Rip Rap Rock (RSP) — Caltrans Rock Slope Protection
 
Our Rip Rap Rock (RSP) is a heavy, angular quarry stone supplied in accordance with Caltrans Rock Slope Protection (RSP) specifications, designed for long-term erosion control, slope stabilization, and hydraulic protection applications.
 
RSP rock is classified primarily by individual rock weight, not by sieve size, making it suitable for projects where resistance to water velocity, scour, and slope movement is critical. These materials are commonly specified for channels, embankments, creek banks, outfalls, levees, bridge abutments, and steep slopes.

Caltrans Rock Slope Protection (RSP) Classifications:
Under Caltrans Standard Specifications (Section 72), Rock Slope Protection (RSP) is classified by individual rock weight, not nominal size. Each class is engineered to resist specific hydraulic forces, flow velocities, and slope conditions.
 
Below are the commonly specified RSP classes and their typical field-applied weight ranges:
No. 2 Backing ~10 – 100 lbs.
Applications: Bedding and backing layer beneath primary rip rap
 
No. 1 Backing ~30 – 200 lbs.
Applications: Filter and transition layer for larger RSP
 
Light (Facing) ~50 – 500 lbs.
Applications: Light-duty slope facing and low-energy channels
 
¼-Ton RSP  ~100 – 700 lbs.
Applications: Creek banks, drainage channels, embankments
 
½-Ton RSP ~200 – 1,000 lbs.
Applications: Moderate-energy channels and slope protection
 
1-Ton RSP ~500 – 2,000 lbs.
Applications: High-flow areas, outfalls, erosion control
 
2-Ton RSP ~1,000 – 4,000 lbs.
Applications: Severe erosion, levees, steep slopes
 
4-Ton RSP ~2,000 – 8,000 lbs.
Applications: High-velocity flow, bridge scour protection
 
8-Ton RSP Up to 16,000+ lbs.
Applications: Critical infrastructure & extreme hydraulic forces
 
Rip Rap Rock Size Ranges:
While Caltrans RSP is classified by weight, contractors and inspectors often need a practical understanding of stone dimensions for placement, equipment selection, and access planning.
 
Below are typical size ranges observed in the field for each RSP category. Actual dimensions may vary based on rock shape and density, but all material falls within Caltrans-acceptable limits for the specified class.

RSP Categories:
Backing / Light RSP
~3"–6" up to 6"–12"

¼-Ton to ½-Ton RSP
~9"–18" up to 12"–24"

1-Ton RSP
~18"–30"

2-Ton RSP
~24"–36"+

4-Ton & Larger
~36" and larger (multi-foot boulders)
 
Physical Characteristics
All Rip Rap Rock (RSP) supplied by North Bay Materials exhibits the following characteristics consistent with Caltrans requirements:
Angular to sub-angular shape for interlocking stability
High density and durability to resist abrasion and breakdown
Minimal flat or elongated pieces, reducing movement under flow
Free of clay, silt, organic matter, and friable material
Resistant to weathering, freeze-thaw, and hydraulic forces
These physical properties ensure that RSP material remains stable under repeated wetting, high-velocity flow, and long-term exposure, making it suitable for permanent erosion-control installations.
 
Placement & Installation Considerations:
Proper performance of Rip Rap Rock (RSP) depends on correct preparation and placement in accordance with Caltrans project specifications.
Subgrade must be properly shaped, compacted, and stable
No. 1 or No. 2 backing rock or geotextile fabric may be required to prevent soil migration
Rip rap is typically placed individually, not dumped, to achieve proper interlocking
Stones should be seated firmly with minimal voids and free from segregation
Installed thickness is commonly 1.5× the maximum stone size, unless plans specify otherwise
Final placement and acceptance are governed by approved plans and inspection requirements.
 
Ordering, Weight & Delivery Areas:
Rip Rap Rock (RSP) is sold by the ton and supplied in Caltrans-compliant weight classes, from backing rock to multi-ton boulders.
Sold by weight, not by cubic yard
Individual stone weights vary by RSP class
Larger classes may require equipment access for placement
One RSP class per load is recommended to prevent segregation
 
Local Delivery Service
North Bay Materials provides bulk rip rap delivery throughout:
Marin County
Sonoma County
Alameda County
Contra Costa County
San Francisco
San Mateo County
Delivery method (dump truck or end-dump) depends on stone size, site access, and placement requirements. Please confirm clearance, dump area, and equipment availability prior to delivery.
 
Rip Rap Rock (RSP) – FAQs
Q. Is this rip rap Caltrans compliant?
Yes. Our Rip Rap Rock (RSP) is supplied to meet Caltrans Rock Slope Protection (RSP) requirements when ordered by specified class.
 
Q. Is rip rap sold by the yard or by the ton?
Rip rap is sold by the ton. Caltrans RSP is classified by individual rock weight, not volume.
 
Q. What RSP class do I need for my project?
RSP class depends on slope, flow velocity, and design requirements. Refer to project plans or contact us for assistance reviewing specifications.
 
Q. Do I need backing rock under rip rap?
Many Caltrans designs require No. 1 or No. 2 backing rock or geotextile fabric to prevent soil migration. Always follow project plans.
 
Q. Where do you deliver rip rap?
We deliver throughout Marin, Sonoma, Alameda, Contra Costa, San Francisco, and San Mateo counties.