Floodproof Window Systems and Glass Flood Walls

Passive systems provide superior design options
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Sponsored by Floodproofing.com
By Peter J. Arsenault, FAIA, NCARB, LEED AP
  • Frames A complete frame system is part of the overall solution for floodproof window systems that is engineered, coordinated, and fabricated to both receive the glass properly and be secured to the building. Structurally welded and manufactured aluminum and steel are used to support the weight of the laminated glass windows. That weight can be substantial, particularly when oversized windows are used, so the proper engineering of the frame is critical. Just like the glass, the frames are also fabricated to withstand the high impact needs of floodproofing regulations. They can also meet fire resistance requirements where needed.

  • From an appearance standpoint, stainless steel or aluminum frames are most common with multiple finishes and colors available to blend with glazing systems in the rest of the building. There are also options for decorative frames and mullions where those are desired. It is also possible to fabricate multiple frame configurations depending on the application and the nature of the window openings. Such details and options are best discussed and reviewed with a manufacturer during the design process.

    Photo courtesy of Floodproofing.com

    Metal frames provide the means to connect the window to the building.

  • Sealants and Gaskets The glass needs to be held in the frame and the joint where the two come together must also be impermeable and strong. Hence, glazing gaskets and sealants are part of the floodproof window system to accomplish that purpose. Sealants or full adhesives can be used to glue the glass to a frame in floodproof window systems. This can create a permanent, continuous attachment of the glazing to the frame. This approach can be particularly appropriate in oversized impact windows and when in-plant structural glazing is being fabricated.
    It is equally important that the gap between the frame and the building construction is tightly sealed, so other gaskets and sealants are used to meet those needs. All these components are critical to the long-term performance of the total system and need to be designed and installed to work together. This coordination is straightforward for the glass to frame sealing since that is all under the control of the fabricating shop/ manufacturer. It is critical that the essential sealing is done in the field, however, for marrying the window units to the wall assembly or other materials in the building envelope. The specific attachment points and substrate need to be capable of accepting the needed gaskets and sealants as compatible products.
  • Beyond the products and materials provided by the manufacturer, there are also other items such as anchors or fasteners that are needed to hold floodproof window systems in place – just as with conventional window systems. In this case, manufacturers can provide fully engineered anchoring specifications indicating the type of fasteners that will work with their products and the types of substrates that they are suitable for. Similarly, installation instructions for those fasteners/ anchors can be provided indicating the spacing of them and the minimum penetration depth needed. All of this is important because proper anchoring of these heavy window units is needed to transfer loads properly to the building structure and not pass undue stresses onto other materials.

    Glass Flood Walls

    Preventing or containing flood waters on a building site or even in a public outdoor space is also a demonstrated need in many locations. The not-for-profit organization known as the Waterfront Alliance in New York City has looked at a variety of strategies in this regard. They have developed the WEDG program which looks at ways to blend the water’s edge with human activity. (https://wedg.waterfrontalliance.org/) Foremost among their strategies is a cooperative, natural, and often passive means to create sites along the water that enhance their use while protecting from flooding and harm.

    A particular technique that is consistent with ongoing, cooperative use and protection, is the incorporation of low, permanent walls that are capable of keeping floodwater at bay. It has been recognized further that making such walls as visually unobtrusive as possible would be quite desirable. But what if they were visually transparent? That’s the focus of glass flood walls – use them in site or landscape designs to create flood barriers that still retain visibility.

    Glass flood walls can act as a decorative, but transparent, “fence,” that protects a site near an ocean, bay, or riverfront. As such, it can serve a dual purpose to contain a site (i.e., boundaries of a park), keeping people either inside or outside while also serving to stop floodwaters. Installation of glass flood walls is feasible on sea walls or bulk heads to add additional protection without blocking the view.

    Glass Flood Wall Attributes

    Glass flood walls act the same way floodproof glass windows do, just located on the site instead of in the building. They create a permanent, passive system that is always ready and does not need to be deployed. They can readily be designed and installed to meet all applicable regulatory standards. They can be engineered and fabricated to withstand hydrostatic pressure and impact loads from floating debris.

    Materials for glass flood walls are similar to those for floodproof window systems. The glass is custom laminated suited to the particular requirements of a project. Frame materials include aluminum, structural extruded aluminum, or stainless-steel type 304 or 316. Structural stainless-steel complying with ASTM A240 is also an option. Gaskets and sealants are just as critical here as they are in windows and are provided as well by the manufacturer. This combination of proven materials means that the total system is extremely resistant to environmental corrosion as well as the onslaught of flooding. Aesthetically, the size, configuration and color of the framing can be custom assembled to suit the design scheme for the project. It is also possible to work with the aesthetics of the frames based on an inside or outside covering of the frame with the glazing system.

    Photo courtesy of Floodproofing.com

    Glass flood walls provide a permanent barrier to flood waters without sacrificing visibility.

    Custom Systems

    Beyond standard floodproof windows and glass flood walls, there are other options that are possible using the same or similar product design and fabrication methods. These can include the following custom fabrication systems.

    • Curved Window Some building designs call for curved windows or glass walls, particularly in retail or hospitality design. Some manufacturers have the capability to provide such curved glass systems that are also floodproof. Some of the possible attributes of curved systems include a clear view of up to nearly 470 square feet in a single section. It is possible to combine multiple sections into a multi-curve design. Low-iron glass can be used to maximize the quality of view and avoid any coloration from the glass. Relatedly, the glass can have custom printing to enhance the viewing experience. The frames can be custom fabricated in aluminum or stainless steel. All of this can be assembled to resist fairly high pressures on the order of 120 pounds per square foot.
    • Walkable Skylights Some building designs, whether new or existing, incorporate skylights into walkable surfaces. This was done historically on sidewalks above vaults or basement spaces below or done inside buildings to help stream natural light to spaces that otherwise would have none. These situations can be desirable from a design standpoint but create real concerns if they need to resist flooding. Here again, custom floodproof glass systems can provide a solution. Manufacturers have produced approved products up to 132 square feet with a weight capacity of 200 pounds per square foot. They can accommodate virtually any custom shape, including the ability to bend the glass up to 90 degrees in some cases. All of these design options are available and the systems can still be rated for design pressures of up to 120 pounds per square foot.

    Cost Comparison

    All building projects involve a discussion of cost and floodproofing projects certainly do as well. Keep in mind though, that when considering different flood proofing options, it is quite important to understand all the costs associated with any solution. For example, in large commercial buildings, deployable active panels may be seen as less expensive than passive systems in terms of first costs. However, they will require the construction of a large amount of dedicated storage space that needs to be considered as part of the overall first cost. Furthermore, they will take hours for a team of people to deploy which creates an ongoing operating cost to the owner. To assist in this assessment of cost, calculator tools are available to help layout the lifetime costs of different systems and allow an easier comparison floodproofing options for a project. These calculators include three types of cost factors: 1) the Initial Investment including the design, engineering, product/material costs plus amounts for shipping and installation; 2) Lifetime costs including depreciation, maintenance, storage, and required annual tests; 3) Deployment costs which will understandably vary depending on the number of floodproofing products used and the number of flood events. Using the above as a basis, let’s consider an example of protecting eight 4-by-6-foot openings, comparing only floodproof window systems against traditional windows protected by 4-foot-tall flood panels.

    • The passive approach is to use eight 4-by-6-foot floodproof window systems.
      • The initial investment is estimated at $17,344 per window, installed or a total of $138,752.
      • The annual upkeep for this system is $0.
      • The 5-Year cost of ownership is therefore $138,752.
    • The active approach is to use traditional windows and deploy 4-foot-tall flood panels around the outside of the windows.
      • The initial investment in this case is estimated at $100,544.
      • The annual upkeep for this system is estimated at $8,274 per year.
      • The 5-Year Cost of Ownership is thus $141,914.

    In this example, then, the passive solution shows a lower cost of ownership than the active system. It also demonstrates that the return on investment for the passive system is less than five years compared to the active solution.


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    Originally published in Architectural Record
    Originally published in February 2022