Made in the USA • Patented • Proved Worldwide
What Is JAWS® Small Screed Chair?
JAWS® Small screed chair is a stay-in-place concrete screed chair designed to support 2x4 wood screeds and aluminum, magnesium, or steel screed rails up to 1-1/2″ (40 mm) wide.
The patented JAWS® “teeth” securely grip the screed rail during placement and release easily as you move down the pour line.
Designed For
- Slab-on-grade construction
- Elevated slabs
- Concrete overlays
- Vapor barrier slabs
- Bridge decks and infrastructure projects
- Super flat floors requiring FF/FL compliance
- Industrial and commercial flooring
Why Contractors Choose It
- JAWS “teeth” hold rails securely yet release easily
- Will not bounce off rebar or rod during placement
- Works with 2x4 wood screeds and metal rails
- Virtually indestructible under normal placement conditions
- Non-conductive and non-corrosive for extreme environments
How It Works
- Set your grade. Run a string line or laser at finished slab elevation. When using the MAKO Driver with the JAWS Small Screed Chair and a 2x4 wood rail (actual height 3-1/2”) lower the string line 1.6 inches below finished slab elevation. This adjustment compensates for the extra height of the 2×4 so the top of the screed aligns with finished slab elevation. Be sure to confirm the actual height of your rail compared and calculate string line or laser heights.
- Choose your mounting structure. Use 1/2" rebar, all-thread, or similar (3/8"–5/8" also works). The internal fins in the chair grip the mounting structure and hold it in place.
- Load the assembly. Insert mounting structure into the JAWS Small, then place the MAKO Driver over it.
- Drive to height. Drive with a mallet until the Driver marker aligns with the string line. Now your screed supports are set at the proper height to accept the screed.
- Repeat spacing. Install screed supports every 3–4 feet along the screed run.
- Set your screed rail. Place 2x4 lumber or 1.5" screed rail on the JAWS Small. The top of the rail is automatically at finished grade. (A 1-1/2” ID screed pipe works as well but the stringline needs to be adjusted.)
- 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 Small stay embedded in the concrete—no removal, no disruption to the slab.
Key Specifications
-
Supports: 2x4 lumber or aluminum/magnesium/steel rails up to 1-1/2″ wide
-
Fits Mounting Structures: 3/8″–5/8″ (1/2″ recommended)
-
Overall Height: 3.50″
-
Minimum Height (2x4): 5-1/4″ (133 mm) to finished elevation
-
Spacing: 3–4 ft depending on conditions
-
Installation Tool: MAKO Driver
-
Material: Impact-resistant medical grade polypropylene
- Made in USA
Frequently Asked Questions
What rails does JAWS Small support?
JAWS Small supports 2x4 wood screeds and aluminum, magnesium, or steel rails up to 1-1/2″ wide.
What mounting structures can be used?
Fits mounting structures from 3/8″ to 5/8″ including rebar, threaded rod, stakes, dowels, PVC, or conduit.
How far apart should supports be spaced?
Typically every 3–4 feet depending on rail length and sub-grade conditions.
Can JAWS Small be left in the slab?
Yes. JAWS Small is a stay-in-place form made from medical grade polypropylene and will not corrode.
Can it be used with hand or mechanical screeds?
Yes. JAWS Small works with both hand and mechanical screeds.
Downloads
JAWS Small Product Data Sheet
