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Strength, Stiffness and Solid Hardwood Performance
F-grades are Australia's system for describing the structural capacity of timber. The "F" number is the characteristic bending strength in megapascals, so a higher number means a stronger, stiffer member — F17 carries around 17 MPa and F27 around 27 MPa. Both grades are visually stress-graded to AS 2082 (Visually Stress-Graded Hardwood for Structural Purposes), giving engineers and builders a predictable, standards-based reference for design to AS 1720.1 and the National Construction Code. Because these grades are cut from dense, naturally durable Australian hardwoods, they bring far more than raw strength. The same density that delivers high load capacity also gives excellent fastener holding, natural above-ground durability, termite resistance and — in many species — a BAL-29 bushfire rating. F17 is the sensible choice for the bulk of structural framing where strength and value matter most; F27 is specified where loads are heavy, spans are long, or the member is left exposed and appearance counts. Our team can help you decide which grade your project calls for.
Why Choose F17 & F27 Hardwood from JVS Timber
Where F17 & F27 Hardwood Performs Best
Floor joists, bearers and long-span floor beams in suspended floor systems.
Roof beams, rafters, ridge and hip beams in residential and commercial roofs.
Load-bearing wall framing and multi-storey structural members.
Exposed structural beams, rafters and feature frames left on show (F27).
Deck and verandah joists, bearers and heavily loaded balcony structures.
Trusses, transfer beams and lintels over large openings.
Portal frame members in residential and light commercial construction.
Any application where the engineer specifies F17 or F27 as the minimum grade.
F17 or F27 — Which Grade Do You Need?
The two grades share the same standard and the same family of durable hardwood species; the difference is structural capacity and, often, appearance. F17 is the everyday builder's hardwood — strong, dependable and cost-effective, and the right choice for the majority of floor and roof framing where standard loads and spans apply. F27 is the high-strength grade, around 60% stronger in characteristic bending, reserved for heavy loads, longer spans and situations where the member is left exposed and its rich colour and grain become a design feature. In practice, many builds use both: F17 for concealed general framing and F27 where an engineer calls for extra capacity or where an exposed beam needs to look as good as it performs. Remember that F-grades describe strength, not looks — where appearance is critical, ask about select or appearance grades as well. And in every case, size and detail members using AS 1684, the relevant span tables and a project engineer where required; the grade sets the strength, but the correct section for a given load and span comes from those tables. Tell us your loads, spans and whether members are exposed, and our team will point you to the right grade.
Get Your Free QuoteF17 & F27 Hardwood Durability & Standards
Both F17 and F27 are visually stress-graded to AS 2082, which guarantees the structural strength of the member at the time of grading, and both are cut from dense, naturally durable Australian hardwoods that resist decay and termites — many species offering Class 1 durability and, where the species qualifies, a BAL-29 bushfire rating suitable for bushfire-prone areas (confirm per AS 3959). As a natural structural product, exact species, colour and durability vary with supply, so where a member is exposed, in-ground or in a bushfire area, confirm the species and its ratings for your project. Structural grading addresses strength rather than appearance, so for exposed feature members specify a select or appearance grade in addition to the structural grade where the look matters. Our team can advise on species, seasoning, grade and finish to suit your application.
Get Your Free QuoteSustainable & Ethically Sourced
JVS Timber sources F17 and F27 hardwood from certified producers and supplies product compliant with Australian industry standards. As renewable, naturally durable, high-strength timbers, F-grade hardwoods perform for decades without chemical treatment — an inherently sustainable choice, and a beautiful one where left exposed. FSC- or PEFC-certified options may be available on request.
Get Your Free QuoteF17 & F27 Hardwood Sizes & Availability
JVS Timber supplies F17 and F27 hardwood in the common structural sections — such as 70, 90, 140, 190, 240 and 290 depths in 35 and 45 mm thicknesses — and in a range of lengths, seasoned or unseasoned. Whether you need a few members for a single home project or bulk structural hardwood for a development, our team can confirm current stock, sizes and competitive trade pricing, delivered Australia-wide. Send us the sizes, lengths and grade from your engineering documentation and we will confirm availability.
Get Your Free QuoteHardwood F17 & F27 — Frequently Asked Questions
Both are structural hardwood stress grades graded to AS 2082; the number is the characteristic bending strength in MPa, so F27 (around 27 MPa) is considerably stronger and stiffer than F17 (around 17 MPa). F17 is the everyday builder's hardwood for general framing, while F27 is the high-strength grade for heavy loads, longer spans and exposed feature members.