Constructing a major new concrete building is a messy and complicated process, but one particular piece of equipment helps make the procedure a lot smoother; to construct concrete walls and floor slabs, the liquid material must be poured into a mould. Also known as formwork, these pieces are specially assembled to fit the needs of each part of a construction project… but it there is repetition from floor to floor, fly forms — or table forms — can be used again after the liquid concrete has cured from a previous pour.
When dealing with simpler floor layouts, usually above the more complicated ground floor or garage levels, trusses are assembled and covered with plywood. Layers of steel rebar are then placed to sandwich any electrical and mechanical lines atop the plywood, and concrete is poured to cap the floor. Once the concrete cures, sections of the truss are released and the whole form can then be pulled out, initially by the crew, and then attached to cables and hoisted — or flown, hence the term 'fly form' — by the tower crane, to repeat the job again on the next level above.
To ensure strength for the new floor while the concrete continues to cure to its full strength, temporary shoring jacks are installed for a few more weeks. The image below shows two Toronto projects, INDX Condos and EY Tower, both utilizing the fly form technique. Yellow shoring poles are visible on the top floors below the uppermost level with its fly forms, helping support the work above.
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From 2015 to 2017, UrbanToronto and its sister publication, SkyriseCities, ran an occasional series of articles under the heading Explainer. Each one took a concept from Urban Planning, Architecture, Construction, or other topics that often wind up in our publications, and presented an in depth look at it. It's time to revisit (and update where necessary) those articles for readers who are unfamiliar with them. While you may already know what some of these terms mean, others may be new to you. We are publishing or updating and republishing Explainer on a weekly basis. This article is an update of one that first appeared in 2015.
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