SG8 Timber

Five labels, five separate jobs

A compliant order may need all five. Removing any one because another looks familiar creates ambiguity. An H3.2 140 x 45 product is not necessarily SG8; an SG8 product is not necessarily treated for exterior use.

How grade evidence travels to site

Structural timber carries grade identification through authorised marks, producer information or pack documentation. MBIE has published technical information for builders and inspectors on identifying structural timber, and CodeHub provides public references to grading resources. Keep marks legible until inspection and record pack labels when the delivery is opened.

• Check the grade mark against the purchase order before cutting.
• Do not accept a species or grade substitution solely because dimensions match.
• Separate damaged, heavily distorted or unreadable pieces for review.
• Preserve treatment and grade evidence independently.
• If a member is engineered outside a standard solution, follow the engineer's exact schedule.

SG8 does not contain a span table

A member's permitted span depends on section, spacing, load, support condition, restraint, moisture and the design method. SG8 supplies material properties to that calculation. It does not turn every 140 x 45 joist into the same span.

A quote comparison that stays honest

Suppose one quote lists '140 x 45 H3.2' and another lists '140 x 45 SG8 H3.2'. They are not yet comparable. Ask the first supplier to confirm structural grade and both suppliers to confirm species, finished size, length mix, treatment system, moisture condition and identification.

1. Copy the design schedule into a line-item request.
2. Require explicit values rather than 'or equivalent'.
3. Record proposed substitutions in a separate column.
4. Have design-sensitive changes reviewed before acceptance.
5. Reconcile labels and marks on arrival.

Visual grade, machine grade and damage after grading

Structural timber may be graded through approved visual or machine processes. The grade mark applies to the product as produced within that grading system. Deep notches, large holes, splitting, decay or site damage can invalidate the assumptions that made the member acceptable. Get project-specific review rather than deciding that a remaining portion still 'looks like SG8'.

Appearance and structural acceptability overlap only partly. Knots and slope of grain matter to grading, but cosmetic colour variation may not. Conversely, a smooth clear-looking board without an authorised structural mark is not proven SG8. Keep appearance selection and structural acceptance as separate inspections.

• Locate grade marks before cutting members into short lengths.
• Follow the design for holes, notches and bearing cuts.
• Quarantine pieces with transport damage through critical zones.
• Do not plane a structural member smaller to fit an incorrect connector.

Where SG8 appears in a deck quote

A deck schedule might call for H3.2 SG8 radiata pine joists and bearers. The merchant can then price sizes and lengths, but only the design tells which section spans between which supports. Ask quotes to preserve member names: a bearer and joist can share size while having different quantities, lengths and connections.