The Requirement
Requirement K1 applies to the design and construction of stairways, ladders and ramps. It does not apply to steps or access routes outside a building other than the circumstances set out in paragraph 1.1.3.
Additional requirements may be necessary for access routes which form part of:
(i) means of escape in case of fire (see Technical Guidance Document B);
(ii) means of access for people with disabilities (see Technical Guidance Document M).
Reference should be made to Technical Guidance Document D for guidance in relation to manufacturing and other tolerances applicable to building components generally.
Stairways and Ladders
1.1.1 Paragraphs 1.1.2 to 1.1.20 give some guidance on good practice insofar as it relates to non-complex buildings of normal design and construction.
1.1.2 In this sub-section:
flight means the part of a stairway or ramp between landings;
going means the horizontal distance between the nosing of a tread and the nosing of the tread or landing next above it;
pitch means the angle between the pitch line and the horizontal;
rise means the vertical distance between the top of a tread and the top of the tread, landing or ramp next above or below it;
stairs means a succession of steps and landings that make it possible to pass on foot to other levels;
tapered step means a step, the nosing of which is not parallel to the nosing of the step or landing next above it;
tread means the upper surface of a step.
1.1.3 In the case of steps immediately outside an external door of a building (i.e. part of the building): (a) where there are three steps or less, only the recommendations in Table 1 and par. 1.1.4 apply; and (b) where there are more than three steps, all the provisions of this sub-section apply.
For accessible stepped approaches to building entrances, see Technical Guidance Document M – Access and Use.
Rise, Going and Pitch
1.1.4 In any stairs –
(a) all of the steps should be of appropriate dimensions and be of suitable construction,
(b) all steps should have the same rise,
(c) all parallel steps should have the same going, (d) all tapered steps should have the same going.
Diagram 1 shows how to measure the rise and going of a step.
Diagram HK1 - Measuring rise and going - Extract from TGD K
Table 1 contains recommendations on maximum rise, minimum going, maximum pitch, and optimum values in each case based on I.S. 158:1987 and BS 5395-1:2010.
Table HK1 - Rise, going and pitch - Extract from TGD K
1.1.5 Any series of three risers or less occurring at a change of level in a floor, balcony or roof and such like, need only comply with Table 1 and par. 1.1.4. The other provisions of this sub-section do not apply in such cases.
1.1.6 The varying tread width of a tapered step can cause people to misjudge distances and can lead to falls. For this reason, the use of tapered steps should be avoided. If it is necessary to use them, they should preferably be situated at the bottom of the stairs. Public stairs should not contain tapered steps. Where consecutive treads are used, a uniform going should be maintained. For tapered treads, the going should conform with par. 1.1.4 when measured as follows:
(a) if the flight is narrower than 1000 mm, measured in the middle, and
(b) if the flight is 1000 mm or wider, measured 270 mm from each side.
In addition, the going at the narrow end should be a minimum of 75 mm (see Diagram 2).
Diagram HK2- Measuring tapered treads - Extract from TGD K
Construction of steps
1.1.7 Steps should have level treads. Steps may have open risers but in such cases the nosing of any tread should overlap, on plan, the back edge of the tread next below it by at least 16 mm (see Diagram 1). For steps suitable for ambulant disabled people refer to Technical guidance Document M – Access and Use.
1.1.8 A stairway with open risers should be constructed so that a 100 mm diameter sphere cannot pass through the opening between adjacent treads, unless the stairway is unlikely to be used by children under five years old. Diagram 2 Measuring tapered Par.1.1.6 treads
Headroom
1.1.9 Headroom over the whole width of any stairs, measured as shown in Diagram 3, should generally be not less than 2 m. In the conversion of a loft where space is limited, headroom measured at the centre of the stairs should be not less than 1.9 m but may reduce to not less than 1.8 m at the side of the stairs if there is a minor projection.
Diagram HK3 - Measuring headroom - Extract from TGD K
Widths of Stairs
1.1.10 Private stairs should have a clear width of not less than 800 mm however; in certain circumstances they may need to be wider (See Technical Guidance Document M – Access and Use, Section 3.3.2.2). In the case of semi-public and public stairways, designers should bear in mind the requirements for stairs which:
(a) form part of a means of escape, reference should be made to Technical Guidance Document B – Fire Safety;
(b) provide access suitable for ambulant disabled people, reference should be made to Technical Guidance Document M – Access and Use.
Length of Flights
1.1.11 There should not be more than sixteen risers in any one flight. A flight containing one or two risers in private stairs should be situated at the bottom of the stairs. For stairs suitable for use by ambulant disabled people, see guidance in Technical Guidance Document M – Access and Use.
1.1.12 In places of assembly to which large numbers of people have resort, there should be no more than two consecutive flights each having a maximum of twelve risers, without a change in direction of at least 30° between flights (see Diagram 4).
Diagram HK4 - Change of direction in places of assembly - Extract from TGD K
Landings
1.1.13 A level landing should be provided at the top and bottom of every flight except that a landing may not be necessary between a flight and a door if the total rise of the flight is not more than 600 mm and the door slides or opens away from the steps. The landing may include part of a floor. The width and going of the landing should be at least as great as the smallest width of the flight.
1.1.14 Landings should be clear of permanent obstruction. A door opening on to a landing should be so positioned that there will be a clear space of at least the full width of the flight between the door swing and the flight. In the case of private stairs, the landing at the bottom of a flight may be reduced in length provided a clear space of at least 400mm is maintained between the flight and the door swing (see Diagram 5 for examples)
Diagram HK5 - Landing next to door - private stairs - Extract from TGD K
Loft Conversions
1.1.15 Spiral stairs with goings less than recommended in Table 2 of BS 5395 Part 2: 1984 and alternating tread stairs would not normally be regarded as acceptable. However, they may be considered in the conversion of a loft where space is limited i.e. where there is not enough space to accommodate stairs satisfying par. 1.1.1 to 1.1.14 above and the stairs serves only accommodation which will be used infrequently and, where the accommodation includes only one habitable room. Alternating tread stairs should be in straight flights, have handrails on both sides and the treads should have slip resistant surfaces. The goings and rises for the wider parts of the steps should comply with par. 1.1.4.
Fixed Ladders
1.1.16 A fixed ladder should have fixed handrails on both sides. It should not be used as the primary access to a habitable room.
Handrails
1.1.17 Stairs should have a handrail on at least one side if it is 1000 mm wide or less. It should have a handrail on both sides if it is wider. The top surface of the handrail should be between 900 mm and 1000 mm measured vertically above the pitch line, and between 900 mm and 1100 mm above the landing, Handrails should give firm support. A handrail may form the top of the guarding if the height is suitable (refer to Diagram 6). The handrail should be so constructed and fitted as to be capable of being readily gripped by hand and safely used. Handrails may not be necessary beside the two bottom steps of private stairs.
Diagram HK6 - Guarding design - Extract from TGD K
Guarding
1.1.18 Stairs should be guarded at the sides (see Diagram 6), except where the total rise is no more than 600 mm, in which case guarding may not be essential. Suitable guarding would include a wall, screen (including glazing), railing or balustrade.
1.1.19 Guarding should be designed and built in such a way that it does not present unacceptable risks of accidents in service. Where guarding contains glazing, it should be safety glazing in accordance with the recommendations of BS 6262-4: 2005. In buildings which are likely to be used by children under five years old, guarding should be so constructed that a 100 mm diameter sphere cannot pass through any openings in the guarding. Guarding should not be readily climbable and should be designed in such a way as to discourage young children from climbing it. Features in the guarding that might provide a foothold should be avoided e.g. horizontal rails.
Where a cut string is used, the triangular space formed by tread and riser is allowable, provided the bottom edge of the guarding is not more than 50 mm above the nosing line. The triangular space formed by the tread and riser is not allowable to stairs in dwellings and common stairs in blocks of flats.
1.1.20 The appropriate heights and strength of guarding is set out in Diagram 6.
Further Guidance
1.1.21 Further guidance on stairways and ladders is given in the following:
IS 158: 1987 Closed String Wood Stairs
BS 5395-1: 2010 Stairs, Part 1, Code of practice for the design of straight stairs and winders;
BS 5395-2: 1984 Stairs, ladders and walkways, Part 2 Code of practice for the design of helical and spiral stairs;
BS 5395-3: 1985 Stairs, ladders and walkways, Part 3 Code of practice for the design of industrial type stairs, permanent ladders and walkways;
BS 6180: 2011 Barriers in and about buildings, Code of practice;
I.S. EN 1991-1-1:2002 Eurocode 1: Actions on structures – Part 1-1: General actions – densities, self-weight, imposed loads for buildings (including Irish National Annex 2005)
I.S. EN 14975:2006+A1:2010 Loft ladders. Requirements, marking and testing.
Ramps
1.2.1 A ramp should be so constructed that the slope does not exceed 1:20, except in the case of an individual flight the length of which is not greater than 10 m, when the slope may be greater. Under no circumstances should the slope exceed 1:12.
1.2.2 Ramps and their landings should have clear headroom throughout of at least 2000 mm (see Diagram 3).
1.2.3 A ramp should be clear of permanent obstructions. A door should not swing across the sloping part of any ramp.
1.2.4 Ramps should have a clear width of not less than 800 mm. Further guidance on the width of ramps is provided in Technical Guidance Document B - Fire Safety and Technical Guidance Document M – Access and Use.
1.2.5 A ramp less than 1000 mm wide should have a handrail on at least one side. It should have a handrail on both sides if it is wider. Handrails should be at a height of between 900 mm and 1000 mm, measured vertically, and give firm support. A handrail may form the top of a guarding if the height is suitable. The handrail should be so constructed and fitted as to be capable of being readily gripped by hand and safely used. For handrails on ramps providing access for people with disabilities refer to Technical Guidance Document M – Access and Use.
1.2.6 A landing should be provided at the top and bottom of every ramp. Landings should be level, except where they are formed by the ground, in which case they may slope up to 1:50 provided that the ground is suitably paved. A landing may include part of a floor. The width and length of the landing should be at least as great as the smallest width of the ramp and doors should open away from landings. However, a door swing may encroach on landing space at the bottom of the ramp in a dwelling as described in par. 1.1.14.
1.2.7 Ramps and their landings should be guarded at the sides in the same way as stairs (see pars. 1.1.18 to 1.1.20).
