Mid-Rise Timber Buildings

2nd MTC International Conference on Wood Architecture 9 November 2017

Boris Iskra Forest & Wood Products Australia

National Manager – Codes & Standards

Introduction

Mid-rise Timber Buildings Presenter:

Boris Iskra BE (Civil), Grad Dip. Building Fire Safety & Risk Engineering

Has worked in the timber industry for 30 years in a range of roles including Technical Director at the Timber Promotion Council (Vic). Currently the National Manager – Codes & Standards for Forest & Wood Products Australia.

Introduction

Speaker involved with:

• Development of the Proposal-for-Change (PFC) for Mid-rise Timber Buildings

• Stakeholder engagement to understand areas of concern and to address these during the PFC development phase

• Running of the fire risk-based model assessments for Class 2, 3 and 5 Buildings

• Undertaking required fire testing of building elements to support the PFC and use of timber products

• Development of educational resources

• Delivery of stakeholder workshops/seminars

NCC 2016 – Proposal for Change: Timber Construction

Prior to NCC 2016, timber construction systems in Australia have been restricted to 3 storeys under the ‘Deemed-to-Satisfy’ (DTS) provisions with higher buildings requiring an ‘Alternative Solution’ pathway for compliance purposes.

Project: Forte Living Location: Docklands, Melbourne

Project :: Ruskin St Townhouses Architect :: Marcus O’Reilly Architect Location :: Elwood, VIC Photographer :: Dianna Snape

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Maximum Storey Height for Timber DTS Buildings - 2013

NCC 2016 – Proposal for Change: Timber Construction

Globally however, many countries now allow construction of timber systems

well above 3 storeys.

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Italy

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Belgium

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No Sprinklers With Sprinklers

Maximum Storey Height for Timber DTS Buildings - 2016

NCC 2016 – Proposal for Change: Timber Construction

Globally however, many countries now allow construction of timber systems

well above 3 storeys.

NCC 2016 – Proposal for Change: Timber Construction

To assist in bringing Australia in line with international practices Forest & Wood Products Australia (FWPA) has undertaken a detailed fire testing program and in Feb 2015 submitted a

Proposal for Change (PFC) to the ABCB seeking the modification to the National Construction Code, Building Code of Australia Volume 1 (NCC), DTS provisions to allow the use of

fire-protected timber construction systems.

NCC 2016 – New Timber Construction Provisions

The 2016 NCC, has been amended to now allow under the Deemed-to-Satisfy (DTS) provisions the use of fire-protected timber construction systems in

Class 2 (apartments),

Class 3 (e.g. hotels) and

Class 5 (offices) buildings

up to 25 metres in effective height

(herein termed ‘mid-rise construction’).

Mid-rise

2016 NCC Compliance Pathways

Two pathways are available under the NCC to demonstrate performance

Image of new WS Design Guide

Rise in

storey

Type of Construction

Class 2 Class 3 Class 5 Class 6 Class 9a Class 9b

Apartments Hotels Office Shops Healthcare Schools &

public

buildings

4 or more

A A A A A A

3 A A B B A A

2 B B C C B B

1 C C C C C C

Maximum Timber Storey Height by Building Classification (NCC 2015)

Low-rise

Maximum Timber Storey Height by Building Classification (NCC 2016)

Mid-rise

Major New Opportunity

• O

Apartments (Class 2) eg Hotels (Class 3) Office Buildings (Class 5)

• A major new opportunity for a wide range of timber products and systems

Overview of Proposal for Change

The proposal:

• Building effective height of not more than 25m.

• Protected by automatic fire sprinklers complying with Specification E1.5 of the BCA.

• Fire-Protected Timber used in applications where the BCA DTS requires the element to be of non-combustible construction or concrete or masonry.

• Cavity barriers specified for timber framed construction to address risk of fire spread via cavities.

• No reductions in FRLs proposed despite provision of automatic fire sprinklers.

New DTS Provisions

• The new DTS provisions cover both

• traditional ‘lightweight timber framing’ and

• new ‘massive timber systems’ such as cross laminated timber (CLT)

Lightweight timber framing

CLT

Fire resistant plasterboard

and consist of the use of appropriate layers of fire resistant plasterboard – to provide ‘fire- protected timber’ – and the use of compliant automatic sprinkler systems.

Fire-Protected Timber

General Timber (High level of protection to timber)

• FRL lightweight timber-framed

construction e.g. 90, 120, 140 x 45mm

• Additional precautions to reduce risk of fire spread to cavities e.g. Sprinkler system plus 2 x 13mm fire-

grade plasterboard for walls, 2 x 16mm fire-grade plasterboard for ceilings

• Additional precautions to reduce risk if fire enters or starts in cavity

e.g. cavity barriers

Fire-grade plasterboard

Timber framing

Fire-Protected Timber

Massive Timber (Lower level of protection to timber)

• Minimum 75mm thickness of massive timber element, with required FRL, with no concealed spaces between plasterboard coverings and timber

e.g. CLT, Glulam, LVL • Precautions to reduce risk of timber

ignition e.g. Sprinkler system plus 1 x 16mm fire-

grade plasterboard for walls, 1 x 16mm fire-grade plasterboard for ceilings

• High inherent fire resistance of massive timber

• Comparable to minimum definition in US for heavy timber

Fire -grade plasterboard

Massive timber

Summary of General Fire Design Principles

Mid-Rise Timber Buildings have a number of critical layers of fire protection

Secondly, the use of fire-protected timber Protects timber in the low probability event that the sprinklers fail

Thirdly, the use of cavity barriers to prevent fire or smoke spread through the cavities if the fire-protection is breached or cavity fire occurs

Firstly, the use of automatic fire sprinklers to suppress a fire before the timber structure is threatened

Fourthly, the use of non-combustible insulation to minimise fire spread in cavities if the fire-protection is breached or cavity fire occurs

Timber Construction Options for

Mid-rise Timber Buildings

Design of Mid-Rise Timber Buildings

Building Form – Class 2 or 3: Multi-residential or Hotels

Class 2 – Apartments and Class 3 – e.g. Hotels tend to be honeycombed type structures with many closely spaced walls. There are a number of ways these could be constructed

Building Form – Class 2 or 3: Multi-residential or Hotels

Multi-Res Apartments

6 – 8 Storeys

Lightweight Timber

+

Massive Timber

Multi-Res Apartments

1-6 Storeys

Lightweight Timber

Conventional framing upper walls closer stud

centres lower walls

Multi-Res Apartments

6 - 12 Storeys

Massive Timber

(CLT)

Massive Wood Panel Systems

Massive Panel Construction (min. 75mm thickness)

• LVL • Cross Laminated Timber • Glued/nail Laminated Timber

Typical Construction Approaches - Apartments

Podium level • Often concrete (certainly

basement)

Apartment floors • Lightweight timber systems • Massive timber systems, or • Combination

Building Form – Class 5 Offices

Heavy Timber

Post & Beam

(Glulam)

Portal Frames

Efficiencies & Cost Benefits of Timber Systems

• Direct savings from faster methods of construction compared to traditional steel and concrete structures due to both: • increased scope for off-site prefabrication • lighter and more easily manipulated and installed materials

• Reduced foundation requirements due to lighter above-ground structure;

• Reduced on-site costs & OH&S issues, particularly with a shift to more prefabricated solutions;

• Increased ability to commence follow-on trades earlier in the construction process, reducing the overall construction program time to completion;

• Reduced on-site construction infrastructure (preliminary costs) such as fixed cranes, site accommodation, storage areas, scaffolding and edge protection, hoists and so on ; and

• Increased accessibility of the construction site and far lower impacts on noise and site activities on local neighbourhoods (less truck movements & workers); a major benefit for suburban multi-residential developments.

WS Design Guide: Costing Case Studies

See costing case study guides available from woodsolutions.com.au web site

Research

Test Program

Demonstration of performance of Fire Protected Timber

Approx. dimensions 4 m x 4 m x 2.4 m. Opening of 2 m width x 1.2 m height. Fire Load 740 MJ/m2 enclosures

Fire resistant wall construction

Timber Construction

2 layers of 13mm fire-grade plasterboard

timber studs

combustible insulation

Control

2 layers of 13mm fire-grade plasterboard

steel studs

non-combustible insulation

30 minutes

Control test Timber framed test

Enclosure Temperatures

Protected Steel Column Temperatures

Average Temperature Non-Fire Side of Walls

Fire Resistance Level (FRL)

FRL means the grading periods in minutes determined in accordance with Specification A2.3, for the following criteria— (a) structural adequacy; and (b) integrity; and (c) insulation,

and expressed in that order.

NCC Part A1.1 Definitions

Integrity – ability of an element of construction to resist the passage of flames and hot gases from one space to another

Structural adequacy – ability of a loadbearing element to support an applied load

Insulation – ability of the surface of an element of construction, on the non-fire side of the element, to maintain a temperature below the specified limits

FRL 90/90/90 RISF 60 lightweight engineered timber floor system being prepared for test

Ceiling System 2 x 16mm fire grade plasterboard fixed to furring channels. Channel spacing 600mm

Non-fire side 2 minutes after end of 90 minute test

Fire Exposed Face after test

Timber Buildings

Australian Case Studies

Project :: The Green Builders :: Frasers Property (prev. Australand)

Location :: Parkville, Vic

Design Team IrwinConsult TimberTruss & SmartStruct Timber Systems TecBeam Floor Cassette & Prefabricated Wall Frames Build Period Floor System – 1.5 Days per Level Wall System – 5.0 Days per Level

The Green

Project :: Forté Living Builders :: Lend Lease Location :: Melbourne, Vic

807 Bourke St Victoria Harbour 10 storeys 23 apartments 4 townhouses

Forté

The Gardens

Architect :: Strongbuild

Engineer :: AECOM

Builder :: Strongbuild

Height :: 6, 7 & 8 storey CLT

Location :: Macarthur Gardens, NSW

International House Sydney

Architect :: Tzannes Architects

Engineer :: Lend Lease

Builder :: Lend Lease

Height :: 7 storey office building

Location :: Barangaroo, Sydney

Image Credits: Jonathan Evans Image Credits: Jonathan Evans

Image Credits: Dijana Tasevska Image Credits: Dijana Tasevska

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Thank-you

WoodSolutions™: Design Guides