Part 3.9.2 Barriers and handrails

NCC 2019 Volume Two Amendment 1

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Part 3.9.2 Barriers and handrails

Appropriate Performance Requirements

Appropriate Performance Requirements

Where an alternative barrier is proposed as a Performance Solution to that described in Part 3.9.2, that proposal must comply with—
1. Performance RequirementP2.5.2; and
2. the relevant Performance Requirements determined in accordance with A2.4(3).
Where an alternative handrail is proposed as a Performance Solution to that described in Part 3.9.2, that proposal must comply with—
1. Performance RequirementP2.5.1(b)(i); and
2. the relevant Performance Requirements determined in accordance with A2.2(3) and A2.4(3) as applicable.

The following figure depicts typical stairway and barrier members and associated terminology. Some items have been omitted for clarity.

Figure 3.9.2.0 Typical stairway and barrier members

Legend:

Stringer
Baluster
Barrier
Tread
Riser
Landing
Handrail
Newal post
Open riser
Winders (tapered treads)
Handrail
Landing barrier
Barrier

Explanatory information:

For a required barrier to an external trafficable structure in an alpine area, the requirements of this Part need to be read in conjunction with the requirements of Part 3.10.4. Safety barrier requirements for swimming pools are contained in Part 3.10.1.

Explanatory information:

In addition to the requirements of this Part, a barrier and handrail must comply with the structural requirements of Part 3.0. The structural requirements refer to the barrier and/or handrail being designed and constructed to withstand any combinations of loads and other actions to which it may reasonably be subjected and the structural resistance of the materials and forms of construction used for the barrier or handrail.

A window forming a part of a barrier must comply with the glazing assembly provisions of Part 3.6, and therefore is not required to comply with AS/NZS 1170.1 (structural design actions - referenced in Part 3.0) as it is exempted by Part 3.6. The Part 3.6 provisions consider the wind loading on the glazing and human impact requirements.

3.9.2.1 Application

Compliance with this acceptable construction practice satisfies Performance Requirements P2.5.2 for barriers and P2.5.1(b)(i) for handrails, by complying with—

(a)

3.9.2.2, 3.9.2.3 and 3.9.2.5 for barriers to prevent falls; and

(b)

3.9.2.4 for handrails; and

(c)

3.9.2.6 and 3.9.2.7 for protection of openable windows.

3.9.2.2 Barriers to prevent falls

(a)

A continuous barrier must be provided along the side of a trafficable surface, such as—

(i)

a stairway, ramp or the like; and

(ii)

a floor, corridor, hallway, balcony, deck, verandah, mezzanine, access bridge or the like; and

(iii)

a roof top space or the like to which general access is provided; and

(iv)

any delineated path of access to a building,

where it is possible to fall 1 m or more measured from the level of the trafficable surface to the surface beneath (see Figure 3.9.2.1).

(b)

The requirements of (a) do not apply to—

(i)

a retaining wall unless the retaining wall forms part of, or is directly associated with a delineated path of access to a building from the road, or a delineated path of access between buildings (see Figure 3.9.2.2); or

(ii)

a barrier provided to an openable window covered by 3.9.2.6 and 3.9.2.7.

Explanatory information:

Intent:

The intent of the barrier requirements is to prescribe provisions to minimise the risk of a person falling from a stairway, raised floor level (such as a balcony) or the like. 3.9.2.2 sets out when barriers are required to be provided and 3.9.2.3 contains the requirements for the construction of barriers.

Barriers and children:

Children are at particular risk of falling off, over or through ineffectively designed or constructed barriers. Accordingly the requirements of this Part aim to ensure that a barrier reduces the likelihood of children being able to climb over a barrier or fall through a barrier.

Figure 3.9.2.1 Barriers-when required

Figure 3.9.2.2 Barriers-when required for retaining walls

3.9.2.3 Construction of barriers to prevent falls

A barrier required by 3.9.2.2 must comply with the following:

(a)

Barrier height: The height of a barrier must be in accordance with the following:

(i)

The height must not be less than 865 mm above the nosings of the stair treads, the floor of a ramp or the like (see Figure 3.9.2.3).

(ii)

The height must not be less than—

(A)

1 m above the floor of any landing, corridor, hallway, balcony, deck, verandah, access path, mezzanine, access bridge, roof top space or the like to which general access is provided (see Figure 3.9.2.2 and Figure 3.9.2.3); or

(B)

865 mm above the floor of a landing to a stairway or ramp where the barrier is provided along the inside edge of the landing and does not exceed a length of 500 mm.

(b)

Transition zone: A transition zone may be incorporated where the barrier height changes from 865 mm on the stairway flight or ramp to 1 m at the landing (see Figure 3.9.2.4).

(c)

Openings in barriers: Openings in barriers (including decorative balustrades) must be constructed so that they do not permit a 125 mm sphere to pass through it and for stairways, the opening is measured above the nosing line of the stair treads (see Figure 3.9.2.3).

(d)

Barriers to certain non-habitable rooms: A barrier to a stairway serving a non-habitable room, such as an attic, storeroom or the like that is not used on a regular or daily basis, need not comply with (c) if—

(i)

openings are constructed so that they do not permit a 300 mm sphere to pass through; or

(ii)

where rails are used, the barrier consists of a top rail and an intermediate rail, with the openings between rails not more than 460 mm.

(e)

Restriction on horizontal elements:

(i)

Where it is possible to fall more than 4 m, any horizontal elements within the barrier between 150 mm and 760 mm above the floor must not facilitate climbing.

(ii)

For the purpose of (i), the 4 m is measured from the floor level of the trafficable surface to the surface beneath.

Explanatory Information:

For a window forming part of a barrier, any horizontal elements such as a window sill, transom or rail between 150 mm and 760 mm above the floor is deemed to facilitate climbing.

(f)

Wire barriers: A barrier constructed of wire is deemed to meet the requirements of (c) if it is constructed in accordance with 3.9.2.5.

(g)

Glass barriers and a window forming part of a barrier: A glass barrier or window serving as a barrier must comply with Part 3.6 and the relevant provisions of this Part.

Explanatory information:

Part 3.6 contains the glazing assembly provisions for glass barriers and windows forming part of the barrier, however, the barrier would still need to comply with the relevant requirements of this Part for required height, allowable openings, etc.

(h)

Barrier loading forces: A barrier, except a window serving as a barrier, must be designed to take loading forces in accordance with AS/NZS 1170.1.

Figure 3.9.2.3 Barrier construction

Figure 3.9.2.4 Measuring heights for barriers and handrails and where transition zones are allowed

3.9.2.4 Handrails

(a)

Handrails to a stairway or ramp must—

(i)

be located along at least one side of the stairway flight or ramp; and

(ii)

be located along the full length of the stairway flight or ramp, except in the case where a handrail is associated with a barrier the handrail may terminate where the barrier terminates; and

(iii)

have the top surface of the handrail not less than 865 mm vertically above the nosings of the stair treads or the floor surface of the ramp (see Figure 3.9.2.4); and

(iv)

be continuous and have no obstruction on or above them that will tend to break a handhold, except for newel posts, ball type stanchions, or the like.

(b)

The requirements of (a) do not apply to—

(i)

a stairway or ramp providing a change in elevation of less than 1 m; or

(ii)

a landing; or

(iii)

a winder where a newel post is installed to provide a handhold.

Explanatory information:

3.9.2.4 addresses requirements regarding location, height and extent of handrails. Where a barrier and handrail are installed together, 3.9.2.4 is to be read in conjunction with 3.9.2.2, 3.9.2.3 and 3.9.2.5.
A handrail is required on at least one side of the stairway flight or ramp. The top rail of a barrier may be suitable as a handrail if it meets 3.9.2.4 and is able to be grasped by hand to provide support to the person using the stairway or ramp.
3.9.2.4(a)(ii) requires a continuous handrail which must extend the full length of the stairway flight or ramp except where the handrail is associated with the barrier, in which case the handrail can terminate where the barrier is allowed to terminate. This allows for the barriers to geometric stairways such as elliptical, spiral, circular or curved stairways to finish a few treads from the bottom of the stairway.
3.9.2.4(a)(iii) requires a minimum handrail height of 865 mm. This height provides comfort, stability, support and assistance for most users.
3.9.2.4(b) outlines where a handrail need not be provided, this includes—

where a stairway or ramp is providing a change in elevation less than 1 m; or
a landing for a stairway or ramp; or
winder in a stairway if a newel post is installed to provide a handhold.

3.9.2.5 Construction of wire barriers

A wire barrier is deemed to meet the requirements of 3.9.2.3(c) if it is constructed in accordance with the following:

(a)

For a horizontal or near horizontal wire system—

(i)

when measured with a strain indicator, it must be in accordance with the tension values in Table 3.9.2.1; or

(ii)

when measured for a maximum permissible deflection, it must not exceed the maximum deflections in Table 3.9.2.3.

(b)

For a non-continuous vertical wire system—

(i)

when measured with a strain indicator, it must be in accordance with the tension values in Table 3.9.2.1 (see Note 4); or

(ii)

when measured for maximum permissible deflection, it must not exceed the maximum deflections in Table 3.9.2.3.

(c)

For a continuous vertical or continuous near vertical sloped wire system—

(i)

it must have wires of no more than 2.5 mm diameter with a lay of 7 x 7 or 7 x 19 construction; and

(ii)

changes in direction at support rails must pass around a pulley block without causing permanent deformation to the wire; and

(iii)

supporting rails must be spaced of not more than 900 mm apart and be of a material that does not allow deflection that would decrease the tension of the wire under load; and

(iv)

when the wire tension is measured with a strain indicator, it must be in accordance with the tension values in Table 3.9.2.2 when measured in the furthermost span from the tensioning device.

Table 3.9.2.1 Wire barrier construction—Required tension for stainless steel horizontal wires

			Clear distance between posts (mm)
			600	800	900	1000	1200	1500	1800	2000	2500
Wire dia. (mm)	Lay	Wire spacing (mm)	Minimum required tension in Newtons (N)
2.5	7x7	60	55	190	263	415	478	823	1080	1139	x
		80	382	630	730	824	1025	1288	x	x	x
		100	869	1218	1368	x	x	x	x	x	x
2.5	1x19	60	35	218	310	402	585	810	1125	1325	x
		80	420	630	735	840	1050	1400	1750	x	x
		100	1140	1565	x	x	x	x	x	x	x
3.0	7x7	60	15	178	270	314	506	660	965	1168	1491
		80	250	413	500	741	818	1083	1370	1565	x
		100	865	1278	1390	1639	x	x	x	x	x
3.0	1x19	60	25	183	261	340	520	790	1025	1180	x
		80	325	555	670	785	1025	1330	1725	1980	x
		100	1090	1500	1705	1910	x	x	x	x	x
4.0	7x7	60	5	73	97	122	235	440	664	813	1178
		80	196	422	480	524	760	1100	1358	1530	2130
		100	835	1182	1360	1528	1837	2381	2811	3098	x
4.0	1x19	60	5	5	10	15	20	147	593	890	1280
		80	30	192	300	415	593	1105	1303	1435	1844
		100	853	1308	1487	1610	2048	2608	3094	3418	3849
4.0	7x19	60	155	290	358	425	599	860	1080	1285	1540
		80	394	654	785	915	1143	1485	1860	2105	2615
		100	1038	1412	1598	1785	2165	2735	x	x	x

Notes to Table 3.9.2.1 :

Lay = number of strands by the individual wires in each strand. For example a lay of 7 x 19 consists of 7 strands with 19 individual wires in each strand.
Where a change of direction is made in a run of wire, the tensioning device is to be placed at the end of the longest span.
If a 3.2 mm diameter wire is used, the tension figures for 3.0 mm wire are applied.
This table may also be used for a set of non-continuous (single) vertical wires forming a barrier using the appropriate clear distance between posts as the vertical clear distance between the rails.
X = not allowed because the required tension would exceed the safe load of the wire.
Tension measured with a strain indicator.

Table 3.9.2.2 Continuous wire barrier construction—Required tension for vertical or near vertical stainless steel wires

Wire dia. (mm)	Lay	Wire spacing (mm)	Maximum clear space between rails (mm)
			900
			Required tension in Newtons (N)
2.5	7 x 19	80	145
		100	310
		110	610
2.5	7 x 7	80	130
		100	280
		110	500

Notes to Table 3.9.2.2 :

Lay = number of strands by the number of individual wires in each strand. For example a lay of 7 x 19 consists of 7 strands with 19 individual wires in each strand.
Vertical wires must have two pulley blocks to each 180 degree change of direction in the wire.
Near vertical wires may only require one pulley block for each change of direction.
Wire tension measured with a strain indicator.
The table only includes 7 x 7 and 7 x 19 wires due to other wires not having sufficient flexibility to make the necessary turns.

Table 3.9.2.3 Continuous wire barrier construction—Maximum permissible deflection for stainless steel wires

		Clear distance between posts (mm)
		600	900	1200	1500	1800	2000
Wire dia. (mm)	Wire spacing (mm)	Maximum permissible deflection of each wire when a 2 kg mass is suspended at mid span (mm)
2.5	60	17	11	9	8	8	8
2.5	80	7	5	5	5	X	X
3.0	60	19	13	8	7	7	7
3.0	80	8	6	6	5	5	5
4.0	60	18	12	8	8	7	7
4.0	80	8	6	4	4	4	4

Notes to Table 3.9.2.3 :

Where a change of direction is made in a run of wire, the 2 kg mass must be placed at the middle of the longest span.
If a 3.2 mm diameter wire is used, the deflection figures for a 3.0 mm wire are applied.
This table may also be used for a set of non-continuous (single) vertical wires forming a barrier using the appropriate clear distance between posts as the vertical clear distance between the rails. The deflection (offset) is measured by hooking a standard spring scale to the mid span of each wire and pulling it horizontally until a force of 19.6 N is applied.
X = not allowed because the required tension would exceed the safe load of the wire.
This table has been limited to 60 mm and 80 mm spaces for 2.5 mm, 3 mm and 4 mm diameter wires because the required wire tensions at greater spacings would require the tension to be beyond the wire safe load limit, or the allowed deflection would be impractical to measure.

Explanatory information:

For the purpose of 3.9.2.5, a wire barrier consists of a series of tensioned wire rope connected to either vertical or horizontal supports serving as a guard to reduce the risk of a person falling from a roof, stairway, raised floor level or the like.
To assist in the application of 3.9.2.5, the following terms are explained:
1. Continuous - where the wire spans three or more supports.
2. Non-continuous - where the wire only spans between two supports.
3. Pulley block - a device consisting of a wheel in which a wire runs around to change its direction.
4. Permissible deflection - is the allowable bending of the wire.
5. Support rails - are horizontal components of the barrier system that span across the top and bottom to provide structural support.
Table 3.9.2.1 and 3.9.2.2 contains tension requirements for wires in vertical and horizontal wire barrier systems with varying post spacings, wire spacings and wire types, whereas Table 3.9.2.3 contains deflection requirements for use in horizontal and vertical barrier systems. The figures contained in the tables were derived from testing the spacing combinations in order to prevent the passage of a 125 mm diameter solid cone penetrating between the wires at a predetermined force.
It is important to read the notes to the Tables as they provide additional information on their application to horizontal, vertical and near vertical wire barriers.
Wire barriers deflect under loading conditions, even when tightly tensioned. This is particularly relevant over the service life of the barrier as the wire tends to lose its tension. Therefore, care needs to be taken to ensure that wire tension will be maintained during the life of the barrier. In some situations, it may be necessary to incorporate "lock-off" devices to prevent loosening of the wire. Likewise, if a threaded anchor bears against a soft wood post or rail, the anchor may indent the post or rail, thus loosening the wire.
Temperature effects on the tension of the wire may be significant but there is little that can be done to allow for temperature variation in service. The shorter the wire span, the lesser the effect will be.
Stainless steel wire with a lay of 1 x 19 has the greatest elastic modulus and will take up the same load with less extension than equivalent wires with other lays.
A wire barrier excludes wire mesh fences and the like.
Sharp ends of wires at terminations and swages need to be removed for the safety of children and other people. No wire end should protrude more than half the diameter of the wire from the swage or termination fitting.
It should be noted that 3.9.2.5 is only one form of compliance solution which can be used to demonstrate compliance with P2.5.2(f) and (g). The following means of verification are available:
1. V2.5.1.
2. The Deemed-to-Satisfy Provisions in 3.9.2.5.
3. A Performance Solution that uses one of the other NCC Assessment Methods which verifies that P2.5.2(f) and (g) will be achieved.

3.9.2.6 Protection of openable windows - bedrooms

(a)

A window opening in a bedroom must be provided with protection, where the floor below the window is 2 m or more above the surface beneath.

(b)

Where the lowest level of the window opening covered by (a) is less than 1.7 m above the floor, the window opening must comply with the following:

(i)

The openable portion of the window must be protected with—

(A)

a device capable of restricting the window opening; or

(B)

a screen with secure fittings.

(ii)

A device or screen required by (i) must—

(A)

not permit a 125 mm sphere to pass through the window opening or screen; and

(B)

resist an outward horizontal action of 250 N against the—

(aa)

window restrained by a device; or

(bb)

screen protecting the opening; and

(C)

have a child resistant release mechanism if the screen or device is able to be removed, unlocked or overridden.

(c)

Where a device or screen provided in accordance with (b)(i) is able to be removed, unlocked or overridden, a barrier with a height not less than 865 mm above the floor is required to an openable window in addition to window protection.

(d)

A barrier covered by (c) must not—

(i)

permit a 125 mm sphere to pass through it; and

(ii)

have any horizontal or near horizontal elements between 150 mm and 760 mm above the floor that facilitate climbing (see Figure 3.9.2.5).

Figure 3.9.2.5 Protection of openable windows—bedrooms

3.9.2.7 Protection of openable windows - rooms other than bedrooms

(a)

A window opening in a room other than a bedroom must be provided with protection where the floor below the window is 4 m or more above the surface beneath.

(b)

The openable part of the window covered by (a) must be protected with a barrier with a height of not less than 865 mm above the floor.

(c)

A barrier required by (b) must not—

(i)

permit a 125 mm sphere to pass through it; and

(ii)

have any horizontal or near horizontal elements between 150 mm and 760 mm above the floor that facilitate climbing.

(See Figure 3.9.2.6)

Figure 3.9.2.6 Protection of openable windows - rooms other than bedrooms

Explanatory information:

Intent

The intent of 3.9.2.6 and 3.9.2.7 is to reduce the risk of a person (especially a young child) falling through an openable window.

Protection of openable windows - bedrooms

Where the floor level below an openable window in a bedroom is less than 2 m there are no specific requirements. For an openable window 2 m or more above the surface beneath, openable windows are required to restrict passage of a 125 mm sphere using any one of the following design solutions:

The window be designed such that any opening does not allow a 125 mm sphere to pass through (e.g. louvres) and be capable of resisting a 250 N force when directed against the window.
The window be fitted with a fixed or dynamic device that is capable of restricting the window opening so it does not allow a 125 mm sphere to pass through and is difficult for a young child to operate. The restricting device must be capable of resisting a 250 N force when directed against the window such as a casement window or in attempting to push a sliding window open. An internal screen with similar parameters may be installed.
The window be fitted with an internal or external screen that does not allow a 125 mm sphere to pass through and which must resist a horizontal outward force of 250 N.

If the openable part of the window is at least 1.7 m above the floor, no further protection is required.

Restricting devices

Where a device or screen is securely fixed in position (e.g. a screen pop riveted to the window frame) so it cannot be unlocked, overridden, or is very difficult to remove without for example a drill, the 865 mm barrier would not be required as the securing method is considered a fixture and not a child resistant release mechanism. 3.9.2.6(b)(ii)(C relates to a screen or window restricting device protecting an openable window in a bedroom. The screen or opening restricting device may be installed in a manner that allows it to be removed, unlocked or overridden in the event of a fire or other emergency to allow safe egress. In these situations the unlocking device must be child resistant.

Child resistance could be achieved by the need to use a tool, key or two hands.

There are a number of hardware options available. Short chain winders and barrier screens will allow windows to comply with this requirement. Sliding window locks may lock a sash so a 125 mm sphere cannot pass through. Where provision is made to fully open the window beyond 125 mm then the child resistant release mechanism is required in addition to the device resisting a 250 N force as required by 3.9.2.3(b)(ii)(B).

3.9.2.6 in addition prescribes that an 865 mm barrier (sill) would be required. A wall beneath an openable window or fixed glazing under the openable part of a window which meets the height requirements (e.g. transom at least 865 mm above the floor) can be considered as the barrier if the criteria in 3.9.2.6 are met.

Protection of openable windows - rooms other than bedrooms

A wall beneath an openable window or fixed glazing under the openable part of a window which meets the height requirements (e.g. transom at least 865 mm above the floor) can be considered as the barrier if the criteria in 3.9.2.7(b) are met.

Use of the term 'window'

The term "window" is not italicised in 3.9.2.6 and 3.9.2.7 and as such, is not restricted to the definition of "window" in the NCC. The reason for this is to also capture windows that may let in air but not light, e.g. metal louvres. A metal louvre or openable panel would not fit in the NCC definition of window but is subject to the window barrier provisions.

Filter

Part 3.9.2 Barriers and handrails

Appropriate Performance Requirements

Explanatory information:

Explanatory information:

3.9.2.1 Application

3.9.2.2 Barriers to prevent falls

Explanatory information:

3.9.2.3 Construction of barriers to prevent falls

Explanatory Information:

Explanatory information:

3.9.2.4 Handrails

Explanatory information:

3.9.2.5 Construction of wire barriers

Explanatory information:

3.9.2.6 Protection of openable windows - bedrooms

3.9.2.7 Protection of openable windows - rooms other than bedrooms

Explanatory information: