Stanley Modular Flatpack Homes and Classrooms - Construction
Flatpack homes and schools
Timber-based panellised system, delivered as a flatpack system
Stanley Modular constructs panellised timber-framed building systems, which are supplied as prefinished panels for schools and homes. These are undertaken as individual projects and have been installed throughout New Zealand.
Wall, ceiling and floor panels are constructed at the Stanley Modular site in Matamata and transported to site by flat-deck trucks. Typically, 90% of the labour cost is in the factory and only 10% on the site. This reduces the need for site activities and the management of waste and materials becomes easier.
The major site activity is the construction of foundations prior to the arrival of the panellised system, with the connection of services and limited finishing activities happening on site.
Waste reduction initiatives
The use of a factory to construct the panels means that waste from construction activities and labour can all be managed from a central point, as this makes the collection and sorting of waste easier.
A factory survey instrument was used to collect the information below, which shows a high rate for the productive use of material and a low wastage rate.
Included in the completed building
In another building panel/module/product leaving the factory
Returned to the supplier
In a recycling bin leaving the Stanley factory
In a waste bin destined for landfill leaving the Stanley factory
Achieving these figures takes continued vigilance and staff engagement, as much higher rates of wastage are typical without a focus on waste management. Waste is minimised because the environment is controlled, panels are designed to fit bespoke timber sizes, and any excess materials are used for other panels or modules.
A complete 3-bedroomed house can be transported to site on a single 8 m flat-deck truck, with flatpack panels on the front, roofing on the back and a 4 m trailer with the bathroom modules. Several trips to site are then required for foundations and services, but this is significantly less than the 29 trips taken for a typical on-site build.
In a typical build, 1200 kg of timber is wasted - Stanley Modular only waste around 10% of this:
- LVL and glulam products arrive on site precut to the correct sizes - the only machining is when large products are built for specific purposes.
- Untreated timber offcuts that are too small to be used elsewhere for dwangs or blocking are taken by staff for firewood.
- Treated timber offcuts are taken by staff to the appropriate landfill.
- Treated sawdust is used on site to deal with minor diesel or oil spills from the operating plant before being taken to a landfill for contaminated materials.
- No market exists in Matamata for untreated sawdust, so this is also landfilled.
- Including foundations, the main metal wastage is from fasteners.
- Reductions in waste have been found when all gun nails use galvanised nail strips (except when stainless are required), which prevents operators from mixing up nail types, resulting in rework.
- Bugle-head screws are used on site for connection of panels, due to their holding power, and strength, which minimises the number of screws needed and wastage from breakages.
The main plastic waste (other than staff food containers) is:
- short lengths of materials, such as PVC shower moulding strips, which cannot be jointed (because of leakage concerns)
- shrink wrap - this is used on some projects for weather protection during storage or transport to site but is expensive to recycle and can concentrate condensation problems.
Stanley Modular are starting to use the Gib ReadyLockTM prefinished interior lining system. This eliminates the use of wet trades on site, speeding up the completion of projects. Minor amounts of painting, plumbing and roofing are completed on site, with prefinished bathroom modules being completed in the factory and transported to the site.
Time is a major saving in the operation of the Stanley Modular operation, where it is estimated that construction is 30% faster in the factory than on site.
- Stanley Modular has an agreement with their major building materials supplier to only deliver materials on Tuesdays and Fridays - this minimises both transportation and factory storage needs.
- No time is lost to weather (except for foundations or site cladding work).
- All materials are immediately to hand.
- Council inspections are quicker since the factory environment is well controlled and its location does not move!
- While computer numerical control (CNC) machinery maximises the usable material from sheets and planks, the main saving is in terms of time - CNC is 50% faster than manually controlled machinery.
Stanley Modular can still improve in their waste management practices but provide a great example of how a prefabricated building system can minimise waste, improve productivity and speed up construction for residential and school projects.