Overview
Forte Living is a 10 storey apartment building made from cross laminated timber (CLT). Standing at 32.2m it is the world tallest modern timber apartment building and highest made from CLT. It is also the first Australian building to be made from CLT.
The building comprises 759 CLT panels of European spruce (picea abies), weighing a total of 485 tonnes. The spruce for the CLT panels was grown and harvested in Austria, the panels were manufactured then shipped to Australia in 25 shipping containers.
The building arrived like flat pack furniture, including the 5,500 angle brackets and 34,550 screws required for erection.
Forté will positively affect the environment by directly storing (sequestering) 761 tonnes CO2. When considering the emitted CO2 that would occur if an equivalent concrete or steel buildings was used, the advantage would increases to 1,451 tonnes of CO2 or the equivalent of taking 345 cars off the road for a year.
Using timber is also estimated to save 7.7 ML of water and also lower eutrophication (the supply of excess nutrients to the water system) by 75%.
In addition, the smart design and efficient systems of the building could save residents an average over $300 per year on energy and water bills. The building is targeting a 5 star green star As Built rating.
You can view a short time lapse video of the building of Forte here.
Fire engineering solutions are described in Structure and Interior tabs.
Acoustic advantages and environmental benefits are described in the Exterior tab.
Structure
Cross laminated timber (CLT) is a panel product built up from narrow timber boards, about 20 mm thick, that are laid side by side to form layers. Like plywood, each succeeding layer is laid perpendicular to the preceding layer. Each layer is then glued and the entire panel is pressed and trimmed to size.
Each panel is then cut to specific dimensions from the CAD drawing using a CNC router that uses a computer guided saws and drills that forms the panel to its final shape. At this stage opening for doors and windows and channels for electrical wiring and other services were also cut into the panels.
Forte's ground floor and first storey floor slab were constructed from geopolymer concrete. This was due to the larger spans required in the retail space and general good practice to keep timber away from the ground.
Once the concrete had set, the CLT panels were transported from their storage site, a disused wharf shed a short distance away. The panels were then raised into their final position and connected together with screws and metal brackets. The first panels erected were those that formed the stair and lift cores, these were stood vertically. Once the cores were in place, panels were placed on their sides to form internal and external walls. The panel width is the storey height of the building.
Panels were then laid on top of the walls to form floors. The process was repeated until the full height of the building was reached. The roof was constructed in the same method as each floor.
The exterior cladding was applied as the scaffolding and screen were removed, revealing the building as it was 'unwrapped'.
Building with Wood
Durability
CLT is made from European spruce which is considered as non-durable i.e. Class 4 timber. Protection from termites and weather are the two key durability issues addressed.
Termite protection is provided by a concrete slab at ground level and then protected by TermiMesh. This is very similar to how a house is protected.
Durability from weather is achieved by a rain screen of aluminum panels. Supplementing this there is a cavity between the rain careen panels and CLT that allows any water to drain out.
The balconies and roof are constructed with CLT and have a water proof membrane finish.
Building regulations
Building Classification
Class 2 - apartment building (levels 1 to 9)
Class 6 - retail building (ground)
Fire
This building is classified by the NCC as mixed building classification as it has retail (Class 6) on the ground floor and apartments (Class 2) for the remainder of storeys.
Fire Resistance
As the building has a Rise in Storey of 9, the building's Type of Construction is A, Type A construction deemed-to-satisfy provisions limits the use of timber in some applications.
Type A construction deemed-to-satisfy (DtS) provision places limits on the materials that can be used in the building construction as well as the level of fire resistance required. For external walls they are required to be constructed from non-combustible materials. Load bearing internal walls required to achieve a fire rating are required to be constructed from concrete or masonry. Lift shafts and Fire isolated stairs are also required to be non-combustible.
The use of CLT can not comply with the non-combustible DtS provisions of the NCC. To meet the NCC an Alternative Solution was proposed to satisfy the relevant performance provsions. The design solution met most of the DtS fire resistance levels required within Victoria for this building classification with the exception of the balcony floors and the external walls.
In addition, the design solution ensured that:
- Structurally, the building has been designed through disproportionate collapse. That is, the CLT has been analysed in relation to ensuring that should a wall section be damaged, that the remaining structure is able to take the load.
- Fire resistance is initially achieved through the direct fixing of fire grade plasterboard combined with the charring of the timber ensuring that the structural component required is maintained through the provision of sacrificial layers. That is, each CLT panel is typically, 5 layer 128 mm thick used for the walls and 5 layer 148mm thick CLT panels for the floors. Structurally, only 3 layers are required providing 2 layers of additional protection from the sacrificial layers of timber.
- The connections of the wall panels to floor panels maintain the appropriate fire ratings through being incorporated within the centre layer of the panel or through being covered by screed / fire grade plasterboard.
- The fire isolated stair shaft and lift shaft provided their own unique challenges particularly in relation to the deemed to satisfy requirement for fire stairs to retain their integrity in the case of local failure or damage to the shaft. This has been achieved through the design of a double shaft system in which each shaft achieves the required fire rating however do not rely on the other for structural connection.
In the consultation with the Melbourne Metropolitan Fire Brigade, a site specific construction methodology and plan was developed to take into consideration specific requirements when working with timber. This included items such as ensuring that the fire hydrant system was operational from when the timber construction commenced (as opposed to when the building reached an effective height of 12m), site sheds were located more than 10m from the structure, two exits were available off the site and no welding occurred within one hour of the end of the day.
Exterior
The exterior of the building is clad with metal commercial façade consisting primarily of AluBond, however parts were also covered with Lysaght and recycled hardwood timber. These finishes provide the rain screen to the CLT structure.
The balconies to the buildings are an extension of the CLT flooring of the main building structure. The CLT is covered with screed and a water proof membrane that is then finished with tiles.
The CLT used in the balcony floor to each apartment is exposed to the underside. A timber stain and polyurethane seal is used to protect the timber, but other than the finish no additional protection is necessary.
Acoustic advantages
The system used in Forte meets and exceeds building code deemed to satisfy minimum requirements. The floor uses a combination of products to deal with airborne sound as well as impact noise. The floors in the living area are engineered timber and any hard surface floors require greater impact noise consideration. This project uses a number of techniques such as concrete screed topping, direct fixed and or resilient mounted plasterboard and suspended ceiling and resilient mat to improve airborne and impact noise similar to standard construction.
Bulk insulation is placed in the cavity of the suspended ceiling and direct fixed plasterboard.
Wall systems use the addition of frames lined with plasterboard to provide acoustic isolation between apartments.
Environmental Benefits
Carbon storage
485 tonnes of cross-laminated timber (CLT) was used in the building construction.1 This equates to 216 tonnes of stored carbon which absorbed 792 tonnes of CO2 during its growth.2
Lower carbon footprint
In comparison to a standard concrete and steel building Forte reduces CO2 emissions by over 1,451 tonnes.3
That's like taking 407 cars off the road for a year.4
A full life cycle assessment conducted by staff of RMIT University, compared Forte with a standard apartment building constructed with reinforced concrete.5
The carbon footprint of Forte was 22% lower if carbon storage in the timber was included and 13% lower if carbon storage was not included.
If the carbon footprint of the building materials alone were considered, the carbon footprint of the Forte building was 30% lower than the concrete reinforced building.
Renewable & Sustainable Resource
All timber used in Forte is a renewable resource. The CLT is from sustainably managed spruce forests in Austria.
Green Star
Forte targeted a 5 Star As Built Green Star building in Australia.
Sustainable Forest Management (SFM) Certification
All the timber used is chain of custody certified to internationally recognised sustainable forest management standards.
All the CLT used in the building is chain of custody certified to PEFC (Program for the Endorsement of Forest Certification) standards.
All the Australian hardwood engineered floors are chain of custody certified to Australian Forestry Standards (AFS).
1. Andrew Nieland, Lend Lease (2013) Building with Cross-Laminated Timber: is this our future? Available at http://www.timberqueensland.com.au/Docs/News%20and%20Events/Events/Andrew-Nieland_web.pdf
2. Based on 12% moisture content and carbon content of 50.5% (by weight) cited in Durlinger, B., Crossin, E. and Wong, J. (2013) Life Cycle Assessment of a cross laminated timber building. Available at http://www.fwpa.com.au/rd-and-e/market-access/230-life-cycle-assessment-of-a-cross-laminated-timber-building.html. One tonne of carbon in timber is formed by the conversion of 3.67 tonnes of carbon dioxide. Source Forest Wood and Australia's Carbon Balance. Available at http://www.plantations2020.com.au/assets/acrobat/Forests,Wood&CarbonBalance.pdf
3. Andrew Nieland, Lend Lease (2013) Building with Cross-Laminated Timber: is this our future? Available at http://www.timberqueensland.com.au/Docs/News%20and%20Events/Events/Andrew-Nieland_web.pdf
4. The average CO2 emissions for a passenger car in Australia in one year (2010) is 3.56 tonnes. Calculation based on information in Australian Bureau of Statistics (2012) Year Book Australia 2012. Available at http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/1301.0~2012~Main%20Features~Transport%20activity~187 & Australian Government (2008) Greenhouse gas emissions calculator. Available at http://www.environment.gov.au/settlements/transport/fuelguide/environment.html
5. Durlinger, B., Crossin, E. and Wong, J. (2013) Life Cycle Assessment of a cross laminated timber building. Available at http://www.fwpa.com.au/sites/default/files/PRA282-1112_Life-Cycle_Assessment_of_a_cross_laminated_timber_building.pdf
Calculations:
Parameter | Unit | Value | Reference | |
Average distance a passenger vehicle travels in one year | km | 13,900 | ABS 2012 | |
Average rate fuel consumption for passenger vehicle is | litres / 100 kilometres | Petrol 11.1 Diesel 11.4 LFG/CNG 13.6 | ABS 2012 | |
Proportion of fuel used by passenger cars | % | Petrol 84% Diesel 8% LFG/CNG 8% | ABS 2012 | |
| kg CO2 emissions / litre of fuel consumed | Petrol 2.3 Diesel 2.7 LFG/CNG 1.6 | Australian Government 2008 | |
Average CO2 emissions for a passenger car in one year | CO2 emissions (tonnes) | 3.56 tonnes | Calculated |
Average CO2 emissions (in tonnes) for a passenger car in Australia over one year = [(13,900 x 11.1 x 84% x 2.3) + (13,900 x 11.4 x 8% x 2.7) + (13,900 x 13.6 x 8% 1.6)] / 1000
Interior
The interiors are like most apartments, lined with plasterboard and then painted. Other than a featured CLT wall there is no indication inside the apartments that the building is constructed from timber.
The featured CLT wall is a clear coat seal to blend in with the light colours used elsewhere in the interior. An Australian hardwood blackbutt engineered wood floor is laid throughout the living area.
The fire stairs and stair well however are exposed CLT.
Building with Wood
Fire benefits
Fire resistance is the key issues that needed to be addressed as some timber applications do not meet the deemed-to-satisfy building regulations (More details in the Structure tab).
The walls are generally 128 mm thick of CLT with 13 mm fire resisting plasterboard direct fixed both sides. The bare timber wall used as a feature in the apartment is 128 mm thick of CLT. All required walls achieve the deemed to satisfy fire rating required of FRL of 90/90/90
The floor is generally 146 mm thick with 2 layers of 16 mm fire resisting plasterboard again direct fixed. The floors again achieve the fire rating required of FRL of 90/90/90.
The external wall uses a combination of fire resistant plasterboard and the char capacity of timber itself and was considered through fire safety engineering analysis to achieve the deemed to satisfy fire rating from the inside but through fire safety engineering analysis for a fire exposure from outside. The outer layer of CLT to one elevation where the building is exposed within 6m of another allotment is thickened to provide the resistance from fire in that direction.
Penetrations through all fire rated elements are dealt with in the usual methods however extensive testing pursuant to the Australian Standards was undertaken to demonstrate compliance in accordance with the standard and applicable requirements of Part A of the National Construction Code Series - Volume One, Building Code of Australia.
Sprinklers are also used. They were not included as deemed to satisfy but allowed consideration of particular concessions pursuant to Victoria variation to the National Construction Code Series - Volume One, Building Code of Australia. It is also noted that sprinklers provide social sustainability to the occupants of the building through minimizing any disruption / relocation in the event of a fire emergency.
