REGULATED LANDSCAPES Diagramming Scottish Building Standard 4.3: Stairs and Ramps
COMPLIANT ARCHITECTURE
Liam Ross
Scottish Building Standards / Domestic Handbook Safety / Mandatory Standard 4.3: Stairs and Ramps Introduction Stairs and ramps should be constructed to be within limits recognised as offering safe and convenient passage and designed so that any person who is likely to use them can do so comfortably and safely, with the minimum amount of difficulty.
Ramps Surfaces with a gradient of 1 in 20 to not more than 1 in 12 are considered to be ramps and recommendations are made on such surfaces to ensure the safety and amenity of users. Gradients of more than 1 in 12 are considered too steep to negotiate safely and are not recommended. Steep gradients require both greater effort to ascend and more care when descending. As a general principle, the steeper the gradient of a ramp, the shorter the flight should be. A pedestrian ramp should be constructed in accordance with the following table:
Treads (other than a private stair): Rise: 100-170mm Going: ≤ 250 Tread: ≥ Going Pitch: ≥ 34º
Max. gradient 1 in 20 1 in 15 1 in 12
Notes: 1. All rises in a flight should be of uniform height; 2. In a straight flight, or in a part of a flight that is straight, measurement should be uniform along the centreline of the flight; 3. Where a flight consists partly of straight and partly of tapered treads, the going of the tapered treads should be uniform and should not be less than the going of the straight treads; 4. The going measured at the narrow end of a tapered tread should be at least 50 mm; 5. The aggregate of the going and twice the rise should be at least 550 mm and not more than 700 mm.
Max. length 10 m 5 m 2 m
Max. rise 500 mm 333 mm 166 mm
Notes: 1. The maximum flight length for a particular gradient can be interpolated as follows: 3 m long for a gradient of 1 in 13, 4 m long for a gradient of 1 in 14, and so on. Level and Gently Sloping Ground For the purpose of this guidance, level is a gradient of not more than 1 in 50, and gently sloping is a gradient of more than 1 in 50 and not more than 1 in 20. Gently sloping gradients should be provided with level rest points of not less than 1.5 m in length, at intervals dependent on the gradient of the sloping surface. This should follow the same relationship given for ramp flights, e.g. up to 20 m apart for a slope of 1 in 30, 30 m for a slope of 1 in 40 and so on. Recommendations for ramps are provided in the guidance to standard 4.3.
28.6°
Flights 1200.00 Climbing stairs can be tiring to many people. Whilst landings can provide a safe resting point, the flight itself is not intended to do so. The maximum number of rises between landings should therefore be limited. Generally, a flight should have not more than 16 rises. Below a minimum number of steps, it becomes difficult to signal a change 1200.00 of level, which can contribute significantly to a trip hazard. Generally, a flight should have at least 3 rises. The minimum length of a stair landing, measured on the centreline of travel, should be either 1.2 m or the effective width of the stair, whichever is less. 10.4°
1200.00
2.7°
2000.00
1200.00
2.9°
5000.00
1200.00
2.5°
9000.00
1200.00
1°
1200.00
1200.00
28.6°
1200.00
10.4°
1200.00
2.7°
2000.00
1200.00
2.9°
5000.00
1200.00
2.5°
500
9000.00
1200.00
1°
11.3°
34°
170 100
250
1200.00
REGULATED LANDSCAPES Diagramming Scottish Building Standard 4.3: Stairs and Ramps Scottish Building Standard 4.3 regulates the geometry of stairs and ramps to provide for safe and comfortable access within and around buildings. It sets limits on the going, rise and pitch of stairs, recognizing that the more public a stair – the less familiar it is to its user – the more shallow its pitch should be. It sets limits on the length of a flight, noting that short flights pose a trip hazard, while long flights are tiring, requiring regular breaks. It limits the pitch and length of ramps, ensuring that the steeper a ramp, the more frequently it is broken. And recognising that the ground is never truly level, it establishes categories of gently-sloping ground, as well as considering the minute falls required for surface water drainage. The limits set by the standard are principally bodily indices – measurements of accepted limits to comfortable gait, to the duration and extent of acceptable exertion, and of our familiarity with, and attentiveness to, our environment. In complying with this standard, our built environment becomes both an anthropometric index, and a regulatory devise; it measures, represents, and limits, bodily movement. This also requires the regulation of the natural environment. Not being built to our measure, the natural terrain is frequently inaccessible; being variously too steep to ascend comfortably, not providing regular resting places, offering trip hazards, as well as being liable to ponding. This project – Regulated Landscapes – makes a series of proposals for accessible routes across a natural terrain. Each proposal begins by taking a specific clause of Scottish Building Standard 4.3, and using it as a means of measuring the accessibility of that terrain. Seeking to maximize the accessible area at the same time as minimizing the modification of the terrain, each proposal explores tolerances within the regulation that allow for a close fit between the bodily abstraction and the specific terrain. In doing so, the project enjoys the control of regulation as a means of measuring, and coming close to, the irregularity of the land.
LANDSCAPE with SHORT CONTOURED FLIGHTS Rise: 100-170mm Going: ≤ 250 Tread: ≥ Going Pitch: ≥ 34º
28.6°
Notes: 1. All rises in a flight should be of uniform height; 2. In a straight flight, or in a part of a flight that is straight, measurement should be uniform along the centreline of the flight; 3. Where a flight consists partly of straight and partly of tapered treads, the going of the tapered treads should be uniform and should not be less than the going of the straight treads; 4. The going measured at the narrow end of a tapered tread should be at least 50 mm;
Flights Climbing stairs can be tiring to many people. Whilst landings can provide a safe resting point, the flight itself is not intended to do so. The maximum number of rises between landings should therefore be limited. Generally, a flight should have not more than 16 rises. Below a minimum number of steps, it becomes difficult to signal a change of level, which can contribute significantly to a trip hazard. Generally, a flight should 1200.00 have at least 3 rises. The minimum length of a stair landing, measured on the centreline of travel, should be either 1.2 m or the effective width of the stair, whichever is less. 1200.00
10.4°
1200.00
2.7°
2000.00
1200.00
2.9°
5000.00
1200.00
2.5°
9000.00
1200.00
1°
1200.00
250
500
11.3°
34°
170 100
Treads
LANDSCAPE with SHORT CONTOURED FLIGHTS proposes a stair with short flights that are parallel to and bear upon the contours of an exising terrain. Landings provide tolerance to accomodate the difference between the irregularly of the natural contours, and the requirement for regular goings. The required minimum length of landings limits the area of terrain which the stair can access. Above: 1. Area of terrain between 5 & 15 degrees 2. 450mm contour-lines 3. Short flighst parallel to contours (3 No. treads, 250mm going x 150mm rise). 4. Minimum 1200mm landings.
Left to right, top to bottom: a) relevant regulatory clauses; b) diagram mapping relevant clauses against terrain; c) Plan, section and elevation of proposal; d) model of landscaped surface.
28.6°
LANDSCAPE with GENTLY SLOPING LANDINGS
10.4°
Treads
9000.00
1200.00
1°
Max. rise 500 mm 333 mm 166 mm
2.5°
Max. length 10 m 5 m 2 m
2.9°
Ramps
2.7°
Level and Gently Sloping Ground For the purpose of this guidance, level is a gradient of not more than 1200.00 1 in 50, and gently sloping is a gradient of more than 1 in 50 and not more than 1 in 20. Gently sloping gradients should be provided with level rest points of not less than 1.5 m in length, at intervals dependent on the 2000.00 1200.00 gradient of the sloping surface. This should follow the same relationship given for ramp flights, e.g. up to 20 m apart for a slope of 1 in 30, 30 m for 5000.00 1200.00 a slope of 1 in 40 and so on. Recommendations for ramps are provided in the guidance to standard 4.3.
Rise: 100-170mm Going: ≤ 250 Tread: ≥ Going Pitch: ≥ 34º
Max. gradient 1 in 20 1 in 15 1 in 12
1200.00
1200.00
Flights Generally, a flight should have at least 3 rises. The minimum length of a stair landing should be either 1.2 m or the effective width of the stair, whichever is less.
500
11.3°
34°
170 100
250
LANDSCAPE with GENTLY SLOPING LANDINGS exploits the possibility of a landing to be be gently sloping. 1200mm long landings are laid across the landscape at 1700mm intervals, wherever the cross-fall generated is less than 1 in 20. These landings are connected with short flights or ramps, whenever the height difference between landings falls within legal limits. 1. Indicative contour-lines. 2. Parallel sections at 1700mm centres. 3. 1200mm landings, normal to terrain, maximum 1:20 pitch
Left to right, top to bottom: a) relevant regulatory clauses; b) diagram mapping relevant clauses against terrain; c) Plan, section and elevation of proposal; d) model of landscaped surface.
LANDSCAPE with LONG SHALLOW RAMPS
1200.00
2.7°
2000.00
1200.00
Max. rise 500 mm 333 mm 166 mm
2.9°
5000.00
1200.00
2.5°
9000.00
1200.00
1°
1200.00
250
500
11.3°
34°
170 100
Max. length 10 m 5 m 2 m
10.4°
Max. gradient 1 in 20 1 in 15 1 in 12
Notes: 1. The maximum flight length for a particular gradient can be interpolated 1200.00 as follows: 3 m long for a gradient of 1 in 13, 4 m long for a gradient of 1 in 14, and so on. 28.6°
Ramps Surfaces with a gradient of 1 in 20 to not more than 1 in 12 are considered to be ramps and recommendations are made on such surfaces to ensure the safety and amenity of users. Gradients of more than 1 in 12 are considered too steep to negotiate safely and are not recommended. Steep gradients require both greater effort to ascend and more care when descending. As a general principle, the steeper the gradient of a ramp, the shorter the flight should be. A pedestrian ramp should be constructed in accordance with the following table:
1200.00
LANDSCAPE with LONG SHALLOW RAMPS proposes a series of ramps that spring from and terminate on existing contours. The requirement for a minimum length of landing and width of ramp limits area of terrain which the ramp can access. 1. Area of terrain between 3 and 20 degrees. 2. 450mm contour-lines. 2. 1200mm landing guides 4. Minimum 9000mm ramps, rising 450mm
Left to right, top to bottom: a) relevant regulatory clauses; b) diagram mapping relevant clauses against terrain; c) Plan, section and elevation of proposal; d) model of landscaped surface.
2.5°
9000.00
2.9°
1200.00
1°
1200.00
250
500
11.3°
34°
170 100
Flights Generally, a flight should have at least 3 rises. The minimum length of a stair landing should be either 1.2 m or the effective width of the stair, whichever is less.
Level and Gently Sloping Ground For the purpose of this guidance, level is a gradient of not more than 1200.00 1 in 50, and gently sloping is a gradient of more than 1 in 50 and not more than 1 in 20. Gently sloping gradients should be provided with level rest points of2000.00 not less than 1.5 m in length, at intervals dependent on the 1200.00 gradient of the sloping surface. This should follow the same relationship given for ramp flights, e.g. up to 20 m apart for a slope of 1 in 30, 30 m for 5000.00 1200.00 a slope of 1 in 40 and so on. Recommendations for ramps are provided in the guidance to standard 4.3.
2.7°
Rise: 100-170mm Going: ≤ 250 Tread: ≥ Going Pitch: ≥ 34º
1200.00
10.4°
Treads
28.6°
LANDSCAPE with GENTLY SLOPING GROUND
LANDSCAPE with GENTLY SLOPING GROUND creates an accessible route across a terrain that is neither ramp nor stair. It analyses the extent to which the terrain is already legally accessible as ‘gently sloping’; i.e. falling below the minimum pitch categorised as a ramp. It then plots a gently sloping traversing route across the remaining terrain, tilting the ground to comply with maximum permissable cross-falls for accessible routes. 1. Area of terrain greater than 1:40 pitch 2. Area of terrain less than 1:40 pitch 3. Triangulated mesh, minimum face 2400mm 4. 1:40 traversing contour 5. Area of modified ground. 6. Line of retaining walls.
Left to right, top to bottom: a) relevant regulatory clauses; b) diagram mapping relevant clauses against terrain; c) Plan, section and elevation of proposal; d) model of landscaped surface.
Compliant Architecture is a design, research and teaching project based at the University of Edinburgh. It conducts text-based research into the emergence of building regulations, design-research that illustrates the limits they impose, and taught design modules that explore the architectural potential of those limits. The project hopes to render visible the architectural knowledge manifest in regulatory programmes, looking beyond their instrumental ends to the material phenomena they index.
COMPLIANT ARCHITECTURE Assistant:
Liam Ross
Vsevolod Kondratiev-Popov
Š The University of Edinburgh 2011 No part of this publication may be reproduced without prior permission from the author. liam.ross@ed.ac.uk www.architecture.ed.ac.uk