New Zealand · Acceptable Solution
B1/AS1: Structural provisions for buildings
Acceptable Solution B1/AS1 for structural provisions within its stated scope under clause B1 of the New Zealand Building Code.
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- Second edition · effective 28 July 2025
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B1 STRUCTURE ACCEPTABLE SOLUTION B1/AS1
Buildings and structures
Part 2. Buildings and structures
2.1 Masonry
2.1.1 Reinforced concrete masonry
2.1.1.1 Reinforced concrete masonry shall comply with NZS 4229 subject to:
a) the modifications in Subsection 2.1.2 and Subsection 2.1.3; and
b) the additional requirement for welded steel mesh in Subsection 2.1.4.
2.1.2 Referenced documents
2.1.2.1 In NZS 4229, replace reference to AS/NZS 4671:2001 with AS/NZS 4671:2019.
2.1.3 Concrete slab reinforcement
2.1.3.1 In NZS 4229, replace Clause 7.8.3 with:
a) “All slab-on-ground reinforcing shall extend to within 75 mm of the outside edge of the slab
(including the foundation wall) and shall consist of a minimum 2.27 kg/m2 welded Grade
500E reinforcing mesh sheets (1.14 kg/m2 in each direction), which shall be lapped at sheet
joints such that the overlap measurement between the outermost cross wires of each fabric
sheet is equal to the greater of one of the following:
• the spacing of cross wires plus 50 mm,
• 150 mm, or
• the manufacturer’s requirements.
Slabs shall have a maximum dimension of 18 m between free joints.”
2.1.4 Welded steel mesh
2.1.4.1 Where Grade 500E welded steel mesh is specified, it shall meet the requirements of
Subsection 3.2.2 of the Building Product Specifications.
2.2 Steel
2.2.1 Light steel frame
2.2.1.1 Light steel frame buildings shall comply with NASH Standard Part 2 Light Steel framed
buildings.
2.3 Timber
2.3.1 Timber-framed buildings
2.3.1.1 NZS 3604 can be used for houses and small buildings subject to the modifications and
additional requirements for:
a) referenced documents in Subsection 2.3.2; and
b) definitions in Subsection 2.3.3; and
c) bracing in Subsection 2.3.4; and
d) timber piles in Subsection 2.3.5; and
e) timber decks in Subsection 2.3.6; and
f) concrete slab-on-ground floors in Subsection 2.3.7; and
g) slab-on-ground in expansive soils in Subsection 2.3.8.
2.3.2 Referenced documents
2.3.2.1 In NZS 3604, replace reference to AS/NZS 4671:2001 with AS/NZS 4671:2019.
MINISTRY OF BUSINESS, INNOVATION AND EMPLOYMENT 28 JULY 2025 Page 7
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