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Building with Tilt-Up | Frequent Questions

FAQ: General Questions

The TCA Technical Committee provides answers to common questions about Tilt-Up construction as well as some tips and techniques.

 

What is the typical thickness of a panel?
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.
What is the minimum size building that is economical?
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.
What is the minimum height building that is economical?
Panels up to 96 feet in height have been used in some areas, but special cranes and spreader bars are required for panels over 30 feet in height. It is generally better to have the panels all nearly the same height and less than 30 feet.
Are there any limits to the number or location of openings?
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.
What size crane is needed to lift the panel?
It is best to let the crane company determine this, based on the size and weight of panels involved. A rule of thumb for the size, however, is two to three times the weight of the panel.
Are there any site conditions that limit Tilt-Up?
Yes, the following should be considered: Access by the crane to the job site. Relatively flat terrain to allow the crane operation. Any power lines, ditches, railroad tracks, or other obstructions which limit crane operation. Other buildings very close to where panels must be placed.
What really holds the Tilt-Up panels in place?
The roof structure acts as a diaphragm to horizontally support the wall at the top, and the curb on the footing supports it laterally at the bottom. The panels are generally not connected together to allow for expansion and contraction without cracking. The panels are only positively connected to the roof at their centers near the top.
What information is needed to bid a building, and how long does it take?
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.
What information is needed to design and detail a building, and how long does it take?
The finalized floor plan, the soil report and decisions on all the bid options are needed, along with any planning commission requirements. With this information, the design and detailing for plans to submit to the building department will take a minimum of four weeks.
How do you insulate a Tilt-Up wall?
Tilt-Up, much like most structural envelopes can receive insulation on the inside through the use of furring systems or the outside with EIFS. The most effective method of insulating Tilt-Up walls, however, is the method known as "sandwich". This method is placing a layer of insulation between a structural concrete layer and an architectural or non-structural concrete layer during the casting of the panel and then tilting this entire construction as a panel. This method is made possible by structurally connecting the two concrete layers through the insulation layer. As soon as the panel is erected to final position, the inside layer becomes structural and load-bearing, while the outer concrete layer is suspended from it to allow for temperature changes without cracking. It is critical that these two layers remain independant from each other except for the connection through the insulation. TCA Member Companies that supply these sandwich systems include Composite Technologies Corporation and Owens Corning.
What is the fire resistance of a Tilt-Up panel?
The fire resistance of Tilt-Up walls is easily referenced and/or calculated in the current UBC and IBC codes. Fire resistance is related to an R rating that determines time duration based on the thickness and type of material. Whether a solid concrete panel or an insulated sandwich panel, Tilt-Up fire resistance can be determined with little effort.

The following table is reprinted from the data contained in both the UBC and IBC codes. It shows the relative thickness required for each aggregate type to meet the listed fire resistivity rating.

Fire Resistance of Single-Layer Concrete Walls
(UBC/IBC Tables)

 

1 hour

1½ hour

2 hour

3 hour

4 hour

Aggregate Type

Minimum equivalent thickness (inches)

Siliceous

3.5

4.3

5.0

6.2

7.0

Carbonate

3.2

4.0

4.6

5.7

6.6

For more information on fire rating Tilt-Up concrete panels order the TCA Fire Resistance Reference Topic (link to our Resource Order Form).

Additional references can be found in Concrete Technology Today from the PCA in Vol. 23 No. 1 on page 4 and in Vol. 24 No. 3 on page 5.

About the TCA

Founded in 1986, the Tilt-Up Concrete Association (TCA) strives to improve the quality and acceptance of site-cast Tilt-Up construction, a method in which concrete wall panels are cast on-site and tilted into place. Tilt-Up construction is one of the fastest growing industries in the United States, combining the advantages of reasonable cost with low maintenance, durability, speed of construction and minimal capital investment. At least 10,000 buildings, enclosing more than 650 million square feet, are constructed each year using this construction method.

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