Page 29 - Build 161

top surface provides continuous support for wall plate
concrete or concrete masonry foundation wall
225 mm minimum
ground line
foundation wall footing
Figure 2 Stepped foundation wall – footing bars only.
Other requirements for foundation walls include that:
● the top surface of the foundation wall provides
continuous support for the wall plate
● the underside of the footings is horizontal
● the footings are at least 200 mm below cleared
ground level and on solid bearing ground
● the minimum height for walls is at least 225
mm above nished ground level
● the maximum height from the underside of the
footing to the top of the wall is no more than 2 m except at step in footing when height may be 2.6 m for a maximum length 1.5 m.
Di erent when stepped foundation walls
Where the ground is sloping or uneven, the founda- tion wall may need to be stepped to accommodate changes in ground level and remain within the maximum permitted height for foundation walls.
Requirements for stepped foundation walls are described in NZS 3604:2011 clauses 6.11.2, 6.11.4 and 6.11.5 and in Figure 6.12 (see Figure 1). These include that:
● the maximum height of the wall at an overlap may be increased to 2.6 m for a wall length of up to 1.5 m
● steps must have a minimum horizontal overlap of 450 mm
● when both top and bottom surfaces of the wall are stepped, the steps must overlap 450 mm minimum both vertically and horizontally
● additional horizontal and vertical D12 reinforcing bars are required at the steps
as shown in Figure 6.12 (in addition to the reinforcing requirements for foundation walls as shown in Figures 6.13, 6.14 and 6.15)
● where they are required, horizontal reinforcing bars must be lapped by at least 500 mm
● when the oor framing is supported on jack studs, the underside of the wall and footing must be stepped at least 600 mm, and the length of wall on the lower side of the step must be no less than 1.2 m and no more than 5 m long.
Note that, if the top surface of the founda- tion wall is level, the footing may be stepped to accommodate ground slope but there is no minimum step height (see Figure 2).
KIWI MADE
wall plate on DPC
ground line
no minimum step height when top surface is not stepped
reinforcing shown in foundation footing only (other foundation wall reinforcing as per NZS 3604:2011, Figures 6.13, 6.14 and 6.15 omitted for clarity)
2.0 m maximum (except at steps in footing when height may be 2.6 m for maximum length of 1.5 m)
200 mm minimum or to solid bearing ground
DJ6626_PI_Kiwimesh_BRANZ_Built_ad_59x245mm_v7_o2l.2in/0d6d/171 9:20 AM Build 161 — August/September 2017 — 27