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Plywood, LVL & Glulam: engineered timber for NZ builders

A plain-English rundown of the engineered timber you order – plywood, LVL, glulam and more – what each one is, what it’s for, and how the grades work.

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Engineered timber is sawn wood broken down and re-glued — as veneers (plywood, LVL), laminations (glulam) or chips (OSB, particleboard). Doing that removes the natural defects (knots, sloping grain) that weaken solid timber, so you get higher, more predictable strength, longer spans and bigger sheet sizes than you could ever cut from a log. That’s why beams, bracing panels, gussets and flooring use it.

Sheet products — sheathing, flooring & bracing

These are the panels you nail up for wall and roof sheathing, lay for flooring, or use in bracing systems.

Beam products — lintels, deep beams & portal frames

These are the engineered members you use where solid timber can’t span or carry the load.

F-grades vs SG-grades

LVL and plywood use F-grades (F8, F11, F17, F22), which correspond approximately to sawn-timber SG grades but with higher characteristic stress values, because the manufacturing process removes the defects. As a rough guide, F11 LVL is roughly equivalent to SG10 sawn timber for typical residential use.

Plain-English guide, not advice. This page helps you understand and navigate the rules — it is general information, not design, engineering or consent advice, and it does not reproduce the copyrighted tables of NZS 3604 or any Standard. Always check the current Standard or Acceptable Solution and your BCA, and use a suitably qualified LBP, engineer or QS where it matters.

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Common questions

What is engineered timber and why is it stronger than solid wood?

Engineered timber is sawn wood broken down and re-glued — as veneers (plywood, LVL), laminations (glulam) or chips (OSB, particleboard). Breaking it down removes the natural defects like knots and sloping grain that weaken solid timber, so you get higher, more predictable strength, longer spans and bigger sheet sizes than you could cut from a log. That’s why beams, bracing panels, gussets and flooring use it.

What does the Type A bond stamp on plywood mean?

Type A is the exterior bond type. Structural plywood is stamped with its F-grade plus the bond type, and Type A means it’s rated for exterior use. Marine plywood (F22/F27) and OSB for exterior use also carry a Type A bond.

Is LVL treated for outdoor use?

Not typically. Standard LVL beams (such as Carter Holt HySpan or Tilling SmartLVL15) are for indoor dry use only. H3.2 treated LVL is available on special order if you need it for exterior conditions.

How do F-grades compare to SG-grades?

LVL and plywood use F-grades (F8, F11, F17, F22), which correspond approximately to sawn-timber SG grades but with higher characteristic stress values because manufacturing removes the defects. As a rough guide, F11 LVL is roughly equivalent to SG10 sawn timber for typical residential use.

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