Tilt up or tilt-slab is a type of building, and a construction technique using concrete. The process resembles barn raising specifically and wood platform framing generally. It is cost-effective for low buildings.
In this method modular concrete elements (i.e. walls, columns, structural supports, etc.) are formed on a concrete slab; usually the building floor, but sometimes a temporary concrete casting surface near the building footprint. After the concrete has cured, the elements are tilted from horizontal to vertical with a crane and braced into position until the remaining building structural components (roofs, intermediate floors and walls) are secured.
Tilt up construction is a dominant method of construction throughout North America, Australia, and New Zealand. It is not significantly used in the UK, Ireland, and other regions, although popularity is increasing.
Concrete elements can also be formed at factories away from the building site. Tilt up differs from prefabrication in that the moulds are designed for a specific building and usually not reused.
Tilt up construction requires significant organization and collaboration on the building site. This increases project complexity but also gives designers more control.
Next, a chemically reactive bondbreaker is sprayed on the form's surfaces to prevent the cast concrete from bonding with the form or slab, allowing the cast element to separate from the casting surface once it has cured. This is a critical step, as improper chemical selection or application will prevent the lifting of the panels, and will entail costly demolition and rework.
A rebar grid is constructed inside the forms, after the form release is applied, spaced off the casting surface the desired distance with plastic "chairs" or dobe blocks. The rebar size and spacing is generally specified by the engineer of record.
Concrete is then poured into the forms, filling the desired thickness and surrounding all steel inserts, embedded features and rebar. The forms are removed when the concrete is cured, and the element is tilted into place.
Like all concrete construction, tilt up buildings are fire-resistant. In addition, wall panels can be designed to sag inward when damaged, which minimizes collapse (this can also be done with prefabricated panels).
Some authors believe that tilt up was one of the concrete construction methods used in Ancient Rome or the ancient Middle East. Modern tilt up, made with reinforced concrete, was first used in America circa 1905. Early erection was done using tilt tables, but the development of the mobile crane and truck mixers allowed tilt up construction to grow. Tilt up gained widespread popularity in the post World War II construction boom. Tilt up was not used successfully in Australia until 1969.
Most early tilt up buildings were warehouses. Today the method is used in nearly every type of building from schools to office structures, houses to hotels. They range from single story to more than seven and can be up to 30 metres in height.
An early example of this method is found in the innovative Schindler House, built in 1922 in West Hollywood, California. Architect Rudolf Schindler claimed that with the assistance of a small hand-operated crane, just two workmen were needed to raise and attach the tilt-up walls.
Many finish options are available to the tilt up contractor, from paints and stains to pigmented concrete, cast-in features like brick and stone to aggressive erosion finishes like sandblasting and acid-etching. Shapes are also a feature that have become dominant in the tilt up market, with many panels configured with circular or elliptical openings, panel tops that are pedimented or curved, facades that are curved or segmented and featured with significant areas of glazing or other materials.
TCA offers primarily educational, networking and exposure benefits to its members. TCA also offers an Achievement Awards program annually, recognizing the best examples of tilt up construction over a variety of end uses.