BS 8103-3:2009
Structural design of low-rise buildings - Code of practice for timber floors and roofs for housing

Standard No.

BS 8103-3:2009

Release Date

2009

Published By

British Standards Institution (BSI)

Latest

BS 8103-3:2009

Replace

BS 8103-3:1996 08/30140202 DC-2008

Scope

This Part of BS 8103 gives recommendations for the sizes of timber elements, fixings, and their connections with masonry walls, etc. It applies to detached, semi-detached, terraced houses and flats (with not more than four self-contained dwelling units per floor, accessible from one staircase) of not more than three storeys above ground, intended for domestic occupation. The recommendations also apply to single-storey non-residential buildings, e.g. domestic garages and annexes, not exceeding 36 m in floor area. The design of proprietary housing systems, i.e. cross wall constructions, timber framed houses, steel or concrete framed constructions, concrete panel constructions, is not covered by this standard. The recommendations of this Part of BS 8103 are applicable only to housing where: a) the construction comprises masonry walls, timber roofs, suspended timber or precast concrete intermediate floors, suspended timber or concrete ground floors (either suspended or ground bearing); b) the roof profile is symmetrical duopitch, monopitch or flat; NOTE 1 Pitched roofs of trussed rafter or traditional constructions are covered, but not constructions using principal trusses. Hip ends and “L” shaped plans are not specifically covered although values are given for jack rafters. c) the maximum clear span of a pitched roof does not exceed 12.0 m and imposes a total load on the supporting perimeter walls not greater than 12 kN/m run; d) gable and separating walls are of masonry construction extending up to the roof line in the case of pitched roofs; e) the roof area is not larger than 200 m2 on plan; or, in the case of pitched roofs where no parapets exist, one of the roof dimensions does not exceed 10 m; f) there are no other buildings within 1.5 m of the perimeter of the building; g) the roof has no abrupt changes of height greater than 1 m on which snow drifting could occur; NOTE 2 This limitation does not apply to the change of height between the main roof and the roof of a lower annexe, if the roof area of the annexe does not exceed 36 m. Chimneys and dormers whose vertical elevation areas, against which a drift could form, are less than 1 m, need not be considered as being an abrupt change of height. h) the maximum clear span of any floor joist or flat roof joist does not exceed 6.0 m; i) the design wind criteria is within the scope of BS 8103; NOTE 3 Guidance is given in BS 8103-1 and BS 8103-2 on how to determine whether the design wind criteria for a building on a particular site is within the scope and application of BS 8103. Guidance is given in Annex M regarding the determination of snow load for a particular site. j) no part of any wall or roof is higher than 15m above the lowest adjacent ground level; k) floor joists, ceiling joists, flat roof joists, common or jack rafters or trussed rafters are spaced at centres which do not exceed 600 mm; l) the stability requirements and dimensional limitations accord with BS 8103-1:1995+A1:1995, Clause 5. The sizes of timber shown in the span tables are limited to those normally readily available but do not preclude the use of larger or different sizes if justified by specialist calculation. The design requirements and those for durability and timber preservation given in this Part of BS 8103 are related only to structural considerations. For trussed rafter roofs, this standard contains only as much information as is necessary and mainly comprises references to BS 5268-3.

BS 8103-3:2009 Referenced Document

• BS 1202-1 Specification for nails — Part 1 : Steel nails
• BS 1210 Specification for wood screws
• BS 1297 Specification for Tongued and grooved softwood flooring
• BS 4190 ISO metric black hexagon bolts, screws and nuts. Specification*， 2014-10-31 Update
• BS 4320 
• BS 4978 Visual strength grading of softwood. Specification*， 2017-11-30 Update
• BS 5268-3 Structural use of timber — Part 3 : Code of practice for trussed rafter roofs
• BS 5534 Slating and tiling for pitched roofs and vertical cladding. Code of practice*， 2018-02-28 Update
• BS 5628-3 Code of practice for the use of masonry — Part 3 : Materials and components, design and workmanship
• BS 6100-3 Building and civil engineering – Vocabulary – Part 3: Civil engineering – General
• BS 8103-1 Structural design of low-rise buildings. Code of practice for stability, site investigation, foundations, precast concrete floors and ground floor slabs for housing*， 2011-11-30 Update
• BS 8103-2 Structural design of low-rise buildings. Code of practice for masonry walls for housin*， 2013-09-30 Update
• BS 8417 Preservation of wood.Code of practice*， 2011-03-01 Update
• BS EN 13556 Round and sawn timber - Nomenclature of timbers used in Europe
• BS EN 13986 Wood-based panels for use in construction - Characteristics, evaluation of conformity and marking
• BS EN 1912 Structural Timber — Strength classes — Assignment of visual grades and species
• BS EN 1991-1-1 Eurocode 1 : Actions on structures — Part 1 - 1 : General actions — Densities, self - weight, imposed loads for buildings
• BS EN 1991-1-3 Eurocode 1 : Actions on structures — Part 1 - 3 : General actions — Snow loads
• BS EN 912 Timber fasteners. Specifications for connectors for timbers*， 2011-07-31 Update
• BS EN ISO 3166-1 Codes for the representation of names of countries and their subdivisions - Country code*， 2020-09-30 Update
• EN 15228 Structural timber - Structural timber preservative treated against biological attack

BS 8103-3:2009 history

• 2009 BS 8103-3:2009 Structural design of low-rise buildings - Code of practice for timber floors and roofs for housing
• 1996 BS 8103-3:1996 Structural design of low-rise buildings - Code of practice for timber floors and roofs for housing