If you've ever worked on a slope stabilization project — highway cuts, construction grading, pipeline restoration, or mine reclamation — you've probably dealt with erosion control blankets. Curlex, North American Green, straw blankets with netting — they've been the go-to solution for decades.
And if you've dealt with them, you know the pain: crews on steep hillsides pinning blankets by hand, blankets that lift, tear, channel water underneath, and leave gaps that erode faster than bare soil would have. Then you're back out there re-stapling, re-seeding, and wondering why the "erosion control" is causing more erosion.
There's a better way. Flexterra HP-FHP (High Performance - Flexible, Hydraulically-applied Product) is a sprayable erosion control matrix that eliminates the blanket entirely. It's applied through a hydroseeding unit, bonds directly to the soil surface, and outperforms traditional erosion blankets in independent testing — at a lower installed cost. Across Pittsburgh, Westmoreland County, and all of Western Pennsylvania's notoriously steep terrain, Flexterra is replacing rolled erosion control products on projects where performance actually matters.
The Short Version
Flexterra HP-FHP is a hydraulically applied erosion control blanket that goes on in minutes, bonds to any soil surface, conforms to irregular terrain, and delivers 99%+ erosion control effectiveness in third-party testing. No pins, no staples, no crew on the hillside, no blanket failure. It's what erosion blankets should have been all along.
The Problem with Traditional Erosion Control Blankets
Rolled erosion control products (RECPs) like Curlex, straw blankets, and coconut fiber mats have been the industry standard for slope protection since the 1970s. The concept is simple: unroll a blanket over freshly seeded soil, pin it down with metal or plastic staples, and the blanket holds the soil in place until grass establishes.
In theory, it works. In practice — especially on the steep, irregular terrain throughout Western Pennsylvania — the problems are well known to anyone who's installed them:
-
1.
Ground Contact Gaps
Erosion blankets are flat. The ground is not. On rocky, rutted, or irregular surfaces — which describes most cut slopes in our area — the blanket can't conform to every contour. Those gaps between blanket and soil become channels where water accelerates underneath, eroding the very soil the blanket was supposed to protect. We call this "tunneling" and it's the single most common failure mode for rolled blankets.
-
2.
Seam and Edge Failures
Blankets come in rolls — typically 8 feet wide — which means a hillside requires multiple overlapping strips. Every seam, every overlap, every edge is a potential failure point. Wind lifts edges. Water enters seams. One loose staple and the blanket peels back like a bandage, taking the seed and soil with it.
-
3.
Labor-Intensive Installation
Installing erosion blankets on steep slopes is brutal, dangerous work. Crews carry heavy rolls up hillsides, unroll them by hand, and drive staples every 3-4 feet — often on slopes steeper than 2:1 where footing is treacherous. A crew of 4 might install 5,000–8,000 square feet per day on a steep slope. The labor cost often exceeds the material cost.
-
4.
Seed Displacement During Installation
On a proper installation, seed is applied to the soil before the blanket goes down. But the act of walking on the slope to install the blanket — and the weight of the blanket itself — displaces the seed. Crew foot traffic pushes seed downhill, creating bare spots at the top and seed accumulation at the bottom.
-
5.
Blanket Inhibits Growth
Particularly with thicker blankets like excelsior (Curlex), the dense fiber mat can actually impede grass emergence. Seedlings struggle to push through the blanket material, leading to thin, spotty establishment underneath a blanket that looks like it's "working" from the outside. When the blanket eventually degrades, the thin turf can't hold the soil on its own.
-
6.
Not Suitable for Every Surface
You can't staple a blanket to solid rock, fractured shale, or concrete rubble — all common surfaces on construction slopes, highway cuts, and mine sites in our region. If you can't anchor it, you can't use it.
What Is Flexterra HP-FHP?
Flexterra HP-FHP is a Hydraulically Applied Flexible Growth Medium (FGM) manufactured by Profile Products. Unlike rolled blankets, Flexterra is a dry product that gets mixed with water in a hydroseeding tank and sprayed directly onto the slope surface through a hose or tower nozzle.
When applied, the interlocking fibers in Flexterra form a continuous, flexible erosion control matrix that bonds to the soil surface — no pins, no staples, no seams. The matrix conforms to every rock, rut, and irregularity in the terrain because it's a liquid when applied and a bonded mat when dry.
What Makes Flexterra Different from Standard Hydromulch
Standard wood fiber hydromulch provides modest erosion control — it holds seed in place and retains some moisture, but it lacks the structural integrity to handle serious erosion forces. On a steep slope in heavy rain, standard hydromulch washes off.
Flexterra is engineered differently:
-
•
Crimped Interlocking Fibers — Flexterra's proprietary fiber blend includes crimped, interlocking synthetic and natural fibers that mechanically bond to each other when dry, creating a three-dimensional matrix with significantly higher tensile strength than standard hydromulch.
-
•
Cross-Linked Tackifier System — Rather than simple guar-based tackifiers that dissolve in the first rain, Flexterra uses a cross-linked adhesive system that strengthens as it dries and maintains bond through multiple rain events.
-
•
Moisture Management — The fiber matrix holds up to 10x its weight in water, creating a sustained moisture environment for seed germination that rolled blankets can't match. The seed isn't just covered — it's suspended in a moisture-rich cocoon.
-
•
Seed-to-Soil Contact — Because Flexterra is applied as a slurry with the seed mixed directly in, every seed is in direct contact with the soil surface and surrounded by the protective matrix. No blanket sitting on top of the seed hoping for contact.
How Flexterra Works
Step 1: Mix
Flexterra is loaded into a hydroseeding tank along with water, seed, fertilizer, and any site-specific amendments. The slurry is mixed to a thick, uniform consistency — heavier than standard hydroseed but still pumpable through standard equipment.
Step 2: Spray
The slurry is hydraulically applied to the slope surface through hose or tower nozzle. The operator controls application thickness in real time — heavier application on the steepest sections, concentrated flow areas, and high-erosion risk zones. A single operator can cover terrain that would take a 4-person blanket crew an entire day.
Step 3: Bond
As the slurry dries (typically 12-24 hours), the interlocking fibers cross-link and form a cohesive, flexible mat bonded directly to the soil surface. Unlike a rolled blanket resting on the soil, Flexterra becomes part of the soil surface — filling every crack, depression, and irregularity with a continuous protective layer.
Step 4: Protect
The cured matrix immediately provides erosion protection — deflecting raindrop impact, slowing sheet flow, and preventing rill formation. It maintains its protective function through the critical germination period (2-6 weeks), then gradually biodegrades over 12-18 months as the established vegetation takes over the erosion control role.
Step 5: Grow
Seed germinates within the moisture-rich matrix and grows right through it. Unlike dense rolled blankets that can suppress seedling emergence, Flexterra's open fiber structure allows grass to push through freely while still providing erosion protection. The result: faster, more uniform vegetation establishment compared to blanket-covered seeding.
Flexterra vs. Curlex: Head-to-Head Comparison
| Factor | Curlex / Rolled Blankets | Flexterra HP-FHP |
|---|---|---|
| Ground contact | Gaps on irregular terrain. Tunneling risk. | 100% contact. Conforms to every surface irregularity. |
| Seams & edges | Multiple seams every 8 ft. Edge failure common. | Zero seams. Continuous coverage. |
| Installation labor | 4-person crew, 5,000-8,000 sq ft/day on steep slopes. | 1-2 person crew, 20,000-40,000+ sq ft/day. |
| Worker safety | Crews working on steep, unstable slopes. | Applied from road or base. No one on the slope. |
| Anchoring | Requires staples/pins. Can't anchor to rock. | Self-bonding. Works on rock, clay, rubble. |
| Seed contact | Seed applied separately, then blanket laid over it. | Seed mixed directly in slurry. Intimate soil contact. |
| Grass emergence | Dense mats (excelsior) can suppress seedling growth. | Open fiber structure allows free growth. |
| Moisture retention | Moderate. Blanket covers but doesn't hold water at seed level. | Holds 10x its weight. Moisture surrounds each seed. |
| Irregular terrain | Poor conformity. Rocks, stumps, ruts all create gaps. | Perfect conformity. Liquid application fills all voids. |
| Typical erosion control | 85-95% when properly installed | 99%+ in independent ASTM testing |
Performance Data: The Numbers Don't Lie
Flexterra HP-FHP has been extensively tested under ASTM D6459 (Standard Test Method for Determination of Erosion Control Blanket Performance in Protecting Hillslopes from Rainfall-Induced Erosion) — the same test protocol used to evaluate rolled erosion control blankets.
-
✓
99.7% erosion control effectiveness — in ASTM D6459 large-scale testing on 3:1 slopes with 4 in/hr simulated rainfall intensity
-
✓
Outperforms single-net straw blankets — which typically test at 85-92% effectiveness under the same conditions
-
✓
Comparable to double-net excelsior (Curlex) — but without the installation challenges, seam failures, and ground contact issues that reduce real-world blanket performance below lab results
-
✓
Functional longevity of 12-18 months — providing protection through multiple growing seasons as permanent vegetation establishes
Lab Performance vs. Real-World Performance
Here's the critical distinction: erosion blankets test well in labs but underperform in the field. Lab tests use smooth, uniform soil beds — perfect blanket conditions. Real slopes have rocks, roots, ruts, and irregularities that prevent full contact. Every gap is a failure point. Flexterra's real-world performance closely matches its lab performance because it conforms to actual terrain conditions. A blanket's real-world performance is almost always worse than its lab rating.
Best Applications for Flexterra
While Flexterra can be used almost anywhere a rolled blanket would be specified, it's especially superior in these situations:
Highway & Road Cuts
PennDOT and municipal road projects with steep cut slopes along Routes 30, 22, 76, and local roads throughout Pittsburgh and Westmoreland County. No crew on the slope = faster completion and better safety.
Construction Site Slopes
New developments in North Huntingdon, Irwin, Greensburg, and Murrysville where graded slopes need NPDES-compliant erosion control before permit closeout. Flexterra installs faster and allows earlier stabilization.
Pipeline & Utility Corridors
Gas pipeline rights-of-way and utility easement restoration where disturbed soil runs for miles across steep, varied terrain. Flexterra covers ground 4-5x faster than blanket crews.
Rocky or Irregular Terrain
Fractured shale, exposed rock faces, and rubble-strewn slopes throughout Western PA's coal country where you simply can't staple down a blanket. Flexterra bonds to whatever surface exists.
Channels & Swales
Concentrated flow areas where blankets are prone to undermining and liftoff. Flexterra's bonded matrix stays put in flow velocities up to 15 ft/sec — critical for stormwater channels on steep sites.
Difficult Access Sites
Slopes where blanket delivery and installation logistics are impractical — remote mine sites, steep ravines, bridge abutments. A hose reaches where blanket rolls can't go.
Why This Matters in Western Pennsylvania
Western PA is arguably the worst-case scenario for rolled erosion control blankets — and the best-case scenario for Flexterra. Here's why our region's conditions favor sprayable erosion control:
-
•
Steep, Hilly Terrain Everywhere
From Pittsburgh's hillside neighborhoods to the ridges and valleys of Westmoreland, Fayette, and Indiana Counties, our terrain is defined by steep grades. Every road project, development, and pipeline crosses slopes that make blanket installation difficult and dangerous. Flexterra eliminates the slope-access problem entirely.
-
•
Heavy Clay and Shale Soils
Our soils don't hold staples well. On exposed clay and shale cut slopes — the surface you see on virtually every highway and construction site — blanket pins pull out under the weight of wet blankets. Flexterra doesn't need pins because it bonds chemically and mechanically to the soil surface.
-
•
High-Intensity Rain Events
Western PA receives 38-42 inches of rain annually, including intense summer thunderstorms and long-duration fall rains. These events test erosion control systems to their limits. The continuous, bonded coverage of Flexterra handles high-intensity rainfall better than seamed blankets with potential gap failures.
-
•
Freeze-Thaw Cycles
Our winters cycle above and below freezing constantly. Freeze-thaw heaves staples out of the ground and lifts blanket edges. Flexterra's bonded matrix flexes with the soil surface through freeze-thaw cycles without losing contact or creating gaps.
-
•
Coal Country Legacy
Decades of mining left countless disturbed sites with rock rubble, acid soils, and irregular terrain where blankets are essentially unusable. Flexterra — often combined with BSM (Biotic Soil Media) — is reclaiming these sites across Westmoreland County, Fayette County, and surrounding areas.
Cost Comparison: Installed Price Is What Matters
On a spec sheet, Curlex and other rolled blankets can look cheaper per square foot than Flexterra. But the installed cost — material plus labor — tells a very different story, especially on steep or large-scale projects.
| Cost Component | Curlex / Rolled Blankets | Flexterra HP-FHP |
|---|---|---|
| Material cost | $0.15–$0.45/sq ft | $0.10–$0.25/sq ft |
| Staples/anchoring | $0.03–$0.08/sq ft | $0.00 (self-bonding) |
| Installation labor | $0.25–$0.60/sq ft (steep slopes) | $0.08–$0.15/sq ft |
| Separate seeding step | $0.05–$0.10/sq ft | Included in application |
| Total installed cost | $0.48–$1.23/sq ft | $0.18–$0.40/sq ft |
| Repair/re-installation rate | 15-30% of blanket area typically needs repair | Minimal touch-up. Spray additional if needed. |
The Hidden Cost: Blanket Repair Cycles
On a typical highway or construction slope, erosion blanket installations require at least one repair visit — often more. Blankets lift, seams fail, and bare spots develop. Each repair visit involves crew mobilization, material, and the same dangerous slope work as the original installation. When you factor in repair costs, the total lifecycle cost of blankets almost always exceeds the one-time cost of Flexterra — which rarely needs touch-up because there are no seams, edges, or pins to fail.
Frequently Asked Questions
Is Flexterra approved for use on PennDOT projects?
Flexterra HP-FHP is listed as an approved Hydraulically Applied Erosion Control Product (HECP) and can be specified on PennDOT and municipal projects throughout Pennsylvania. It meets or exceeds the performance specifications typically required for slope erosion control on transportation projects.
Can Flexterra replace blankets on an existing spec?
In many cases, yes. If a project spec calls for a rolled erosion control blanket (RECP) at a certain performance level, Flexterra can often be submitted as an equal or superior alternative. We work with project engineers to demonstrate that Flexterra meets or exceeds the specified erosion control performance requirement. Many engineers are making the switch once they see the installed cost comparison and field performance data.
How steep of a slope can Flexterra handle?
Flexterra is routinely applied on slopes of 1:1 and steeper — slopes where blanket installation would be extremely dangerous and the products would struggle to maintain contact. The hydraulic application means slope angle is limited only by how far the hose can reach, not by crew safety on the surface.
What happens if a section doesn't establish well?
Touch-up is simple — spray additional Flexterra with seed onto the problem area. No ripping up blankets, no re-stapling, no major re-mobilization. This is one of Flexterra's biggest practical advantages: the repair process takes minutes, not hours.
Does Flexterra work in channels and concentrated flow areas?
Yes. Flexterra HP-FHP is rated for flow velocities up to approximately 15 ft/sec in its unvegetated state. Once vegetation establishes, the combined system handles even higher flows. For severe channel applications, it can be combined with turf reinforcement mats (TRMs) for permanent high-flow protection.
Can Flexterra be applied in winter?
The product can be applied whenever the ground isn't frozen solid and rain isn't actively falling. For winter applications with dormant seeding, Flexterra protects the slope through winter and the seed germinates in spring — actually an excellent combination for projects that finish in late fall or winter. We do this regularly across Western PA.
Is Flexterra biodegradable?
Yes. Flexterra is composed of wood fibers, biopolymers, and natural materials that biodegrade over 12-18 months — timed to coincide with permanent vegetation establishment. Unlike some plastic-netted blankets that leave synthetic netting in the soil for years (a problem for wildlife and aesthetics), Flexterra leaves nothing behind but healthy, vegetated soil.
Where do you provide Flexterra applications?
TruScape provides Flexterra HP-FHP applications across the greater Pittsburgh metro area and all of Westmoreland County, including North Huntingdon, Irwin, Greensburg, Latrobe, Murrysville, Jeannette, Mt. Pleasant, and Ligonier. For larger commercial, DOT, and reclamation projects, we service a broader region of Western Pennsylvania.
Done Wrestling with Erosion Blankets?
Flexterra HP-FHP delivers better erosion control, faster installation, and lower total cost than rolled blankets — on every slope in Western Pennsylvania. Let us show you how it works on your next project.
Request a Project Consultation