Solutions for Barrier-Free Bathrooms
|Limiting construction height|
It is estimated that the number of Americans aged 65 and over will increase from 40 million in 2010 (13% of the population) to an estimated 72 million in 2030 (20% of the population).1 As the baby boomers enter this age group, they may have decreased mobility and find difficulty in stepping into a tub or even over a modest 6-inch shower curb. The popularity of large Jacuzzi tubs in bathrooms seems to have run its course, and many builders now have moved away from these space-consuming and somewhat energy inefficient luxury fixtures to installations with multiple shower heads and sometimes a steam generator, all in the same space.
Another phenomenon that is changing the way we design bathrooms is homeowners’ increasing preference for “Aging in Place.” Here we see the elderly who are not selling their homes and moving into retirement villages or assisted-living quarters, but modifying their homes to make them more user-friendly and accessible as they age.
Over the last couple of years, there has been some new advancement in building material technology which now allows the construction of barrier-free bathrooms that are relatively easy to construct, and enhance functionality and performance.
Here we explore some of these solutions and recommendations.
Moisture management is a systematic method to contain water in both liquid and vapor form and enable it to pass through an assembly efficiently using materials that are not adversely affected by moisture.
Water management remains one of the biggest challenges in shower construction. No material can completely eliminate water vapor transmission. In fact, a few years back, the terminology for a vapor barrier was changed to vapor retarder, as the only true vapor barrier is solid glass or metal. There is a standard for thin load-bearing waterproof membranes which can be directly bonded to with tile called ANSI A 118.10. This standard, however, is only for waterproofing and does not have any performance criterion for vapor transmission which is commonly tested under ASTM E-96.
With many showers today featuring multiple shower heads and steam generators, it is now more important than ever that the substrates (walls, floors and showers) be waterproof, and in most cases resistant to steam/vapor. The Tile Council of North America (TCNA) will be revising the 2013 TCNA Handbook for Ceramic, Glass and Stone Tile Installations for continuous steam rooms calling out that the waterproofing membrane should have a perm rating of .5 or less (previously < 1.0) using ASTM E-96-E at 90% relative humidity. This is in recognition of the high service requirements found in steam showers and steam room applications.
Another challenge in barrier-free applications is limiting construction height. This is particularly demanding when using a shower pan method which works with a two-stage drain and requires a mortar bed as in TCNA Detail B414. This can create excessive construction height as the minimum thickness of the mortar bed is 1 ¼ inches (31 mm) at the lowest point, which will then increase by approximately ¼ inch (6 mm) in 12 inches (305 mm) to create the slope required for drainage. Depending on the size of the shower, the construction height can easily increase to 2 inches (52 mm) or thicker, which in barrier-free construction can cause challenges at the doorway/entrance of the bathroom.
With the arrival of ANSI A 118.10 membranes in the early 1990s, drains were soon introduced with an integrated bonding flange so that a thin load-bearing waterproof membrane could be adhered to it to create a waterproof connection. This type of drain was added to the TCNA Handbook several years ago and can be found under Detail B422.
This approach provided a great advantage insofar as allowing the low construction height to be maintained as a result of the drains being installed directly onto the substrate without a mortar bed. The slope can be started from almost zero, and again, depending on the size of the shower room, heights can be maintained relatively low. For instance, a shower with a 48-inch (1,220-mm) radius will only have a construction height of 1 inch (25 mm). Typically, these membranes are continued up the wall onto solid backing to ensure that walls are waterproof. An expanded high-density polystyrene board with bondable/waterproof facers can also be substituted if nothing has been attached to the studs. There are multiple advantages to these boards: they are extremely light, can be cut with a utility knife on site, have an R-value and are waterproof/vapor retardant.
Another new entry into barrier-free bathrooms that expands design opportunities is the introduction of linear drains. A variety of designs from a number of manufacturers allow these drains to be placed in different strategic locations throughout the shower. Drains which work with an ANSI A118.10 membrane, like the integrated bonding flange drains, allow for low-construction height assemblies as a result of being installed directly onto the substrate.
In addition, utilizing a linear drain allows floor designs with only one or two slopes, which allows for large-format tile and stone slabs to be installed in the shower areas. It should be noted that standard drains measuring 4 to 6 inches (100 to 150 mm) x 4 to 6 inches (100 to 150 mm) only allow the use of small-format tile, in most cases no larger than 12 x 12 inches (305 x 305 mm) to be able to evacuate water.
The floor either has to be designed in a cone configuration or made into four planes to allow for the water to be directed to the drain. Linear drains on the other hand, can be placed adjacent to the wall and below the shower head, or at the threshold in the front of the shower area, allowing then for a single slope. Linear drains can also be placed in the middle of the shower floor, which creates two floor sections, each sloping toward the drain.
Another addition that enhances the construction of barrier-free bathrooms is prefabricated benches, made of solid expanded polystyrene (blocks) or assembled in place with extruded/expanded foam panels. Both versions allow for benches to be configured in many dimensions that are 100% waterproof and do not require framing or an elaborate fastening system.
A final new technology that is available for barrier-free bathrooms is prefabricated floor panels that are made with one, two or four slopes, depending on the style and placement of the drain. Typically, these products are made of expanded polystyrene and are not only user-friendly, but also contribute additional benefits. Utilizing a pre-sloped shower panel makes it simple to create a flat and evenly sloped surface to reduce the possibility of lippage and “bird baths” in the floor surface. For example, because the floor panel is made of a thermal-resistant material approximately 4 R-value per 25 mm, the tile acquires some increased insulation so it is not as cold as when bonded to a mortar bed or concrete slab. In addition, the weight is substantially reduced versus a mortar bed or concrete leveling bed which weighs approximately 16.4 pounds per square foot (80 kg/m2), and depending on the density of the extruded polystyrene panel there are also sound attenuation contributions as well. Many building codes for wood frame construction require a minimum of 10 pounds per square foot (48.82 kg/m2) dead load and 40 pounds per square foot (195.29 kg/m2) live load, so the reduced weight of a prefabricated shower tray can eliminate the need for reinforcements such as blocking or additional I-joists.
The trend towards barrier-free bathrooms has quickly gained ground, and seems to be the design of choice for a variety of reasons — whether these be aesthetical or functional. Designing and building these types of bathrooms will become an important skill for many tile installers. With proper planning, and the use of some of the new materials such as integrated bonding flange drains, linear drains, prefabricated trays and expanded polystyrene wall boards, these types of bathrooms can be accomplished with increased ease. These bathrooms can be extremely stylish and often allow for limited spaces to be maximized. A barrier-free bathroom can be both practical and elegant — by recognizing some of the challenges and incorporating new materials, we can now break barriers in the bathroom, and achieve better more functional spaces for all.
1 For more information, visit wwww.agingstats.gov/agingstatsdotnet/Main_Site/Data/2012_Documents/Docs/EntireChartbook.pdf.