Build 139 — December 2013/January 2014 — 41Build 145 — December 2014/January 2015 — 41

DESIGNRIGHT Bracing for

monopitch roofsJUDGING BY THE NUMBER OF CALLS TO THE BRANZ HELPLINE, THERE’S SOME CONFUSION AROUND BRACING REQUIREMENTS FOR MONOPITCH ROOFS. HERE, WE SORT OUT THE ISSUE.

BY ALIDE ELKINK, FREELANCE TECHNICAL WRITER, WELLINGTON

THE BRACING REQUIREMENT for monopitch roofs

is addressed in NZS 3604:2011 Timber-framed

buildings paragraph 10.3.4.

Simply stated, it requires that bracing for

monopitch roofs must comply with paragraphs

10.3.2 (for light roofs) or 10.3.3 (for heavy roofs),

but it also includes an exemption.

Raked wall framesParagraph 10.3.4 does not require roof plane

diagonal bracing if:

● the wall frames extend and are braced up to

the underside of the rafters, and

● the ceiling lining is attached directly to the

underside of the rafters.

This will only apply where the wall frames are

raked (see Figure 1).

Level top plates and trussesWhere the wall frames have level top plates

and the roof framing consists of trusses or a

strutted roof, either roof plane or roof space

bracing is required in accordance with para-

graphs 10.3.2 and 10.3.3 for light and heavy roofs

(see Figure 2).

In this case, the highest end of the trusses is

considered the ridge line and requires at least

two braces over its length. Figure 2 shows both

roof plane bracing and roof space bracing as

alternatives.

Figure 1 Monopitch roof with full-height braced walls.

Notes:1. Ceiling support framing and dwangs omitted for clarity.2. The high back wall below the ridge of the monopitch roof must be braced to the full height of the wall (not shown).

fascia board

fascia boardtop plate

rafters with ceiling attached to their underside – roof plan bracing not required

bottom plate

raked top plate

wall bracing

raked wall frame

flying rafter

outrigger

bracing required to full height of high back wall

MONOPITCH ROOFS BRACING REQUIREMENTS

wall bracing

THE BENCHMARK HAS BEEN SET.

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WAVE216

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CBI21643 BUILDERS BENCHMARK (210x275mm).indd 1 22/10/14 2:18 pm

42 — Build 139 — December 2013/January 201442 — Build 145 — December 2014/January 2015

Figure 2 Monopitch truss roof with level top plate.

fascia board roof plane bracing (alternative 1)

monopitch roof trusses

fascia board

sheet wall bracing to top platebraced wall framing

with level top plate

sheet wall bracing to top plate

roof space bracing desirable (alternative 2)

lateral support for trusses

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FLA00185 Smartfit Build 275x210.indd 1 15/10/14 2:36 PM