1Is it commercially viable?
Pres-Lam is a new technology therefore only limited historical data exists, but, recent comparisons suggest that the same building constructed from steel, reinforced concrete or Pres-Lam all cost about the same for total out-turn cost. Feedback from constructors that have built recently constructed Pres-Lam buildings consistently indicate that construction time is rapid and crane times and capacities are all reduced compared with building a similar structure in pre-cast concrete. These and other factors result in the Pres-Lam option being very, if not the most competitive option for an open plan timber building.
2Is it “green” and sustainable?
As an engineered timber structure, Pres-Lam provides the easiest, most competitive way of achieving a carbon neutral building (cradle to gate). All research and development to date has focused on the use of engineered timber made from pinus softwood grown in sustainably managed forests in Australasia. Recent comparative studies show that a multi-storey engineered timber building easily achieves carbon neutrality with the sequestered carbon present naturally within the harvested logs off-setting the CO2 emissions associated with the selective use of reinforced concrete in the foundations or timber-concrete-composite floors and steel, glass and aluminium used in the roof, cladding and joinery components of the building. The same study indicates that the carbon footprint of a Pres-Lam building over its full lifetime (i.e. including all operational energy use) is around 1.69 tonnes CO2 eq. / m2 and this is more than 13% less than the carbon footprint of the same building constructed from steel. Timber is a renewable building material which is in plentiful supply from sustainably managed and certified forests throughout the world.
3Is it low energy use?
When buildings are designed to a high performance specification with high levels of insulation, maximum use of solar gain and energy efficient glazing throughout. This minimises heat loss by the building and ensures energy costs associated with heating are minimised.
4Does it have good inter-floor acoustic isolation and dynamic response?
Inter-floor acoustic isolation is an important characteristic of any building complex that is potentially available for mixed use. Sound is transmitted as air-borne and impact induced air pressure fluctuations and is essentially transmitted from floor to floor in all multi-storey buildings directly through the floors separating the storeys and via flanking paths involving the connections between floors and other components of the building. Floors within a Pres-Lam building use industry standard solutions to minimise acoustic transmissions from one storey to the next whist at the same time providing for long-spans that enable open-plan and flexible use buildings with few load bearing walls. When using a timber floor, dynamic or vibration response is also an important characteristic that influences both quality perception and overall flexibility of use. Floors are critically designed to ensure that the resonant frequency response of exceeds the minimum acceptable threshold frequency, ensuring user comfort and confidence.
5Is the technology proven?
What data or supporting evidence do you have? Are there any existing examples that I can view? Pres-Lam buildings have been and continue to be the subject of extensive engineering research and development., exploring and improving the use of this unique technology. All of the fundamental principles have been tested experimentally under laboratory conditions and there exists substantial data and results that supports the characterisation of the system and its resilience. In addition to this many internationally peer reviewed journal papers on the subject have been published lead by the University of Canterbury and their partners around the world. See more including current research the Pres-Lam research page. 12 built examples exist in New Zealand and around the world, with more on the way. The NMIT Arts and Media building was the first commercial Pres-Lam building in the world, and was officially opened on 31st Mar 2011. International examples include the Framework building in Portland, Oregon and the House of Natural Resources in Zurich. Check out more examples at our projects page.
6Is it durable? Its timber, won't it decay?
The architectural design of the buildings is such that the Pres-Lam walls and frames forming the building are normally contained inside the building envelope. This means that the engineered timber can be untreated and will not be subject to fungal decay as it will remain dry and protected from external moisture and weather conditions. Timber is only subject to fungal attack when it is subjected to high levels of moisture and water for prolonged periods. The building facades and cladding systems are designed to ensure that the structural timber remains fully shielded from rain and other adverse weather conditions. Additionally, as much of the structural timber is open and visible inside the building, any ingress of moisture that has inadvertently penetrated the building envelope will be easily detected and the building envelope ingress problem can be repaired before any decay problems initiate. In areas or designs where the engineered timber structural members may be exposed to prolonged contact with water the structural members will be pre-treated to a standard required to prevent fungal decay.
7Is the build system open plan and flexible enough to cope with multiple use and tenant changes?
A specific advantage of the Pres-Lam structural system is that it enables very long spans and large grid spacing to be easily designed and specified. This was previously unachievable with timber constructions and as a result a large number of load bearing walls were typically required. Using the Pres-Lam system, engineered timber buildings with grid spacing comparable to reinforced concrete and steel are a very real option. Open plan buildings can be fitted out internally with “temporary” infill non-load bearing walls and barriers as specific use requires and this ensures the floor plates remain flexible for future use changes.
8Does it have a modern, light, open, warm appeal to it?
Timber as a construction material is timeless. It has a warm attractive aesthetic appeal universally liked. Large section engineered timber (LVL or Glulam) members that form the structural components of an Pres-Lam building form an attractive overall appearance and give the occupants a genuine sense and perception of robustness and strength.
9Why is this better than similar reinforced concrete or steel office and retail buildings?
Simply put Pres-Lam can match the equivalent reinforced concrete or steel building in achieving required structural strength and general amenity but in addition to this it offers: Lighter weight construction that simplifies design and reduces foundation costs for multi-storey buildings situated on difficult soil conditions. The natural beauty and visual appeal of exposed timber. An environmentally sound choice that enables carbon neutral building constructions to be easily achieved. A strength without weight structure that minimises acceleration loads caused by ground shaking. A construction system that has resilience and construction simplicity central to its philosophy.
10But it's multi-storey timber....am I swapping an earthquake risk for a fire hazard risk?
Fire safety has been a crucial component of Pres-Lam research and design, with the objective of providing owners and users of large timber buildings with confidence about personal safety and property protection. Despite the fact that all wood can burn, there are ways to imbue large timber buildings with very high levels of fire protection. Fire resistance is essential in all multi-storey buildings, to prevent the spread of the fire to upper floors and to thereby help prevent structural collapse. Large timber members, such as Pres-Lam beams, columns and walls have excellent fire resistance because of their large member sizes and the predictable rate of charring. The level of fire resistance can be calculated using standard charring rates from your local code.
11Could I relocate some or all of the buildings in a few years’ time?
Another attractive benefit of Pres-Lam construction is its ability to be easily deconstructed, relocated and reconstructed. It is therefore quite conceivable that a low-rise multi-storey building constructed within a CBD precinct could be subsequently deconstructed, transported to a new site and reconstructed some years after its original construction. An example of this to date is the EXPAN building that was located on Engineering Road at Canterbury University. This structure was originally built inside the university laboratory and was used for seismic and other testing for 1 year. It was subsequently deconstructed and reconstructed in its current location on campus. Follow a ‘real time’ test during the Canterbury Seismic sequence of 2010 and 2011 the building was used as the offices of the Structural Timber Innovation Company. When the company wound up in 2013 the building was deconstructed, awaiting its next reincarnation.
12Can a couple of additional storeys be added in the future?
Pres-Lam is very modular, and the large structural elements are all pre-fabricated off-site. This, coupled with the lightweight of the engineered timber, means that it is very easy to design and add additional storeys in the future, provided it does not exceed the design limit of the original foundation system.
13Is it rapid to construct – how quickly can I get tenants or my own organisation in there?
The Pres-Lam construction system provides for a very rapid construction sequence. Construction times are reduced due to the following: All large structural elements are fabricated off-site. This means earthworks and foundation placement can be happening whilst structural members are fabricated elsewhere. The structural elements are all held together by post-tensioned tendons or bars running through hollow beams and walls. This means the structure is erected very rapidly as there is no requirement for large numbers of conventional nails and other wood fasteners to be applied on site. Minimal temporary bracing and propping is required as the construction sequence progresses, reducing overall construction time and cost. Collectively these attributes enable a rapid construction time which means the building can be available to lease or for occupation in the shortest possible time.