Concrete101: Forming

Form work is what a cupcake tray is to cooking cupcakes-without the mold, your left with a lump of nothing. The form work is the mold for concrete and creates the shape of the concrete using a series of wood, composites or steel forms. Form work not only holds the shape of the concrete as it dries; it also bears the weight of the pressing concrete and must be built strong to resist the weight.

The basics of form work begins with the blueprints. A simple sidewalk requires a minimum of drawings and therefore a minimum of form work and materials. A complex two story stem wall requires multiple pours and deep footers, thereby requiring a complex blueprint and a complex set of forms, with multiple materials. Know your limits when doing and concrete work DIY. Remember, you can only pour concrete once, it has to be right the first time, every time and there is no exception to the rule.

With that disclaimer in mind, basic footings that adjoin to the house-like a covered carport-are best left up to the professionals. Typically any slab that bears weight or is on sloping land is going to have a footer. But if you're daring, you can request a personal walk through from Construct101. A Skype/phone consultation from a state "A" certified general contractor can walk you through the process of more complex home improvement projects like carport footings.

Slabs like a detached or abutting patio, sidewalks and driveways all require no footer and can easily be done by the average homeowner or weekend DIY aficionado. Simple sidewalks and driveways require no excavation (except for grass and surface roots).

Forms made from pressure treated 1x4's are placed on the surface of the ground and held in place with stakes. Making your own stakes is easy and can be done by ripping a 2x4 precut stud in half with a circular saw. Using a miter saw, cut four 45 (or 52 if your saw has it) degree angles one end of each half of the ripped boards; cut the other end square to length as needed into thirds or halves.

Long runs of 1x4 stock are easy to bend and curve to the landscape as needed for driveways and sidewalks, while using 2x4's work best for rigid straight lines on rectangular and square slabs. Tighter curves require different material. 1x4 pieces of hardy plank or other cementious siding boards flex quit a bit when bent at radiuses and arcs. Scoring the back of the form with vertical lines will help increase the bend into an even tighter radius.