Plumbing the Depths—of ADA and Low-Flow
A panel of noted plumbing engineers and designers discuss major issues in commercial plumbing: code revisions, compliance with the Americans with Disabilities Act (ADA), toilet parity and low-flush technology. Finally, they define what they feel are the major issues in commercial plumbing today in this month's M/E Roundtable.
A panel of noted plumbing engineers and designers discuss major issues in commercial plumbing: code revisions, compliance with the Americans with Disabilities Act (ADA), toilet parity and low-flush technology. Finally, they define what they feel are the major issues in commercial plumbing today in this month’s M/E Roundtable.
CONSULTING-SPECIFYING ENGINEER: Have standard codes made progress toward helping plumbing designers comply with ADA requirements?
GEORGE: Yes, I think the plumbing codes have addressed the accessibility issue in depth, although there may be some room for improvement. There have been many recent code changes that address clearances around fixtures and installation requirements for various barrier-free plumbing fixtures [see “The ADA Final Rule,” opposite]; but remember, the final interpretation of ADA issues rests with the courts.
SCOTT: Provisions are included to some degree in each of the model plumbing codes. ADA is a federal law and is written in legal language, not in code language. There are guidelines that “codify” the ADA such as ANSI [American National Standards Institute] A117.1 and the ADAAG [Americans with Disabilities Act Accessibility Guidelines], which further identifies what is required for compliance.
HIGGINS: The impact, whatever it may be, won’t be felt until jurisdictions begin to adopt the codes, and adoption remains a local issue.
CSE: Has there been any progress toward incorporating ADA design requirements into a unified national standard code?
HIGGINS: Yes, the regulatory requirements have been incorporated into codes. However, the underlying, thorny issue of jurisdiction-and therefore code enactment- still remains.
SCOTT: Because of the lack of a single model-plumbing code, progress is slow at best. The major code bodies have been encouraged to develop a single model plumbing code by the American Institute of Architects, American Society of Plumbing Engineers, the Plumbing Manufacturers Institute and others.
GEORGE: The accessibility issue is one of the areas that many feel should be covered in the building code, while others, for enforcement reasons, feel plumbing fixture issues should be covered in the plumbing code so that the plumbing inspector has jurisdiction over the inspection of fixture mounting heights and clearances.
HEIDEMAN: Personally, I don’t feel enough progress has been made to incorporate ADA or accessibility standards into plumbing codes. Most plumbing codes today only mention that if a building or structure requires accessibility by the disabled, the designer should follow local established codes.
CSE: Is meeting ADA design requirements enough, or does one need to go beyond just the minimum requirements? What are the most effective steps that plumbing engineers can take to meet with ADA compliance?
HEIDEMAN: In certain buildings or areas, you would design beyond the minimum requirements based upon the needs of the occupants. In some cases we have seen nearly 100-percent ADA-compliant buildings or areas within a building. There are several proposed changes to the ADA that will affect architectural areas of a building and, in turn, the plumbing. The most effective steps a plumbing engineer can take to assure a building is compliant is to perform a fixture count for the building and apply the required percent use for ADA-compliant fixtures.
GEORGE: The plumbing-design engineer should meet with the architect during the schematic-design and design-development phases of the project. During these meetings, the engineer should look for fixture clearances and possible conflicts with the plans and ADA requirements. The early stages of the project are also good times to select the fixtures and review them with the architect. Often the architect will want to have some input on the selection of electric water coolers or other fixtures in high-visibility spaces.
HIGGINS: ADA has been accepted by the design industry as a set of standards to follow as far as required. As engineers, we should be open to the expansion of our designs wherever embellishments don’t frivolously extract dollars from our clients’ pockets. Over the last decade, clients have come to accept that there will be, for example, one oversized stall in the toilet rooms. What started out as, “You can’t fight city hall,” has segued into, “Well, that’s just the way it’s done.”
SCOTT: Depending on the type of building, the requirements of the ADA change. If the project is a renovation, the provisions for compliance are different than for new construction. Some of the decisions in renovation projects need to be made by the building owner and not by the design professional. Sometimes the minimum requirements can be difficult to establish, but it is not as difficult to design systems for compliance as it was 10 years ago. As more engineers become familiar with the requirements, it is not such a problem to solve.
CSE: Have advances in product design, such as complete, modular units that are ADA-compliant, become a fundamental part of your designs? Have such products made specifying easier?
SCOTT: Of course, the availability of these products has assisted and become a fundamental part of our designs. But as far as making the job easier, I don’t think they have. Since the ADA is written in legal language and certain portions can be interpreted differently, the development of products can depend on how a manufacturer interprets the language. Finding products that are truly similar can be somewhat difficult.
HIGGINS: They certainly make specifying equipment simpler. Specification writing has always been an effort to put requirements in writing clearly and concisely; it’s my preference to point to a catalog and ask for “one of those” than to write half a page, draw plans, elevations and details, and still leave the contractor wondering.
GEORGE: ADA-compliant fixtures are becoming standard in all buildings and our specifications reflect the barrier-free fixtures. There are still products out there that claim to meet ADA that, in my opinion, may not really be accessible.
HEIDEMAN: I have not made modular ADA units a part of design, nor have I seen much on modular units. Most owners have specific requirements on manufacturers and material for use in their buildings. What has made the job easier for the specifying engineer is that most manufacturers have an ADA-compliant book or specifier’s guide in addition to their normal catalog. This allows the engineer to look in a specific location for ADA-compliant fixtures.
CSE: Toilet parity-so-called “potty parity”-is especially important for high-use facilities, such as sports arenas and airports. Are other types of facilities affected?
HEIDEMAN: You would also need to include cinemas, theatres and convention halls as high-use facilities. In cinemas you have time slots between shows where you have a large influx of patrons into the toilet rooms. Convention halls can be set up with several meeting rooms for certain conventions.
HIGGINS: Read any national code and you find the same approach: the number of water closets in a building is driven by the number of occupants. The code goes on to stipulate that up to half of the water closets in the male facilities may be replaced by urinals. This strongly implies that half of the occupants are assumed to be women. In 15 years of design work, this has always been my inference. This assumption becomes more universally applicable as women continue to move into traditionally male workplaces.
CSE: Does this issue ever affect your designs? If so, how?
GEORGE: In a recent football stadium design, we provided several hundred fixtures more than what was required by code. We also provided restrooms with water closets and lavatories that could be changed to men’s rooms or women’s rooms based on the probable percentage of men or women at a given event. The architects and owner agreed to do this to minimize the long lines at the restrooms at various events.
SCOTT: Certainly the design of the plumbing system is affected by such issues. Knowing how a facility will operate and what the programming issues are will establish the number of fixtures required for a given facility. Once the number of fixtures is established, and knowing how the facility will be used, the engineering of the system can be straightforward.
HEIDEMAN: In some cases, the architect or owner will not want to add additional fixtures because the size of the toilet rooms become larger than can be accommodated in a certain area. Thus, the design follows minimum requirements set forth by the local adopted code. This is not to say that “potty parity” is a bad idea or regulation; however, the engineer needs to understand how to apply the regulations.
CSE: Many localities are passing “potty parity” ordinances requiring twice the number of women’s toilets. What are some of the design challenges posed by toilet parity legislation?
HEIDEMAN: The first challenge is to accommodate the space requirements within a building or area of a building. The second challenge is to size the water and waste piping to accommodate the added fixtures.
One question that always comes to mind in high-use facilities is the usage factor of the fixtures. Do you apply usage factors, and to what extent do you apply factors when you have a situation that requires twice as many women’s toilets? Old rules stated that you did not utilize usage factors on high-use facilities. You would assume that at some point you would have 100-percent usage in an area of the building. The question now being asked is whether to apply usage factors to the building or area since you have “potty parity.” You may still design for 100-percent usage for a particular bank of restrooms, and apply a usage factor for the mains serving the area or building.
SCOTT: I think that the greatest design challenge is knowing about the legislation. With so many localities passing ordinances for their particular jurisdiction, it is difficult sometimes to know when additional fixtures are required.
GEORGE: The state of Michigan and the city of Detroit have passed local amendments to the model code requiring more fixtures in assembly occupancies than are required in the model codes. For multiuse assembly facilities, we have met or exceeded the code requirements.
CSE: Environmental concerns and initiatives, such as low-flow ordinances, seem to have an enormous impact on plumbing design. What are some of the specific challenges involved when incorporating such equipment as low-flow toilets and wastewater recycling into plumbing designs?
GEORGE: The Energy Policy Act of 1992 requires all water closets installed in public buildings after January 1996 to flush with 1.6 gallons per flush (gpf) or less. The old water closets flushed with 3.5 to 5 gpf. Most engineers might think that the flow rate and pipe sizes should decrease with the 1.6-gpf fixtures and allow for the use of smaller pipe sizes, but this is not the case with flush-valve fixtures. The flow rates stay the same or are slightly increased depending on the flush-valve manufacturer. The 1.6 gpf is accomplished by decreasing the time that the flush-valve cycles. This, in some cases, requires the flow rate to slightly increase.
HEIDEMAN: The greatest challenge in designing around ultra low-flow (ULF) fixtures is the drainage piping design. Almost all design engineers know that ULF fixtures do not carry the solid waste as far as non-ULF fixtures. The challenge is to determine the carry distance of the waste and incorporate the carry distance into the design of the drainage system. This may seem easy, but it is not easy to design. The design engineer needs to determine when additional waste streams enter the drainage system to help carry the waste material to the building drain and then out of the building to the municipal sewer system.
This problem will be compounded with codes allowing wastewater recycling. Some municipalities allow “gray-water” recycling, which includes a separate drainage system for showers, lavatories and sinks within the building. The gray-water drainage system is piped into a separate municipal sewer system and takes away additional sources of wastewater by carrying waste to the building drain and municipal sewer system. There has not been enough research to determine the overall carry distance of waste material utilizing ULF fixtures; therefore, most design engineers are using very conservative approaches to drainage piping design.
SCOTT: Understanding the impact on the entire plumbing system by seemingly small changes is the greatest challenge. Many of the model plumbing codes have recognized that the reduction in the water-closet volume can present a problem. Adequate research has not been performed which deals directly with the building drainage system and the effect of the low-flow fixtures we are now using. However, with the changes to the plumbing codes, we have the ability to reduce the size of the drainage piping, thus increasing the depth of water flowing through the piping. We have a better understanding now of how the drainage system is affected by the low-flow fixtures, but more research is needed in this area.
CSE: What are some of the alternatives and options for low-flow equipment? Have suppliers and manufacturers taken the initiative in providing products that meet with standards?
HEIDEMAN: I believe manufacturers continue to develop better products that meet ULF requirements. Their in-house research is producing ULF fixtures that have better appeal to the design engineer and interior designer.
GEORGE: An alternative to gravity toilets or flush valves is to use pressure-assist water closets. Pressure-assist units use the water pressure to capture air and pressurize it, which gives the water a push during the flush. These units work exceptionally well but can cost in excess of one thousand dollars per fixture.
SCOTT: Vacuum systems can be an alternative depending on the type of facility being designed. I firmly believe for every product there is an application, but knowing when to use the product is the challenge. Vacuum systems can offer some options in certain installations that may be better than conventional solutions. Vacuum systems do rely on more equipment to perform the same task as a gravity-drainage system and will probably not be a common solution until water is so scarce there are no other options.
CSE: What is the biggest issue affecting plumbing system designs today?
HEIDEMAN: The biggest issue is ULF fixtures and how to design a plumbing system that accommodates them. As we continue to design around ULF, it is paramount that the design engineer understands its effect on the drainage system and water-supply system. Some designers feel that because we are using half the water consumption, the water sizing to the fixture can be smaller. This is not necessarily true. ULF flush valves still have relatively the same flow rate as non-ULF flush valves, but some believe that the water service should be reduced. The end effect is high-pressure drops and water hammer in the domestic water system. A lot of individuals would say get rid of ULF, but the reality is that we need to understand ULF and how to design a plumbing system to accommodate it.
HIGGINS: As has been the case for years, the major issue is local jurisdictions clinging to outmoded codes and driving construction costs up. Authorities need to adopt a longer range view and accept a performance-based enforcement approach.
GEORGE: Several issues need to be addressed: Most graduate mechanical engineers have little or no plumbing-design experience. There are a few architectural engineering programs at accredited schools that offer a few classes on plumbing design as part of the curriculum.
Also, plumbing design engineers need to be more active in the code development process. There has been a rush to propose legislation on water conservation without research into whether the mandated requirements will work.ïcseï