Made in the USA • Patented • Jobsite-Proven • Non-conductive • Non-corrosive
What Is the Adjustable JAWS® RailFin Concrete Screed Support Kit?
The Adjustable JAWS® RailFin Concrete Screed Support Kit is a complete bundled MAKO system designed for fast, accurate grade setting using 1/4″ flat rolled steel screed rails.
This kit combines JAWS® RailFin Screed Chairs, FinStand® Adjustable Supports, and Base Plate 4.5® to create a stay-in-place, height-adjustable screed support system for vapor barriers, concrete overlays, sand/rock subgrades, elevated decks, sloped slabs, bridge work, and super flat floor projects.
Threaded rods (all-thread), hex nuts, and flat washers are sold separately.
What’s Included
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100 JAWS® RailFin Screed Chairs
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100 FinStand® Adjustable Supports
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100 Base Plate 4.5®
Designed For
- Vapor barrier slabs (membrane-safe Base Plate)
- Concrete overlays
- Slabs on sand or rock sub-grade
- Elevated decks (wood or metal)
- Sloped slabs and grade transitions
- Bridge decks, waterways, and power plant projects
- Super flat floors requiring FF/FL compliance
- Flat rolled steel rail screed systems
Ideal for use on super flat floors to stay compliant with ACI 302.1R-04, ACI 117, and ASTM E1155. Iowa DOT approved.
System Compatibility
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Screed Rail Supported: 1/4″ flat rolled steel rail (commonly 1/4″ x 2″ or 1/4″ x 2-1/2″)
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JAWS Mounting Range: Fits rebar or rod 3/8″–5/8″ (10–16 mm)
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Threaded Rod: FinStand uses 1/2″-13 all-thread (cut to slab depth)
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Vertical Adjustment: Up to 1-3/4″ (45 mm) using nut and washer
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Spacing Guideline: Place supports every 3–4 ft (1 m)
Key Specifications
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Minimum Assembly Height: Using a 1/4″ x 2-1/2″ flat rolled steel rail from the bottom of the Base Plate to finished elevation is approximately 5-3/4″ (146 mm)
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Load Capacity: Holds up to 1,000 lbs (system-dependent)
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JAWS RailFin Feature: Internal “fins” hug rebar/rod to prevent bounce-off during placement
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Base Plate Feature: Will not puncture vapor barrier; textured underside grips adhesives; can be secured with screws, nails, or construction glue
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Material: Impact-resistant medical grade polypropylene (non-metallic)
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Coverage: 100 RailFins + 100 FinStands + 100 Base Plates per box (approx. 3,000 sq ft / 278 m²)
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Rod Guidance: Use steel threaded rod for slabs over 8″ (200 mm)
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Threaded Rod / Hardware: Sold separately. Rod length determines finished slab height (see slab depth chart).
Compliance, Approvals & Patents
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Standards: ACI 302.1R-04, ACI 117, ASTM E1155
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Approvals: Iowa DOT approved (other states pending)
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Patents: 8,096,182 | 8,544,182 | Patent Pending
How It Works
- Place Base Plate 4.5 on vapor barrier, overlay, sand, rock, or other substrate.
- Snap FinStand into Base Plate until locked securely.
- Insert 1/2″-13 threaded rod (sold separately), cut to slab depth.
- Adjust height up to 1-3/4″ using nut and washer.
- Install JAWS® RailFin onto rebar/rod (3/8″–5/8″ range).
- Place 1/4″ flat rolled steel screed rail into the JAWS teeth.
- Space supports every 3–4 feet and begin concrete placement.
For slab depth and all-thread length selection, refer to the FinStand slab depth chart. For slabs over 8″ (200 mm), steel threaded rod is recommended.
Why Contractors Choose This Kit
- Complete adjustable flat-rail screed system including vapor barrier-ready Base Plate
- Stable setup on membranes, overlays, sand, and rock
- Precise grade control for sloped or elevated slabs
- Non-conductive and non-corrosive for extreme environments
- Engineered for consistent results on super flat floors
Frequently Asked Questions
Does this kit include threaded rod, nuts, and washers?
No. Threaded rods (all-thread), hex nuts, and flat washers are sold separately.
Can this be used on vapor barriers without puncturing the membrane?
Yes. Base Plate 4.5 is designed to sit on vapor barriers without puncturing them.
How far apart should supports be placed?
Typically every 3–4 feet depending on rail length and sub-grade conditions.
Does the MAKO® Driver work with JAWS® RailFin?
No. The MAKO® Driver is not designed to work with JAWS® RailFin chairs.
Recommended Add-Ons
- Nylon or Steel All-Thread (1/2″-13)
- Hex Nuts + Flat Washers
Downloads
JAWS® RailFin Product Data Sheet
FinStand® Product Data Sheet
Base Plate 4.5® Product Data Sheet
