What are erosion control wattles?
Erosion control wattles are tubular sediment logs, typically 8 to 12 inches in diameter and 10 to 25 feet long, made of straw or fiber packed inside a mesh netting. Placed across a slope on contour, they slow runoff, trap sediment, and let filtered water pass through. Contractors also call them straw wattles, fiber rolls, sediment logs, or erosion tubes. The terms are used interchangeably.
By the HMNDP Editorial Team. Last reviewed: June 2026.
The core idea is simple. A wattle is a porous dam laid horizontally along the face of a graded slope. Water hits it, ponds briefly, drops its suspended soil, and seeps through the netting instead of racing downhill and cutting rills.
Most wattles are filled with rice straw or wheat straw held in photodegradable or biodegradable netting. Higher-durability versions use coir (coconut fiber) or excelsior (curled wood fiber) for longer service life. All three sit within the broader family of erosion control products used on construction sites and disturbed ground.
What erosion control wattles are used for
Wattles do four jobs on a slope: they slow and trap sediment and debris, filter stormwater so cleaner water leaves the site, reduce soil erosion by breaking long slope runs into short ones, and help hold back chemical-laden runoff. On regulated sites they serve as a named best management practice (BMP) inside a Stormwater Pollution Prevention Plan (SWPPP).
Grading and civil contractors deploy them two ways. As a perimeter barrier, wattles ring the toe of a slope or a disturbed area to catch sediment before it reaches a street, storm drain, or waterway. As interval or check barriers, they run at spaced intervals across the slope face to shorten flow length and cut runoff velocity.
Because they are placed on contour, wattles pond water on the upslope side just long enough for suspended soil to settle. That settling is what keeps sediment on site and out of downstream systems, which is the whole point of a SWPPP sediment-control device. For living, long-term slope stabilization, wattles pair well with plants that anchor soil against erosion once vegetation establishes.
Wattle sizes, materials, and types compared
Straw wattles are the cheapest and shortest-lived, coir wattles cost the most and last longest, and excelsior sits in between. Standard sizes run 8, 9, 12, and 20 inches in diameter, most commonly in 10-foot and 25-foot lengths. Match diameter to expected flow: bigger diameters handle longer or steeper slopes and concentrated channels.
| Type | Fill material | Typical lifespan | Best use | Relative cost |
|---|---|---|---|---|
| Straw wattle | Rice or wheat straw | 6 to 24 months | Short-term slope and perimeter control | $ |
| Excelsior (wood fiber) | Curled aspen or pine | 2 to 5 years | Longer projects, moderate flow channels | $$ |
| Coir (coconut fiber) | Coconut coir | 4 to 10 years | Streambanks, permanent-vegetation slopes | $$$ |
Netting matters as much as fill. Photodegradable polypropylene mesh is common and cheap but can leave plastic residue, so many jurisdictions now require 100 percent biodegradable jute or coir netting near waterways or where equipment will mulch the wattle in place.
For diameter selection, a common rule of thumb is 8 to 9 inches for slopes under 25 feet long, 12 inches for slopes up to about 50 feet or steeper grades, and 20 inches where flow concentrates. When sheet erosion covers a broad face, contractors often combine wattles with an erosion control blanket for full-surface protection.
How to install a straw wattle correctly
Correct wattle installation depends on three things competitors rarely state: keying the wattle into a shallow trench, staking it tight to the ground, and overlapping ends so water cannot escape between rolls. Skip any of these and runoff undercuts or flanks the wattle, and it fails. Follow these steps on contour, perpendicular to the slope.
- Dig a shallow trench. Excavate a trench 2 to 4 inches deep (roughly one-third of the wattle diameter) along the contour line so the wattle beds into the soil rather than sitting on top of it.
- Lay the wattle in the trench. Set it snug against the upslope wall with no gaps underneath. Full ground contact is what forces water through the fibers instead of under them.
- Stake it down. Drive 1×1 or 2×2 inch wooden stakes through or immediately against the wattle every 3 to 4 feet, and closer (2 to 3 feet) on steep grades. Leave 2 to 3 inches of stake above the wattle.
- Overlap the ends. Butt and overlap adjoining wattles by at least 12 inches, tucking the upslope end behind the next so runoff cannot slip through the joint.
- Backfill the upslope side. Tamp excavated soil against the uphill face to seal the base and eliminate the gap where undercutting starts.
Inspect after every significant rain. Remove accumulated sediment once it reaches about half the wattle height, and re-stake or replace any roll that has slumped, floated, or lost ground contact.
How far apart to space wattles on a slope
Wattle spacing tightens as the slope steepens. On a gentle 4:1 slope, intervals of about 30 feet are common, while a steep 2:1 slope often needs wattles every 10 feet. The goal is to break the slope into short segments so water never gains erosive speed. Always confirm intervals against your SWPPP or local BMP manual.
| Slope ratio (H:V) | Approx. grade | Typical wattle interval |
|---|---|---|
| 4:1 or flatter | 25% or less | 25 to 40 ft |
| 3:1 | 33% | 20 to 25 ft |
| 2:1 | 50% | 10 to 15 ft |
| 1:1 | 100% | 10 ft or less |
These intervals are representative starting points. Site-specific spacing may be tighter depending on soil type, rainfall intensity, and the agency reviewing your plan, so treat the numbers as a design baseline rather than a fixed standard.
Cost per foot: wattles vs. silt fence
Straw wattles typically cost about $0.80 to $1.50 per linear foot in materials, with a 9-inch by 25-foot roll running roughly $20 to $35. Silt fence material can look cheaper per foot, but its installed cost climbs once trenching and machine time are added. Wattles win on speed of deployment and reuse-free removal on short jobs.
| Factor | Straw wattle | Silt fence |
|---|---|---|
| Material cost | ~$0.80 to $1.50/ft | ~$0.30 to $0.60/ft |
| Install labor | Low, hand-staked | Higher, trench and compact |
| Best terrain | Slope faces, contours | Perimeter, flatter ground |
| Removal | Often left to biodegrade | Must be pulled and hauled |
| Sediment capture | Filters through fibers | Ponds behind fabric |
Coir and excelsior wattles cost more, commonly $2 to $6 per foot, which buys multi-year durability. The right choice depends on project length: for a slope that will be vegetated within a season, a straw wattle is usually the lower total cost. Compare full options across the broader erosion control category before buying at volume.
Lifespan, biodegradation, and removal
Straw wattles typically last 6 to 24 months before the straw and netting break down, while coir wattles can hold up 4 to 10 years. Fully biodegradable wattles can often be left in place to decompose and enrich the soil. Those with plastic netting usually must be removed once the slope is stabilized.
Lifespan depends on sun, moisture, and traffic. Ultraviolet exposure degrades polypropylene netting first, and repeated wetting speeds straw breakdown. Coir and excelsior resist both, which is why they anchor streambanks and long-duration jobs.
On removal, follow your permit. If the netting is 100 percent biodegradable jute or coir and the slope carries established vegetation, many plans allow the wattle to stay and compost in place. Where synthetic netting was used, or the plan requires it, pull the wattles, dispose of them properly, and reseed any bare trench line so the removal itself does not restart erosion.
Frequently Asked Questions
What are erosion control wattles used for?
Erosion control wattles are used to slow runoff, trap sediment and debris, and filter stormwater on graded slopes and construction sites. Laid on contour, they shorten slope length so water cannot gain erosive speed, and they serve as a recognized sediment-control BMP inside a SWPPP. They also help hold back soil and chemical-laden runoff before it reaches drains or waterways.
How much do erosion control wattles cost per foot?
Straw wattles typically cost about $0.80 to $1.50 per linear foot, with a standard 9-inch by 25-foot roll running roughly $20 to $35. Longer-lasting coir and excelsior wattles cost more, commonly $2 to $6 per foot. Pricing varies by diameter, netting type, quantity, and region, so request bulk quotes for large projects to lower the per-foot rate.
How do you install a straw wattle correctly?
Dig a shallow trench 2 to 4 inches deep along the contour, set the wattle snug against the upslope wall, and drive wooden stakes through or beside it every 3 to 4 feet. Overlap adjoining wattle ends by at least 12 inches, then backfill and tamp soil against the uphill face. Full ground contact forces water through the fibers instead of underneath.
How far apart should wattles be placed on a slope?
Spacing tightens as the slope steepens. On a 4:1 slope, intervals of 25 to 40 feet are common; on 3:1, about 20 to 25 feet; on a steep 2:1 slope, roughly 10 to 15 feet. The goal is to break the slope into short segments so runoff never builds speed. Always confirm intervals against your SWPPP or local BMP manual.
How long do straw wattles last before they break down?
Straw wattles typically last 6 to 24 months before the straw and netting degrade, depending on sun, moisture, and traffic. Excelsior wood-fiber wattles last about 2 to 5 years, and coir wattles can hold up 4 to 10 years. Ultraviolet exposure and repeated wetting speed breakdown, so choose fiber and netting rated for your project duration.
Wattles vs. silt fence: which is better for sediment control?
Wattles are usually better on slope faces because they filter water through their fibers, install by hand, and can biodegrade in place. Silt fence often suits flatter perimeters and ponds sediment behind fabric, but it costs more to trench, install, and remove. For short, sloped jobs, wattles typically deliver lower total cost; long perimeters may favor silt fence.
What size (diameter and length) straw wattle do I need?
Match diameter to flow. Use 8 to 9 inch wattles for slopes under 25 feet long, 12 inch for slopes up to about 50 feet or steeper grades, and 20 inch where flow concentrates in channels. Standard lengths are 10 feet and 25 feet. Longer 25-foot rolls reduce the number of end overlaps you have to seal.
Are straw wattles biodegradable, and do you have to remove them?
Straw wattles are biodegradable when filled with straw and wrapped in jute or coir netting; these can often be left to decompose and feed the soil. Wattles with photodegradable plastic netting usually must be removed once the slope is stabilized. Follow your permit or SWPPP: where synthetic netting is used, pull and dispose of the wattles, then reseed the trench line.