Spotted Gum vs Blackbutt Timber Decking
Which Timber Decking Should Builders Choose?
Spotted Gum and Blackbutt are premium Australian hardwood decking options, each with its own pros and cons.
- Spotted Gum decking is extremely hard-wearing and visually striking, making it ideal for high-traffic areas.
- Blackbutt decking is consistent, reliable and easier to install, making it a popular choice and a strong option for BAL-rated projects.
Timber selection can directly influence the speed of installation, client expectations around colour variation, finish and long-term maintenance. This blog explains the difference between Spotted Gum and Blackbutt decking, and the benefits and pitfalls of both timber species.
Spotted Gum Decking (QLD & NSW)
Timber properties
- Bushfire Rating BAL29
- Durability Class 1 (Above Ground)
- More than 40 years above ground and 15-25 years inground
- Naturally resistant to termites
- Low tannin content
- Hardness 10.1 Janka Rating
- Natural colour variation from light browns through to deep charcoal tones, depending on QLD or NSW Spotted Gum variants
Installation considerations
- Pre-drilling recommended for Spotted Gum decking to high-density
- Tougher on blades and fasteners compared to other hardwoods
- Stainless steel fixings are essential, particularly in coastal environments
- Correct board spacing is critical to manage natural movement
Finishing and maintenance
- Accepts oils and stains well
- Can be left to weather naturally or coated to retain colour
- Regular oiling required to maintain colour consistency
Availability
- Secure supply early for large or commercial decks
- Spotted Gum decking is available in random and set lengths
Common Issues
- End-splitting can occur if boards are not sealed
- Colour variation, particularly in QLD variations
Blackbutt Timber Decking
Timber Properties
- Durability Class 1 above ground
- More than 40 years above ground
- 15-25 years in-ground
- Natural resistance to termites
- Hardness 8.9 Janka Rating
- Bushfire Rating BAL29
- Straight grain with a uniform appearance
Installation considerations
- Blackbutt decking is easier to cut, drill and fix than denser hardwoods
- Predictable movement when installed according to recommendations
- High extractives and tannin in mature blackbutt timber
Finishing and maintenance
- Accepts oils and stains evenly for a consistent finish
- Can be left to weather naturally or oiled
- Straightforward maintenance
Availability
- Widely stocked in standard decking sizes
- Available in random and set lengths
- Reliable lead times for residential projects
Common Issues
- Surface wear may show over time in very high-traffic areas
- Blackbutt decking can surface check
- Colour change will occur if left uncoated
- Machines and holds fasteners well
- Correct fixing and moisture management reduce the risk of cupping or movement
Bowens Extensive Timber Decking Range
Bowens offers high-quality Spotted Gum and Blackbutt timber decking options alongside Merbau decking, Tallowwood decking, Karri decking and more. Browse our range of timber decking online or in-store today.
To find other timber species that might be suitable for your next build, explore our blog, “Deck out the deck,” for a breakdown of their properties.