JAWS RailFin Screed Support System

For 1/4" x 2" Flat Rolled Screed Rails

MADE in the USA

The MAKO JAWS RailFin Screed Support System provides fast, repeatable elevation control for concrete placement using 1/4" Flat Rolled screed rails. Designed for slab-on-grade and adjustable deck installations, the system allows contractors to set screed supports quickly while maintaining consistent grade throughout the pour.

Internal "FINS" grip the mounting structure helping prevent the chair from bouncing off during concrete placement. An ideal mounting structure is 1/2" however 3/8" or 5/8" can be used.

The JAWS RailFin is installed onto a mounting structure such as rebar, all-thread, GFRP, PVC, or conduit. For slab-on-grade placements, the MAKO Driver allows contractors to drive the support directly to finished elevation using a string line or laser reference.

For elevated placements, the JAWS RailFin can be used with adjustable stand systems to precisely position screed rails over decks or vapor barriers.

Compatible MAKO Components

  JAWS RailFin
Fast installation for slab-on-grade construction.
JAWS RailFin+ FinStand 
Adjustable support for wood or metal elevated decks.
JAWS RailFin + FinStand + Base Plate
Stable support for vapor barrier overlays.
JAWS RailFin + CoilStand 
Supports coil rod installations for deck placements.
JAWS RailFin+ CoilStand + Base Plate 
Adjustable support for vapor barrier placements.

SCREED COMPATIBILITY

  • 1/4" x 2" flat rolled screed rail
  • Supports typically installed 3–4 feet apart along the screed line.
  • Supports hand or mechanical screeds
  • The MAKO Driver does not support JAWS RailFin setup

THREADED ROD LENGTH DEPENDS ON SLAB THICKNESS 

Cut the threaded rod or coil rod based on the slab thickness using the recommended lengths from the slab depth chart. 

SLAB DEPTH RECOMMENDED ROD LENGTH
4.5" - 6.25" 2.25"
5.5" - 7.25" 3.25"
6.5" - 8.25" 4.25"
7.5" - 9.25" 5.25"
8.5" - 10.25" 6.25"
9.5" - 11.25" 7.25"
10.5" - 12.25" 8.25"

For slabs greater than 6" we recommend using a steel threaded rod instead of nylon.

Two blue and gray plastic tools with measurement labels on a white background


1-3/4" VERTICAL ADJUSTMENT

Using the nut and washers, the FinStand or CoilStand allows up to 1-3/4" of vertical adjustment, enabling precise height control and easy grade adjustments during setup.

 

 MINIMUM THREAD ENGAGEMENT REQUIRED FOR STABILITY IN SETUP

Two diagrams showing incorrect and correct ways to use a stand with a fin, marked by red 'X' symbols.

Proper setup is essential when using the FinCap or JAWS screed chairs on elevated decks or vapor barrier slabs. The threaded rod must be installed a minimum of 1" into the barrel of the screed chair and 1/2" into the FinStand to maintain stability. If these engagement depths are not met, the assembly may become unstable and move during concrete placement.

 

SYSTEM ADVANTAGES

  • Precise elevation control
  • Faster screed setup
  • Consistent grade across the pour
  • Compatible with multiple mounting structures
  • Supports adjustable deck and vapor barrier installations

 

TYPICAL APPLICATIONS

Slab-on-grade construction

Elevated slabs

Metal pan deck pours

Wood deck pours

Vapor barrier slabs

Industrial floors and manufacturing facilities

Super-flat floors requiring high FF/FL compliance