Studs and plates to NZS 3604

How it is worked out

1. 1

   Which table

   Table 8.2(a), its High wind zone row

   Why Where the wall stands chooses the table: a single or top storey, a lower storey or subfloor, or a wall with no roof or floor on it; a 3 kPa floor above reads Section 14's. An external wall reads its wind zone's row, and an internal wall's studs are the same in every zone.

   NZS 3604:2011 8.5.1.3, Table 8.2(a)

2. 2

   Its height and load

   A 2.4 m stud read at 2.4 m, a loaded dimension of 4 m read at 4 m

   Why The loaded dimension is the width of roof or floor the wall holds up. Between two figures the table gives, the next one up is read, never a figure in between.

   NZS 3604:2011 1.3, Table 8.2(a)

3. 3

   The studs

   90 × 45 at 600 mm spacing

   Why Each stud spacing has its own column, and studs set closer may be smaller. The stud is where your spacing's column meets the row read.

   NZS 3604:2011 Table 8.2(a)

   Stud size, High wind zone, loaded dimension 4 m, Table 8.2(a)

   Stud height	300 mm spacing	400 mm spacing	600 mm spacing
   2.4 m	–	90 × 35	90 × 45
   2.7 m	90 × 35	90 × 45	90 × 70
   3 m	90 × 35	90 × 70	90 × 70
   3.6 m	90 × 90	140 × 45	140 × 45
   4.2 m	140 × 45	140 × 90	140 × 90
   4.8 m	140 × 90	140 × 90	190 × 90

4. 4

   Trimming studs

   45 mm thick each side of an opening up to 1.8 m wide, read with the 45 mm studs this wall needs at 600 mm spacing

   Why The studs each side of an opening carry the lintel's ends and the wall the opening cuts away, so they thicken as it widens. The table reads them against one stud spacing, whatever the wall's own.

   NZS 3604:2011 8.5.2, Table 8.5

5. 5

   Top plate

   90 × 45, which carries a wall loaded up to 4.9 m with studs at 600 mm spacing; yours is 4 m (read at a truss or rafter spacing of 900 mm)

   Why The top plate carries the trusses, rafters or floor joists sitting on it between the studs, so the load and how far apart they sit decide its size.

   NZS 3604:2011 8.7.1, Table 8.16, Figure 8.13

6. 6

   Bottom plate

   70 × 45, which carries a wall loaded up to 5.9 m with studs at 600 mm spacing; yours is 4 m (read at a joist spacing of 450 mm)

   Why The bottom plate carries the studs' load across the floor joists under it, so the load and the joists' spacing decide its size.

   NZS 3604:2011 8.7.2, Table 8.17

7. 7

   Top plate fixing

   Type B at 600 mm centres: 2 end nails, 90 × 3.15 and 2 wire dogs, or another holding at least 4.7 kN (read at a roof member spacing of 900 mm, a wall loaded 4 m, High wind zone)

   Why Wind lifts the roof, and the top plate with it. The fixing to the studs or lintel under it is chosen by the roof members' spacing, the load and the wind zone.

   NZS 3604:2011 8.7.6, Table 8.18, Figure 8.12

8. 8

   Bottom plate to the floor

   2 of 100 × 3.75 every 600 mm; power-driven, 3 of 90 × 3.15 every 600 mm

   Why Nails hold the bottom plate down to the floor framing, so the wall neither lifts nor slides.

   NZS 3604:2011 Table 8.19

9. 9

   Nailing

   Studs to the plates: 4 of 75 × 3.15 skewed; power-driven, 4 of 75 × 3.06 skewed; or 2 of 100 × 3.75 end nailed; power-driven, 3 of 90 × 3.15 end nailed

   Why The nails hold each stud to its plates and the plates to each other, so the frame works as one.

   NZS 3604:2011 Table 8.19

   • Top plate 140 × 35 over 90 × 45, or over a lintel: 2 of 100 × 3.75 every 500 mm; power-driven, 3 of 90 × 3.15 every 500 mm NZS 3604:2011 8.7.3, Table 8.19
   • Half joint in a top plate: 3 of 75 × 3.15; power-driven, 4 of 75 × 3.06 NZS 3604:2011 8.7.3, Table 8.19