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Adjustable Structural Supports Since 1951.

6x6 Screw Jack

per SJ-6
69 reviews

The Ellis 6x6 Screw Jack attaches to 6x6 lumber and provides 6" adjustment for building a fast and reliable adjustable support. It's bulky steel design allows contractors to safely support loads up to 30,000 lbs.  Use as permanent or temporary support in commercial concrete construction and structural repair jobs that require heavy duty long lasting support jacks.  

Availability: In Stock

Item #

safe load capacity

type of finish




30,000 lbs

Powder Coated

22 lb



30,000 lbs

Galvanized Finish

22 lb


Product Overview

The Ellis 6x6 Screw Jack is engineered with heavy gauge - high quality steel to yield high strength and longevity.  Our products are tested in extreme load situations to determine ultimate load capacity, however; for safety, load ratings on our site include a safety factor of 2.5 to 1 (or better)!

Demonstration Video

Ellis Screw Jack 6x6 Specifications:

  • 30,000 LB Safe Load Capacity!
  • For Vertical / Horizontal Support in permanent or temporary commercial construction, trench shoring and collapse rescue applications.
  • Galvanized or Painted Finish.
  • Use Standard with Dressed 6x6 Lumber (5.5" Sq.), cut square to any length.
  • 15-3/4" Overall Height (screwed down).
  • Full 6" Adjustment with 1.75" dia. acme threaded screw with 4 threads per inch.
  • Simply turn the "U" Shaped Handle to Adjust Height of Screw Jack. Lift up to 1800 lbs by hand or 4000 lbs. with a 2"x4"x6' piece of lumber placed between screw and handle for extra leverage.
  • Screw is Greased for easy tuning and to prevent rusting.
  • Base Plate swivels independent of the screw and 4 3/8” diam. holes are provided to secure it to a solid foundation.
  • Properly brace as required to prevent lateral shifting
  • Screw Jack is equipped with a safety lock.  Tighten safety lock with a 6mm Allen Wrench once final adjustment has been made to prevent accidental height adjustment to jack post.
  • 6x6 Heads are available for securing vertical 6x6 to horizontal beam: Purlin Splicer, Joist Holders, Pivoting, Reshore Spring.

Maximum Safe Working Loads

Total shore height including SJ-6 Maximum safe load capacity
6' 30,000 lbs.
8' 30,000 lbs.
10' 27,000 lbs.
12' 20,000 lbs.
14' 15,000 lbs
16' 11,500 lbs.
18' 8,000 lbs.
20' 6,000 lbs.

Load capacity based on actual load test results Douglas Fur #1 6x6 dressed lumber (5.5" square). Capacities include a standard 2.5/1 safety factor. Lumber must be cut square on both ends. Do not exceed recommended allowable safe load ratings in the above chart.  Do not extend screw past advertised adjustment range.

*Caution, the acme screw of the 6x6 GALVANIZED Screw Jack will completely separate from the acme nut if screwed out too far. Do not extend the acme screw past the maximum adjustment of 6". This will insure that the threads of the acme nut will be used to support a heavy load.  For maximum safe load capacity to be obtained, Ellis Screw Jack should be used with a 6x6 lumber cut to at least 5.5" long and subject to support straight loads only. We recommend tightening set screw in the side of the Screw Jack with a 6mm allen wrench prior to loading. Before construction begins it is recommended that you consult with certified structural engineer for approval of our products within your application.

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