3
Threats Composite Ignores
Zero
Coatings To Reapply
1999
Manufacturing Since
25+
Years Manufacturing
Jetty Decking: Composite Versus Traditional Timber
Composite jetty decking costs more per square metre than timber at purchase, and wins on the second number: what the structure costs to own over twenty years, including the days it is closed to the public while somebody works on it.
The core difference is what the two materials do when they get wet. Timber absorbs water, swells, dries, shrinks and eventually splits. Composite does not absorb water at all, so the cycle that degrades a timber board never starts.
| Composite | Hardwood Timber | |
|---|---|---|
| Water Absorption | Negligible | High — swells and shrinks |
| Rot & Fungal Decay | Not susceptible | Susceptible, especially at fixings |
| Marine Borers | No food value | Vulnerable below the splash zone |
| Corrosion At Fixings | Non-conductive, no rust staining | Steel fixings rust and split the board |
| Ongoing Maintenance | Wash down | Oil, sand, replace boards |
| Slip Resistance When Wet | Gritted surface available | Falls away as the surface weathers |
Jetty Decking Durability and Low Maintenance
Maintenance on a timber jetty is not one job, it is a cycle. Oil or seal the boards, sand back the surface as it greys and roughens, chase down the boards that have cupped or split, then replace the ones that have gone soft around a fixing. Each pass needs access, weather, labour and usually a closure.
Composite boards change the nature of that work. There is no coating to reapply, because the colour runs through the material rather than sitting on top of it, and there is nothing for water to get into. Cleaning is a wash down. That is a meaningful saving for a council, a marina operator or a mine site where mobilising a crew to a remote structure costs more than the materials do.
Budgets tend to capture materials and installation and quietly ignore closure. Every maintenance cycle on a public jetty means barriers, signage, a safety plan and a structure out of service. Counting those days properly usually shifts the comparison well before the end of the first decade.
Resistance to Rot, Rust and Marine Borers
Three things eat marine structures, and a glass-reinforced composite is immune to all three.
Rot
Fungal decay needs moisture inside the material. Composite has no cellulose to break down and does not take up water, so the mechanism is not available.
Rust
Steel fixings in salt corrode, stain the deck and expand as they do it, splitting the board from the inside. Composite is non-conductive and takes stainless or composite fixings.
Marine Borers
Teredo and similar organisms are why timber piles and low decking fail early in warm Australian waters. They consume timber and have no interest in a composite.
Timber fails fastest exactly where nobody can see it: at the bearer contact, around fixing holes and below the splash zone. That is what makes a timber inspection regime expensive as well as necessary.
Anti-Slip Jetty Decking Surfaces for Safety
A jetty is a wet surface people walk on, often carrying something, often in bare or boat-soled feet. Slip resistance is not a nice-to-have; on a public structure it is a liability question.
Composite decking and moulded FRP grating can be produced with a gritted, moulded-in anti-slip surface that is part of the board rather than a coating applied over it. That distinction matters, because a coating wears off in the traffic lanes first, which is precisely where people walk. A moulded surface keeps its texture as it wears.
Open FRP grating is worth considering where drainage is the priority. It sheds water immediately, lets light through to the water below, and gives a consistent grip pattern underfoot. Our grating and pultruded profiles and fibreglass flooring are both used this way on walkways and platforms.
Jetty Decking Longevity in Saltwater Environments
Salt water is a chemical attack, ultraviolet is a surface attack, and tidal movement is a mechanical one. A jetty gets all three at once, every day, without maintenance windows.
Glass-reinforced composites were adopted in marine and offshore work because they hold their structural properties through that combination. They do not corrode, they need no sacrificial coating system, and they do not lose section to rust the way steel substructures do. For an asset owner, the practical result is a longer replacement interval and a maintenance budget that can be forecast rather than guessed.
The other advantage is weight. Composite components are a fraction of the mass of steel equivalents, which matters when materials have to be barged out or carried by hand along a structure that will not take a vehicle.
Specify these before you order
- Span and load: board thickness and bearer spacing work together. Confirm structural spacing against actual loading rather than assuming timber centres carry over.
- Surface finish: specify the anti-slip requirement explicitly, particularly for public access or disability compliance.
- Fixings: stainless or composite. Mixing metals in a salt environment causes problems that surface years later.
- Thermal movement: allow the expansion gaps the manufacturer nominates, especially on long runs in full sun.
- Edges and penetrations: plan cut-outs for cleats, ladders and services at design stage so boards are cut once.
If you are weighing jetty decking options for a specific structure, see our marine work or send us the layout and loading and we will work through it with you.
Frequently Asked Questions
Common questions about jetty decking, answered by our Adelaide workshop.
Is composite decking slippery when wet?
Not if the anti-slip surface is specified properly. Composite boards and FRP grating are available with a gritted texture moulded into the surface rather than applied as a coating, which means it wears at the same rate as the board instead of rubbing off in the walking lanes. Specify the slip rating you need up front, particularly for public access or disability compliance, because the plain-finish version of the same board behaves very differently underfoot.
How long does composite jetty decking last?
Considerably longer than timber in the same exposure, because none of the usual failure mechanisms apply. There is no rot, no corrosion at fixings, and nothing for marine borers to feed on. In practice the replacement interval is driven by the structure underneath and by mechanical damage rather than by the boards degrading. What matters more for budgeting is that the maintenance in between is a wash down rather than a coating cycle.
Can composite boards be fitted to an existing timber substructure?
Often yes, but bearer spacing needs checking rather than assuming. Composite and timber boards do not span identically, so the centres that suited the original deck may need adjusting to suit the new board thickness and the loading. It is also worth assessing the condition of the substructure at the same time, since there is little value in laying a fifty-year deck surface onto bearers with ten years left in them.
