Steps outside buildings

Returning to mundane matters, the National Building Regulations in Britain call for ground floors to be at least 150 mm above the natural exterior level, hence a step is needed at all entries (Figure 5.9a) or else a ramped pavement where disabled access is mandatory (Figure 5.9b). The 1998 National Building Regulations call for textured pavings at ramps to identify such features for the blind and partially sighted. Both elements can be combined in a single design (Figure 5.9c). The dimensions of the basic form should be in scale with the door, which now has to be wide enough for a wheelchair, the depth should be a comfortable footspace.

Providing a flight of steps by external doors needs to take into account safety of egress, space for door swings and a walking distance before the first riser, say a distance of 1 800 mm minimum (Figure 5.10a). Balustrade protection should be given to both sides or handrails

Spanish Steps

Figure 5.5c Spanish Steps, Rome: Detail of gentle riser-to-tread proportion

provided where the platform category of stairs is employed. Balustrading constructed with tubular steel can incorporate electrical conduit and lighting systems placed within the handrail profile. In many European countries ramp blocks are built into the flight (Figure 5.10b),

Spanish Steps

Figure 5.5a Spanish Steps, Rome, 1721-3, designer: Francesco de Sanctis: Key plan (from Schuster, F., Treppen, Hoffman Verlag, 1949)

Figure 5.5b Spanish Steps, Rome: General view

mmmmm.

Figure 5.6 A veritable palace of garden rooms: Villa Garzoni, Collodi, 1652

but in Britain ramped circulation has to follow a defined slope of given width (refer to the Building Regulations regarding the disabled in Chapter 10). The imposing civic entrance to the Law Courts in Vancouver is a very successful application of these principles on a monumental scale, the complex levels combining a sitting out area with diagonal ramps and stairs for ceremonial purposes (Figures 5.10c and 5.10d). The concept relates to platform steps employed in pyramid form with both external and internal corners. The main advantage is the prominence that such forms give to entries (Figures 5.11a and 5.11b). Direct flights of stairs are more practical and easier to adapt for safety with guard rails and perimeter balustrading (Figure 5.11c) and with ramps accommodated alongside. Direct flights can also be devised to handle vast crowds of people, as in the layout of sports stadia. In these circumstances the steps are divided into passageways of 1 800 mm widths separated by engineered guard rails, with groups of stairs limited to 16 risers between landings;4 failure can produce a catastrophe (Figure 5.11 d). In Britain, such stairs have to break their alignment at every third landing. Similar provisos exist when designing the approaches to pedestrian bridges or underpasses, the customary layout having a choice of stairs and ramps.

Reverting to simple steps placed by building entries, there are severe constructional restraints that affect the design solution. By illustration, the plinth or block of steps can be made as a ground slab independent of the building mass (Figure

Figure 5.7a Italianate detail: Tapered layout for perspective effect

Long radius to nosing

Eccentric angles turn view to that direction

Long radius to nosing

Eccentric angles turn view to that direction

Slight camber to nosing line improves perspective -(can be arranged on plan or by cambering treads)

Perspective shape lengthens upward view and shortens ' downward view

Slight camber to nosing line improves perspective -(can be arranged on plan or by cambering treads)

Perspective shape lengthens upward view and shortens ' downward view

Curved platform steps rising to an opening

Curved platform steps rising to an opening

Figure 5.7b Italiante detail: Pinched space at stair location

Figure 5.7d Italiante detail: Differing heights of balustrade to give greater distance, Powys Castle (date unknown)

Figure 5.7e Italiante detail: Curved line of tread to improve visual effect. Renishaw, 1990s, designer: Sir George Sitwell

5.12a), or else as a cantilever extension of the ground floor slab or adjacent wall (Figure 5.12 b). The other concepts involve independent framing in steel or timber (Figures 5.12c and 5.12d).

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