Architectural Linear Drains for Indoor and Outdoor Use

Different product offerings suit many situations beyond bathrooms
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Sponsored by Infinity Drain
By Peter J. Arsenault, FAIA, NCARB, LEED AP
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There may be other performance considerations too such as ease of maintenance and durability over time, both of which are commonly met based on the attributes already discussed. Of course, it is best to specify particular testing requirements and check with manufacturers to ascertain the actual performance capabilities of any drainage products.

Design Considerations

Incorporating architectural drains into a total space design requires an understanding of the different components of a system. Each can be selected, adjusted, customized, and specified to suit the needs and design intent of a project.

  • Channel Assembly/Catchment This component is the working part of the drain that is concealed below the cover and fabricated to first catch, then direct, the water to the drainpipe. It is the part that needs to be designed into the floor or surface so that it provides the needed performance and is integrated as a flush finished condition. Depending on the application, there may be a need to provide for a waterproofing material or membrane around the channel, just as with any surface that is exposed to water. The type of waterproofing can vary depending on the nature or type of drain and compatibility with the material of the channel assembly. Commonly, the channel assembly is made from stainless steel, but some PVC channels are also available. There are several general types to select from.
  • Site-Sizable Installations consist of modular linear drain components that can be cut-to-fit on site or joined together to create any length. The outlet for this type can be located anywhere along the channel run. These are available in kit lengths or as a set of components in both stainless steel and PVC. Site-sizable installations can use most standard, compatible waterproofing methods.
  • Fixed-Length Installations are prefabricated to specific lengths to be installed directly into the onsite construction. They include pre-pitched channels with a set outlet location. Both standard kit sizes and custom fabrication are available. Made from stainless steel, they are intended to be installed with most standard waterproofing methods.
  • Fixed-Flange Installations are used when a vertical outlet is needed for connection to the drain piping. They include a pre-pitched flanged channel with set outlet location and a vertical (down) outlet. Standard kit sizes or custom fabrication are available made from stainless steel. This type should only be installed with liquid membrane or fabric sheet waterproofing methods.
  • Side Outlet Installations are used where a vertical outlet is not practical or possible. They also include a pre-pitched flanged channel with a set outlet location and horizontal (side) outlet. Standard kits sizes or custom fabrication are available in stainless steel. As with fixed flange installations, side outlet channels should only be installed with liquid membrane or fabric sheet waterproofing methods.

The heights of channel assemblies are typically on the order of 1-5/8-inch, although a low-profile 1-inch channel is available for site sizable installations. The lower channel height makes barrier-free installation easier in some cases. Such reduced height channels are likely to be reinforced on the sides with extra grooves or flanges to provide increased stability in mortar set installations.

  • Drain Covers The visible part of the architectural drainage system is the cover. Typically, these are metal grates most often fabricated from different types of stainless steel. The thickness of the steel can vary from 18-gauge down to 7-gauge to suit different project weight-bearing conditions. The final appearance can vary based on the selection of the pattern of openings (linear grille, holes, etc.) and the final color of the finished metal – there are numerous options for both. In this way, the drain grate can either blend into the floor surface to be less noticeable or be used to create a contrasting line that works toward a purpose in the overall design.

If the desire is to have the cover blend into the surrounding surface and visually disappear, then there are also options to have a linear opening on either side of a central section that is designed to receive finishing material or tile that matches the surroundings. In this way, the linear drain takes on the same appearance as the surrounding floor or outdoor surface. If complete obscurity is sought, then there is also the option of using a recessed reveal slot drain such that the flooring extends over the flange of the channel and allows the water to enter into the channel via a 3/8-inch reveal in the surface of the floor. A small removable panel allows the channel and drain line to be accessed in this case. Because of these different approaches, it is easy to see why linear architectural drains offer an elegant and coordinated look for architects and designers to create well-designed, elegant spaces without the visual interruption of the grates or covers.

  • Other Considerations There are a few other things that can come into play when making design decisions about architectural drainage systems. As noted earlier, there are prefabricated sloped metal pans available that can streamline the installation of a sloped floor and drainage system. The size and slope options should be verified with a manufacturer, but in some cases, using this available product can mean less construction time and cost than traditional installations of flooring and deck surfaces. Relatedly, manufacturers should be consulted for lead times on different products, particularly if customization is needed. Generally speaking, fast turnaround times are possible but always subject to change.

Photo courtesy of Infinity Drain

Different drain gratings allow for different appearances, including exposed stainless steel and ceramic tile-covered drains, to match flooring or concealed reveals.

With a better understanding of both the performance and design aspects of architectural drainage, we can now turn our attention to some specific types of installations. There are many different places where architectural drainage systems are appropriate for use. While some people have only thought of them for shower installations, John Flaa of Infinity Drain has seen firsthand how many other applications are possible. He comments, “We often talk of ‘thinking outside the shower’ when it comes to architectural drainage given the wide applications where linear drains can be utilized.” With this in mind, we next look at three common, general application types – outdoor travel paths, outdoor spaces, and indoor spaces.

Drainage For Outdoor Travel Paths

Paths of travel are common for all building sites whether for pedestrians or vehicles. Commonly, such paths are paved with asphalt, concrete, or masonry or covered with other materials, such as wood or tile for decking or similar surfaces. The surface may be fairly smooth or textured, but if they are outdoors, then they are subject to receiving water that needs to be collected and drained away. Several different applications are discussed further as follows.

Walkways for Pedestrian Traffic

Outdoor pedestrian walkways always deserve careful attention for slip resistance and proper drainage. A common approach is to simply slope walkways toward one side so that water drains off them and onto the ground. However, areas with plantings or berms may not readily accept runoff and, in fact, may block it. Further, large, paved walkways or locations that are subject to more than typical amounts of water (whether due to rain or irrigation overspray etc.) can overwhelm the ground and saturate it to the point that it cannot receive any more runoff. That means water builds up and puddles along the edge of the walkway and can cause problems, either for the walkway and ground or for people.

A solution for these conditions is to add a continuous linear drain along the edge of the walkway to receive and remove the water. Underground piping may be needed in this case, which can be accessed by vertical channel outlets from the drain directly down into the piping. Alternatively, horizontal, side outlets could be used to help distribute the water underground to a larger natural area where it can be more easily absorbed.

Photo courtesy of Infinity Drain

Architectural linear drains along the edge of pedestrian sidewalks or walkways help ensure that water does not collect there and cause problems.


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Originally published in Architectural Record
Originally published in June 2022