Structural Timber
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How to choose structural timber for Melbourne projects

Use this category to compare framing members, treated pine sizes, and structural grades before you move into delivery, permit, or quote decisions.

Decision pointWhat to compare firstWhy it matters
GradeMGP10 vs F7Span, engineering sign-off, and framing compliance are easier to verify when grade is chosen before price.
TreatmentH3 vs H4Above-ground members and in-ground/contact members do not belong in the same treatment class.
Section size70x35 to 290x45 and related postsMember size controls stiffness, span, and whether the timber belongs in framing, posts, rails, or general outdoor work.

Useful comparison paths

Read the structural timber guideUse the MGP10 guide when you still need to confirm grade, treatment class, or framing logic before you shortlist products.Compare timber postsJump to the Posts category if the job is now clearly about post selection rather than framing members.Review pergola permit basicsUse this guide when the structural timber path is tied to a pergola or outdoor structure that may need permit clarification.

Engineering checkpoints before ordering

What size joists do I needUse this guide when the member path is now about joists, framing logic, and quote-ready timber sizing.Bearer size guideCheck bearer sizing before structural timber is priced as a finished frame path for a deck or outdoor build.H2 vs H3 treated pineUse this guide when treatment class is still unclear before you lock in joists, rafters, pergola members, or deck framing timber.

Why shop with BuildBarn Melbourne

  • Fast 48-hour Melbourne delivery
  • Cheapest price guarantee (Price match)
  • Trade accounts available
Request a timber quoteSend the member sizes, quantities, and delivery suburb when the next step is a full framing or post takeoff.Check Hallam pickup and deliveryUse this path for longer members, heavy packs, or jobs that may be easier to collect from Hallam.Browse Melbourne delivery areasConfirm suburb coverage and practical delivery expectations before pricing oversized timber loads.

Frequently Asked Questions — Structural Timber

MGP10 (Machine Graded Pine) and F7 (visually stress-graded pine) are both structural grades of treated pine suitable for residential framing, but they are classified differently. MGP10 is mechanically tested with a characteristic bending strength of 10 MPa and is the most widely specified grade for floor joists, wall frames, and roof rafters under AS 1684. F7 is visually graded and broadly equivalent in strength — it is commonly accepted as a substitute where MGP10 is unavailable. For most Melbourne residential projects, MGP10 is the preferred choice as it is more familiar to engineers and building inspectors. Always refer to your structural engineer's specifications before substituting grades.
The Hazard Class (H) rating indicates the level of chemical preservation applied to protect timber against rot, fungi, and termites. H3 treated pine is designed for above-ground external use where the timber is exposed to wetting and drying — typical applications include decking boards, pergola rafters, and fence rails. H4 treated pine is required for in-ground or in-concrete contact, such as fence posts, retaining wall uprights, and landscaping sleepers. Using H3 timber in an H4 application (e.g., burying it in soil) will significantly reduce its service life and may void compliance with the NCC. BuildBarn clearly labels all treated pine by H-class — our staff can confirm the right grade for your application.
AS 1684 (Residential Timber-Framed Construction) is the primary Australian Standard governing the design and construction of timber frames in Class 1 and Class 10 buildings — houses, garages, and outbuildings. It specifies span tables for bearers, joists, rafters, and wall studs based on timber grade, spacing, load conditions, and wind classification zone. Key requirements include: using structurally graded timber (minimum MGP10 or F7 for load-bearing members), correct connection hardware (joist hangers, hurricane ties, framing anchors), and a compliant fixing schedule. All structural timber sold at BuildBarn meets AS 1684 span table requirements — our team can assist in selecting the correct member sizes for your project.
All compliant structural timber sold in Australia must carry a visible grade stamp showing the species, stress grade (e.g., MGP10), H-class treatment (if applicable), and the certifying body's accreditation mark. This stamp is your assurance that the timber has been independently verified to meet AS 2082 (for visually graded hardwood) or AS/NZS 1748 (for machine-graded pine). At BuildBarn, every piece of structural timber is sourced from reputable Australian mills and carries full certification. We strongly advise against using unstamped or off-grade timber for structural applications — it creates significant safety risks and will fail council inspection.
For standard structural timber sizes — including Treated Pine MGP10 in 70×35, 90×35, 90×45, and 140×45 mm — BuildBarn holds large quantities in stock at our Hallam warehouse for same-day collection or next-day delivery across Melbourne. For bulk project orders, custom lengths, or large-volume requirements, we recommend placing your order 2–3 business days in advance to guarantee availability and allow us to arrange efficient delivery scheduling. Trade account holders benefit from priority dispatch, dedicated account management, and competitive trade pricing. Contact our team at 1800 979 678 to discuss your project requirements.
Once the project is clearly about framing members rather than general material browsing, it usually helps to move into joist and bearer sizing guidance. That is the point where member role, spacing logic, treatment class, and quote planning all begin to matter together.
H2 and H3 belong in different outdoor-use conversations, so the customer should not treat them as simple substitutes. The right treatment path depends on whether the timber is staying in a more protected framing role or moving into above-ground external exposure where weathering and wetting matter more.
Usually yes when the pergola project still has unresolved approval or structural-scope questions. At that point, the cleaner path is to clarify the permit and framing logic before the timber order is treated as complete.