Timber Grades and Appearance Specification

While structural grading ensures timber meets engineering performance requirements, appearance grading governs how timber looks in finished applications. This is critical for exposed timber elements-such as internal linings, joinery, ceilings, feature posts or external cladding-where timber’s natural features are celebrated as part of the architectural aesthetic. Appearance grading manages the type, size and frequency of visible natural features, providing a benchmark for clients, designers and certifiers to agree on expectations.

Australian Appearance Grades

In Australia, appearance grading for hardwoods is primarily governed by AS 2796.2, which defines allowable:

• Knots (tight or loose)
• Gum veins and resin pockets
• Checks and surface splits
• Wane and edge defects
• Insect pinholes or mineral stains

This standard underpins most local mill and supplier appearance grading practices. Common appearance grades include:

Figure 4: Select Grades to AS 2796 example. Source: TDG 14 p25

Considering Characterisation

Timber is inherently variable. While structural grading governs strength and appearance grading manages obvious surface features, the deeper visual character of timber comes from its natural colour, texture and figure. These properties are inherent to each piece, shaped by species, growth environment, and even how the timber was cut and processed. They play a powerful role in the look and feel of finished spaces.Understanding these aspects helps designers and specifiers anticipate variation, coordinate finishes, and select the right timber for each visual intention.Even within a specified appearance grade, it’s normal to see:

• Knots: tight knots are structurally sound and often add visual interest.
• Gum veins: dark streaks formed by natural resin flows.
• Wavy or interlocked grain: creating attractive patterns like curl, fiddleback, flame, quilt, crotch, spalt, or ray fleck.
• Surface checks: small cracks that may open or close with seasonal humidity.

These are not defects but part of timber’s organic characterisation. Selecting the right appearance grade ensures these features align with design intent.

Figure 5: Common characterisation, fiddleback, gum vein, and surface check. 

Colour Variation

Timber colour comes from natural pigments and extractives in the wood. It varies:

• Between species: Blackbutt tends toward pale blondes and light browns, Spotted Gum ranges from grey-browns to rich chocolates, Jarrah can be deep reds.
• Within species: Even a single pack can show lighter sapwood and darker heartwood, or subtle shifts depending on soil, climate and age.
• Over time: Exposure to light (especially UV) will mellow or darken most timber. Many Australian hardwoods develop a richer tone indoors, while externally they gradually weather to silver grey.

Note: Colour is rarely a grading criterion under Australian Standards - it’s accepted as natural variation. Where a project demands tighter colour control, this needs explicit negotiation with suppliers (e.g. sorting to narrower colour bands).

Texture - Fine to Coarse

Texture refers to the relative size and density of the wood fibres:

• Fine-textured timber: Smooth under a hand plane or sander, shows subtle grain patterns (e.g. Brush Box, some softwoods).
• Coarse-textured timber: May show more dramatic porosity or grain ridges (e.g. Mountain Ash).

Textureis influenced by:

• Species anatomy: Hardwoods often range more widely from coarse to fine.
• Cut surface: Dressed (planed) timber shows a cleaner surface, while rough sawn or bandsawn surfaces keep small ridges or furrows.

This matters for finishing:

• Film-forming coatings (like paints and varnishes) suit smooth dressed surfaces for best adhesion and appearance.
• Penetrating oils and stains often work well on rough sawn or textured surfaces, highlighting grain depth.

Figure 6: Texture examples, softwood sample exhibiting a fine texture, and a hardwood sample exhibiting a coarse texture.

Figure - the unique visual signature

Figure is the striking visual pattern caused by the wood’s internal structure beyond basic grain direction. It’s shaped by growth conditions, species quirks, and how the timber was cut. Examples include:

• Wavy or fiddleback grain: Creates shimmering light patterns, common in Tasmanian Oak or Blackwood. Often seen when quarter-sawn.
• Bird’s eye or pommele: Clusters of small circular features, prized in some furniture species.
• Gum veins and resin pockets: Can run dramatically across the board, adding character, especially in Spotted Gum or Ironbark.

These natural effects are not defects - they are often the most valued aesthetic aspects, especially when enhanced by clear finishes or oils.

Figure 7: Curl, Birds Eye / Pommele, and Resin Pocket

Design & specification considerations

When selecting timber for appearance, especially in exposed applications, consider:

• Species choice: Match typical colour, texture and figure to the design mood (e.g. pale subtle species for Scandinavian-inspired spaces, richly featured species for warm, rustic interiors).
• Sawing method: Quarter sawn timber tends to be more dimensionally stable and shows distinctive vertical grain lines. Back sawn boards often highlight cathedral patterns or more dramatic grain swirls.

Finish compatibility:

• Clear finishes and oils will amplify natural colour and figure.
• Stains can even out tone slightly but still showcase underlying grain.
• Paint conceals figure entirely but still relies on stable, well-prepared surfaces.

Tip: Always confirm expectations with clients using physical samples, not just species descriptions or grade labels. Each board is unique, and design stories are best told with realistic variation in mind.

Because timber is natural, boards will vary even within a grade. Best practice on site is to:

• Lay out boards from multiple packs before installation, mixing tones and features to achieve a balanced look.
• Order 5-10% extra to allow on-site selection and trimming of pieces with less desirable features for that location.

Selecting the right structural and appearance grades is not just a technical compliance exercise - it directly shapes the visual narrative and emotional feel of a space. The grade you specify effectively sets the rules for how much timber’s natural variability becomes part of the design story.

Well-chosen grades align the organic qualities of timber with architectural goals, whether that means highlighting flawless continuity or celebrating raw, rustic character.

High precision, clean modern design

For minimalist spaces where clean lines, subtle textures and uniform surfaces are priorities:

• Choose Select appearance grades or Grade A glulam, which tightly limit knots, gum veins and colour variation.
• Structurally, pair this with high GL grades that maintain long, sleek spans without excessive depth or visual bulk.

This combination supports contemporary interiors or commercial lobbies where natural material warmth is desired without overt natural irregularities.

Warmth, authenticity and natural storytelling

If the architectural language celebrates timber’s natural story - knots, veins, subtle colour shifts - then Medium or High Feature grades are an intentional choice. They bring out:

• Gum veins and resin pockets as organic tracery across boards.
• Knots as points of visual interest, often enhanced by clear oils or penetrating stains.

This suits designs aiming for rustic, industrial, country or lodge-style expressions. It’s also a common choice for hospitality interiors like cafes and restaurants where character is more important than perfect uniformity.

Expressed structure vs hidden framing

It’s critical to differentiate between timber meant to be seen and timber concealed within walls or roofs:

• Expressed structure: exposed beams, rafters or trusses need both the right stress grade (to safely span the distance) and a higher appearance grade so natural features look intentional, not like defects.
• Concealed framing: internal studs, noggings and hidden joists primarily require a compliant structural stress grade (like F7, MGP10). Appearance grade is irrelevant here, since these elements will be covered by linings or claddings.

This balance ensures you’re paying for visual quality only where it matters.

Integrating with finishing systems

Your finish choice must always complement the grade:

• Paints and opaque stains: These conceal most natural features, making Select grades sometimes unnecessary. However, stable, smooth substrates (typically fine-grain, quartersawn) still perform best under paint to avoid surface checking or resin bleed.
• Clear oils and transparent coatings: These accentuate figure, knots and veins. For designs that highlight timber’s character, Medium or High Feature grades become a deliberate design asset.

Considering the user experience

Beyond style, think about how occupants will experience the timber up close:

• In high-touch areas like stair handrails or benchtop edges, uniform Select grades with fewer knots may be more comfortable to the eye and hand.
• In large ceiling or wall expanses, a scattering of knots and veins across High Feature boards can create rhythm and break visual monotony.

Selecting the right timber is never just about ticking a box for compliance - it’s about ensuring every element of a building performs structurally and contributes to the intended design story. This guide has shown how:

• Structural grading systems - F-grades, MGP grades and GL/LVL ratings - guarantee that timber meets load and span requirements under the NCC 2022 and relevant Australian Standards.
• Appearance grading controls the presence of natural features like knots, gum veins and grain patterns, aligning timber’s inherent variability with architectural intent.
• Colour, texture and figure are the deeper expressive qualities of timber, shaping warmth, contrast and visual interest, especially when combined with the right finishing systems.

Ultimately, matching grades and features to each design vision - from sleek minimalism to richly organic - ensures timber does more than just support a building; it becomes part of its character. Timber is unique among building materials for its combination of natural beauty, renewable credentials and structural versatility. By specifying grades thoughtfully, coordinating with finishes, and working closely with suppliers on expectations, you can deliver projects that meet both engineering and aesthetic ambitions - creating spaces that are strong, durable, and truly welcoming.