NZS 3604 Bracing

Bracing a timber-framed house against wind and earthquake: its walls on one plan with every maker's systems, and its roof.

  • NZS 3604:2011
  • Building Product Specifications1st Edition Amendment 12 Apr 2026
Tools

How each step is worked out: wall bracing, roof bracing, what NZS 3604 covers.

BuildingWall bracingRoof bracing

The building

What the demand tables are read by. The wind and earthquake zones come from the project.

Light roof · gable · 20°Walls · lightConcrete slabSoil: Not known (taken as E)2455+ storey

Roof

Form and pitch A gable's ends rise straight up, a hip's slope in, a mono-pitch slopes one way. A hip roof takes the across wind figure both ways (5.2.8), a mono-pitch the higher of the two (5.2.7).

Gable, 20°, from the roofs drawn →A room in the roof space adds to the earthquake demand (5.3.4.3).

Can NZS 3604 brace it?

Ground to roof top NZS 3604 covers buildings no taller than this from the lowest ground to the top of the roof (1.1.2(c)). Worked from the wall heights, the floor's height above the ground and the roof.
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Roof pitch No roof plane may be steeper than this (1.1.2(i)).
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Wind zone not set NZS 3604 covers the Low to Extra High wind zones; a site past them wants specific design (Table 5.4). The zone is the project's.
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Walls and roof inside the wind tables The wind tables give figures for each storey's height to the roof top and the roof's height above the eaves within a band. Where a level is outside it, the Wall bracing tab says which and by how much.
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Wings and floor steps Wings and floor steps
each its own project

Each level reads

Draw the walls →

From the project

Wind zone
Earthquake zone

Site subsoil class The site's subsoil class, A rock to E very soft. Not known, it is taken as E (5.3.3).

The grid lines on this plan are bracing lines, for designing the wall bracing only. Do not set out foundations, walls or anything else on site from them.

NZS 3604 caps what a wall bracing element counts per metre, lower on a timber floor than on a concrete slab (5.4.2). Where a maker's rating is above the cap, the element counts the cap, applied before the height scales it down.

Section 14 is written for buildings with 3 kPa floors. Where only some floors are, a level is read off Section 14's tables where any floor it holds up is 3 kPa: the upper walls the upper floor, the lower walls that and a timber ground floor, a single storey's walls a timber ground floor, and the subfloor any floor.

Where a roof needs more braces than its ridges' least, the rest are shared among its ridges by their length, a reading of spreading them evenly along the ridge.

This page reads NZS 3604:2011 and the Building Product Specifications and sets out what they say. It is not a substitute for reading them, for the judgement of a suitably qualified person, or for the decision of the building consent authority.

standards.govt.nz