Barriers and handrails

Measuring the height of fall from a deck

Building Code Clause F4 (Safety from Falling), in F4.3.1, states:

The need for a barrier when someone could fall vertically 1 metre or more is quite clear in Clause F4. If a deck or patio is 1.5 metres above a flat lawn, then the height someone could fall is obviously 1.5 metres. A 'fall' need not be vertical, though. One dictionary definition of 'to fall' is 'to descend rapidly from a higher to a lower level'. Fatal mountain climbing falls unfortunately occur from time to time, but many of them are not vertical falls. A slope of 45° is steep enough for someone to tumble down and injure them-selves (stairs in a house typically have a slope of about 40°).

A court decision some time ago (Judge MA Frater, DC Gisborne, 29 May 1998) dealt with a situation where there was a cliff with a platform at the top, 800 mm above a small retaining wall and set back about 1 metre from it. The judge said:

The recent determination decision on 'safety from falling'

Determination No. 2008/81 considered the situation where a proposed low deck, 500 mm high, would be close to a steep rock retaining wall. If there was no barrier on the deck, the determination concluded the deck needed to be 1200 mm from the face of the wall to protect people from falling off the deck and tumbling down the wall.

The need for a barrier on a low deck

Determination No. 2008/81 has made clear that the horizontal distance to a steep slope must be considered when deciding the need for a barrier on a deck. In light of this determination, where the ground slopes gradually away from a deck a reasonable approach is to measure the height of fall at a distance of 1200 mm out from the deck.

Building consents for low decks

A low deck may not need a building consent. Schedule 1 of the Building Act lists the building work not needing a consent. Included is 'the construction or alteration of any platform, bridge, or the like from which it is not possible for a person to fall more than 1 m even if it collapses'. In most cases, therefore, if a deck does not need a barrier, it will not need a consent. Of course, a low deck is still a 'building' and its construction must comply with the Building Code.

Handrail heights on stairs and landings

The Acceptable Solution D1/AS1 says that Clause D1 requires handrails on all stairs. Handrails must be 'positioned between 900 and 1000 mm above the pitchline'. The pitchline is defined as 'the line joining the leading edge or nosings of successive stair treads'. The Acceptable Solution F4/AS1 (Table 1) requires barrier heights in buildings other than housing to be 900 mm on stairs and ramps, and 1100 mm elsewhere. Thus the barrier height on a landing, other thanin housing, must be 1100 mm.

If the stair handrail is fixed on the top of the stair barrier and carried onto the landing barrier, it will be 1100 mm high on the landing. This height is acceptable because the function of a handrail is to provide safety on a stair flight and its height on a landing is not critical. The handrail (and barrier) can rise to the 1100 mm height over a transition zone about 300 mm long, depending on the stair slope.

Barriers and Clause B2 'Durability'

Table 1 of Acceptable Solution B2/AS1 specifies the durability requirements of nominated building elements. Table 1 states that safety barrier support posts and handrails must have a durability requirement of not less than 50 years. A 'handrail' is a defined word in the Building Code, but in the context of a barrier means the top rail of the barrier. Table 1 states a durability requirement of not less than 15 years for balusters. The words 'baluster' and 'balustrade' are both defined in the B2 Compliance Document. A 'baluster' is defined as 'a post providing support for the top and bottom rails of a barrier' and 'balustrade' as the 'infill parts of a barrier'. In this context, therefore, the balusters are part of the balustrade or infill, and not the main support posts for the barrier.

Handrails mounted on the top of stair barrier.

Handrails mounted on top of stair barriers.

 Barriers and Clause B2 'Durability'.