Jahn® Forming System
PROPER "A" BRACKET INSTALLATION
INSIDE WALL PANEL ERECTION
INSIDE CORNER FORMING, OUTSIDE CORNER FORMING
INSTALLATION OF JAHN CORNERLOCK
INSTALLATION OF STRONGBACKS
JOINT COVER DETAILS
INSTALLATION OF SECOND LIFT OF PLY
Bracket is made of high strength steel with a cadmium plated eccentric and painted body which is rust resistant. Designed for use with single 2x4 waler. Can be installed either before or after walers are in place. Can be used for any type of wall forms and may be used repeatedly.
Jahn C® bracket is used to attach vertical strongbacks for form work alignment. Designed for use with single 2x4 walers and 8-1/4" end. Eccentric securely holds form work while compensating for minor variations in lumber sizes. Bracket can also be used to support a horizontal plywood joint.
The Jahn cornerlock is used at outside corners to secure the 2x4 walers. Only two nails are needed for attachment, while barbed plates grip the side of the 2x4's for positive non-slip action. The locking handle has a "Cam Action", drawing the walers together at true right angles. No special tools are needed for either installation or stripping.
JAHN® TIE EXTENDER
Converts short end snapties to standard end snapties. With the Jahn® C bracket and 2x4’s, vertical strongbacks are possible at any point in the form.
JAHN® Scaffold Jack
The all steel unit designed to fit 24"x24", 16x24" tie and waler spacings. This jack has a built in guardrail receptacle and is designed to hold two 2x10 planks for a comfortable working platform. Space jacks at 8'-0" maximum centers.
Note: Snapties are not designed to carry scaffold bracket loads.
Designed for use with a single 2x4 strongback for vertical form alignment, this liner clamp can be installed after erection of the forms and is not limited by form-tie spacing. Sturdy, galvanized construction reduces maintenance and replacement, and speedy installation reduces forming costs. Strongbacks are used to align and not to strengthen forms. They are normally used on one side only, spaced 6' horizontally. Liner clamps should attach the strongback to every other single waler.
The steel tie holder is fabricated from high carbon steel and heat treated for added strength. Easily installed and removed; will not turn or fall off.
A thin, strong clip used primarily for adding extra height to form panels. A common use of the Panel Clip is as an aid to setting standard narrow filler panels horizontally on the top of a wall of form panels. Standard wall ties can be used to tie the wall at the joint between the fillers and the normal wall panels. 50 pieces per carton.
Unsafe toenail connections can be eliminated and waler lumber saved by using this bracket. Fasten to studs with double head nails, insert walers and secure with Steel Wedge. Normal spacing 4' on center. Available in one size for 2x4's.
Gang drilling the plywood is the only preparation required. Holes need to be drilled 1/8" larger than the snap tie head. Normally a 9/16" diameter drill bit will be required. We recommend you drill a maximum 5 plywood panels.The 5/8" take-up of the eccentric on the Jahn "A" Bracket allows a snap tie with a L&W dimension of 4-3/4" to be used with a 5/8" or 3/4" plywood. The 5/8" take-up on the "C" bracket allows it and 81/4" snap ties to be used on 5/8" plywood.
Snaptie Spacing and Rate Placement:
The most common snap tie spacings being used with the Jahn Forming System are shown below. For different rates or pour and/or other tie spacing, contact Masons Supply. Refer to the back cover for addresses and phone numbers.
Plywood Used Strong Way (Face Grain Parallel to Spacing)
Notes: The above recommendations are based on the use of 3/4" Plyform Class I, and 2x4 S4S studs (Douglas Fir-Larch, Southern Pine or equal having a minimum allowable fibre stress of 1,200 psi). Design is based on all formwork members being continuous over four or more supports. Normal weight concrete made with type 1 cement, no admixtures or pozzolan, slump no more than 4 inches and vibration limited to 4 lineal feet or less.
Good forming practices require that a level footing be used as a starting point for all forming applications. Snap a chalk in back of the plywood thickness and nail down a 2x4 plate.
Plywood Panel Erection:
Erect, plumb, nail to plate and temporary brace the first sheet of plywood.
Erect additional sheets of plywood by nailing them to the 2x4 plate and temporary wood cleats at the top corners. Make sure the joints are tight. If panels are to be stacked, ensure that the panel tops are level.
Installation of Snapties and "A" Brackets:
Place the ends of the Snapties through the holes in the plywood. The 43/4" L&W Snaptie, Standard is recommended for use with the Jahn "A" Brackets, 5/8" or 3/4" plywood and 2x4 wales.
Two workmen can install the snap ties with speed and economy. One inserts the tie through the tie hole and the other attached the "A" bracket.
Proper "A" Bracket Installation:
Installation of Wales:
Install the Walers into the brackets working from top to bottom of the panel and tightening the eccentric as you go. Waler joints should occur at a bracket or a scab should be utilized to reinforce the joint (see sketch).
(Without Waler In Place)
1. Place the "A" bracket on the tie end by slipping the tie end into the slots in the bracket.
2. Rotate the eccentric loosely over the tie end.
3. Drop 2x4 waler in place. Seat 2x4 with hammer, if neccessary.
RETURN TO TOP
(With Waler In Place)
1. Slip the back slot in the bracket body over the tie directly behind the head.
2. Push the bracket toward the plywood until the tie head emerges through the front of the bracket.
3. Rotate the eccentric over the tie head and tighten.
RETURN TO TOP
Inside Wall Panel Erection:
The inside panel sequence is the same as the outside panel described above except for the placement of the plywood panels over the tie ends. This can be accomplished by two workmen by starting at the bottom and moving the panel from side to side and up and down to align the snap ties with the holes in the plywood.
Inside Corner Forming:
No special treatment is required for inside corners other than the alternating of the wales as shown in the sketch. It is advantageous to start the inside corners with full size plywood panels to facilitate forming the outside corners.
Outside Corner Forming:
Install the first outside panel in line with the first inside panel. Filler panels, the same thickness as the wall plus the plywood thickness, are then used to fill out the exterior corner.
Installation of Jahn® Cornerlock:
The cornerlock eliminates costly overlapping and blocking of the wales. Its cam action draws the wales securely together. Place one wale flush at the corner and let the other extend past the flush one. Slip the cornerlock into place with the handle perpendicular to the wale. Nail the cornerlock in place and rotate the handle 90° toward the wale. A snug, tight outside corner is a accomplished.
Installation of Strongbacks:
Strongbacks are used to aid in form alignment and to tie stacked panels together. Loose 2x4's are used in conjunction with Jahn "C" Brackets and 81/4" L&W snap ties or 43/4" L&W snap ties with the Jahn Tie Extenders to strongback the forms. Normal strongback spacing is 8'-0" on center.
Joint Cover Details:
Alternate A - Drill 9/16" diameter hole 11/8" down from top edge of the lower sheet of plywood. Install snap tie, "A" Brackets and wale and then the upper sheet of plywood. Nail the upper sheet of plywood to the wale.
Alternate B - Install snap tie in the joint between the panels. Add double wales and a "C" Bracket.
Alternate C - Nail 4x4 wale to lower sheet of plywood, hold the wale in place with strongbacks and add upper sheet of plywood.
Lift the plywood sheet and place it into position. Hold the sheet in place with a short 2x4 spacing block, snap tie and "C" Bracket placed toward the top of the panel and nail the bottom of the sheet to the joint cover wale.
Set additional panels by nailing them to the joint cover wale and securing them to the previous panel with a small wood cleat.
Install the snapties, brackets and wales - working bottom to top.
Note: Snap ties are not designed to carry scaffold bracket loads.