(construction and fit out)(2018 exc. GST both buildings)
Litecrete precast concrete cladding panels, Litecrete precast
concrete planters, prestressed flooring ribs, timber pre-nail wall
frames & trusses by PlaceMakers (PrefabNZ Member)
PROJECT CHALLENGES
Real Living Group is the owner-operator of The Oaks Retirement
Village in Warkworth. The clients desired a robust cladding system
that would give the two Oaks buildings a sense of permanence. The
external building envelope was required to be attractive, safe,
weathertight, durable and low maintenance. The primary criteria for
success was to develop a robust, buildable structure that complied
with the New Zealand Building Code.
The basement of the project was almost the full footprint of the
site and limited large vehicle access. Heavy trucks were also
restricted on site due to the stringent controls on ground-movement
that concerned the proximity of neighbouring buildings. As a
result, one loading bay was established on Neville Street, the only
other site accessible Street, that took up eight car parks and was
managed by a gateman.
The basement level of the design sat below the site’s very high
water table and high water inflows. A top-down construction
methodology was used to overcome this issue.
This meant the ground floor and foundation piles were
constructed before the excavation for the basement. Cut-off piles
were used to form perimeter basement walls to stabilise the site
and support the neighbouring buildings. To reduce the overall
construction time, work commenced on the superstructure as
excavation for the basement proceeded.
The very weak soil and high water table meant the structures
weight was limited. The cladding, therefore, needed to be
light-weight as well as meeting the design requirements of the
project. Precast Litecrete panels met these factors and were the
predominant cladding material. The panels are manufactured from
local pumice aggregate which is 40% lighter than standard precast
concrete. This reduced the beam and foundation loads which allowed
for considerable savings in both buildings’ weight and cost.
The Litecrete panel thickness was designed for insulation,
fire-rating and durability requirements of the New Zealand Building
Code (NZBC). The panels allowed for quick installation and
enclosing of both buildings. This meant internal fit-outs could
proceed quickly and assist in meeting the timeframe.
Client: Real Living Group
Kalmar Construction Ltd
Morconsult Ltd
Kalmar Construction / Harbour Construction
Litecrete / Wilco
Brown Day Group
8000m² both buildings
Component + Panel
Contractor:
Architect:
Floor Area:
Prefab Type:
Prefab Materials Used:
Structural Engineer:
Builder:
Supplier:
Completed September 2018
Status:
February 2019 HOW to Prefab
2018Queen StreetWarkworthAuckland
The Oaks Retirement villageThe Oaks Project expresses the
benefits of lightweight precast concrete panels when building on a
site with a high water table and low weight restriction. Litecrete
offers the appearance of traditional concrete but allows for a
lighter structure and a safer build.
PROJECT INTENT
COST (NZD)40M30M 50M 60M 18m 20m 22m 24m 26m
TIME (months)
The Oaks Retirement Village
The main structure comprised of mild-steel frames, in-situ
concrete shear walls, and Rib and Timber Infill concrete floor
diaphragms. These structural elements were designed to give the
most compact floor-to-beam depth with sufficient strength and
stiffness to resist seismic induced loads.
A lot of planning time was spent exploring options to visually
break up the facade while creating as many similar panels and
therefore fewer precast molds for maximum production efficiency and
minimal cost.
The Litecrete cladding panels were 150mm thick and covered a
two-level height on the building’s exterior. The units were fixed
at each corner to the adjacent floor structure with structural
steel brackets. It took approximately two days to clad one floor of
each building. In comparison to an in-situ methodology, the use of
precast panels saved many weeks.
Precast Litecrete planter boxes were also developed to hang off
the structure at level one. The planter boxes were lifted by crane
and welded into place, approximately one hour was spent on each
unit. Time efficiencies were created by Kalmar Construction by
lifting the boxes onto formwork by crane and moved into place by
hand. This allowed the crane to be used elsewhere on the project,
speeding up the project timeline.
The Oaks is the largest retirement village that has used precast
concrete panels in Warkworth. On completion, the developer held
several open days, each attracting up to 800 people. The residents
of The Oaks say they love their new home and the facilities it
houses.
All prefabricated elements were delivered to site on a flat-deck
truck. A tower crane was used to lift each panel into position and
all of the fixing work was carried out from inside the building
before the crane hook was released. Prefabrication was, therefore,
safer and allowed for higher quality control which resulted in the
desired facade.
The use of precast panels meant fewer trades were required to
construct the building’s envelope, decreasing on-site labour and
increasing cost efficiencies.
MATERIAL
DELIVERY / ASSEMBLY
FEEDBACK
The Oaks living room space
Litecrete panels being lifted by crane into position
The Oaks under construction
HOW to PrefabThe Oaks Retirement Village
REFERENCES
Tim Ellery (Kalmar Construction Ltd). Personal Communication
with Eleni Timoteo. January, 2019.
Andrew Mortimer (Morconsult Ltd). Personal Communication with
Eleni Timoteo. January, 2019.
Images: Courtesy of Kalmar Construction Ltd For more information
on this project visit:realliving.co.nz
prefabnz.com
