Robert Akin patented the tilt-slab method of concrete construction used in the construction of the Schindler House. 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 more than 29 metres (96 feet) 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. The first tilt-up built home in Ontario, Canada was built in 2017. Appearance Early tilt-up architecture was very minimalist and boxy. Recent techniques have expanded the range of appearance and shape. 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. Association The Tilt-Up Concrete Association (TCA) is the international trade association for tilt-up concrete construction. TCA is a membership-based association, with nearly 500 members worldwide. TCA members can be contractors (general contractors or tilt-up subcontractors), engineers, architects, developers, consultants, suppliers, specialty trade firms, educators and students. 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. Risks In the wake of the 2011 Joplin tornado in which seven people were killed in a Home Depot when the panel walls collapsed after the store was hit by an EF5 tornado, engineers in an article published in The Kansas City Star criticized the practice. They said that once one wall falls, it creates a domino effect. Twenty-eight people in an un-reinforced training room in