Designer piles into foundation system
‘‘This system is a lot cheaper than many of the repairs and rebuilds we’ve seen. You just need a jack.’’ Nigel Colenso, ABI Piers founder
Christchurch firm ABI Piers has designed a foundation system tailored for lightweight homes.
Founder and designer Nigel Colenso has a background in construction and project management and saw opportunity in the new builds going up around the city.
The foundation system is suitable for all types of land but particularly Canterbury’s TC3-zoned land, which is prone to liquefaction and movement.
Colenso and his son Chris have been working on development, patenting and accreditation of the stainless steel pilings for about three years.
Nigel Colenso observed the rebuilding of several commercial buildings during the post-quake recovery in Canterbury.
‘‘It occurred to me that all these new commercial buildings had base isolation systems so why not residential homes?’’ he said.
‘‘We know there will be earthquakes and there’s a chance of liquefaction. This system is a lot cheaper than many of the repairs and rebuilds we’ve seen. You just need a jack.’’
The stainless steel adjustable piers or piles sit on a concrete base or footing and have bolts so that in the case of future foundation movement they can be adjusted to re-level a lightweight home up to two storeys high.
The piles have an estimated life span of 50 years.
A metal plate at the top of the pile allows the house’s wooden bearers to move in an earthquake and return to the correct position because the pile is tensioned to the bearers with springs.
The Building Research Association (BRANZ) has appraised the system and certified it for its seismic mechanical properties.
‘‘The Adjustable Base Isolation Pier System utilises springs as a mechanism to absorb the seismic energy, and friction between the superstructure and the foundation pier as a dampening mechanism,’’ it said.
‘‘In the opinion of BRANZ the system is fit for purpose and will comply with the Building Code.’’
The Colensos have developed a website and pamphlets explaining the system, and have carried out demonstrations for architectural firms, the Christchurch City Council, and others in the construction sector.
They received favourable feedback at a Canterbury Home Show, and are also members of the Superhome movement dedicated to efficient home building.
Several types of foundation systems have been developed and demonstrated in Christchurch since the 2011 quakes, but the ABI Piers system appears to be among the simplest and easiest to install and adjust.
But catching the attention of the building sector to try new systems is proving a challenge, Nigel Colenso said.