Built on Evidence

The MAHC Facility Design & Construction Module aims to fill holes other codes don’t address and provide scientifically based best practices. See where the recommendations have the largest impact.

The following article was published in Aquatics International in the November / December 2012 Issue

The goal of the Model Aquatic Health Code is to codify scientifically proven data in the aquatics industry. When that is not possible, each technical committee is to look first at current best practices in the industry and identify areas within each module that would benefit from future scientific studies and research. Topics within the Facility Design & Construction Module that tend to either deviate or expand upon many published codes at the state and local level include the required depths for starting blocks and diving boards; overhead and underwater lighting; deck areas within an aquatics facility; the design requirements of natatorium structures and support spaces; and several pool features such as infinity edges, bulkheads, and movable floors that are not addressed in the majority of today’s current standards. All recommendations apply to new construction.

The current draft of the FD&C Module defers to the applicable governing body for required water depths and envelopes necessary for the use of starting platforms and diving boards. Today, there are different requirements between USA Swimming, NFSHSA, NCAA and FINA, as well as state and local codes. For facilities that are not under the umbrella of one of these competitive swimming and diving governing bodies, MAHC writers took the position that the most conservative requirements would apply.

Design requirements for lighting — overhead and underwater — was a focus of particular importance. Historically, underwater lighting requirements for swimming pools have been regulated using a watts per square foot of pool surface area measurement. In an attempt to steer aquatics in a direction more consistent with widely recognized electrical units of measurement, equivalent units of initial lumens and efficacy are used alongside watts per square foot. Also, conventional regulations require one level of underwater lighting applicable to all types of pools. The FD&C Module highlighted the different requirements for indoor vs. outdoor pools, as well as pools that accommodate diving vs. those pools that do not. Minimum overhead lighting levels also are required to be met based on whether the pool is indoors or outdoors and whether it’s intended to operate outside the limits of dawn to dusk. It is acknowledged that many of these overhead and underwater lighting standards derive, at least in some part, to historical best practices. It is recommended by the Technical Committee that future studies be conducted to determine minimum lighting requirements based on water depth, hours of operation, overhead lighting design, location and the impact that these variables have on each another.

Another subject related to lighting that was heavily analyzed was glare. In the end, while it is widely acknowledged that glare on the pool surface can provide concern for lifeguarding, it was a tremendously difficult topic to regulate from a code perspective. Instead, recommendations were provided in the annex to the design community to help mitigate this issue. For instance, careful consideration should be given to the placement of windows and skylights in a natatorium. Natural light from directly overhead is less likely to create glare than light through windows at the sides and ends of the pool. Control of glare from artificial light is more likely if the angle of incidence of the main light beam is less than 50 degrees from straight down. Diffuse or indirect light sources also can help to minimize glare.

The FD&C Module also expands upon the traditional definition of pool decks found in most current regulations. Most codes tend to define the term “deck” as a general term that applies to all areas surrounding a pool, and typically governs minimum widths and slope requirements — and little else. From a useability standpoint, the Technical Committee thought it was valuable to separate the terms “perimeter deck,” “dry deck” and “pool deck” from one another. Perimeter deck applies to the minimum required hardscape surface area surrounding the perimeter of the pool. Pool deck is defined as the hardscape surface areas beyond the perimeter deck that is regularly trafficked by wet bathers. Finally, dry deck refers to all pedestrian surface areas within the pool enclosure that are not subject to frequent splashing or constant wet foot traffic (not including landscaped areas, which are addressed and regulated separately). The main purpose for separately defining these areas is to create conditions for acceptable deck materials and finishes in various areas.

The Technical Committee also recognized that a standard minimum slope requirement often cannot be sufficient in and of itself to ensure that no standing water is allowed on the deck. The preponderance of existing codes and established standards were distilled to create minimum slope requirements for smooth finishes (such as ceramic tile and lightly broom-finished concrete), moderately textured finishes (exposed aggregate and medium broom-finished concrete), and heavily textured finishes (brick and heavily broom-finished concrete). It was noted that there is an inherent conflict in the sloping of decks. Steeper slopes provide more construction tolerances and surety in conveying water, particularly in active soil conditions. Shallow slopes are required to meet accessibility guidelines — particularly for cross slopes. It is the intent of the FD&C Module to encourage positive and proper drainage without running afoul of accessibility guidelines.

Many aspects of the unique characteristics of natatoriums and their support spaces are not specifically addressed by the International Building Code, ASHRAE or other existing standards. The FD&C Module fills these gaps so that sound design and construction practices are required for aquatics facilities. It is not intended to be construed as providing relief from applicable requirements in fire-, mechanical-, electrical- and building codes. But the impact of pool chemicals, their corrosive nature, pool combustion equipment, ventilation requirements and the like on typical aquatic environments are all critical design and construction requirements that benefit from being in a standard such as MAHC.

Finally, the FD&C Module adds regulatory parameters for several commonly found elements within today’s pools that are not addressed by the overwhelming majority of current standards. These include pool design elements such as wing walls and infinity edges. Wing walls often are misinterpreted to be “deck” even though they are not intended for foot traffic, but defined as such can trigger minimum-width requirements, drainage and more when they are merely intended to reconcile floor slopes and termination of in-pool elements such as entry stairs. Infinity-edge pools often are required to have decking around 100 percent of the perimeter, which inhibits a traditional “infinity” effect and does not necessarily have to impact life safety.

Pool equipment such as bulkheads and movable floors can seldom be found, if at all, under current pool regulations in the United States, but the MAHC writers thought it was important to regulate these for safety. So potential entrapment issues are addressed under “bulkheads”; and regulations for movable floors are implemented during installation and operation, such as speed of travel, barriers at floor slope transitions, and inability for bathers to access underneath the floor structure at any time.

Ultimately, the FD&C Module strives to merge scientifically proven data into a codified standard, along with industry best practices, and historically overlooked areas of regulation in the ever-changing world of aquatics facility design and construction.

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