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BFM vs Erosion Control Blankets: Which Should You Specify?
Bonded Fibre Matrix (BFM) typically outperforms erosion control blankets on slopes steeper than 3:1, delivering 99% erosion reduction at £0.50–£1.30 per m² with 2–3 operatives. Erosion control blankets cost £8–£12 per m² installed and require 8–12 operatives, but offer immediate protection without a drying period and can be used in channels where BFM cannot. The right choice depends on your slope gradient, programme and site conditions.
Side-by-Side Comparison
| Factor | BFM (Bonded Fibre Matrix) | Erosion Control Blankets |
|---|---|---|
| Installed cost per m² | £0.50–£1.30 | £8–£12 |
| Daily coverage | 2–3 hectares | 0.5–1 hectare |
| Operatives required | 2–3 | 8–12 |
| Maximum slope gradient | 1:1 (45 degrees) | 2:1 (27 degrees) for standard blankets |
| Erosion reduction (vs bare soil) | 99% (C-factor 0.01) | 86–95% (C-factor 0.05–0.14) |
| Drying/cure requirement | Avoid application in heavy rain | None, effective immediately |
| Suitable for concentrated flow | No | Yes (especially Turf Reinforcement Mats) |
| Plastic netting | None, 100% biodegradable | Some types contain plastic netting |
| Seed application | Combined in single operation | Separate operation before blanket placement |
| Functional longevity | 6–12 months | 3 months to 3+ years (varies by type) |
| Ground preparation | Minimal | Fine grading to smooth profile required |
| Anchoring | Bonds directly to soil surface | Stakes, staples or pins at specified intervals |
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What Is Bonded Fibre Matrix (BFM)?
BFM is a hydraulically applied erosion control product made from thermally processed wood fibres (typically around 80% by weight), bound together by water-insoluble cross-linked tackifiers and mineral bonding agents. It is mixed with seed, fertiliser and water in a hydroseeder and sprayed directly onto prepared ground.
Once applied, the slurry dries to form a continuous, porous blanket that bonds directly to the soil surface. This eliminates gaps between the protective layer and the ground, which is where erosion typically begins on blanket-protected slopes.
BFM is 100% biodegradable. It contains no plastic netting, no synthetic components and no materials that need to be removed after vegetation establishes. For a fuller explanation of the product, how it is applied and where it fits on site, see What is Bonded Fibre Matrix (BFM)?
How BFM is tested and measured
Erosion control performance is measured using the C-factor from the Revised Universal Soil Loss Equation (RUSLE). Bare soil has a C-factor of 1.0. High-performance BFM products, such as Profile Hydro-Blanket BFM , achieve C-factors of 0.01 or lower in laboratory rainfall simulations conducted to ASTM D6459 , the standard test method for erosion control product performance. A C-factor of 0.01 represents 99% erosion reduction compared to unprotected soil.
What Are Erosion Control Blankets?
Erosion control blankets (also called Rolled Erosion Control Products, or RECPs) are manufactured mats made from natural fibres such as straw, coconut coir or wood fibre (excelsior), held together with netting. They are physically unrolled onto prepared ground and secured with stakes, staples or pins.
The Erosion Control Technology Council (ECTC) classifies RECPs into temporary biodegradable blankets (lasting 3 months to 3 years depending on the fibre type) and permanent Turf Reinforcement Mats (TRMs) made from synthetic materials for use in channels and areas with concentrated water flow.
Blanket types and longevity
| Blanket Type | Typical Longevity | Best For |
|---|---|---|
| Single-net straw | 3–6 months | Short-term protection on gentle slopes |
| Double-net straw | 6–12 months | Most commonly specified for construction slopes |
| Wood fibre (excelsior) | 12–24 months | Sites needing longer establishment periods |
| Coconut coir | 24–36 months | Steep slopes and high-flow areas |
| Straw/coir blend (70/30) | 12–18 months | Balance of cost and performance |
| Turf Reinforcement Mat (TRM) | Permanent | Channels, swales and concentrated flow areas |
How blankets are tested and measured
Erosion control blankets are tested to the same ASTM D6459 standard as hydraulically applied products. Independent laboratory testing at Auburn University recorded C-factors of 0.05 for excelsior blankets (95% erosion reduction) and 0.12–0.14 for straw blankets (86–88% erosion reduction) on 3:1 slopes under simulated rainfall.
Where BFM Has the Advantage
Steep slopes
BFM is effective on slopes up to 1:1 (45 degrees). Standard erosion control blankets are typically specified for slopes of 2:1 (27 degrees) or flatter. On slopes steeper than 3:1, BFM is often the only practical hydraulic option because blankets are difficult to secure and tend to lift or slide.
Installation speed
A two-person hydroseeding crew can apply BFM to 2–3 hectares per day. Blanket installation typically covers 0.5–1 hectare per day and requires 8–12 operatives for handling, trenching, unrolling and staking. On a 10,000 m² highway embankment, BFM application could be completed in a single day. The same area with blankets would typically take 2–3 days with a significantly larger crew.
Programme protection
Because BFM combines seed, fertiliser, mulch and erosion protection in a single hydraulic application, there is no need for a separate seeding operation before the protective layer goes down. With blankets, seed must be applied before the blanket is laid. If the blanket is placed before seeding, germination may be inhibited.
Cost
The installed cost difference is substantial. At £0.50–£1.30 per m² for BFM compared to £8–£12 per m² for erosion control blankets, BFM is typically 85–95% cheaper on a per-area basis. On a 5,000 m² embankment, the difference could be £35,000–£55,000 in direct costs alone, before accounting for the reduced labour and programme savings.
Access
BFM can be applied by hose from a hydroseeder positioned on an access road, reaching slopes that would be difficult or unsafe for operatives to access on foot with blanket rolls. This makes it particularly effective on rail embankments, dam faces, quarry benches and motorway cuttings where manual access is restricted.
No plastic netting
BFM is 100% biodegradable. Some erosion control blankets contain plastic netting that persists in the environment after the natural fibres decompose. This is an increasing concern on ecologically sensitive sites and projects with environmental compliance conditions.
Where Erosion Control Blankets Have the Advantage
Immediate protection
Erosion control blankets provide effective erosion protection the moment they are staked into position. BFM requires a period of dry weather after application to allow the matrix to cure. Manufacturer specifications typically recommend a minimum of 24 hours without heavy rain after application. In practice, the mulch usually dries within a few hours depending on temperature and humidity, but application should be avoided if very heavy rain is forecast.
On sites where erosion protection is needed immediately and weather conditions are uncertain, blankets offer more predictable timing.
Concentrated water flow
BFM is not suitable for channels, drainage ditches, swales or areas receiving concentrated water flow. These are applications where erosion control blankets, and particularly permanent Turf Reinforcement Mats (TRMs), are the correct specification. TRMs are designed to withstand high shear stresses from flowing water and provide permanent reinforcement for vegetated channels.
In practice, this limitation rarely affects the BFM vs blankets decision on slope protection, because concentrated flow is typically a channel or swale design issue rather than an embankment protection issue.
Established regulatory acceptance
Erosion control blankets have a longer track record in UK highway and rail specifications. While BFM is increasingly specified on major infrastructure projects, some older specifications and method statements may default to blankets. On projects governed by existing specifications, blankets may be the required method regardless of BFM's performance advantages.
When to Use Each Method
Use BFM When:
- Your slope is steeper than 3:1 (18 degrees). BFM is effective up to 1:1 (45 degrees), well beyond the practical limit of most erosion control blankets.
- Your programme is tight. BFM covers 2–3 hectares per day with 2–3 operatives. If time and labour are constrained, BFM typically delivers faster coverage.
- Access is restricted. Slopes that are difficult or unsafe to access on foot (rail embankments, quarry faces, dam walls) can be treated by hose from a hydroseeder positioned at a safe distance.
- Budget matters. At £0.50–£1.30 per m² installed, BFM is significantly cheaper than blankets at £8–£12 per m².
- The site is ecologically sensitive. BFM contains no plastic netting and is 100% biodegradable.
Use Erosion Control Blankets When:
- You need protection in channels, ditches or swales. BFM cannot handle concentrated water flow. Blankets and TRMs are designed for these applications.
- Weather is unpredictable and you need immediate protection. Blankets work the moment they are secured. BFM needs dry conditions during and shortly after application.
- The specification requires them. Some older highway and rail specifications mandate blankets. If the specification is fixed, use what is specified.
- Long-term reinforcement is needed. For permanent channel lining or areas where vegetation alone will not provide sufficient long-term erosion protection, synthetic TRMs offer a permanent solution that BFM does not.
Consider Using Both Methods Together
On complex sites, BFM and blankets can be used together. BFM applied to open embankment slopes for speed and cost efficiency, with erosion control blankets or TRMs installed in drainage channels and concentrated flow areas. This approach gives you the programme and cost benefits of BFM where it works best, with blankets handling the specific conditions where they outperform BFM.
Need Help Choosing the Right Method?
Our technical team can assess your slope gradients, soil conditions and programme constraints to recommend the most cost-effective erosion control specification for your project.
Cost Comparison on a Real Project
To illustrate the practical difference, here is a comparison based on a typical 5,000 m² highway embankment with slopes of 2:1, using 2026 UK pricing.
| Cost Element | BFM | Erosion Control Blankets |
|---|---|---|
| Material and installation cost | £2,500–£6,500 | £40,000–£60,000 |
| Operatives required | 2–3 | 8–12 |
| Estimated installation time | 1 day | 2–3 days |
| Separate seeding operation | No (combined) | Yes (seed before blanket) |
| Estimated total project cost | £2,500–£6,500 | £40,000–£60,000+ |
These figures assume standard site conditions with reasonable vehicle access. Costs will vary with slope gradient, access conditions, seed specification and travel distance. Request a site-specific quote for your project.
Real-World Example
A487 Machynlleth Bridge, Mid Wales
On the A487 Machynlleth Bridge scheme, a 1 km new-build highway project for Tier 1 contractor Alun Griffiths, CDTS North & West provided hydroseeding , conventional seeding , wildflower and BNG seeding and BFM erosion control across the scheme. The site was classified as highly environmentally sensitive, with local-provenance seed and planting specified throughout.
BFM was used on highway embankment slopes where rapid erosion protection was critical to programme and environmental compliance. The hydraulic application method allowed the team to treat slopes efficiently with a small crew, combining seed, fertiliser and erosion control in a single operation rather than requiring separate seeding and blanket installation.
Standards and Specifications
Both BFM and erosion control blankets are tested and specified against recognised industry standards.
ASTM D6459 is the standard test method for determining the performance of erosion control products in protecting slopes from rainfall-induced erosion. C-factor values from ASTM D6459 testing are the primary basis for comparing erosion control effectiveness between products.
In the UK, erosion control on highway and rail schemes is governed by the Design Manual for Roads and Bridges (DMRB) and the Manual of Contract Documents for Highway Works (MCHW) Series 3000 for landscape and ecology. CIRIA C741 provides guidance on environmental good practice on construction sites, including erosion and sediment control measures.
For construction site environmental management more broadly, the Environment Agency's regulatory position statements and CIRIA publications C591 (Infrastructure Cuttings) and C592 (Infrastructure Embankments) provide relevant guidance on slope stability and vegetation establishment.
Save Up to 90% on Erosion Control Costs
BFM delivers faster coverage, fewer operatives and better erosion protection than blankets on most slopes. Get a site-specific comparison for your project.
Frequently Asked Questions
Which is faster to install, BFM or erosion control blankets?
BFM is significantly faster. A two-person crew with a hydroseeder can apply BFM to 2–3 hectares per day, combining seed, fertiliser and erosion protection in one operation. Erosion control blanket installation typically covers 0.5–1 hectare per day and requires 8–12 operatives for handling, trenching and staking.
Which provides better erosion control?
BFM achieves higher erosion reduction in laboratory testing, with C-factors of 0.01 (99% reduction vs bare soil) compared to 0.05–0.14 (86–95% reduction) for typical erosion control blankets tested to ASTM D6459. However, blankets offer immediate protection without a drying period, and TRMs can handle concentrated water flow where BFM cannot.
What is the cost difference between BFM and erosion control blankets?
BFM typically costs £0.50–£1.30 per m² installed. Erosion control blankets typically cost £8–£12 per m² installed. The difference is primarily driven by labour: blanket installation requires significantly more operatives and time per square metre.
Can BFM be used in wet weather?
BFM should not be applied during very heavy rain. However, in practice the mulch typically dries within a few hours of application depending on temperature and humidity. Manufacturer specifications recommend allowing a minimum drying period after application. Experienced applicators plan around weather forecasts to ensure adequate conditions.
What is the steepest slope BFM can be used on?
BFM is effective on slopes up to 1:1 (45 degrees). This is significantly steeper than standard erosion control blankets, which are typically specified for slopes of 2:1 (27 degrees) or flatter. Slopes steeper than 1:1 generally require structural engineering solutions in addition to surface erosion protection.
Can BFM be used in drainage channels?
No. BFM is not suitable for channels, ditches, swales or areas receiving concentrated water flow. These applications require erosion control blankets or permanent Turf Reinforcement Mats (TRMs), which are designed to withstand the shear stresses from flowing water.
Do erosion control blankets contain plastic?
Some do. Many erosion control blankets use plastic netting to hold the natural fibres together. This netting can persist in the environment long after the natural components decompose. Biodegradable netting options are available but less common. BFM contains no plastic components and is 100% biodegradable.
How long does BFM last?
BFM provides effective erosion protection for 6–12 months while vegetation establishes. The fibre matrix gradually biodegrades as grass roots create permanent soil stabilisation. Long-term erosion control comes from the established vegetation, not the temporary matrix.
Can I use BFM and blankets on the same project?
Yes. On complex sites, BFM is commonly used on open embankment slopes for speed and cost efficiency, with erosion control blankets or TRMs installed in drainage channels and concentrated flow areas. This gives you the best performance from each method where it is most effective.
Who can apply BFM?
BFM should be applied by a trained and experienced hydroseeding contractor using mechanically agitated equipment. The mixing process, application rates and multi-directional spray technique all affect performance. Incorrect application, particularly over-application, can inhibit germination and reduce effectiveness.
Summary
BFM is the more cost-effective and faster option for slope erosion control on most UK construction sites, particularly where slopes are steeper than 3:1, programmes are tight, access is restricted or budgets are constrained. Erosion control blankets remain the correct specification for channels and concentrated flow areas, and offer the advantage of immediate protection without a weather-dependent drying period.
For most embankment and slope protection applications, BFM delivers better erosion control at a fraction of the cost and programme impact of erosion control blankets.
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