F4/AS1 Safety from Falling

Where the barrier is

No classified use set. Set it once in the project and this starts on the row A1 puts the building in; F4/AS1 splits on Housing throughout.

What it stands on, as Table 1 names it

What it is built as

This barrier

Table 1 height

1000mm

Table 1

No opening passes

100mm

1.2.1 b)

1. Is it needed

   A fall of 1500 mm (1.5 m), 1 m or more: F4.3.1 needs a barrier.

   F4.3.1

2. Height

   No less than 1000 mm (1 m) at a balcony, deck or floor edge in a house, measured from the finished floor: it is 1000 mm (1 m).

   1.1.1, Table 1, Table 1 Note 1

3. Openings

   In Housing, or where children under 6 are likely: 1.2.1. The barrier is one of Figures 1–4, and no opening lets the sphere through.

   1.2.1

4. Construction

   Figure 2(a), vertical members.

   1.2.1 a), Figure 2(a)

5. Against the figure

   Gaps between vertical members 95 mm; no more than 100 mm.

   Figure 2(a), 1.2.1 b)

6. Against the figure

   Top of the bottom rail 150 mm above the floor; no more than 200 mm.

   Figure 2(a)

7. Against the figure

   Gap under the bottom rail 90 mm; no more than 100 mm.

   Figure 2(a)

8. Strength

   Rigidity and strength are B1's: the structural engineer's specific design of the barrier and its fixings, with the PS1.

   F4.3.4(c), F4.3.4(d), B1/VM1

9. The barrier

   Meets every check F4/AS1 gives it here.

Where the window is

No classified use set. Set it once in the project and this starts on the row A1 puts the building in; F4/AS1 splits on Housing throughout.

The window

What is around it

What protects it

This window

Paragraph

2.1.1

Fall

3000mm

2.1

Sill above the floor

800mm

2.1

Sill the route asks for

760mm

2.1.1 a)

1. Does 2.1 reach it

   The fall is 3000 mm (3 m), more than 1000 mm (1 m), so 2.1 applies.

   2.1

2. Where the sill is measured from

   From the floor: the lower edge is 800 mm up.

   2.1

3. Which paragraph

   An opening 600 mm wide, less than 1000 mm (1 m), in Housing or where children under 6 are likely: 2.1.1.

   2.1.1

4. Sill

   2.1.1 a) The lower edge at least 760 mm above the floor: it is 800 mm.

   2.1.1 a)

5. Restrictor

   2.1.1 b) A restrictor that stops a 100 mm sphere passing through. None is fitted.

   2.1.1 b)

6. Barrier

   2.1.1 c) A barrier at least 760 mm high in front of the opening, solid or with vertical members its full height. None is shown.

   2.1.1 c)

7. The window

   Meets 2.1.1 by 2.1.1 a).

   2.1.1

1. Where a barrier is needed A barrier wherever people could fall 1 m or more from an opening in the external envelope or a floor, or from a sudden change of level within or associated with the building. Except where a barrier would be incompatible with the intended use of an area, and in a building giving pedestrian access in a remote place where the route presents similar natural hazards.

   F4.3.1, Clause F4, limits on application

2. Roofs with permanent access A roof with permanent access has barriers.

   F4.3.2

   N/A
3. Barriers on retaining walls A barrier provided on a retaining wall meets 1.1 and 1.2: Table 1's heights and the constructions of 1.2.

   1.2.5

   N/A

1. Continuous Every barrier is continuous, and extends for the full extent of the hazard.

   F4.3.4(a)

2. Height Of the height 1.1.1 and Table 1 give for where it stands.

   F4.3.4(b), 1.1.1, Table 1

3. Rigidity and strength Constructed with adequate rigidity, and strong enough to withstand the foreseeable impact of people and, where appropriate, the static pressure of people pressing against it.

   F4.3.4(c), F4.3.4(d)

4. Nobody falls through Constructed so that people cannot fall through it.

   F4.3.4(e)

1. Measured from the floor Vertically from the finished floor level, ignoring carpet, vinyl or a covering of similar thickness, on floors, landings and ramps.

   Table 1 Note 1

2. Balconies, decks and floor edges at a house No less than 1000 mm (1 m) for balconies and decks, and at the edges of internal floors and mezzanines, in a detached dwelling or within a household unit of a multi-unit dwelling.

   1.1.1, Table 1

   N/A
3. Everywhere else No less than 1100 mm (1.1 m) in any other building, and in the common areas of a multi-unit dwelling, wherever Table 1 names nothing lower.

   1.1.1, Table 1

   N/A
4. In front of fixed seating No less than 800 mm for a barrier within 530 mm of the front of fixed seating.

   1.1.1, Table 1

   N/A

1. At a house No less than 900 mm on stairs and ramps and their intermediate landings, in a detached dwelling or within a household unit of a multi-unit dwelling.

   1.1.1, Table 1

2. Everywhere else No less than 900 mm on stairs or ramps, in any other building and in the common areas of a multi-unit dwelling.

   1.1.1, Table 1

3. Measured from the pitch line On a stair, the height is measured vertically from the pitch line or the nosings.

   Table 1 Note 1

4. A handrail on the barrier Where a handrail is mounted on top of a stairway barrier, it may rise to 1100 mm (1.1 m) on the intermediate landings.

   Table 1 Note 5

5. The triangle under the bottom rail On a stair, the triangle formed by the riser, the tread and the barrier's bottom rail lets no 150 mm sphere through.

   1.2.1 c), Figure 4

6. Figure 4 A stair barrier as Figure 4 draws it: at least 900 mm above the pitch line, its bottom rail no more than 100 mm from the pitch line measured square to it, no 150 mm sphere through the triangle beneath, and its rails parallel to a pitch line steeper than 35°. Any barrier acceptable on a deck or balcony at 900 mm high is acceptable on a stair.

   1.2.1 a), Figure 4

1. Children kept from getting through A barrier guarding a change of level in an area likely to be frequented by children under 6 restricts their passage.

   F4.3.4(g)

2. One of Figures 1–4 Each barrier is built as one of the constructions Figures 1–4 show.

   1.2.1 a), Figures 1–4

3. Figure 1(a), composite Vertical members from no more than 150 mm above the floor, at the top of the bottom rail, to at least 760 mm, with gaps of no more than 100 mm between them; above them, rails no more than 100 mm apart; and no more than 100 mm under the bottom rail.

   Figure 1(a)

4. Figure 1(b), mesh A square mesh with no more than 35 mm between its vertical wires, its horizontal wires at any spacing; or a diagonal mesh with openings no more than 35 mm, or no more than 50 mm across. No more than 100 mm under the mesh.

   Figure 1(b)

5. Figure 2(a), vertical members Vertical members with gaps of no more than 100 mm, rising from a bottom rail whose top is no more than 200 mm above the floor, with no more than 100 mm under it.

   Figure 2(a)

6. Figure 2(b), horizontal members Horizontal members with gaps of no more than 15 mm between them, and no more than 100 mm between the top rail and the first member, and under the lowest.

   Figure 2(b)

7. Figure 3, glass or other solid material Glass or another solid material, on an upstand of any height. Where it meets the upstand, a ledge on the walking side is no more than 15 mm wide; a wider one is filleted at 60°.

   Figure 3

8. Openings No opening anywhere over the barrier's full height lets a 100 mm sphere through.

   1.2.1 b)

1. Larger openings In an area used only for emergencies or maintenance, and in a building not frequented by children, openings no wider than 300 mm between vertical balustrade members, or 460 mm between longitudinal rails.

   1.2.2 a), 1.2.2 b)

1. Not a seat Built so that it cannot readily be used as a seat.

   F4.3.4(h)

2. Figure 5(a), parapet A parapet 1100 mm (1.1 m) high; where its top is 100 mm wide or more, the top slopes at 30° or more.

   1.2.3, Figure 5(a)

3. Figure 5(b), rail barrier A rail barrier 1100 mm (1.1 m) high, with horizontal rails and a top rail no more than 75 mm wide. Only for areas not frequented by children under 6.

   1.2.3, Figure 5(b)

1. A fall of less than 1 m A fixed seat on a house's deck, where the fall from the deck is less than 1 m, may be built as Figure 6(a): no more than 500 mm high and 400 mm deep.

   1.2.4, Figure 6(a)

2. A fall of more than 1 m Where the fall from the deck is more than 1 m, a fixed seat is built as Figure 6(b): a back at least 760 mm above the seat, solid or of full-height vertical members with gaps of no more than 100 mm, and no opening under the seat that a 100 mm sphere can pass through.

   1.2.4, Figure 6(b)

1. Where the fall is measured from The possible height of fall is measured from the inside floor level next to the window.

   2.1

2. Window seats Where a fixed window seat is provided, the lower edge of the opening is measured from the seat.

   2.1

   N/A
3. Toilet pans and other fixed features Where a toilet pan or any other fixed feature is within 500 mm of a window, measured horizontally, the lower edge of the opening is measured vertically from it.

   2.1

   N/A
4. Narrower than 1000 mm (1 m), where children under 6 are likely In Housing, and in areas of other buildings likely to be frequented by children under 6, a window with an opening less than 1000 mm (1 m) wide has one of: the lower edge of the opening at least 760 mm above the floor; a restrictor that stops a 100 mm sphere passing through the opening; or a 760 mm high barrier in front of it, solid or with vertical members its full height. The sill height counts only where no projection or ledge below the opening would help a child climb.

   2.1.1, 2.1

5. Wider than 1000 mm (1 m), where children under 6 are likely In Housing, and in areas of other buildings likely to be frequented by children under 6, a window with an opening more than 1000 mm (1 m) wide has one of: the lower edge of the opening at the height Table 1 gives for a barrier there; or a barrier of that height in front of it, built to 1.2.1. The sill height counts only where no projection or ledge below the opening would help a child climb.

   2.1.2, 2.1

6. Narrower than 1000 mm (1 m), elsewhere In areas not likely to be frequented by children under 6, a window with an opening less than 1000 mm (1 m) wide has one of: the lower edge of the opening at least 760 mm above the floor; a restrictor limiting the opening to 460 mm in at least one direction; or a 760 mm high barrier in front of it, built to 1.2.2.

   2.1.3

   N/A
7. Wider than 1000 mm (1 m), elsewhere In areas not likely to be frequented by children under 6, a window with an opening more than 1000 mm (1 m) wide has one of: the lower edge of the opening at least 1100 mm (1.1 m) above the floor; a 1100 mm (1.1 m) high barrier in front of it, built to 1.2.2; or a restrictor limiting the opening to 460 mm in at least one direction.

   2.1.4

BalustradeDefinitions

The infill of a barrier, typically between the floor and the top rail.

HandrailDefinitions

A rail that supports a person, or helps them move.

Household unitDefinitions

A building, or part of one, used mainly as the home of one household. A hostel, a boarding house or other specialised accommodation is not one.

Intended useDefinitions

What the building is for, including any reasonably foreseeable occasional use that goes with it, normal maintenance, and what is done in a fire or other emergency; not other maintenance, repairs or rebuilding.

LandingTable 1 Note 2

A platform whose only function is to provide access.

NosingDefinitions

The rounded, projecting edge of a stair tread.

Pitch lineDefinitions

The line joining the leading edges, or the nosings, of the successive treads of one flight.

TheatreDefinitions, Table 1 Note 4

A place of assembly for producing and watching performing arts: an auditorium and a stage, with room to raise and hang scenery clear of the working area.

No height of fall for a roofF4.3.2, 1.2.2 COMMENT

F4.3.2 sets no height of fall, where F4.3.1 sets 1 m. The COMMENT under 1.2.2 softens it where permanent access to a roof is only for maintaining building services: whether a barrier is needed then, and how it is built, depends on the roof's slope and how near the edge is.

Not every retaining wall needs one1.2.5 COMMENT, Determination 1999/012

The COMMENT under 1.2.5: F4.2 is about the likelihood of an accidental fall, and not every retaining wall is somewhere people are likely to fall from. Whether one needs a barrier, and what kind, can be judged by how likely people are to be at its top. It cites MBIE Determination 1999/012.

No height for a retaining wall at a house1.2.5, 1.1.1, Table 1

Table 1's rows for a detached dwelling or a household unit are stairs, ramps and their landings, and balconies, decks and the edges of floors. A retaining wall is none of these, so 1.2.5's pointer back to 1.1 finds no height for one at a house, where every other building has all other locations at 1100 mm (1.1 m). The document does not say which to use; confirm with the building consent authority.

Wharves and loading docksTable 1 Note 3, Clause F4, limits on application

Table 1 Note 3: F4.3.1's limit, a barrier incompatible with the intended use of an area, may take away the need for barriers at places such as working wharves and loading docks.

Construction-site barriers are not on this page1.2.6, Clause F4, limits on application, Index

1.2.6 sets the rails and toeboards of construction-site barriers, the paragraph after it lets scaffolding cross-bracing serve as a top rail, and F4.3.1 does not reach temporary barriers on a site where the fall is less than 3 m. They govern temporary works while the building goes up, not the finished building on the consent drawings, so they are left out here. The paragraph after 1.2.6 has no number of its own: the Document History lists a 1.2.7, and the Index files scaffolding under 1.2.6.

The gaps in the Clause's numberingClause F4

F4.3.3, F4.3.4(f) and F4.3.5 are missing because the Building (Pools) Amendment Act took the swimming pool barriers out of F4. Residential pools are Clause F9's now.

Strength is B1'sF4.3.4(c), F4.3.4(d), F4/AS1 References, F4/VM1, B1/VM1, Practice Advisory 10

F4 asks only for adequate rigidity and strength. F4/AS1 cites no document at all, its References page being empty, and F4/VM1 adopts no test method. The loads are B1's: MBIE's Practice Advisory 10 says every element that stops a fall of 1 m or more, walls, glazed screens and windows included, is designed for the barrier loads of AS/NZS 1170.1 under B1/VM1. In practice a structural engineer designs the barrier and its fixings as specific engineering design and provides a PS1.

Handrails are D1's1.1.1 COMMENT, D1/AS1 1.7.1

The COMMENT under 1.1.1 sends handrails on stairs to D1, and a handrail can be part of a barrier; D1/AS1 1.7.1 sends the barrier back to F4. The two do different jobs: a barrier stops a fall, and a handrail guides and supports.

How long a barrier has to lastB2/AS1 Table C.1.1.1, B2/AS1 Definitions

B2/AS1 Table C.1.1.1 gives a safety barrier's support posts and handrails 50 years, its balusters 15 years, and the bolts fixing structural parts of barriers 50 years. B2/AS1 defines a baluster as a post that supports the top and bottom rails, which is what a support post does, so the words do not settle which members the 15-year row means.

An enclosed balustrade is E2's tooE2/AS1 7.5, E2/AS1 6.2.2.1 a)

Where the barrier is an enclosed balustrade on a deck, E2/AS1 7.5 governs its weathertightness: a drained cavity behind the cladding, the junctions with the wall and the deck, and a capping whose top is free of penetrations under 6.2.2.1 a), which rules out fixing a handrail down through it.

Glass in a barrierNZS 4223.3 Section 22, NZS 4223.3 Outcome statement

F4/AS1 says nothing about glass beyond Figure 3's shape. NZS 4223.3 states that it is a means of compliance with B1, F2 and F4: its Section 22 covers glass barriers, and it covers glazing that protects a fall of 1 m or more. Consent authorities commonly ask for its human impact note on the drawings.

Children over 61.2.1, 1.2.2, F4.3.4(e)

1.2.1 is for areas likely to be frequented by children under 6; 1.2.2's larger openings are for buildings not frequented by children at all. A building used by older children, a secondary school say, is in neither, and F4/AS1 gives it no opening size. F4.3.4(e) still holds: a barrier people cannot fall through. Confirm with the building consent authority.

The top of a stair in a houseTable 1, Table 1 Note 2

A landing is a platform whose only function is access. Where a stair arrives at a floor, the edge of that floor is the edge of an internal floor, 1000 mm (1 m), not the stair's 900 mm.

Cinemas, theatres and stadiumsTable 1 Note 4

Table 1 Note 4: a barrier 800 mm high in front of fixed seating would be appropriate in cinemas, theatres and stadiums.

Landings outside a houseTable 1, Table 1 Note 2, Table 1 Note 5

For any building but a house, Table 1 names stairs and ramps at 900 mm but not their landings. A landing is a platform, not a stair, so it reads as all other locations, 1100 mm (1.1 m), and Note 5 lets a handrail on the stair's barrier rise to 1100 mm (1.1 m) there, which is how the two meet. Our reading; confirm with the building consent authority.

Figure 4's rail gap is not the limitFigure 4, 1.2.1 c), D1/AS1 Table 6

Figure 4 draws the bottom rail no more than 100 mm above the pitch line. On a main private stair at D1/AS1 Table 6's limits, a 190 mm riser and a 280 mm tread with no nosing, a rail that far up leaves a triangle a 216 mm sphere passes through, where 1.2.1 c) allows under 150 mm. The sphere is the limit that governs, and the rail sits much closer to the pitch line than Figure 4's figure. Worked out from the geometry, which is ours; the numbers are the two documents'.

Raking rails and the stair's pitchFigure 4, 1.2.1 COMMENT 3, D1/AS1 Table 6

Figure 4 draws its rails parallel to the pitch line of a stair marked steeper than 35°, and the COMMENT under 1.2.1 says near-horizontal rails are easily climbed. Read as the figure's condition, raking rails suit only a stair steeper than 35°. D1/AS1 Table 6 allows at most 32° for an accessible stair, 37° for a common or main private stair, 41° for a secondary private stair and 47° for a service or minor private stair: so never on an accessible stair, and on a main stair only between 35° and 37°. The reading of the figure is ours; the numbers are the two documents'.

What likely to be frequented means1.2.1 COMMENT 1, Determination 2001/09

The COMMENT under 1.2.1: buildings classified as Housing are always likely to be frequented by children under 6. Elsewhere it means more than an occasional visit, an expectation that small children will be there regularly, and parts of a building can differ: a shopping mall's public areas are, its food preparation and stock areas are not. It cites MBIE Determination 2001/09.

Climbing1.2.1 COMMENT 2, 1.2.1 COMMENT 3

The COMMENTs under 1.2.1: F4.3.4(g) does not mean that no child under 6 can climb a barrier. These constructions stop almost all children up to 3 years old from climbing, and can guide an alternative design. Full-height vertical members are the hardest to climb. Horizontal or near-horizontal rails running the full height are easily climbed by 2-year-olds, even with a 200 mm wide top rail or a barrier sloping inwards at 15°.

Crowds1.2.3 COMMENT

The COMMENT under 1.2.3: this matters most where crowds gather, in cinemas, stadiums and bars.

E2's capping slopes are flatterFigure 5(a), E2/AS1 Table 4.5.1.1, E2/AS1 6.2.2.1

E2/AS1 slopes a parapet or enclosed balustrade's metal capping at 5° at least, and a flush-finished EIFS or fibre cement top at 10°. Outside Housing, a top 100 mm wide or more slopes at 30° or more under Figure 5(a), so a capping detailed only to E2's minimum is not Figure 5's.

The seat backFigure 6 COMMENT

The COMMENT on Figure 6: the seat back's height gives a small child the same climb as the window rule of 2.1.

A deck exactly 1 m up1.2.4, Figure 6

1.2.4 covers a fall of less than 1 m and one of more than 1 m, and a deck exactly 1 m up is in neither. Confirm with the building consent authority.

Why the sill height2.1 COMMENT

The COMMENT under 2.1: the height of the opening's lower edge above the floor usually decides whether a window is safe for small children, and a window seat or a toilet pan makes the opening easier to reach.

A wide window is a balcony2.1.1 COMMENT 1

The COMMENT under 2.1.1: below 1000 mm (1 m) wide, a 760 mm sill is enough to keep older children and adults from falling through; a wider opening is treated as a balcony, with Table 1's heights.

No restrictor for a wide window2.1.1 b), 2.1.2

In Housing, and wherever children under 6 are likely, a restrictor is a route only for an opening narrower than 1000 mm (1 m), under 2.1.1 b). 2.1.2 offers none for a wider one, only the sill height or a barrier. The document does not define opening width.

Not for Housing2.1.3 and 2.1.4 COMMENT

The COMMENT under 2.1.3 and 2.1.4: they do not apply to Housing, where 2.1.1 and 2.1.2 cover every window.

A fall of exactly 1000 mm (1 m)F4.3.1, 2.1

F4.3.1 needs a barrier where the fall is 1 m or more, but 2.1's routes apply only where the fall from an open window is more than 1000 mm (1 m). A window with a fall of exactly 1000 mm (1 m) is reached by the Clause and by none of 2.1.1 to 2.1.4. Confirm with the building consent authority.

An opening exactly 1000 mm (1 m) wide2.1.1, 2.1.2, 2.1.3, 2.1.4

2.1.1 and 2.1.3 are for openings less than 1000 mm (1 m) wide, and 2.1.2 and 2.1.4 for openings more than 1000 mm (1 m). An opening exactly 1000 mm (1 m) wide is in none of them. Confirm with the building consent authority.

A restrictor and ventilationG4/AS1 Definitions, G4/AS1 2.2.1.2 COMMENT 1, G4/AS1 2.2.1.3

G4/AS1 measures a window's net openable area on the face dimensions of the openable part, so on its own words a restrictor fitted for 2.1 does not reduce it; G4/AS1 2.2.1.3 asks that an openable window can stay fixed open.

Fixed glazing2.1, F4.3.1, NZS 4223.3 Section 22

2.0 covers opening windows only. A fixed window or glazed screen that stops a fall of 1 m or more is a barrier under F4.3.1 all the same, and NZS 4223.3 is where glass barriers and glazing protecting such a fall are set out.