Seasonal Winds
91permitting stairs to be contained within a central core. On rare occasions, some
exiting from stairs may be permitted into a building lobby; while convenient, this is not good practice as conditions in the lobby will not be knowable from upper floors, where occupants make their decision about escape routes.
Some considerations when designing for exiting include the following:
Exit travel must be intuitive and unimpeded; therefore any doors (in corridors, to staircases, etc.) must open in the anticipated direction of escape. To prevent crushing, these doors must have panic hardware installed that will automatically unlock and open if hit or pressed. Panic hardware must extend across the full width of the door, and is best located at waist level, between 36 in. and 42 in.
above the floor so that the body’s center of mass will contact it. Arms and hands may well be trapped against other parts of the door (Fig. 2.1.11).
Stairs leading to basements must have clear indications at the ground floor that evacuees should not continue down further, but should exit the stair there.
Many codes require a physical gate to prevent panicked occupants from running into the basement, but in practice these are often left open to avoid inconveni-ence. No matter what the code, signage at the exiting level is a good practice.
Maximum opening size 650 cm2 (100 in.2)
Swing in direction of travel Panic hardware
“Fail safe” closer
Minimum opening width 36 in.
Figure 2.1.11. Exit doors have particular requirements to ensure their proper operation during a fire.They must swing in the direction of fleeing occupants, they must be no less than 910 mm (36 in.) wide, and they must have panic hardware to open any latch.This last requirement prevents crowds from piling up against the door and preventing an occu-pant from operating a handle or button – the panic bar unlatches the door when pressure is applied to it, whether that is from a single user or a growing crowd. Doors that provide fire separation must additionally have ‘fail-safe’ closers, and have a limited amount of allow-able glass area. Note that, despite this limitation, a vision panel is often desirallow-able to allow exiting occupants a view of what’s on the other side of the door.
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Common sense suggests that occupants not be forced to exit through areas of danger (storage, kitchens, machine rooms, factory floors). While codes will often prohibit individual instances of this, good practice again requires architects to consider likely evacuee behavior and to guard against accidental circulation into these areas.
Despite our best efforts, occupants will often evacuate a building through the same route that brought them in – whether or not there is a more convenient or safer path. Codes often require that a building’s ‘main’ entrance thus be sized to allow half of the building’s population to escape through it (during the Station Nightclub fire in West Warwick, RI, in 2004 many fatalities occurred within a few yards of illuminated, signed exits as occupants tried to run to the main, rear doors).
Elevators are notoriously prone to failure during building fires. Worse, they are likely to get stuck or even open at a floor that is fully aflame due to its extreme heat. Therefore, elevators never count as code exits, and usually must be dis-abled when a building alarm goes off, returning immediately to the ground floor and waiting there. Fire fighters may then use a special key to unlock the cabs’
mechanisms in order to gain access to the affected areas. Some codes being con-sidered at the time of writing propose to allow elevators as secondary exits if they are encased in fully fire resistant shafts, however this goes against the pre-vailing wisdom that has consistently discouraged elevator use in a fire.
Conclusions
A building’s circulatory design is an important aspect of its architectural impact.
Very often we want to use these spaces to celebrate the building’s functions or connections. Yet fire codes are often quite rigorous in how these spaces may be used or configured; codes often prohibit furniture or storage in any designated exit route. It is often, therefore, worth considering a second circulatory system in large buildings dedicated to fire escape. This may consist of stairs with dedi-cated uses, or networks of corridors that are not accessed during typical daily operation. While this may seem wasteful of space and resources, the inherent safety of a properly designed exiting system may allow other, purely architectural circulatory elements to be arranged and developed according to different requirements.
At the same time, the requirements of life-safety systems may align with archi-tectural desires. Fire stairs, for example, may be worthy elements of expres-sion in an overall architectural massing strategy, as they provide both vertical emphasis and (if expressed or clad on the outside in glass) natural human scale. Renzo Piano’s headquarters building for Debis in Berlin, Germany, for example, uses a main fire stair as a metaphorical ‘prow’, offering a distinctive finish to the building mass (Fig. 2.1.11). Life-safety systems, while notoriously onerous in their requirements, are like so many other aspects of building design best considered early in the process, when their particularities may be absorbed into an overall architectural strategy.
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Frequently asked questions
Are codes absolute? Or if my design falls just outside of the code’s parameters, will it be rejected by code officials? Compliance with codes is interpreted by gov-ernment and/or institutional officials. Often, municipalities will permit these officials to issue variances that permit single instances of non-compliance.
However, this does not come with a waiver of responsibility for the designers, and in the event of a fatality or injury due to fire the design’s non-compliance may expose the design team to significant legal risk.
Can fire walls include glass? For low fire ratings (1h in particular) walls and doors may have limited amounts of glass. However this must typically be wire glass, which provides additional structural integrity in a fire situation. Glass products that use chemical interlayers for additional fire resistance are also available and may provide significant protection for larger areas. However this comes at additional expense, and such glass products often have an inevitable color variation that may limit their acceptability.
How do wheelchair users evacuate a multi-story building in a fire? This is a com-mon and slightly chilling problem in reconciling accessibility with fire safety.
Most codes assume that wheelchair users can be assisted or carried down short runs of stairs. However, for buildings above three stories, there are generally code requirements for additional space within fire stair enclosures large enough for one or two wheelchair parking spaces. These provisions assume that rescue will come within the rated time for these enclosures, and that these occupants can be carried by fire fighters.
Why do most elevators in newer buildings have fire doors in front of them? Is this to keep people from using them in a fire? Recent codes recognize the potential for elevator shafts to act as very efficient fire chimneys, particularly given their lightweight doors and tall, narrow spaces. Large buildings will often have fail-safe closer doors that will activate and seal off elevator lobbies from occupied or potentially combustible areas to prevent fire infiltration into vulnerable elevator shafts.
Why shouldn’t I use fire sprinklers in hotel rooms to hang clothes? Is this a safety issue? Not so much. Most sprinklers contain a small, fragile vial of liquid that, when heated, expands rapidly, breaking the vial and eliminating the only barrier to a fully pressurized pipe system behind. Hangars are notorious for breaking this vial and deluging hotel rooms.
Glossary and formulas
Active Containment Fire control strategy relying on mechanical systems (usually piped water) to suppress fire.
Building Codes Regulatory documents that restrict construction to established, safe practices. May be prescriptive, giving detailed dimensional and/or material criteria, or performance-based, requiring design teams to assert acceptable levels of building performance.
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Building Integrity Element of life safety design that emphasizes the relia-bility of the building’s structure and fabric during a fire or other hazardous situation.
Clear Width A measure of an escape component’s capacity. Often determined by multiplying the worst-case anticipated occupancy by a code-specified width (typically 0.2 in.
or 5 mm per person), but generally no less than 44 in.
(112 mm) for corridors and stairs.
Containment Element of life safety design that discourages fire from spreading.
Discharge Space A public or open area that is sized to accommodate the escaping population of a building.
Escape Element of life safety design that enables occupants to physically remove themselves from hazardous situations.
Fire Resistance The ability of a component or material to withstand fire without burning or transmitting dangerous amounts of heat. Usually determined in laboratory settings.
Fire Stair An staircase that meets all code requirements for access and is separated from any occupied or poten-tially hazardous area by a significant fire-resistive wall (usually 2 h or more).
Notification Element of life safety design that alerts occupants of a hazardous situation
Occupancy Type Classification of a building or building space based on its perceived use. Specified by most building codes as a means of assessing integrity and escape requirements.
Panic Hardware Bars and latches on doors that enable operation by pressure instead of turning. Usually required by codes on doors in fire exits or corridors to pre-vent panicking crowds from piling up against them.
Passive Containment Fire control strategy relying on the fire-resistive nature of construction materials to contain fire.
Travel Distance The length of a path drawn from a room to the first place of fire refuge – usually an exterior exit or fire-protected staircase. Typically limited by codes to no more than 250 ft or 75 m, occasionally more if the building is fully provided with sprinklers.
Further reading
Allen, E. and Iano, J. (2002) Designing with Building Codes (Chapter 1), The Architect’s Studio Companion: Rules of Thumb for Preliminary Design, 3rd ed (New York: Wiley), pp. 3–14.
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2.2 Accessibility
95 Accessibility Definitions
Legal history
Anthropomorphic Data Basic parameters of wheelchair dimensions Fine grained data – grips, etc.
Accessible Design Principles Requirements
Stairs Rise and run
Code and ADA requirements
Detail design – treads, handrails, landings, and guardrails
Ramps Code and ADA requirements
Detail design – surfaces, handrails, and landings
Introduction
In designing for the ‘general public,’ the profession has had a nasty history of leaving a significant percentage of that public out, either providing routes that are inaccessible to some, or making circulation and function within a building difficult for others.
Nearly one in five Americans or Europeans is unable to fully negotiate or use architectural configurations designed for the average occupant. Disabilities come in a variety of forms, and increasingly our profession has been charged with creating inclusive environments, that restrict fewer individuals from the spaces we design.
There is a long legal history behind the current North American standard of
‘universal’ or ‘accessible’ design. Prior to World War II, there was no federal leg-islation making discrimination against persons with disabilities illegal. As veterans who had been wounded or disabled returned, and as medical care increased both quality and quantity of life for those with disabilities, a movement grew seeking protection against discrimination in hiring. However it was not until 1964 that the federal government took up the problem of environmental discrimination.
Employers could still prevent people with disabilities from working, however unintentionally, by providing inaccessible environments and workplaces.
Legislation through the 1960s and 1970s required federally funded buildings to comply with a short list of architectural standards designed to remove bar-riers to users of wheelchairs. An ANSI standard was developed to provide reliable standards of design. However, the federal government’s efforts did not apply to the private sector, and civil rights advocates continued to press for comprehensive accessibility legislation.
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The Americans with Disabilities Act (ADA) – the legal climate in America
In 1990, the ADA was signed into law, extending civil rights protection to roughly 43 million Americans with disabilities. It covers broad areas of employment, pub-lic services and accommodations and housing.
While the ADA has provided a much needed change in opening up jobs, activ-ities and environments for people with disabilactiv-ities, it has had numerous critics – not for its intent, but rather for its mechanism. Because the ADA is civil rights legislation, it is enforced by civil courts. Compliance with its prescriptive stand-ards is enforced not by an agency with expertise, but rather by the courts. There is thus no room for ‘designed’ solutions – rather every place of employment of public accommodation must comply directly with the quantitative information of the ADA, under threat of lawsuit from potentially injured parties.
While numerous building codes have adopted portions of the ADA, it remains the standard for accessibility throughout the US. Compliance is generally manda-tory for most employers, government agencies, and ‘privately operated estab-lishments in which the public are served.’ These entities must make ‘reasonable accommodations’ for any person with a disability. Case law has generally required any new construction for these entities to comply with ADA, and for existing con-struction to be modified on an as-needed basis. Renovation of an existing build-ing is a tricky situation. These projects will generally be required to provide
‘reasonable’ accommodation.
Note that about the only completely exempt building type is single-family resi-dential housing. Even this, however, has become the subject of code require-ments, notably in Naperville, IL, which now has substantial standards for accessibility in all new construction. ‘Visitability’ is an important idea in resi-dential design, encouraging at least one accessible entry and a suite of rooms (including a toilet room) that can be easily negotiated by wheelchair users.
Other building types pose different challenges. Sports arenas and theaters, for example, present particularly tricky design problems because of their sloped seats. It is not practical to allow accessible routes to every seat in a theater, but it is also discriminatory to cluster all accessible seating at the front, or at the rear. Strategies that offer some variety in locations, views, access to ancillary spaces, and ticket pricing have all been successfully employed in these types of project.
Society has demanded an increased awareness and response to accessibility issues. Thus, like life safety codes, we propose to offer basic strategies that can be incorporated early in the design process, eliminating ‘retrofit’ solutions and inevitable frustration later on.
Universal design – good practice
‘Accessible design’ ‘disabled design’, and ‘handicapped-accessible’ are all prob-lematic terms, as they imply a special effort being made for users of wheelchairs 2 Circulation
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and other disability-specific equipment or components. Recently the term
‘Universal design’ has been proposed as a way of pointing out that our buildings should incorporate accessibility principles as a matter of course. ‘Clip-on’ solu-tions are not only aesthetically problematic, they stigmatize and often separate occupants with disabilities. The ‘stair lift’ is a prime example of this. Users of wheelchairs must operate loud machinery to travel a short distance, while their companions who can walk must wait for them to be lifted into place. (Often these require a key, or assistance from a security guard, heightening the prob-lem). A better solution would be to find ways to take up – or eliminate – small changes in level, putting walkers and users of wheelchairs on a ‘level playing field.’
With that in mind, recall some basic anthropomorphic dimensions (see Fig. 2.2.1). Allowing for wheelchair passage in corridors, for example, is rela-tively simple – 910 mm (36 in.) provides enough clearance for operators to comfortable maneuver ahead. Obstructions that limit this distance to 810 mm (32 in.) for brief periods are also acceptable. However, most corridors must accommodate people traveling in both directions. While the code minimum of 110 mm (44 in.) allows someone to move sideways past a wheelchair, this is obviously an awkward situation. Even allowing enough room for someone to comfortably walk past a wheelchair – 1220 mm (44 in.) – does not allow for the obvious case of two wheelchair users passing at the same time. However, 1500 mm (60 in.) allows this to occur comfortably, and therefore from a Universal Design standpoint, this should be an absolute minimum dimension.
Note that the 1500 mm (60 in.) dimension is also the required space for a wheelchair user to turn completely around, based on the width of a typical device. While it is possible to turn a wheelchair in the ‘T’ shape as shown, allowing room for a full 180° turn allows users to maneuver comfortably.
The 1500 mm (60 in.) minimum corridors obviate any tricky or uncomfort-able maneuvering. This is also important for elevator cabs; while a ‘T’ turn will allow a wheelchair user to maneuver in and out, it may require difficult maneuvering to turn around inside the cab. Rather than backing in, frustrated wheelchair users may simply face the back wall and reverse out of a cab in this situation – an awkward and potentially dangerous situation if there is traffic in front of the cab door. If room for a full 1500 mm (60 in.) turn is allowed inside the cab, the user can access the elevator without special effort.
Perhaps the most pressing needs occur in toilet rooms. While some advo-cates prefer separate toilet rooms that provide full 1500 mm (60 in.) maneu-vering clearances, the ‘separate but equal’ provisions in ADA require some percentage of multi-stall toilet rooms to meet minimum (some would say sub-minimum) anthropomorphic requirements. Toilet rooms with minimum dimen-sions required for an ADA-acceptable stall require the user to make a difficult transfer, using grab bars and turning around between the wheelchair and the toilet fixture. (Note, too, that because of planning efficiencies, the dedicated
‘accessible’ stall is often at the far end of a series of stalls. The user must there-fore back out down the row of stalls to exit if the stall is in use – hardly a desir-able result.) A much better (though more spatially intensive) stall design would allow the user can maneuver a wheelchair parallel to the fixture, and simply transfer laterally, and would include a 1500 mm (60 in.) turning circle as well.
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1525mm (60 in.)
915 mm (36 in.)
915mm (36 in.)610mm (24 in.)
915 mm (36 in.) 1220 mm (48 in.)
1525 mm (60 in.)
Figure 2.2.1. Basic planning dimensions for wheelchair accessibility in circulation areas.
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Universal design – fine grain
In addition to these relatively simple planning standards, we need to pay attention to the smaller scale anthropomorphic requirements of a variety of occupants. Most pressing is the need to provide accommodations for persons who need to reach services – shelves, sinks, telephones, door handles, and elevator buttons – from a sitting position (Fig. 2.2.2). While the geometry of the occupant’s reach allows greater high and low reach from a ‘side approach,’
that is, where the occupant can pull alongside the required service. In general, we avoid placing any service – in particular electric outlets – lower than 15 in.
from floor height, and try to restrict most amenities – telephones, paper towel holders, etc., to no more than 48 in. above floor height. (Note, too,
from floor height, and try to restrict most amenities – telephones, paper towel holders, etc., to no more than 48 in. above floor height. (Note, too,