Loaded dimension - PDF document

Loaded dimension A BUILD READER HAS ASKED WHAT IS THE CORRECT LOADED DIMENSION FOR A LINTEL SUPPORTING A HIP ROOF. THE CORRECT ANSWER IS: IT DEPENDS. DESIGN RIGHT LOADED DIMENSIONS FOR NZS 3604:2011 LINTELS Actually, it depends on quite a lot of things, but the most important question to ask is whether it is to be a stick-framed roof or a trussed roof? Once this is answered, the best way to work out the loaded dimension (LD) for the lintel is to use the following rules of thumb. Stick-framed roof The loaded dimension for a lintel in a stick- framed roof is half the distance (D1 or D2 in Figure 1) from the wall corner to the far end of the lintel. Then use NZS Timber- framed buildings lintel tables to get its size. Trussed roof (Lintel 1), the loaded dimension is half the distance from the end wall to the girder truss or truncated girder truss (see D1 in Figure 2). A lintel in the side wall (Lintel 2) is more complex as it is likely to have a girder truss landing on it. There are a lot of variables making it dicult to determine the load from the girder truss. NZS3604:2011 lintel tables don’t provide for supplier for a lintel size by specic engineering design (SED) as part of the roof package. Stick-framed roof. Figure 1 BY ROGER SHELTON, BRANZ SENIOR STRUCTURAL ENGINEER D1 D2 Lintel 1 Lintel 2 Note: Ceiling framing omitted for clarity. Loaded dimension (LD) of: D2 2 2  Lintel 1 =  Lintel 2 = The loaded dimension is a measure of the weight of the construction that contributes to the member under consideration. 30 — Build 133 — December 2012/ January 2013 Trussed roof. Figure 2 D1 Lintel 1Lintel 2 girder truss (truncated shown) Loaded dimension (LD) of: Lintel 1 = Lintel 2 by SED jack truss Build 133 — December 2012/ January 2013 — minimum width specied for other stairways in household units, D1/AS1 recommends 850 mm as a practical minimum width. Landings are required at the top and bottom of all ights of stairs and wherever a door opens directly onto a stairway. The only exception is if the rise of the ight is less than 600 mm and no door opens over the steps. Landings must be at least the same width as the stairs and a minimum of 900 mm long. D1/AS1 Table 7 sets out the maximum height between landings as no more than 2.5 m for a common stairway and 4 m for a private stairway. Curved, spiral and winder stairways Curved, spiral and winder stairways are per - mited. They must meet the same requirements as straight flight stairs, but the pitchline is measured:  300 mm from the outside curve of a stair when the stair is less than 1 m wide  300 mm from the inside curve of a stair when the stair is over 1 m wide. For a winder stair, the pitchline is:  measured at the centre of the stair when the stair is less than 1 m wide  300 mm from the inside curve of a stair (same as for curved stairs) when the stair is over 1 m wide. Lighting levels D1/AS1 Table 8 sets out stairway lighting level requirements. For safety, they should be lit, preferably automatically. Want to keep The Right Stu? Either cut out or download articles from www.branz.co.nz/welcome_to_build RIGHT STUFF Five to watch People tell us about new things all the time, and while we don’t review or recommend consumer products, we figure you might want to know what’s out there. ADVERTISING PROMOTION Opinion Shorts ADVERTISING PROMOTION