plasterboard on the underside of the rafters the effects of deflection under concentrated (point) load do not need to be considered as per guidance given in BS 5268-7.5 clause 4.3. The imposed load should be calculated in accordance with BS 6399:Part 3:1988 Code of practice for imposed roof loads, as a rule of thumb for altitudes not exceeding 100m you can use a uniformly distributed load of 0.75 kN/m² and for most other areas exceeding 100m but not exceeding 200m you can use 1 kN/m², for parts of Scotland, Pennines, North East England and heights over 200m you will need to refer to BS 6399 Part 3.Īs there are no brittle finishes e.g. Rafters are to have minimum end bearing of 35mm. Wane as allowed in BS 4978:2007+A2:2017 is permitted in all sections included in these span tables. Timber to be covered, these span tables do not apply to timber which is fully exposed to the elements. Holes and notches cannot be drilled or cut into the rafters unless proved adequate by specialist calculations. The calculations on which these span tables are based conservatively assume that the rafters are not continuous over the purlins, but they can be continuous over the supporting purlin if required. These span tables are based on the assumption that the tiling battens fastened to the top of the rafters will provide adequate lateral restraint and also ensure that lateral loads are distributed. title: wooden wendy cost.xlsx created date: 20151212120700z. It is also assumed ceiling joists will be used to transmit the horizontal component of thrust occurring at eaves level to complementary rafters. 1/300th of span roof rafters for sabs s5 graded pine floor joists for sabs s5 graded pine commercial applications spacing safe span table for south african pine based on sans 1008:2007 edition 4 spacing 1,5 kn/m2 0,125 kn/m2 1,5 kn 1/300th of span domestic applications. These span tables only apply to roof systems with four or more rafters. These span tables do not apply to trussed rafter roofs. The dead loads shown at the top of span table above do not include the self weight of the rafters, however, the rafter self weights are included (in addition to the dead loads) in the calculations used to determine permissble clear spans. The allowable clear spans have been calculated in accordance with BS 5268-2:2002 Structural use of timber - Part 2: Code of practice for permissible stress design, materials and workmanship and BS 5268-7.5:1990 Structural use of timber - Section 7.5 Domestic rafters. Spans for rafters shall be in accordance with Tables R802.5.1(1) through R802.5.1(8). Note that these are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction.Dead load per square metre (in kN/m²) supported by raftersĬentre-to-centre spacing of rafters (in mm) South Holland Residential Code 2012 > 8 Roof-Ceiling Construction > R802 Wood Roof Framing > R802.5 Allowable Rafter Spans. This is the right way to fix truss clips connecting the rafter and wall plate. Vertical strapping at eaves pitched roofsĪt eaves level, vertical straps 1m long should be fixed as shown in the diagram opposite at a maximum of 2m centres. Effective strapping at gable wallĮach strap should be fixed as shown in the diagram opposite with noggins between the rafters to support the metal strap along its whole length. Gable walls need to be strapped to the roof at the maximum 2m centres using 30 x 5m galvanised mild steel straps. This diagram illustrates the typical arrangement of a rafter and purlin roof and shows the dimensions referred to in the tables above. The first span table is for rooftop location the. Roof with ceiling not attached to rafters, grinded snow load 50 Psf, dead load 20 Psf, deflexion bound L/180. Rafters GL8 Single Span Dry Use Roof weight 20kg/m2 Roof snow load 0 kPa Loads Deflection limits Batten Spacing Roof 0.2 kPa Dead Loads Span/300 or 20mm 1200mm for sheet roofs Live Load 0.25 kPa Live loads Span/250 330mm for tile roofs 1.1 kN Wind load Span/150 Snow Load 0. Roof pitch between 30 and 45 degrees strength class C24 Size of purlins in mm The spacing tables on this show top the following deuce design scenarios: Rafts with limit does attached up rafters, dwell load 20 Psf, dead load 20 Psf, deflexion limit L/180.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |