9.15.3.

(1) Footings shall be provided under walls, pilasters, columns, piers, fireplaces and chimneys that bear on soil or rock, except that footings are permitted to be omitted under piers or monolithic concrete walls if the safe loadbearing capacity of the soil or rock is not exceeded.

(1) Footings shall rest on undisturbed soil, rock or compacted granular fill.

(2) Granular fill shall not contain pyritic material in a concentration that would adversely affect its stability or the performance of assemblies separating dissimilar environments.

(1) Except as provided in Sentence 9.15.3.4.(2), the minimum footing width or area requirements provided in Articles 9.15.3.4. to 9.15.3.7. shall apply to footings where,

(a) the footings support,

(i) foundation walls of masonry, concrete, or flat insulating form foundation walls,

(ii) above ground walls of masonry, flat insulating form foundation walls or light wood frame construction, and

(iii) floors and roofs of light wood frame construction,

(b) the span of supported joists does not exceed 4.9 m, and

(c) the specified live load on any floor supported by the footing does not exceed 2.4 kPa.

(2) Except as provided in Sentence 9.15.3.4.(2), where the span of the supported joists exceeds 4.9 m, footings shall be designed in accordance with Section 4.2.

(3) Where the specified live load exceeds 2.4 kPa footings shall be designed in accordance with Section 4.2.

(1) Except as provided in Sentences (2) and (3) and in Articles 9.15.3.5. to 9.15.3.7., the minimum footing width or area shall comply with Table 9.15.3.4.

(2) Where the supported joist span exceeds 4.9 m in buildings with light wood-framed walls, floors and roofs, footing widths shall be determined according to,

(a) Section 4.2., or

(b) the following formula:

W = w • [∑ sjs / (storeys • 4.9)]

where,

W = minimum footing width,

w = minimum width of footings supporting joists not exceeding 4.9 m, as defined by Table 9.15.3.4.,

∑ sjs = the sum of the supported joist lengths on each storey whose load is transferred to the footing, and

storeys = number of storeys supported by the footing

(3) Where a foundation rests on gravel, sand or silt in which the water table level is less than the width of the footings below the bearing surface,

(a) the footing width for walls shall be not less than twice the width required by Sentences (1) and (2), and Articles 9.15.3.5. and 9.15.3.6., and

(b) the footing area for columns shall be not less than twice the area required by Sentences (1) and (2), and Article 9.15.3.7.

(1) The strip footing widths for exterior walls shown in Table 9.15.3.4.v1 shall be increased by,

(a) 65 mm for each storey of masonry veneer over wood frame construction supported by the foundation wall,

(b) 130 mm for each storey of masonry construction supported by the foundation wall, and

(c) 150 mm for each storey of flat insulating concrete form wall construction supported by the foundation wall.

(1) The minimum strip footing widths for interior loadbearing masonry walls shown in Table 9.15.3.4.v1 shall be increased by 100 mm for each storey of masonry construction supported by the footing.

(2) Footings for interior non-loadbearing masonry walls shall be not less than 200 mm wide for walls up to 5.5 m high and the width shall be increased by 100 mm for each additional 2.7 m of height.

(1) The footing area for column spacings other than shown in Table 9.15.3.4.v1 shall be adjusted in proportion to the distance between columns.

(1) Footing thickness shall be not less than the greater of,

(a) 100 mm, or

(b) the width of the projection of the footing beyond the supported element.

(1) Where step footings are used,

(a) the vertical rise between horizontal portions shall not exceed 600 mm, and

(b) the horizontal distance between risers shall be not less than 600 mm.