NZS 3604:2011 questions from the floor – answered by BRANZ

BRANZ answered some questions about NZS 3604:2011 Timber-framed buildings during its recent 'You Asked' seminar series. These questions include:

Do the span tables in NZS 3604:2011 Timber-framed buildings allow for point loads on bearers or joists such as might occur where there is an isolated internal post?

No. All tables in NZS 3604:2011 are based on loads being evenly distributed across members such as beams, joists, and bearers.

Can you still use a bent rebar to hold down a bottom plate?

Under NZS 3604:2011, a 10 mm diameter plain rebar embedded into a foundation wall can be used to fix down the sole or bottom plate to subfloor jack stud framing. NZS 3604:2011 does not allow a bent embedded rebar to be used to hold down a bottom plate of wall framing to a floor slab.

How is the design of the structure of eaves widths over the dimensions given in NZS 3604:2011 to be dealt with?

Eave overhangs that are greater than the limits given in NZS 3604 (750 mm) must be specifically designed to resist the uplift forces as a result of the overhang of the eaves.

In a cavity, won’t the horizontal plastic tape required to restrain the flexible wall underlay be a trap for water that gets on the wall underlay?

The whole purpose of the cavity is to prevent water getting onto the wall underlay. If it does, there is a much bigger problem that needs to be addressed.

Can you extrapolate a loaded dimension?

No – take it up to the next value.

What are the tying down requirements for jack studs that are installed between the lintel and the top plate?

The answer is given in Build 143 on page 32.

Where 140 mm wide bottom plates are used with a concrete masonry foundation wall, can the fixing down requirements of NZS 3604 for in situ foundation walls be used rather than those for masonry foundation walls because the fixing is further in from the edge of the slab?

Yes, as long as the distance from the edge of the poured concrete (where it abuts the shell of the header block) is more than 50 mm.

Under E2/AS1, can flashing tapes be used as a back flashing?

No, as flexible flashing tape does not meet the requirements of E2/AS1 clause 4.3 Acceptable flashing materials.

Published in building.

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