6
INTRODUCTION TO FORMWORK UNIT 1
Learner Resources ATPeResources.com/QuickLinks Access Code:
FORMING MATERIALS AND METHODS
Spread footings for inverted T-shaped foundations are usually formed with 2 × 6 planks on residential projects and a minimum of 2 × 10 on commercial projects. See Figure 6-2. Planks are also used to form foundation walls in some forming systems.
Various methods are used for foundation form construction. All methods require sheathing, studs and/or walers, bracing, and a means of tying the form walls together. See Figure 6-1. With the exception of insulating concrete forms (ICFs), forms are temporary structures and should be constructed for easy dismantling. Duplex nails are used wherever practical since they can be quickly removed. Sheathing is fastened to stakes or studs with just enough nails to hold it in place. An adequate number of braces and ties should be used to keep the walls aligned and in place.
Framing and Bracing Materials A wall form is subjected to great pressure when concrete is placed. The pressure increases as the wall height increases. A fast concrete placement rate also places a greater strain on the forms.
Sheathing Various panel products may be used for form wall sheathing, including high-density overlay (HDO) plywood, Plyform®, and fibreglass-reinforced-plastic (FRP) plywood. Plyform is manufactured specifically for concrete form construction. Plyform panels are available in 1220 mm × 2440 mm (4′ × 8′) sheets and 16 mm (⁵⁄₈″), 19 mm (³⁄₄″), 26 mm (1¹⁄₈″), and 31 mm (1¹⁄₄″) thicknesses. HDO plywood, Plyform, and FRP plywood can be reused many times.
An area must be properly excavated before foundation forms are constructed.
217