A silt barrier is any temporary structure that traps sediment-laden runoff before it leaves the site. Pick the wrong type for the flow rate or the slope and it washes out in the first storm.
Australian sites use three main categories day to day: silt fence, coir logs, and sandbag or filter tube check banks. Each handles a different flow regime, and the cost and install time vary significantly. Getting the mix right is what separates a site that passes council inspection from one that gets a notice.
This guide covers the silt barrier options used across Australian construction, landscaping and revegetation projects, how each compares for flow rate, slope and install time, and where to use them on a typical job.
Looking for the kit? Jump straight to our erosion control products or the silt fence range.
A silt barrier slows sheet flow long enough for suspended sediment to drop out of the water before it reaches a drain, waterway or neighbouring property. It does not filter clean water. It holds water back against the barrier, the flow rate drops, and sediment settles on the uphill side where it can be collected later.
This means two things for how they are specified. The barrier must be sized for the catchment area it is protecting, and it must be installed to pond water rather than let flow slip under or around it. Most silt barrier failures are installation problems, not product problems.
There is no single silt barrier that suits every site. Sheet flow on a flat building pad calls for a different product than concentrated flow through a grassed swale, and revegetation on a steep batter is different again. The three main types cover most situations, often installed together on the same job.
Silt fence is the default for perimeter sediment control on construction sites. Woven geotextile fabric pinned to star pickets, running along the downhill side of a disturbed area. Works well for sheet flow, quick to install, easy to repair. Our standard option is the Silt Fence Roll 0.86m x 100m Standard Green, with longer rolls for bigger sites.
Cylindrical logs of coconut fibre staked along contour lines. Slow velocity, trap sediment, and double as a seedbed for revegetation. The coir breaks down over 2 to 5 years so there is no removal required at the end. Suited to swales, batters and low-flow drainage lines. The Coir Log 200mm x 3m is the most common size on Australian projects, with 150mm and 300mm available for smaller and larger flows.
Sandbag check dams placed across grassed swales or minor channels. Slow concentrated flow, drop sediment, and are quick to deploy in an emergency. Filter tubes filled with gravel or sand perform the same role with a longer service life. Relevant products include Premium Green Sandbags 860 x 370mm 50 Pack and Geotextile Filter Tube 150mm x 2m 100gsm.
On larger sites, a silt barrier is one part of a bigger erosion control kit. Coir matting stabilises batters while the silt fence catches what gets past it. Star-shaped steel fence posts are the standard for silt fence support on Australian sites.
Each type handles flow, slope and site conditions differently. The table summarises how the three main options compare on the factors that matter most during specification and installation.
| Barrier type | Best for | Max slope | Install time | Service life |
|---|---|---|---|---|
| Silt fence | Sheet flow around site perimeters | 2:1 (50%) | Fast | Months to 1 year |
| Coir log | Swales, batters, revegetation sites | 3:1 (33%) | Moderate | 2 to 5 years (biodegrades) |
| Sandbag check dam | Emergency, concentrated flow | Channel only | Very fast | Short-term (removable) |
| Filter tube | Longer-term check dams, drain inlet protection | Channel only | Moderate | Multi-year |
The right choice often depends on the stage of the project. Silt fence goes up first as the perimeter barrier. Coir logs go in where revegetation is planned or where the silt fence will not handle the slope. Sandbags and filter tubes handle the concentrated flow paths that silt fence cannot cope with.
Most silt barrier failures come down to one of three installation mistakes. Putting the fabric on the wrong side of the posts, not trenching the base, or spacing the star pickets too far apart. Each of these is avoidable with a 10 minute refresher before the crew starts.
Common failure point: silt fence installed without a trenched base. Runoff lifts the bottom of the fabric, flow undercuts the fence, and the whole run fills with sediment but lets water pass straight underneath. Always trench the base, even on short runs.
A silt barrier is not a fit-and-forget product. It holds back sediment only while it still has capacity. Councils expect regular inspection, and many ESCPs specify a schedule. The standard cadence is weekly on active sites and after every rainfall event of 10mm or more.
Poorly maintained silt barrier is worse than none. Councils will still expect results against the ESCP, and the barrier that washed out under a 50mm rainfall event does not count towards compliance for the next inspection.
Catchment area is the single biggest factor in sizing. A 200 square metre bare-earth pad generates very different runoff volumes to a 2,000 square metre site, and the barrier length, overlap and backup needs scale accordingly.
| Catchment area | Typical barrier strategy |
|---|---|
| Under 200 m² | Single run of silt fence along downhill side, 1-2 coir logs on steeper slopes |
| 200 to 2,000 m² | Perimeter silt fence plus internal coir log runs, sandbag check dams in swales |
| Over 2,000 m² | Multi-barrier approach: silt fence perimeter, coir matting on batters, filter tube check dams in drainage lines, sediment traps at discharge points |
On very large sites, silt barrier is usually paired with a sediment basin at the main discharge point. The barrier catches sediment locally, the basin catches anything that gets through at scale.
A silt barrier spec that gets specified and installed properly usually costs a fraction of what a council notice or a creek remediation job costs. The cost-effective approach is to match the product to the flow regime rather than over-specifying silt fence everywhere.
A common mistake is running silt fence across steep batters where coir logs would hold far better. The fence fills quickly, flow overtops or undercuts, and the run has to be replaced two or three times over the life of the job. Coir logs on the same line hold longer and seed the slope at the same time.
The right silt barrier for a site depends on catchment, slope, expected flow, and how long it needs to stay in place. Most Australian jobs run a perimeter of silt fence, with coir logs and sandbag check dams filling in where the fence cannot cope. Getting the mix right upfront is more cost-effective than reworking it after the first storm.
All Stake Supply stocks the full silt fence range, coir logs in every standard size, sandbags, filter tubes and the star pickets to hold them all in place. Call the team if you are unsure which mix suits your catchment and slope.
Not sure which silt barrier your site needs? Browse the erosion control category or contact the team for advice on specification and quantities.
