Source:  Tilt-Up Concrete Association
www.tilt-up.org/faq

• What is the typical thickness of panel?
• What is the minimum size building that is economical?
• Are there any limits to the number or location of openings?
• What information is needed to bid a building, and how long does it take?
• Will the crane damage the floor?
• What is the best method to form panels?
• What are the recommended tolerances for the panels?
• What are the safety factors for lifting and bracing inserts?
• At what phase of the job should I plan the erection sequenced?
• What wind velocity should panels be braced for?
• When and how should braces be removed from panels?

The minimum thickness for commercial walls is generally 5½ inches with 7¼ inches the most typical thickness reinforced with 1.3 to 2.5 psf of reinforcing.

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Some as small as 5,000 square feet can be economical, if they are relatively tall. Several small buildings clustered together may also prove economical. Special finishes on the walls, such as exposed aggregate or form liners may make Tilt-Up an economical choice.

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There is no real limit to the number or location of openings, but their location can be critical. Openings closer than the minimum from the end of the panel supporting a concentrated roof load can add considerable reinforcing, thickened concrete or steel columns. The minimum distance is one-eighth the eave height, or two feet, whichever is less.

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With the preliminary floor plan, desired height, wall finishes, mansards, type of roof, preliminary soil report and building code jurisdiction may permit it to be completed in a week.

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Not if it has been properly constructed with the correct sub-grade and compaction. The crane should extend outriggers when lifting heavy loads, and use rolling outriggers when driving with heavy loads. The crane should not be allowed to get near the edge of the slab, especially when deep fills are used.

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The edge forms are usually of wood with a bracket or wooden block periodically connected to the floor. These brackets are spaced to reduce deflection in the edge forms during placement. These brackets are glued, nailed, or bolted to the floor, depending upon the acceptability of the required patching to the owner.

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The tolerances for Tilt-Up construction supported by the TCA can be obtained from the THE TILT-UP CONCRETE ASSOCIATION’S GUIDELINE SPECIFICATIONS in Standard 3-part CSI Format as found in section 1.6.  Tolerances in this section address the following:

• Height & Width of Basic Panel
• Thickness
• Skew of Panel or Opening
• Openings Cast Into Panel
• Location/Placement of Embedded Items
• Deviation of Concrete Reinforcing Steel Cover
• Joint Width Variation
• Joint Taper and Panel Alignment

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The Federal OSHA and American National Standards Institute use a two-to-one safety factor inclusive of all loads for Tilt-Up, and a four-to-one safety factor for precast lifting inserts. Bracing inserts do not have a standard, but manufacturers and designers normally Up one-and-a-half-to-one or two-to-one.

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Before the panels are cast, have the crane company representative assist in the layout to ensure that the panels can be lifted in the sequence cast.

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Most panels are designed for a 70mph wind in accordance with the TCA's GUIDELINE for TEMPORARY WIND BRACING of TILT-UP CONCRETE PANELS DURING CONSTRUCTION.

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The panel should be removed after the roof connections and/or diaphragm are completed. Braces should be disconnected from the floor first, and then carefully disconnected at the top and lowered to the ground. If they are dropped or allowed to slide down the wall, they may be damaged.

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