< Previous30 Section 3|Risers & Treads The dimensional irregu- larity of steps is a leading cause of stairway falls, with slips due to over- stepping in descent being the most frequent type of stairway fall. Use Uniform Stair Geometry. For greater usability, stairs in the same staircase should use consistent and uniform stair geometry. A continuous run of equally shaped treads not only enables a more consistent gait pattern for users, reducing the risk of missteps, it has the added benefit of improving the quality of the stair’s construction . Avoid Irregular Steps. It is fairly common to see staircases with a smaller or bigger first or last step. Such irregularities in a stair’s geometry or a stairway’s structure come as a “surprise” to stair users and often lead to falls. Steps should be consistent in size, shape, and occurrences between landings. Avoid Winder Treads. Among the various stair configurations, winding stairways are considered more dangerous than straight stairways. This is because spiral, curved, and winder stairs use treads that vary in depth from one end to the other. These winder or “pie-shaped” treads are tapered, narrowing along the inner radius, making them more difficult to traverse, especially for PLV users. STAIR GEOMETRY31 universal design guidelines for feature stairs synergillc.com | 2022 Dimensional Uniformity. Because riser heights and tread depths that vary are not expected, inconsisten- cies can present tripping hazards to users. Stairs with uniform tread depth and riser height are best for all travelers, and building code specifications for accessible stairways require uniform risers and treads. Tolerance. Stair treads and risers should be of uniform size and shape. IBC dictates the tolerance between the largest and smallest riser height or between the largest and smallest tread depth cannot exceed 3/8 inch (9.5 mm) in any flight of stairs. Note the geometry of the stairs among these stair- case styles. Winder treads vary in depth from one end to the other. Depicted in gray in these diagrams, winder treads are pie- shaped, rather than rect- angular, in shape.32 Section 3|Risers & Treads Avoid Open Risers. Open riser or floating staircases are not recommended for a universal design approach. Blind people, the elderly, and others using canes often count on being able to feel the depth of a stair tread by detecting the riser. Without risers, the cane slides over the back end of the tread, making depth detection difficult. RISERS & TREADS : APPEARANCE The riser is the vertical surface of the stair. Only visible when ascending stairs, risers are a useful visual cue for all users. Use Closed Risers. Closed risers prevent feet and canes from accidentally slipping under treads, and they keep children, pets, and objects on stairs from falling through. 33 universal design guidelines for feature stairs synergillc.com | 2022 In Fill Risers. In-filling all risers is recom- mended, as open risers can be visually confusing, and might cause tripping or a strobing effect. The solid barriers between treads also block distracting views in the background behind the stairs that may draw the user’s attention away from the steps during ascent and cause falls. Alternate Colors. Stairs with risers and treads in different colors, especially high contrast colors, make it easier to detect the stair edge when walking upstairs. Synergi’s stairs in this lobby space at 4747 Bethesda Ave NW provide high- contrasting black and white risers and treads, making each stair easy to detect.34 Section 3|Risers & Treads Solid Surface Treads. Treads are the flat, horizontal portion of a stair that a person places their foot upon. IBC building codes require that the walking surfaces of treads and landings of a stairway should have a solid surface. Tread & Wall / Floor Colors. The color of stair treads should contrast with walls and flooring to alert passers- by, especially those who are visually impaired, to the presence of steps.universal design guidelines for feature stairs synergillc.com | 2022 Avoid Complex Patterns & Textures. While color and texture changes are recommended to indicate depth change, certain kinds should be avoided. Complex color or texture materials and/ or finishes are confusing and require careful inspection prior to navigating. For example, the varying but similar colors of wood can generate the illu- sion of edges in the riser and tread. The muted palette of limited colors used on these stairs may be visually confusing for PLVs and other stair users.36 Section 3|Risers & Treads Avoid Using Glass. Transparent glass can be especially problematic for visibility. The transparency and the reflec- tions in the glass cause PLV to lose their sense of space. Transparent glass can also cause fear for some stair users (especially if the staircase is tall), create immodest sight- lines, and distract stair users from focusing on navigation. Translucent Guardrails.Translucent guardrails can be used to maintain modesty while still allowing natural light to pass through, and translucent risers can create the illusion of openness while preventing others from seeing through them. 37 universal design guidelines for feature stairs synergillc.com | 2022 Avoid Multi-Colored, Bright, or Distracting Patterns. Avoid using multicolored, abstract, or confusing floor coverings. These can be disconcerting to the eye or impair one’s sense of depth perception, making stair users more likely to compromise their safety. 38 Section 3|Risers & Treads RISERS : ANGLE / NOSING A stair edge is where the tread and riser meet. Some stairs have treads that project or hang over the risers beneath them. This overhang is a stair’s nosing or lip. Modify Existing Risers. Where nosing already exists on stairs, a fillet can be added to the underside of the projected nosing to reduce the tripping hazard. When the configuration of the nosing cannot be modi- fied, slip-resistant stripes can be applied to the nosing as an alternative solution. Slip-resistant strips should be 40 mm wide at minimum and should not extend more than 1 mm above the tread surface. Use Vertical Risers. It is recommended that risers be vertical, not angled,. This prevents the stair edges from hanging over the risers beneath them, creating nosings that can present tripping hazards. Avoid Sharp Edges. To avoid sharp edges, treads or nosing should be flush or rounded. 39 universal design guidelines for feature stairs synergillc.com | 2022 Angled Risers (Projected Nosing). A vertical riser can be angled to create a nosing that projects to hang over the riser underneath it. While not optimal, the ADAAG does permit risers to slope under the tread at a 30 degree maximum from vertical, allowing the projected nosing to extend 1½ inches at maximum over the tread below. In these instances, the projected nosing must have the underside of the leading edge curved or bevelled. Square Nosings. Overhanging nosings that have an underside perpendicular to the riser face (square nosing) present a trip hazard, particularly to people who ascend steps by sliding their feet up the surface of the riser or use visual aids to feel the stair. Next >