AS 1684.2-2010 Timber Framing Design PDF

11 AS 1684.2—2010 1.4.5 Width The maximum width of a building shall be 16 000 mm, excluding eaves (see Figure 1.1). 1.4.6 Wall height The maximum wall height shall be 3000 mm [floor to ceiling, as measured at common external walls, that is, not gable or skillion ends (see Figure 1.1)]. NOTES: 1 T...

11 AS 1684.2—2010 1.4.5 Width The maximum width of a building shall be 16 000 mm, excluding eaves (see Figure 1.1). 1.4.6 Wall height The maximum wall height shall be 3000 mm [floor to ceiling, as measured at common external walls, that is, not gable or skillion ends (see Figure 1.1)]. NOTES: 1 The Span Tables for studs given in the Supplements provide for stud heights in excess of 3000 mm to cater for gable, skillion and some other design situations where wall heights, other than those of common external walls, may exceed 3000 mm. 2 Building height limitations apply where wind classification is determined using AS 4055 (see Clause 1.4.2). 3 The provisions contained in this Standard may also be applicable to houses with external wall heights up to 3600 mm where appropriate consideration is given to the effect of the increased wall height on racking forces, reduction to bracing wall capacities, overturning and uplift forces, shear forces and member sizes. 1.4.7 Roof pitch The maximum roof pitch shall be 35° (70:100). 1.4.8 Spacing of bracing For single or upper storey construction, the spacing of bracing elements, measured at right angles to elements, shall not exceed 9000 mm (see Section 8). For the lower storey of two-storey or subfloor of single- or two-storey construction, bracing walls shall be spaced in accordance with Clause 8.3.5.9. NOTE: Bracing walls may be spaced greater than the prescribed limits where the building is designed and certified in accordance with engineering principles. 1.4.9 Roof types Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Roof construction shall be hip, gable, skillion, cathedral, trussed or pitched, or in any combination of these (see Figures 2.2 to 2.7). 1.4.10 Building masses Building masses appropriate for the member being designed shall be determined prior to selecting and designing from the Span Tables in the Supplements. Where appropriate, the maximum building masses relevant to the use of each member Span Table are noted under the Table. The roof mass shall be determined for the various types of roof construction for input to the Span Tables in the Supplements for rafters or purlins, intermediate beams, ridge beams and underpurlins. For rafters or purlins, mass of roof shall include all supported materials. For underpurlins, mass of roof shall include all supported materials except the rafters that are accounted for in the design. For counter beams, strutting beams, combined hanging strutting beams, and similar members, the mass of roof framing (rafters, underpurlins) is also accounted for in the Span Tables in the Supplements. The mass of a member being considered has been accounted for in the design of that member. NOTE: Appendix A provides guidance and examples on the determination of masses. www.standards.org.au  Standards Australia AS 1684.2—2010 12 1.5 DESIGN CRITERIA The design criteria that have been used in the preparation of this Standard are the following: (a) The bases of the design used in the preparation of this Standard are AS 1684.1 and AS 1720.1. (b) The design dead, live, and wind loadings specified in AS/NZS 1170.1, AS/NZS 1170.2 and AS 4055 were taken into account in the member computations, with appropriate allowances for the distribution of concentrated or localized loads over a number of members where relevant (see also Clause 1.4.2). NOTE: Construction supporting vehicle loads is outside the scope of this Standard. (c) All pressures, loads, forces and capacities given in this Standard are based on limit state design. (d) The member sizes, bracing and connection details are suitable for construction (including timber-framed brick veneer) of design category H1 and H2 domestic structures in accordance with AS 1170.4. NOTES: (e) 1 This Standard does not provide specifications for unreinforced masonry construction subject to earthquake loads. 2 Typical unreinforced masonry may include masonry bases for timber-framed houses. The effects of snow loads up to 0.2 kPa on member sizes, bracing and connection details have been accommodated in the design. 1.6 FORCES ON BUILDINGS The design of framing members may be influenced by the wind forces that act on the specific members. When using Span Tables in the Supplements, the appropriate wind classification (e.g., N2), together with the stress grade, shall be established prior to selecting the appropriate supplement to obtain timber member sizes. Assumptions used for forces, load combinations and serviceability requirements of framing members are given in AS 1684.1. Forces applied to timber-framed buildings, which shall be considered in the design of framing members, are indicated in Figure 1.2. Construction load (people, materials) Suction (uplift) Dead load (structure) Dead load (structure) Live loads (people, furniture etc.) Internal pressure Suction Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 All framing members shall be adequately designed and joined to ensure suitable performance under the worst combinations of dead, live, wind and earthquake loads. Members shall also meet serviceability requirements for their application. Wind Dead load (structure) (a) Gravity loads Internal pressure (b) Uplift wind loads NOTE: For clarity, earthquake and snow loads are not shown (see Clause 1.5). FIGURE 1.2 LOADS ON BUILDINGS  Standards Australia www.standards.org.au 13 AS 1684.2—2010 Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Forces on buildings produce different effects on a structure. Each effect shall be considered individually and be resisted. Figure 1.3 summarizes some of these actions. This Standard takes account of these. (a) Racking—Wall deform (b) Overturning—Rotation (c) Sliding—Tendency to slide (d) Uplift—Connection failure FIGURE 1.3 EFFECTS OF FORCES ON BUILDINGS 1.7 LOAD PATHS—OFFSETS AND CANTILEVERS Where applicable, roof loads shall be transferred through the timber frame to the footings by the most direct route. For floor framing, the limitations imposed regarding the support of point loads and the use of offsets and cantilevers are specified in Section 4. NOTES: 1 This load path in many cases cannot be maintained in a completely vertical path, relying on structural members that transfer loads horizontally. Offset or cantilevered floor framing supporting loadbearing walls may also be used (see Figures 1.4 and 1.5). 2 Floor members designed as ‘supporting floor load only’ may support a loadbearing wall (walls supporting roof loads) where the loadbearing wall occurs directly over a support or is within 1.5 times the depth of the floor member from the support (see also Clause 4.3.1.2 and Clause 4.3.2.3). 3 Other members supporting roof or floor loads, where the load occurs directly over the support or is within 1.5 times the depth of the member from the support, do not require to be designed for that load. www.standards.org.au  Standards Australia AS 1684.2—2010 14 Adequate fixing required to backspan support Cantilever Backspan FIGURE 1.4 CANTILEVER Roof or floor load This member designed as not supporting load D Support Offset 1.5 D max. Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 FIGURE 1.5 OFFSET 1.8 DURABILITY Structural timber used in accordance with this Standard shall have the level of durability appropriate for the relevant climate and expected service life and conditions including exposure to insect attack or to moisture, which could cause decay. Structural timber members that are in ground contact or that are not protected from weather exposure and associated moisture ingress shall be of in-ground durability Class 1 or 2 as appropriate (see AS 5604), or shall be adequately treated with preservative in accordance with the AS/NZS 1604 series, unless the ground contact or exposure is of a temporary nature. NOTE: For guidance on durability design, see Appendix B.  Standards Australia www.standards.org.au 15 AS 1684.2—2010 1.9 DIMENSIONS Timber dimensions throughout this Standard are stated by nominating the depth of the member first, followed by its breadth (see Figure 1.6); e.g., 90 × 35 mm (studs, joists etc.), 45 × 70 (wall plates, battens, etc.). Depth (width) Le n Breadth (thickness) h gt Depth Br ea dt h Depth e Br ad th FIGURE 1.6 DIMENSIONS 1.10 BEARING Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 The minimum bearing for specific framing members (bearers, lintels, hanging beams, strutting beams, combined strutting/hanging beams, counter beams, combined counter/strutting beams and verandah beams) shall be as given in the Notes to the Span Tables of the Supplements, as appropriate. In all cases, except for battens, framing members shall bear on their supporting element a minimum of 30 mm at their ends or 60 mm at the continuous part of the member, by their full breadth (thickness). Reduced bearing area shall only be used where additional fixings are provided to give equivalent support to the members. Where the bearing area is achieved using a non-rectangular area such as a splayed joint, the equivalent bearing area shall not be less than that required above. 1.11 STRESS GRADES All structural timber used in conjunction with this Standard shall be stress-graded in accordance with the relevant Australian Standard. All structural timber to be used in conjunction with this Standard shall be identified in respect of stress grade. NOTE: The timber stress grade is usually designated alphanumerically (e.g., F17, MGP12). Stress grades covered by Span Tables in the Supplements to this Standard are given in Table 1.2. www.standards.org.au  Standards Australia AS 1684.2—2010 16 TABLE 1.2 STRESS GRADES Most common stress grades available Other stress grades available F5 F7 F8, F11, F14 F17 Hardwood (seasoned) F17 F22, F27 Hardwood (seasoned Western Australia) F14  Seasoned softwood (radiata, slash, hoop, Caribbean, pinaster pines, etc.) F5, F7, F8, MGP10, MGP12 F4, F11, MGP15 F5, F7 F8*, F11* Spruce pine fir (SPF) (seasoned) F5 F8 Hemfir (seasoned) F5 F8 Species or species group Cypress (unseasoned) Hardwood (unseasoned) Douglas fir (Oregon) (unseasoned) * Span tables in Supplements for unseasoned hardwood F8 and F11 may be used for unseasoned F8 and F11 softwood as well. NOTES: 1 Timber that has been visually, mechanically or proof stress graded may be used in accordance with this Standard at the stress grade branded thereon. 2 Check local timber suppliers regarding availability of timber stress grades. 1.12 ENGINEERED PRODUCTS (EWPs) TIMBER PRODUCTS AND ENGINEERED WOOD Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Fabricated components (e.g., roof trusses, glued-laminated timber members, I-beams, laminated veneer lumber, laminated strand lumber and nailplate-joined timber) may be used where their design is in accordance with AS 1720.1 and their manufacture and use complies with the relevant Australian Standards. Glued-laminated timber, I-beams, laminated veneer lumber (LVL) and laminated strand lumber (LSL) are also commonly referred to as EWPs (engineered wood products). NOTES: 1 Appendix J provides guidance on building practices that are common to the use of EWPs from different manufacturers. 2 In some situations, there are no relevant Australian Standards applicable to the design, manufacture or use of engineered timber products. In such cases, the use of these products in accordance with this Standard is subject to the approval of the regulatory authority and the recommendations of the specific manufacturer, who may require provisions additional to those contained in this Standard. These may include, but are not restricted to, additional support, lateral restraint, blocking, and similar provisions. 1.13 SIZE TOLERANCES When using the Span Tables given in the Supplements, the following maximum undersize tolerances on timber sizes shall be permitted: (a) (b) Unseasoned timber: (i) Up to and including F7 ………………………………………………….. 4 mm. (ii) F8 and above ……………………………………………………………. 3 mm. Seasoned timber—All stress grades …………………………………………. 0 mm. NOTE: When checking unseasoned timber dimensions onsite, allowance should be made for shrinkage, which may have occurred since milling.  Standards Australia www.standards.org.au 17 AS 1684.2—2010 1.14 ALTERNATIVE TIMBER DIMENSIONS The alternative timber dimensions given by this Clause shall not apply to the Span Tables in the Supplements. Where a timber dimension is stated in the clauses of this Standard, it refers to the usual minimum dimensions of seasoned timber. Alternative dimensions for seasoned timber, unseasoned timber and seasoned Western Australian hardwood shall be in accordance with Table 1.3. The size tolerances given in Clause 1.13 are also applicable to these dimensions. TABLE 1.3 Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 ALTERNATIVE TIMBER DIMENSIONS Min. seasoned timber dimension, mm Nominal unseasoned timber dimensions Min. seasoned W.A. hardwood dimensions 19 25 19 32 38 30 35 38 30 42 50 40 45 50 40 70 75 60 90 100 80 120 125 125 140 150 125 170 175 175 190 200 175 240 250 220 290 300 260 1.15 STEEL GRADE AND CORROSION PROTECTION All metal used in structural timber connections shall be provided with corrosion protection appropriate for the particular conditions of use. Where corrosion protection of steel is required it shall be in accordance with AS/NZS 4791, AS/NZS 4534, AS 1397 and AS 1214. The level of corrosion protection provided shall take into consideration weather exposure, timber treatment, moisture and presence of salt. The minimum corrosion protection that shall be applied to metal straps, framing anchors and similar structural connections shall be Z 275. The minimum thickness of metal strap shall be 0.8 mm and the minimum net cross-section area shall be 21 mm 2 , unless noted otherwise. Where other types of corrosion protection are provided, they shall satisfy the requirements of the relevant authority. The min. steel grade for metal strap, framing anchors and similar structural connection shall be G 300. The grade of all other metal components shall be in accordance with the relevant Australian Standards. www.standards.org.au  Standards Australia AS 1684.2—2010 18 1.16 CONSIDERATIONS FOR DESIGN USING THIS STANDARD Prior to using this Standard, the design gust wind speed and corresponding wind classification shall be determined. It shall include consideration of terrain category building height and topographic and shielding effects (see Clause 1.4.2). The wind classification is the primary reference used throughout this Standard. NOTE: The recommended procedure for designing the structural timber framework is to determine first the preliminary location and extent of bracing and tie-down and then the basic frame layout in relation to the floor plan and the proposed method of frame construction. Individual member sizes are determined by selecting the roof framing timbers and then systematically working through the remainder of the framework to the footings, or by considering the floor framing through to the roof framing. Bracing and tie-down requirements should also be considered when determining the basic frame layout to ensure any necessary or additional framing members are correctly positioned. The flow chart shown in Figure 1.7 provides guidance. Reference After determining the maximum design gust wind velocity (refer to AS/NZS 1170.2 or AS 4055 or the relevant a u t h o r i t y ) , s e e Ta b l e 1 . 1 for wind classification. Determine wind classification N1 to N4 Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Consider preliminary location and extent of bracing and tie-down systems and modify framing layout if required Section 8 and 9 Establish basic frame layout and method of construction— floor frame, wall frame and roof frame, including load paths, cantilevers, offsets, etc. Section 1 Floor frame—Section 4 Wall frame—Section 6 Roof frame—Section 7 Determine individual member size Design bracing system Section 8 Check Design tie-down and other connection requirements Section 9 FIGURE 1.7 FLOW CHART FOR DESIGN USING THIS STANDARD 1.17 INTERPOLATION Interpolation shall be made in accordance with Appendix C.  Standards Australia www.standards.org.au 23 AS 1684.2—2010 2.3.2 Lamination of spaced ring beams Ring beams that made up of two spaced members shall be laminated in accordance with Figure 2.8(b). ma 2D x. D Additional nail(s) at point of load or support (a) Vertical nail lamination (strutting beam shown) Packers at max. 1200 mm centres Steel bridging plate/washer for tie-down rod Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Spaced ring beam Plate nailed to each ring beam member with 1/75 x 3.05 mm at max. 600 mm centres 2/90 mm long No. 14 type 17 batten screws connecting ring beam at each packer Tie-down rod Stud (b) Lamination of spaced ring beams FIGURE 2.8 VERTICAL LAMINATION www.standards.org.au  Standards Australia AS 1684.2—2010 24 2.4 STUD LAMINATION In the case of studs at sides of openings and studs supporting concentrations of load, the required size may be built up by using two or more laminations of the same timber type, stress grade and moisture content condition, provided the achieved width is at least that of the nominated size. Studs up to 38 mm thick shall be nailed together with one 75 mm nail at maximum 600 mm centres. Studs over 38 mm but not exceeding 50 mm thick shall be nailed with one 90 mm nail at maximum 600 mm centres (see Figure 2.9). Where screws are used in lieu of nails, they shall be minimum No. 10 screws. They may be at the same spacing and pattern, provided they penetrate a minimum of 75% into the thickness of the final receiving member. Posts shall not be nail-laminated. Plates nailed together over each stud Joints min. 1200 mm apart and staggered Where joints occur in either top plate between studs, and where rafter or truss bears onto top plates, additional blocking shall be provided Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 600 mm max. Multiple studs nailed together at 600 mm max. centres NOTE: Refer to Section 9 for other nominal fixing requirements including plates to studs. FIGURE 2.9 STUD/PLATE LAMINATION 2.5 HORIZONTAL NAIL LAMINATION—WALL PLATES ONLY Wall plates that are made up of more than one section (e.g., 2/35 × 70) shall be horizontally nail-laminated in accordance with Figure 2.9, using— (a) two 75 mm long nails for plates up to 38 mm deep; or (b) two 90 mm long nails for plates up to 50 mm deep (see also Clause 9.2.8). A minimum of two nails shall be installed at not greater than 600 mm centres along the plate. Where more than two plates are used, the nailing requirement applies to each lamination All joins in multiple bottom plates shall occur over solid supports such as floor joists, solid blocking between bottom plate and bearer or concrete slab.  Standards Australia www.standards.org.au 25 AS 1684.2—2010 2.6 LOAD WIDTH AND AREA SUPPORTED 2.6.1 General The supported load width and area are used to define the amount of load that is imparted onto a member. Load width, coupled with another geometric descriptor such as spacing, will define an area of load that a member is required to support. Floor load width (FLW), ceiling load width (CLW) and roof load width (RLW) shall be determined from Clauses 2.6.2 to 2.6.4. For uplift due to wind loads, the definition ‘uplift load width’ (ULW) is used, as ULWs may differ significantly from RLWs depending upon where the structure is tied down. Refer to Section 9 for definition of ULW. 2.6.2 Floor load width (FLW) Floor load width (FLW) is the contributory width of floor, measured horizontally, that imparts floor load to a supporting member. FLW shall be used as an input to Span Tables in the Supplements for all bearers and lower storey wall-framing members. The FLW input is illustrated in Figures 2.10 and 2.11. Location Floor load width (FLW) Bearer A FLW = x + a 2 FLW FLW FLW Bearer B FLW = x + y 2 A B C Bearer C 2 Bearer A FLW FLW FLW = y y x a (b) Supported balcony Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 (a) Cantilevered balcony Type of construction FLW FLW Bearer B FLW = x 2 FLW = x + y 2 Bearer C A x D C B y z Bearer D FLW = y +z 2 FLW = z 2 FIGURE 2.10 FLOOR LOAD WIDTH (FLW)—SINGLE- OR UPPER-STOREY CONSTRUCTION www.standards.org.au  Standards Australia AS 1684.2—2010 26 FLW FLW A B FLW a Type of construction (a) FLW FLW Location Lower storey loadbearing walls FLW FLW y x D C z Floor load width (FLW) Wall A Upper FLW = x +a 2 Wall B Upper FLW = x+y 2 Wall C Wall D Upper FLW = y 2 N/A* Upper FLW = x +a 2 Bearer A Lower FLW = x 2 Upper FLW = x+y 2 Lower FLW = x+y 2 Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Bearer B (b) Bearers supporting lower storey loadbearing walls Upper FLW = y 2 Bearer C Lower FLW = y +z 2 Upper FLW = N/A* Bearer D Lower FLW = z 2 * See single or upper-storey construction. FIGURE 2.11 FLOOR LOAD WIDTH (FLW)—TWO-STOREY CONSTRUCTION 2.6.3 Ceiling load width (CLW) Ceiling load width (CLW) is the contributory width of ceiling, usually measured horizontally, that imparts ceiling load to a supporting member. CLW shall be used as an input to Span Tables for hanging beams, counter beams and strutting/hanging beams. The CLW input is illustrated in Figure 2.12.  Standards Australia www.standards.org.au 27 AS 1684.2—2010 Ceiling load width (CLW) Location D E Walls A, B & C N/A* Beam D CLW = x 2 CLW = y 2 (Hanging beam) CLW CLW x Beam E (Strutting/hanging beam) y A * C B CLW is not required as an input to the Tables for wall framing or bearers supporting loadbearing walls. FIGURE 2.12 CEILING LOAD WIDTH (CLW) 2.6.4 Roof load width (RLW) The roof load width (RLW) is used as a convenient indicator of the roof loads that are carried by some roof members and loadbearing wall members and their supporting substructure. The RLW value shall be used as an input to the relevant wall framing and substructure Span Tables. Figures 2.13 to 2.16 define RLW in relation to various types of roof construction. Type of construction Wall y A RLW = x+y +a 2 B RLW = x+y +b 2 B y x (b) Cathedral A b a A RLW = x +a 2 B RLW = y +b 2 C RLW = x+y 2 A RLW = x +a 2 B RLW = x +b 2 b a C A B b x (c) Skillion Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 (a) Truss x Roof load width (RLW) for member sizing a A B FIGURE 2.13 ROOF LOAD WIDTH (RLW)—NON-COUPLED ROOFS www.standards.org.au  Standards Australia AS 1684.2—2010 28 Type of construction x Wall Roof load width (RLW) for member sizing A RLW = x + a B RLW = y + b A RLW = x +a 2 B RLW = y +b 2 y b a A B (a) No ridge struts x y b a A C B C N/A (see Note) (b) Ridge struts NOTE: RLW may not be applicable where strut loads are supported by studs supporting concentrations of load and the remainder of wall C is deemed non-loadbearing. In this case, the supported roof area shall be determined for the studs supporting concentrated loads. FIGURE 2.14 ROOF LOAD WIDTH (RLW)—COUPLED ROOFS WITH NO UNDERPURLINS Type of construction Roof load width (RLW) for member sizing y x Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 Wall A RLW = x +a 2 B RLW = y +b 3 A RLW = x +a 4 B RLW = y +b 6 b a A B (a) No ridge struts y x b a A C B C N/A (see Note 1) (b) Ridge struts NOTES: 1 RLW may not be applicable where strut loads are supported by studs supporting concentrations of load and the remainder of wall C is deemed non-loadbearing. In this case, the supported roof area shall be determined for the studs supporting concentrated loads. 2 Collar ties have been omitted for clarity. FIGURE 2.15 ROOF LOAD WIDTH (RLW)—COUPLED ROOFS WITH UNDERPURLINS  Standards Australia www.standards.org.au 29 Type of construction AS 1684.2—2010 Wall Roof load width (RLW) for member sizing A RLW = x +a 4 B RLW = y +b 6 C RLW = x y + 4 6 A RLW = x +a 2 B RLW = y +b 2 C RLW = x+y 2 f) W RL roo in a (m A RLW = v +a 2 B B y x b a C A B (a) Cathedral—Framed y x b a C A B (b) Cathedral—Truss v a A RLW =RLW for main roof + v 2 (c) Verandah NOTE: Collar ties have been omitted for clarity. Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 FIGURE 2.16 ROOF LOAD WIDTH (RLW) COMBINATIONS AND ADDITIONS 2.6.5 Area supported The area supported by a member is the contributory area, measured in either the roof or floor plane, that imparts load onto supporting members. The roof area shall be used as an input to Span Tables in the Supplements for strutting beams, combined strutting/hanging beams, combined strutting/counter beams and studs supporting concentrated loads and posts. The floor area shall be used as an input to Span Tables in the Supplements for studs supporting concentrated loads and posts. Typical ‘area supported’ inputs for roofs and floors are illustrated in Figure 2.17. www.standards.org.au  Standards Australia AS 1684.2—2010 30 Underpurlin A B Strutting beam span Strutting beam Roof area supported = ½A x ½B (ridge strutted or not strutted) (a) Typical roof area supported by strutting beam Rafter span A 2 1/ 1/ sp an 2 s p an Post spacing B Joist span C 1/2 Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 1/ Roof area supported = A/2 × B/2 span Floor area supported = C/2 × D/2 2 s pa n Post spacing D NOTE: If the post was the central support for a continuous span verandah beam and bearer, the areas supported would be as follows: (a) Roof area supported = A/2 × B. (b) Floor area supported = C/2 × D. (b) Typical roof and floor area or supported by post FIGURE 2.17 AREA SUPPORTED 2.7 DEFINITIONS—GENERAL 2.7.1 Loadbearing wall A wall that supports roof or floor loads, or both roof and floor loads.  Standards Australia www.standards.org.au 31 AS 1684.2—2010 2.7.2 Non-loadbearing walls 2.7.2.1 Non-loadbearing wall, external A non-loadbearing external wall supports neither roof nor floor loads but may support ceiling loads and act as a bracing wall. A non-loadbearing external wall may support lateral wind loads (e.g., gable or skillion end wall). 2.7.2.2 Non-loadbearing wall, internal A non-loadbearing internal wall supports neither roof nor floor loads but may support ceiling loads and act as a bracing wall. 2.7.3 Regulatory authority The authority that is authorized by legal statute as having justification to approve the design and construction of a building, or any part of the building design and construction process. NOTE: In the context of this Standard, the regulatory authority may include local council building surveyors, private building surveyors or other persons nominated by the appropriate State or Territory building legislation as having the legal responsibility for approving the use of structural timber products. 2.7.4 Roof 2.7.4.1 Coupled roof Pitched roof construction with a roof slope not less than 10°, with ceiling joists and collar ties fixed to opposing common rafter pairs and a ridgeboard at the apex of the roof (see Figure 7.1). A coupled roof system may include some area where it is not possible to fix ceiling joists or collar ties to all rafters; for example, hip ends or parts of a T- or L-shaped house. 2.7.4.2 Non-coupled roof A pitched roof that is not a coupled roof and includes cathedral roofs and roofs constructed using ridge and intermediate beams. Accessed by QUEENSLAND UNIVERSITY OF TECHNOLOGY on 23 Aug 2011 2.7.4.3 Pitched roof A roof where members are cut to suit, and which is erected on site 2.7.4.4 Trussed roof An engineered roof frame system designed to carry the roof or roof and ceiling, usually without the support of internal walls. 2.7.5 Span and spacing 2.7.5.1 General NOTE: Figure 2.18 illustrates the terms for spacing, span, and single and continuous span. 2.7.5.2 Spacing The centre-to-centre distance between structural members, unless otherwise indicated. 2.7.5.3 Span The face-to-face distance between points capable of giving full support to structural members or assemblies. In particular, rafter spans are measured as the distance between points of support along the length of the rafter and not as the horizontal projection of this distance. 2.7.5.4 Single span The span of a member supported at or near both ends with no immediate supports. This includes the case where members are partially cut through over intermediate supports to remove spring (see Figures 2.18(c) and 2.18(d)). www.standards.org.au  Standards Australia