Construction of buildings in bushfire prone areas to AS

Transcription

1 Techical supplemet Australia July 2014 Research ad Product Developmet from James Hardie Costructio of buildigs i bushfire proe areas to AS Scope The ew Buildig Code of Australia (BCA) was itroduced i 2011 ad adopts the updated AS 3959:2009 that covers Costructio of buildigs i bushfire proe areas. These ew bushfire requiremets have bee adopted by all states with variatios i New South Wales, South Australia ad Tasmaia. These state variatios are outlied below: New South Wales: F a Class 1 class 10a buildig deck associated with a Class 1 buildig it must be costructed i accdace with the followig: (a) AS 3959, except f Sectio 9 Costructio f Bushfire Attack Level FZ (BAL FZ). Buildigs subject to BAL FZ must comply with specific coditios of developmet coset f costructio at this level; (b) the requiremets of (a) above as modified by the developmet coset followig cosultatio with the NSW Rural Fire Service uder sectio 79BA of the Evirometal Plaig ad Assessmet Act 1979; (c) the requiremets of (a) above as modified by developmet coset with a bushfire safety authity issued uder sectio 100B of the Rural Fires Act 1997 f the purposes of itegrated developmet. Tasmaia: Tasmaia has adopted the ew AS 3959 but has additioal requiremets f vehicle access ad water supply. the BCA f me ifmatio South Australia: Although the provisios f excluded areas i both the BCA ad the SA Housig Code will be adopted at a later date, all of the other requiremets icludig the ew Bushfire Attack Levels (BAL) have bee adopted i the ew BCA. This techical supplemet is iteded to be used as a guide i the desig ad costructio of buildigs i bushfire-proe areas i accdace to Australia Stadard Costructio of buildigs i bushfire proe areas. This supplemet promotes the successful use of o-combustible James Hardie buildig materials. This techical supplemet does ot cover all areas of bushfire costructio icludig but ot limited to dos, widows, fascias, roofs, peetratios etc. the stadard f other buildig compoets. This supplemet does ot replace the stadard but helps educate desigers ad builders o improvig the perfmace of buildigs whe subjected to bushfire proe areas. This supplemet must be read i cojuctio with the curret Australia Stadard. Overview AS specifies requiremets f the costructio of buildigs i bushfire proe areas i der to improve their resistace to bushfire attack from: Burig embers Radiat heat Flame cotact Ad combiatios of the three attack fms Although the stadard is desiged to improve the perfmace of buildigs whe subjected to bushfire attack i desigated bushfire-proe areas, there ca be o guaratee that a buildig will survive a bushfire evet o every occasio. This is substatially due to the upredictable ature ad behaviour of fire ad extreme weather coditios. There are ow six bushfire attack levels, compared to the existig three. The Stadard cotais costructio solutios f all Bushfire Attack Levels (BAL) s ad costructio requiremets withi the stadard, the BAL s icrease i strigecy as a direct relatioship to the icrease i bushfire attack level. There are o costructio requiremets f the lowest level. The BAL levels iclude: BAL - LOW, BAL , BAL - 19, BAL - 29, BAL - 40, BAL - FZ The umber after the BAL is based o heat flux exposure thresholds i kw/m2. The followig table outlies solutios to iteral flo, deckig ad exteral walls usig James Hardie products. However, the followig table must be read i cojuctio with the curret code. FIGURE 1: AUSTRALIAN BUSHFIRE This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature

2 BUILDING IN BUSHFIRE-PRONE AREAS IN ACCORDNACE WITH AS 3959: 2009 RELATED TO FIBRE CEMENT IN FLOOR AND ONLY Buildig Elemet Australia Stadard 3959: 2009 Requiremet James Hardie Recommedatios CONSTRUCTION FOR BUSHFIRE ATTACK LEVEL BAL s 12.5 AND 19 Cocrete slabs o groud This Stadard does ot provide costructio requiremets f cocrete slabs o the groud. Elevated flos This Stadard does ot provide costructio requiremets f elevated flos, icludig bearers, joists ad floig. Deckig - Flo This Stadard does ot provide costructio requiremets f deckig that is me tha 300 mm from a glazed elemet. Deckig less tha 300 mm (measured hizotally at deck level) from glazed elemets that are less tha 400 mm (measured vertically) from the surface of the deck (see Figure D2, Appedix D) shall be made from: (a) o-combustible material; (b) bushfire-resistig timber (see Appedix F); (c) a timber species, as specified i Paragraph E1 ad listed i Table E1 of Appedix E; F BAL 12.5 (d) PVC-U (e) a combiatio of ay of Items (a), (b), (c) (d) above. F BAL 19 (d) a combiatio of ay of Items (a), (b) (c) above. Walls That part of a exteral wall surface that is less tha 400 mm from the groud less tha 400 mm above decks, carpt roofs, awigs ad similar elemets fittigs havig a agle less tha 18 degrees to the hizotal ad extedig me tha 110 mm i width from the wall (see Figure D3, Appedix D) shall be of: (a) o-combustible material; (b) fibre-cemet exteral claddig, a miimum of 6 mm i thickess; (c) bushfire-resistig timber (see Appedix F); (d) a timber species as specified i Paragraph E1 ad listed i Table E1, Appedix E; (e) a combiatio of ay of Items (a), (b), (c) (d) above. F BAL 12.5 There are o requiremets f exteral wall surfaces 400 mm me from the groud f exteral wall surfaces 400 mm me above decks, carpt roofs, awigs ad similar elemets fittigs havig a agle less tha 18 degrees to the hizotal ad extedig me tha 110 mm i width from the wall (see Figure D3, Appedix D). F BAL 19 This Stadard does ot provide costructio requiremets f exteral wall surfaces 400 mm me from the groud f exteral wall surfaces 400 mm me above decks, carpt roofs, awigs ad similar elemets fittigs havig a agle less tha 18 degrees to the hizotal ad extedig me tha 110 mm i width from the wall (see Figure D3, Appedix D). Joits All joits i the exteral surface material of walls shall be covered, sealed, overlapped, backed butt-joited to prevet gaps greater tha 3 mm. Alteratively, sarkig-type material may be applied over the outer face of the frame pri to fixig ay exteral claddig. Vets ad Weepholes Vets ad weepholes i exteral walls shall be screeed with a mesh with a maximum aperture of 2 mm, made of crosio-resistat steel, broze alumiium, except where the vets ad weepholes are less tha 3 mm (see Clause 3.6), are located i a exteral wall of a subflo space. The followig James Hardie floig o combustible material Scyo Secura exteri floig (Residetial Decks ad iteral areas) Scyo Secura iteri floig (residetial iteral dry ad wet areas) Scyo Secura iteri floig (Residetial Iteral wet area) HardiePael compressed sheet 15, 18 24mm. (Decks ad iteral areas) All James Hardie exteral claddig products, uless they are less tha 6mm thick eg. 4.5mm thick HardieFlex sheets, are suitable f exteral walls whe istalled with vapour permeable membrae. They are deemed as a o combustible material i accdace with C1.12 ad part of the Buildig Code of Australia. They are also deemed a fibre cemet exteral claddig material as they are maufactured i accdace with AS/ NZS au, au au f me ifmatio o James Hardie products. This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature

3 CONSTRUCTION FOR BUSHFIRE ATTACK LEVEL BAL 29 Cocrete slabs o groud This Stadard does ot provide costructio requiremets f cocrete slabs o groud. Elevated flos Eclosed subflo space This Stadard does ot provide costructio requiremets f elevated flos, icludig bearers, joists ad floig, where the subflo space is eclosed with: (a) a wall that complies with Clause 7.4; (b) a mesh perfated sheet with a maximum aperture of 2 mm, made of crosio resistat steel, broze alumiium; (c) a combiatio of Items (a) ad (b) above. Ueclosed subflo space Where the subflo space is ueclosed, floig material, icludig bearers, joists ad floig less tha 400 mm above fiished groud level, shall be: (a) o-combustible (e.g., cocrete, steel); (b) of bushfire-resistig timber (see Appedix F); (c) particleboard plywood floig where the uderside is lied with sarkig-type material mieral wool isulatio; (d) a system complyig with AS ; (e) a combiatio of ay of Items (a), (b), (c) (d) above. This Stadard does ot provide costructio requiremets f elemets of elevated flos, icludig bearers, joists ad floig, if the uderside of the elemet is 400 mm me above fiished groud level. Deckig - Flo Deckig shall be: (a) of o-combustible material; (b) of bushfire-resistig timber (see Appedix F); (c) a combiatio of Items (a) ad (b) above. Walls Walls shall be oe of the followig: (a) Made of o-combustible material (e.g., full masy, brick veeer, mud brick, cocrete, aerated cocrete). (b) Made of timber-framed steel-framed walls that are sarked o the outside of the frame ad clad with: (i) fibre-cemet exteral claddig, a miimum of 6 mm i thickess; (ii) steel sheet; (iii) bushfire-resistig timber (see Appedix F); (iv) a combiatio of ay of Items (i), (ii) (iii) above. (c) A combiatio of Items (a) ad (b) above. Joits All joits i the exteral surface material of walls shall be covered, sealed, overlapped, backed butt-joited to prevet gaps greater tha 3 mm. Alteratively, sarkig-type material ca be applied over the frame pri to fixig ay exteral claddig. Vets ad weepholes Vets ad weepholes i exteral walls shall be screeed with a mesh with a maximum aperture of 2 mm, made of crosio-resistat steel, broze alumiium, except where they are less tha 3 mm (see Clause 3.6). The followig James Hardie floig o-combustible materials: Scyo Secura exteri floig (Residetial Decks ad iteral areas) Scyo Secura iteri floig (residetial iteral dry ad wet areas) Scyo Secura iteri floig (Residetial Iteral wet area) HardiePael compressed sheet 15, 18 24mm. (Decks ad iteral areas) All James Hardie exteral claddig products, uless they are less tha 6mm eg. 4.5mm thick HardieFlex sheets, are suitable f the exteral walls whe istalled with vapour permeable membrae. They are deemed as a o combustible material i accdace with C1.12 ad part of the Buildig Code of Australia. They are also deemed a fibre cemet exteral claddig material as they are maufactured i accdace with AS/NZS com.au, com.au www. scyo.com.au f me ifmatio o James Hardie products. This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature

4 CONSTRUCTION FOR BUSHFIRE ATTACK LEVEL BAL 40 Cocrete slabs o groud This Stadard does ot provide costructio requiremets f cocrete slabs o groud. Elevated flos Eclosed subflo spaces This Stadard does ot provide costructio requiremets f elevated flos, icludig bearers, joists ad floig, where the subflo space is eclosed with a wall that complies with Clause 8.4. Ueclosed subflo spaces Where the subflo space is ueclosed, the floig material, icludig bearers, joists ad floig, shall: (a) be o-combustible (e.g., cocrete, steel); (b) have the uderside of the combustible elemets of the flo system protected with a o-combustible material (e.g., fibre-cemet sheet metal sheet); (c) comply with AS ; (d) be a combiatio of ay of Items (a), (b) (c) above. Deckig Deckig shall be: (a) of o-combustible material; (b) a system complyig with AS , (c) a combiatio of Items (a) ad (b) above. Walls Walls shall be oe of the followig: (a) Walls made from o-combustible material (e.g., full masy, brick veeer, mud brick, cocrete, aerated cocrete). (b) Timber-framed steel-framed walls that are sarked o the outside of the frame ad clad with: (i) fibre-cemet exteral claddig, a miimum of 9 mm i thickess; (ii) steel sheetig; (iii) a combiatio of Items (i) ad (ii) above. (c) A system complyig with AS (d) A combiatio of ay of Items (a), (b) (c) above. Joits All joits i the exteral surface material of walls shall be covered, sealed, overlapped, backed butt-joited to prevet gaps greater tha 3 mm. Alteratively, sarkig-type material may be applied over the frame pri to fixig ay exteral claddig. Vets ad weepholes Vets ad weepholes i exteral walls shall be screeed with a mesh with a maximum aperture of 2 mm, made of crosio-resistat steel broze except where they are less tha 3 mm (see Clause 3.6). The followig James Hardie floig o combustible materials: Scyo Secura exteri floig (Residetial Deck ad iteral areas) Scyo Secura iteri floig (Residetial iteral dry ad wet areas) Scyo Secura iteri floig (Residetial Iteral wet area) HardiePael com pressed sheet 15, 18 24mm. (Decks ad iteral areas) James Hardie 6mm HardieFlex sheets may be a suitable ocombustible material to have o the uderside of a flo system f a ueclosed subflo space. The followig James Hardie exteral claddig products are 9mm thick ad thus ca be used: Scyo Liea weatherboard Scyo Stria claddig Scyo Axo claddig PrimeLie weatherboards ComTex facade pael ad fixig system 9mm ExoTec facade pael ad fixig system au, f me ifmatio o James Hardie products. Although, EasyLap Paels are 8.5mm thick they have also bee approved whe istalled as per the curret istallatio maual. This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature

5 CONSTRUCTION FOR BUSHFIRE ATTACK LEVEL FZ (BAL FZ) Cocrete slabs o groud This Stadard does ot provide costructio requiremets f cocrete slabs o groud. Elevated flos Eclosed subflo spaces This Stadard does ot provide costructio requiremets f elevated flos, icludig bearers, joists ad floig, where the subflo space is eclosed with a wall that complies with Clause 9.4. Ueclosed subflo spaces Where the subflo space is ueclosed, the flo system, icludig bearers, joist ad floig, shall: (a) have a FRL of at least 30/30/30 ad the surface material shall be o-combustible (e.g., cocrete, steel); (b) have the uderside of the combustible elemets of the flo system protected with a 30 mi resistace to icipiet spread of fire system; (c) comply with AS whe tested from the uderside; (d) be a combiatio of ay of Items (a), (b) (c) above. Deckig Deckig shall have o gaps ad be: (a) of o-combustible material; (b) fibre-cemet sheet; (c) a system complyig with AS ; (d) a combiatio of Items (a), (b) (c) above Walls Walls shall be oe of the followig: (a) Walls made of o-combustible material (e.g., masy, brick veeer, mud brick, aerated cocrete, cocrete) with a miimum of 90 mm i thickess. (b) A system complyig with AS whe tested from the outside. (c) A system with a FRL of 30/30/30 -/30/30 whe tested from the outside. (d) A combiatio of ay of Items (a), (b) (c) above Joits All joits i the exteral surface material of walls shall be covered, sealed, overlapped, backed butt-joited to prevet gaps greater tha 3 mm. Alteratively, sarkig-type material may be applied over the frame pri to fixig ay exteral claddig Vets ad weepholes Vets ad weepholes i exteral walls shall be screeed with a mesh with a maximum aperture of 2 mm, made of crosio-resistat steel broze, except where they are less tha 3 mm (see Clause 3.6). The followig James Hardie floig o-combustible materials: Scyo Secura exteri floig (Residetial Decks ad iteral areas) Scyo Secura iteri floig (residetial iteral dry ad wet areas) Scyo Secura iteri floig (Residetial Iteral wet area) HardiePael compressed sheet 15, 18 24mm. (Decks ad iteral areas) A 30/30/30 Wall FRL ca be achieved with James Hardie exteral claddig whe used with other materials, refer to figures 4a, 4b, 5a & 5b f me ifmatio. au, f me ifmatio o James Hardie products. F all areas except BAL Low, a vapour permeable sarkig must have a flammability idex of ot me tha 5. This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature

6 Typical Applicatios Walls/Flos NON-FIRE RATED WALL (o combustible detail) Up to ad icludig BAL 40 There are requiremets i certai cases where the sub-flo space must be fully eclosed with o-combustible material (f which fibre cemet is suitable). There are also cases where the flo must be sheeted udereath with a fire-retardat-treated (FRT) timber a o-combustible material (f which fibre cemet is suitable). I both cases the miimum required thickess of the fibre cemet is 6mm. FIGURE 3: 30/30/30 ONE WAY FRL - OPTION 1 FIGURE 4A: 30/30/30 ONE WAY FRL OVERHANG FOOTING - OPTION 1 FIGURE 2: NON COMBUSTIBLE FLOOR DETAIL FIGURE 4B: 30/30/30 ONE WAY FRL ALIGNED - OPTION 1 FIGURE 3: SLAB ON GROUND DETAIL-NON COMBUSTIBLE ONLY FIRE RATED WALL -30/30/30 F BAL -FZ Whe a miimum 90x45mm wall frame is costructed at 600mm maximum stud cetres usig the below exteral ad iteral wall cofiguratio, it will satisfy a 30/30/30 oe way fire ratig from the outside. FIGURE 5A: 30/30/30 ONE WAY FRL OVERHANG FOOTING - OPTION 2 This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature

7 15mm ECOplywood sheet Layer: All 15mm ECOplywood joits must fall o framig members steel agles at fascia at wall. 15mm ECOplywood sheets must be fixed to framig members at 200mm maximum cetres with screws that are a miimum 50mm log. 16mm Bal Firestop plasterboard sheet layer: Bal Firestop plasterboard butt joits must ot coicide with the 15mm ECOplywood joits. Bal Firestop plasterboard to be fixed to the framig at 150mm maximum cetres aroud the perimeter, as well as at 200mm max cetre spacig alog framig. Plasterboard fasteer to be plasterboard screws. James Hardie 4.5mm HardieFlex sheet layer: FIGURE 5B: 30/30/30 ONE WAY FRL ALIGNED - OPTION 2 Eaves The roof/wall juctio must be sealed by either the use of fascia eaves liigs by sealig betwee the rafters at the lie of the wall. All other types of roofig must be costructed to esure that burig embers do ot peetrate ito the roof space. BAL BAL LOW BAL 12.5 BAL 19 BAL 29 BAL 40 Requiremet No costructio requiremet but mi. 4.5 mm fibre cemet sheet is recommeded No costructio requiremet but mi. 4.5 mm fibre cemet sheet is recommeded No costructio requiremet but mi. 4.5 mm fibre cemet sheet is recommeded Miimum 4.5 mm fibre cemet sheet Miimum 6 mm fibre cemet sheet BAL FZ A system with a FRL -/30/30. See Figure 6. James Hardie 4.5mm HardieFlex sheets ca be butt joited joied with PVC joiters o framig oly. James Hardie 4.5mm HardieFlex sheets caot be joied off framig. The fasteer recommeded i the HardieFlex liig istallatio maual must be icreased by 31mm miimum to allow f the additioal layers behid the HardieFlex liig. James Hardie 4.5mm HardieFlex sheets must be istalled i accdace with the curret James Hardie Eave & Soffit Techical Specificatio. Roofig F roofig costructio ad detailig requiremets refer to AS FIGURE 6: FIRE RATED EAVE DETAIL (FRL -/30/30) * Framig to be at maximum 450mm cetres. This techical supplemet must be read i cojuctio with the curret techical product literature. James Hardie buildig products must be istalled i accdace with the applicable techical product literature. All compoets ad accessies must be istalled i accdace with the respective maufacturer s specificatios. F the product warraty, terms ad coditios refer to the applicable James Hardie techical product literature