Made in the USA • Patented • Jobsite-Proven • Non-conductive • Non-corrosive
What Is the Adjustable JAWS® RailFin Concrete Screed Support System (without Base Plate)?
The Adjustable JAWS® RailFin Concrete Screed Support System is a bundled MAKO system designed for fast, accurate grade setting using 1/4″ flat rolled steel screed rails.
This bundle combines JAWS® RailFin Screed Chairs with FinStand® Adjustable Supports to create a stay-in-place, height-adjustable screed support system for elevated decks, sloped slabs, bridge work, and super flat floor projects. Base Plate 4.5 is NOT included. This bundle is intended for direct attachment to wood or metal decks using the FinStand fastening holes. Threaded rods (all-thread), hex nuts, and flat washers are sold separately.
Designed For
- 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
Why Contractors Choose It
- Complete adjustable flat-rail screed system (without Base Plate)
- Fast setup on wood or metal decks
- Precise grade control for sloped or elevated slabs
- Non-conductive and non-corrosive for harsh environments
- Engineered for consistent results on super flat floors
How It Works
- Set your grade. Run a string line or laser at finished slab elevation.
- Establish your screed line. Snap a chalk line for a wood deck or follow flute on a metal deck. Space supports every 3–4 feet.
- Cut your threaded rod. Cut based on slab depth. (Use steel all-thread for slabs over 6".)
- Secure the FinStand. Fasten to deck - use screws for metal deck or nails on wood deck. Be sure the FinStand sits flat and solid.
- Install threaded rod. Thread into FinStand (minimum 1/2" embedment).
- Install the JAWS RailFin. Place on rod (minimum 1" embedment).
- Adjust to height. Adjust the threaded rod in the FinStand until the top of the threaded rod sits 2.25" below the string line. A nut or washer can be added for fine tune adjustments.
- Repeat spacing. Install screed supports every 3–4 feet along the screed run.
- Set your screed rail. Place a flat rolled steel screed rail onto the JAWS RailFin supports. Typical rail dimensions 1/4" thick x 2" high x 10 ft long. The rail should now sit exactly at finished slab elevation.
- Place and screed. Strike off concrete with hand or mechanical screed, slide screed rail along screed chairs, fill the void with mud, and bull float over.
- Leave in place. JAWS RailFin assembly stays embedded in the concrete—no removal, no disruption to the slab.
Key Specifications
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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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Threaded Rod: 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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Mounting: Direct attachment to wood or metal deck
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Spacing Guideline: 3–4 ft depending on conditions
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Material: Impact-resistant medical grade polypropylene (non-metallic)
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Coverage: Approx. 3,000 sq ft per box
Full Specifications
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Includes: 100 JAWS® RailFin Screed Chairs
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Includes: 100 FinStand® Adjustable Supports
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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″ to 5/8″ (10–16 mm)
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Threaded Rod: FinStand uses 1/2″-13 all-thread (cut to length based on 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) depending on rail length and sub-grade conditions
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Minimum Assembly Height: Using a 1/4″ x 2-1/2″ flat rolled steel bar screed from the bottom of the FinStand to finished elevation is approximately 5-1/4″ (133 mm)
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Load Capacity: Holds up to 1,000 lbs (system-dependent and per product ratings)
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JAWS RailFin Feature: Internal “fins” hug rebar/rod to prevent bounce-off during placement
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FinStand Fastening: Secure to wood deck with nails or to metal deck with #8 or #10 tek screws
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Material: Impact-resistant medical grade polypropylene (non-metallic)
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Coverage: 100 JAWS RailFins + 100 FinStands 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: All-thread, hex nuts, and flat washers are sold separately. Rod length determines finished slab height (see slab depth chart)
Compliance & Approvals
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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
Additional Notes
- Base Plate 4.5 is NOT included in this bundle
- Threaded rods (all-thread), hex nuts, and flat washers are sold separately
- For slab depth and all-thread length selection, refer to the FinStand slab depth chart in the FinStand Product Data Sheet
- For slabs over 8″ (200 mm), steel threaded rod is recommended
- The MAKO® Driver is not designed to work with JAWS® RailFin chairs
Frequently Asked Questions
Is Base Plate 4.5 included?
No. This bundle does not include Base Plate 4.5. It is intended for direct deck attachment using FinStand fastening.
Do threaded rod, nuts, and washers come with this bundle?
No. Threaded rods (all-thread), hex nuts, and flat washers are sold separately.
How far apart should supports be placed?
Typically every 3–4 feet depending on rail length and sub-grade conditions.
When should I use steel threaded rod?
For slabs thicker than 8″ (200 mm), steel threaded rod is recommended.
Does the MAKO® Driver work with JAWS® RailFin?
No. The MAKO® Driver is not designed to work with JAWS® RailFin chairs.
Downloads
JAWS® RailFin Product Data Sheet
FinStand® Product Data Sheet
