Piles were typically concrete, installed to a depth of 300 mm or more.
Houses could be supported fully on piles, or have internal bearer support only provided by piles. External piled walls could be:
- piles supporting the bearers directly, usually on flat sites
- piles with jack framing supporting the floor framing, with asbestos cement sheet cladding and concealed ventilation
- piles with jack framing supporting the floor framing, with a sheet cladding (usually asbestos-cement with ventilation grilles)
- piles with jack framing and base boards.
Piles were typically pre-cast concrete. Timber piles became more common with the introduction of NZS 3604 in 1978 and the availability of H5 treated radiata pine suitable for in-ground use.
Concrete piles were typically 200 x 200 mm, but precast piles could be tapered from 200 x 200 mm at the base to 150 x 150 mm at the top. Timber piles were 125 mm square or 150 mm diameter round.
Piles were installed to a minimum depth of 300 mm or to solid bearing, and were required to finish 150-350 mm above cleared ground level. They were equally spaced in rows to give a maximum bearer span of 1350 mm, and rows were spaced 1.6-4.5 m apart (joist span).
Footings were 300 mm square and a minimum 100 mm deep, or double the projection of the footing.
Where piles extended more than 760 mm above the ground, they were required to have 100 x 38 mm walings bolted with 12 mm diameter bolts at 150 mm above ground level and to each side of the line of piles. A 100 x 75 mm timber brace was fixed between the waling and the bearer of end pairs of piles. The walings and braces were required to be either heart quality, or appropriately treated, timber.
Proprietary 6 and 12 kN metal subfloor fixings were introduced in the 1970s to connect the pile to the bearer to provided resistance to lateral loads.