A range of Australian hardwood boards laid side by side

Owner’s Guide

Timber Selection Guide.

Every species we use, side by side. Structural grades, durability classes, BAL ratings and how each timber ages over the years.

Understanding the specifications

Substantial timber, deliberate character.

To align with the natural feel of TK Garden Heritage, our timbers are chosen for the marriage of structural integrity and natural evolution. Substantial high-grade sections give our outdoor furniture a deliberate, architectural weight and a natural, calming presence in the garden. New here? Start with the current range or timber care guide.

Structural Grade (F-Rating)

Measures the stress grade or bending strength. Higher numbers support more load.

Durability Class

Natural resistance to decay and insects. Class 1 is the most resilient, typically 40+ years above ground.

BAL Rating

Bushfire Attack Level, indicating natural ability to withstand heat and embers.

What to expect over time

All our garden furniture is built to last for decades, but how any natural hardwood weathers depends on your climate, exposure and the finish you choose. We will always tell you honestly what to expect from your chosen timber and how to care for it, and we stand behind the craftsmanship of every joint we make.

Species index

Species Profiles

Every timber, in detail.

Seven Australian species, from the heritage strength of Spotted Gum and Ironbark to the refined blonde of Vic Ash and the rustic charm of Treated Pine. Each profile covers structural, durability and BAL ratings alongside how the timber ages in place.

Spotted Gum

The heritage choice for strength and character.

Trade name: Spotted Gum
Botanical: Corymbia maculata

Aesthetic & evolution

A complex palette of chocolate browns, deep reds and olive greens. Under UV it silvers off into a sophisticated weathered grey. Oiled at intervals it holds its colour and exposed grain.

Best for

Fully exposed outdoor settings where maximum durability and a lifetime investment are required.

Characteristics

Small amount of knots, generally closed
Smooth to touch, sanded to 240 grit
Will not shrink or warp
Extremely dense grain
140mm x 45mm dressed boards

Technical profile

Structural grade: F27
Durability class: Class 1
BAL rating: BAL 29
Seasoning: Seasoned, Kiln Dried

Seasoned Blackbutt

The architect's choice, dressed smooth and kiln dried.

Trade name: Blackbutt
Botanical: Eucalyptus pilularis

Aesthetic & evolution

A beautiful palette from cream to pale brown. Silvers off into a luminous light-grey patina under UV. Oiled at intervals it holds its warm natural colour.

Best for

Premium outdoor dining where a smooth, splinter-free, architecturally clean finish is desired.

Characteristics

Straight, uniform grain
Kiln dried for maximum stability
Dressed and sanded to a silky finish
5mm routed soft round edges
140mm x 45mm boards

Technical profile

Structural grade: F27
Durability class: Class 1
BAL rating: BAL 29
Seasoning: Seasoned, Kiln Dried

Merbau

Rich tones and world-class durability.

Trade name: Merbau
Botanical: Intsia bijuga

Aesthetic & evolution

Famous for rich reddish-brown tones with unique gold flecks in the grain. Mellows into a sophisticated dark silver-grey over the years.

Best for

High-end residential furniture, poolside settings and decking-matched outdoor suites.

Characteristics

Deep bronze consistency
Exceptional dimensional stability
25mm x 90mm kiln dried
Dressed smooth, furniture grade
Excellent for wet zones

Technical profile

Structural grade: F27
Durability class: Class 1
BAL rating: BAL 29
Seasoning: Seasoned, Kiln Dried

Fresh Cut Ironbark

The rugged powerhouse in sleeper sections.

Trade name: Ironbark
Botanical: Eucalyptus sideroxylon

Aesthetic & evolution

Deep nut-browns to dark reds. Seasons in place and silvers off to a deep pewter grey, developing character-rich seasoning checks that prove the density of the hardwood.

Best for

Heavy-duty park benches, robust garden tables and statement heritage furniture.

Characteristics

Substantial sleeper dimensions
Rough-sawn or dressed finish
Cut green, seasons in place over 12 to 24 months
Extremely dense grain
Develops seasoning checks (surface cracks) as it dries

Technical profile

Structural grade: F14 / Landscape
Durability class: Class 1
BAL rating: BAL 29
Seasoning: Fresh, cut green

Victorian Ash / Tasmanian Oak

Elegant, refined and architecturally blonde.

Trade name: Vic Ash / Tas Oak
Botanical: Eucalyptus regnans / delegatensis

Aesthetic & evolution

Straight, open grain with consistent straw-to-honey tones. If left untreated in the elements the blondes deepen and mellow into a soft muted grey.

Best for

High-end interior dining, sheltered patios and heritage pergolas where a refined finish is paramount.

Characteristics

Delicate visual presence with high density
140mm x 45mm kiln dried boards
Not classified as bushfire resisting
Best under cover or indoors
5mm routed soft round edges

Technical profile

Structural grade: F17
Durability class: Class 3
BAL rating: BAL 19
Seasoning: Seasoned, Kiln Dried

Recycled Railway Sleepers

The ultimate heritage timber, a story in every sleeper.

Trade name: Recycled Sleepers
Botanical: Typically Ironbark or Red Gum

Aesthetic & evolution

Naturally aged silver-grey exterior over a deep dark heartwood. Rugged and pre-weathered, with old bolt holes and heritage marks. Maintains its patina indefinitely.

Best for

Authentic heritage furniture, rustic garden features and high-end industrial outdoor settings.

Characteristics

Approximately 125mm x 250mm sections
Sourced from Australia's rail history
Rough texture with authentic holes and dents
Comes as-is, not dressed or sanded
Incredibly stable, already fully seasoned

Technical profile

Structural grade: Varies (high density)
Durability class: Class 1
BAL rating: n/a
Seasoning: Pre-weathered

Treated Pine

The rugged, reliable classic.

Trade name: Treated Pine
Botanical: Pinus radiata

Aesthetic & evolution

Visible knots and organic imperfections. Ages dramatically from pale green/yellow to a rugged driftwood silver that looks beautiful in garden settings.

Best for

Traditional backyard settings, commercial picnic areas and projects where natural rustic charm is desired.

Characteristics

Softwood; can be prone to denting
140mm x 45mm dressed sections
Medium knots, open or closed
Kiln dried, 12-18% moisture
Treated for above-ground use

Technical profile

Structural grade: F7
Durability class: Class 4 (H3)
BAL rating: BAL 12.5
Seasoning: Kiln dried, LOSP treated (CCA free)

Seasoned vs Fresh

The most important technical choice.

The first decision in any project is between seasoned (kiln dried) and fresh (green) timber. This drives how the finished timber furniture will behave in your space over the first two years, and how much character it develops over time.

Feature	Seasoned (kiln dried)	Fresh (green / unseasoned)
Stability	Highly stable, minimal shrinkage or warping.	Will season in place, shrinking slightly over 12 to 24 months.
Texture	Dressed smooth and sanded, soft to the touch.	Rough-sawn or dressed, more organic.
Character	Maintains clean, architectural lines.	Develops seasoning checks (natural surface cracks).
Aesthetic	Refined, high-end, contemporary heritage.	Rugged, massive, homestead heritage.

Heavy-duty as standard.

We use 140mm x 45mm boards or large sleeper sections. Significantly thicker than typical 19mm or 22mm outdoor slats.

Structural F-ratings.

F17 and F27 mean the timber is built to the same structural standards as the frame of a luxury home.

Class 1 & 2 focus.

We prioritise Class 1 and 2 Australian natives so heritage is a promise of longevity, not just a style.

Timber Selection at a Glance

Every species, side by side.

Compare structural grade, durability, best environment and natural aesthetic in one view. Use it to shortlist a species, then dive into the full profiles above for the detail.

Timber species	Structural grade	Durability class	Best environment	Natural aesthetic
Spotted Gum	F27 (Highest)	Class 1	Full exposure	Wavy grain, chocolate & grey tones.
Blackbutt (Seasoned)	F27 (Highest)	Class 1	Full exposure	Clean architectural, honey & cream.
Merbau (Seasoned)	F27 (Highest)	Class 1	Full exposure	Deep red/bronze, luxurious finish.
Ironbark (Fresh cut)	F14 / F17	Class 1	Rugged outdoor	Heavy sleeper, dark red & nut brown.
Vic Ash / Tas Oak	F17 (Strong)	Class 3	Indoor / sheltered	Elegant blonde, straight open grain.
Recycled Sleepers	Varies	Class 1	Heritage garden	Deeply weathered, silver-grey history.
Treated Pine	F7 (Standard)	Class 4 (H3)	General outdoor	Rustic with knots, drifts to pale silver.

The forever table

Top picks

Spotted Gum, Ironbark or Blackbutt.

Class 1 hardwoods with the natural oils and density to resist rot and pests for decades, even as they gracefully silver off.

The refined entertainer

Top picks

Seasoned Blackbutt, Merbau or Vic Ash.

Kiln-dried and sanded smooth. The most stable furniture-grade feel without the natural movement of unseasoned sleepers.

The heritage statement

Top picks

Recycled Sleepers or Fresh Ironbark.

Massive sections that showcase the raw power of Australian hardwood, developing seasoning checks that enhance the antique character.

selection Q&A.

Choosing the right timber.

Victorian Ash / Tasmanian Oak (F17) or Seasoned Blackbutt (F27). Both are kiln dried to a specific moisture content, so in a controlled indoor environment they will not shrink or move, keeping joinery tight and the surface perfectly level.
Merbau and Blackbutt are both exceptionally stable and cope well with poolside or humid coastal settings. Both are Class 1 and F27, and both retain a refined finish long-term.

Why we choose Australian native timber

Materials that have evolved with this climate.

All our timber is 100% sourced and milled in Australia, perfectly acclimated to our UV and humidity. Once you have chosen a species, learn how to keep it looking its best in the timber care guide or talk to our team about your project.

Get in touch Timber care & maintenance Understanding natural timber