materials (ASTM) Standard E2112, “Standard Practice for Installation of Exterior Windows, Doors & Skylights”, as well as the International Residential Code (IRC), provide guidance for the performance and construction requirements for exterior windows.  The International Code Council (ICC) provides direction.

“There are two key principles for effective flashing at windows and doors to allow water to drain down the face of the wall and away from the building:

  • Integrate flashing with the water-resistive barrier (WRB), e.g., house wrap.
  • Install membranes shingle-fashion where the top layer of the WRB or flashing laps over the bottom layer to prevent water draining behind the bottom layer”.

One often overlooked component of window installation is the slope of the windowsill. Windowsills that lack a positive slope away are common in the field and contribute greatly to potential water intrusion, particularly when sill pan flashing is omitted in the sub-sill portion of the wall below the window units. Windowsills that are nearly horizontal or, worse yet, slope back toward the interior of the building, create relatively large edges that can collect water and can expedite deterioration of sealants and lead to water intrusion.

A good construction practice is to have a pronounced slope that aids in prompt drainage of water, thus deflecting it away from susceptible sill interfaces. The Brick Industry Association recommends a slope of 15 degrees away from exterior windows for brick veneer applications. This can be achieved by proper planning with the brick mason and determining the height to the window opening.

Replacement Window Flashing

Image Credit: JLC Online, Replacement Window Flashing  https://www.jlconline.com

Another important tool to prevent water intrusion is the use of a water-resistive barrier (WRB). This is critical in the areas around the window opening, which creates interruptions in the drainage plane. Careful attention should be paid to the details for window openings during the design and installation of the water resistive elements around them to ensure proper water management in these areas. Vital points to remember for the installation of WRB is the preparation of the opening with house wrap, felt, or building paper, and the integration with the sill, jamb, and head flashings in order to maintain a continuous drainage plane. As such, there is prescriptive information in the ASTM E2112 document.

Image Credit: Brick Industry Association, Water Penetration Resistance-Design   https://www.gobrick.com

The sub-sill framing below the window opening is another area that is susceptible to water leaks. This typically occurs at the lower corners of the rough opening in the wall, usually where the coverage of the water resistive barrier is minimal. As such, the pan or sill flashing serves to protect the sub-sill framing of the wall and interior portions of a residence beneath the window openings that are susceptible to leakage. Consequently, the sub-sill drainage provided by pan or sill flashing is crucial in achieving the performance and longevity of installed windows. Lastly, the jamb and head flashings will provide reinforcement to prevent water intrusion.

So, you may ask, “How can I find water leaks in my residence without an invasive approach?”  A non-destructive method to identify water leaks in windows is by thermal imaging. Thermal imaging is an essential tool for detecting moisture intrusion. During an investigation, the infrared technology can quickly and non-invasively zero in on the area of concern to find anomalies that may be created by moisture cooling. Monitoring the weather is crucial for successful results. Consequently, it is imperative to choose the optimum time to test and maintain a proper temperature control.  For example, the greater the span in temperature from the outside to the inside of the residence, the better the thermal results. As such, a warm or hot climate is excellent for thermal inspections since air conditioning is cooling the interior of a residence.  The following image depicts an example of this technique.

As can be seen in the above image, the blue areas below the windowsill illustrate an example of a concealed water leak behind the gypsum wall board. It should be noted that the thermal images can reveal a growing problem that can lead to more extensive water damage to a residence.

This residence had substantial water leaks coming through the windows, consequently developing extensive wood decay around the perimeter of the window frame.  Due to the ability to remain undetected, hidden water leaks can grow to become large losses. Using non-destructive tools, such as the Fluke thermal imaging camera, the source of the leak can be identified without unnecessary destruction of property. Getting to the source of the problem as soon as possible is key to avoiding potentially extensive repair work.

Carlos Zarraga has more than 8 years of engineering experience in the structural field specializing in building design, building components and foundation design.  Carlos has designed and analyzed structures, supervised designers and drafters, prepared construction documents and provided on-site duties for field supervision and inspection of construction projects. Certified in RISA 3D, RISA Foundation and RISA Connection, he is well-versed in the analysis of foundation failures.   He often determines the root cause of failure and the resulting scope of damage.  He has designed retrofits to existing structures in addition to repairing construction defects.  He also has experience in the industrial and petrochemical industry designing structures for materials handling facilities and industrial buildings.  Carlos holds a Bachelor of Science in Civil Engineering from the University of New Orleans.

Water Damage from Leaking Shower Stalls

Author

Have you ever had to have a leaking shower pan for a tiled shower stall replaced, only to have a recurrence a few years later? If so, it is likely that it was not properly built and/or repaired. In most installations, the shower stall is constructed with an underlying one-piece flexible membrane of PVC that is attached to the wall studs before the backer board and wall tile is installed. No nails or screws should penetrate the membrane below the level of the curb of the shower stall. The only opening in the membrane below the curb must be the hole for the shower drain to connect to the house plumbing. The shower drain is designed to allow water on top of the membrane to flow into the drain via weep holes for that purpose. Read More

Graphitic Corrosion – Difficult to determine before a failure!

Author

Graphitic corrosion is a process that may happen in equipment made of iron, particularly grey cast iron, but also ductile cast iron. Graphitic corrosion can lead to unexpected catastrophic failure of the affected part because the cast iron can lose its strength without a visible warning such as a change in size, shape, or appearance. Read More

Uninvited House Guests: Mold and Other Fungal Growths

Author

The wet, relatively warm weather recently experienced in the southeast has caused a high incidence of mold and other fungal growth complaints in homes and other structures.  Engineers at Warren Group are often called upon to investigate the cause(s) of these problems. Read More

Flood Damage to Electrical Equipment

Author

As a result of the recent weather, those of us in South Carolina have gained a renewed appreciation of the damage that can result from flooding. Even a few inches of flood water can result in property damage and a loss of services in addition to the immediate risk of physical harm. Read More

A pipe burst in a heated building: FREEZE Damage??

Author

Have you ever wondered about the cause of a ruptured pipe inside a structure in the dead of winter, and been puzzled because the pipe burst occurred in a heated area? It may seem counter-intuitive, but the cause may have been due to frozen piping. Read More

A Small Water Line Leads to a Large Loss

Author

A large oceanfront house was custom built after two years of planning and construction.  The house had three stories over an elevated foundation.  Shortly after the house was completed, the owners arrived one evening and found water pouring from above when they parked in the garage beneath the living spaces.   Read More

Water Intrusion/Moisture Issues – Finding the Source and Location

Author

What you see is not always what you get.  This commonality exists in the numerous cases I have investigated for water intrusion and moisture issues in buildings.  The source that appears most obvious and straightforward may not, in fact, be the root of the problem at all. Read More

Frozen Tankless Water Heater Losses

Author

Recently, we have seen a number of water damage losses stemming from gas-fired and electric tankless water heaters exposed to freezing temperatures. Tankless hot water heaters have been growing in popularity and use due to their energy savings over traditional water heaters. These units are typically installed on the exterior of a home or business in areas of the country where prolonged freezing or extremely low temperatures are not common. Read More

Snow/Ice Accumulation Leads to a Roof Collapse

Author

During the next several months when temperatures start to fall below the freezing point and winter storms packing cold temperatures, heavy snowfall and ice build-ups bear down on various regions of the country, they can and do bring an assortment of unfavorable conditions that could and will affect your insured’s buildings, businesses, and personnel. Some of these regions have already experienced record-breaking snowfalls and bitter cold temperatures, which in turn have increased the danger of roof or partial roof collapses. Roofs that are properly designed and constructed to applicable codes and standards should be built to withstand loading from snow, drifting snow, water-laden snow and ice build-ups. But are they? Building codes and standards that depict the proper roof loads will vary across the U.S.  They will generally be based on local historical data, including the expected frequency and intensity of these winter storms in a particular region as shown and discussed in ASCE 7-10. Read More

Type ofLoss

Not sure what you're looking for?
Browse All

Select Loss Category