NCC 2016 Volume Two
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Part 3.9.2 Barriers And Handrails

Part 3.9.2 Barriers And Handrails

Appropriate Performance Requirements

Appropriate :

  1. 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 RequirementP2.1.1; and
    2. Performance RequirementP2.5.2; and
    3. the relevant Performance Requirements determined in accordance with 1.0.7.
  1. 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 Requirement P2.1.1; and
    2. Performance Requirement P2.5.1(b)(i); and
    3. the relevant Performance Requirements determined in accordance with 1.0.7.

3.9.2.1 Application

Compliance with this acceptable construction practice satisfies Performance RequirementsP2.5.2 for barriers and P2.5.1(b)(i) for handrails.

3.9.2.2 Barriers to prevent falls

(a)

A continuous barrier must be provided along the side of—

(i)

any roof to which general access is provided; and

(ii)

any stairway or ramp; and

(iii)

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

(iv)

any delineated path of access to a building,

if the trafficable surface is 1 m or more above the surface beneath (see Figure 3.9.2.3).

(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; or

(ii)

a barrier provided to an openable window covered by 3.9.2.5.

3.9.2.3 Construction of barriers to prevent falls

(a)

The height of a barrier required by 3.9.2.2 must be in accordance with the following:

(i)

The height must not be less than 865 mm above the nosings of the stair treads or the floor of a ramp.

(ii)

The height must not be less than—

(A)

1 m above the floor of any access path, balcony, landing or the like (see Figure 3.9.2.1); or

(B)

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

(b)

A transition zone may be incorporated where the barrier height changes from 865 mm on the stair flight or ramp to 1 m at the landing (see Figure 3.9.2.2).

(c)

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 stairs, the opening is measured above the nosing line of the stair treads.

(d)

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)

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

Explanatory information

Explanatory Information:

A window forming part of a barrier is not required to comply with AS/NZS 1170.1 as it is exempted by 3.9.2.3(e). However, a window serving as a barrier must comply with the glazing assembly provisions of AS 2047 or AS 1288. These provisions consider the wind loading on the glass and human impact requirements.

(f)

For floors more than 4 m above the surface beneath, any horizontal elements within the barrier between 150 mm and 760 mm above the floor must not facilitate climbing.

Explanatory information

Explanatory Information:

For a window forming part of a barrier, a window sill between 150 mm and 760 mm above the floor is deemed to facilitate climbing.

(g)

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

(i)

For horizontal wire systems—

(A)

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

(B)

must not exceed the maximum deflections in Table 3.9.2.3.

(ii)

For non-continuous vertical wire systems, when measured with a strain indicator, must be in accordance with the tension values in Table 3.9.2.1 (see Note 4).

(iii)

For continuous vertical or continuous near vertical sloped wire systems—

(A)

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

(B)

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

(C)

must have supporting rails, constructed with a spacing of not more than 900 mm, of a material that does not allow deflection that would decrease the tension of the wire under load; and

(D)

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 and measured in the furthermost span from the tensioning device.

Explanatory information

Explanatory information:
  1. For the purpose of this clause, a wire barrier consist of a series of tensioned wire rope connected to either vertical or horizontal supports serving as a guard to minimise the risk of a person falling from a roof, stairway, raised floor level or the like.
  2. A wire barrier excludes wire mesh fences and the like.
  3. To assist in the application of 3.9.2.3(g), the following terms have been defined:
    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.
  4. and 3.9.2.2 contains tension requirements for wires in vertical wire barrier systems with varying post spacings, wire spacings and wire types. The figures contained in the table 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.
  5. 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.
  6. 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.
  7. 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.
  8. Stainless steel wire with a lay of 1×19 has the greatest elastic modulus and will take up the same load with less extension than equivalent wires with other lays.
  9. 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.

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 7×7 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 1015 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
80 155 290 358 425 599 860 1080 1285 1540
100 1038 1412 1598 1785 2165 2735 X X X
Notes:
  1. Lay = number of strands by the number of individual wires in each strand. For example a lay of 7×19 consists of 7 strands with 19 individual wires in each strand.
  2. 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.
  3. If a 3.2 mm wire is used the tension figures for 3.0 mm wire are applied.
  4. 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.
  5. X = Not allowed because the required tension would exceed the safe load of the wire.
  6. 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 Widest spacing between wires (mm) Maximum clear spacing between rails (mm)
900
Required tension in Newtons (N)
2.5 7x19 80 145
100 310
110 610
2.5 7x7 80 130
100 280
110 500

Notes:

  1. Lay = number of strands by the number of individual wires in each strand. For example a lay of 7×19 consists of 7 strands with 19 individual wires in each strand.
  2. Vertical wires require two pulley blocks to each 180o change of direction in the wire.
  3. Near vertical wires may only require one pulley block for each change of direction.
  4. Tension measured with a strain indicator.
  5. The table only includes 7×7 and 7×19 wires due to other wires not having sufficient flexibility to make the necessary turns.

Table 3.9.2.3 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) Minimum required tension in Newtons (N)
2.5 60 17 11 9 8 8 8
80 7 5 5 5 X X
3.0 60 19 13 8 7 7 7
80 8 6 6 5 5 5
4.0 60 18 12 8 8 7 7
80 8 6 4 4 4 4
Notes:
  1. 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.
  2. If a 3.2 mm wire is used the deflection figures for 3.0 mm wire are applied.
  3. 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.
  4. X = Not allowed because the required tension would exceed the safe load of the wire.
  5. 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.
(h)

A glass barrier must comply with AS 1288.

Figure 3.9.2.1

BARRIER CONSTRUCTION

v2_Fig3921_2012.svg
Note: For the purposes of this Figure, a 125 mm sphere must not pass between rails or through the opening when measured above the nosing line.

Figure 3.9.2.2

TRANSITION ZONES

v2_Fig3922_2015.svg

Figure 3.9.2.3

BARRIERS — WHEN REQUIRED

v2_Fig3923_2015.svg

3.9.2.4 Handrails

(a)

Handrails to a stairway or ramp must—

(i)

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

(ii)

be located along the full length of the 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; and

(iv)

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; or

(iv)

a stairway or ramp in a Class 10 building.

Explanatory information

Explanatory Information:
  1. A barrier top rail may be suitable as a handrail if it meets 3.9.2.4.
  2. A handrail is only required on one side of the flight or ramp.
  3. The handrail may extend the full length of the 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 would allow for the barriers of geometric stairways such as elliptical, spiral, circular or curved stairways to finish a few treads from the bottom of the stairway.
  4. An example of where a handrail is not required would be a flight consisting of 5 risers as the change in elevation is less than 1 m.
  5. A handrail is not required for winders if a newel post is installed to provide a handhold.

3.9.2.5 Protection of openable windows

(a)

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

(b)

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

A barrier with a height not less than 865 mm above the floor is required to an openable window—

(i)

in addition to window protection, when a child resistant release mechanism is required by (b)(ii)(C); and

(ii)

where the floor below the window is 4 m or more above the surface beneath if the window is not covered by (a).

(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.

Explanatory information:

Explanatory information

Explanatory information:

The intent of 3.9.2.5 is to limit the risk of a person (especially a young child) falling through an openable window. Where the floor level below an openable window is less than 2 m there are no specific requirements. For an openable window in a bedroom 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:

  1. The window be designed such that any opening does not allow a 125 mm sphere to pass through (e.g. louvres).
  2. 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 restricting 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.
  3. 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.

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 3.9.2.5(b)(ii)(B).

in addition prescribes that an 865 mm barrier (sill) would be required. A wall beneath an openable window can be considered as the barrier if the criteria in (d) are met.

relates to the height of a barrier under an openable window in a room that is not a bedroom in a Class 1 building or a window in a Class 10 building.

The term "window" is not italicised in 3.9.2.5 and as such, is not restricted to the definition of "window" in the BCA. 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 BCA definition of window but is subject to the window barrier provisions.