The two most common types of foundations found in central Oklahoma are conventional footing and stem wall ("conventional" for short) and post-tension slab and foundation ("post-tension" for short).
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There are pros and cons to both approaches, so be sure to ask plenty of questions when buying or building a house.
Here are some things to look out for.
With a conventional foundation, you have a trench in the ground at least 18 inches deep and anywhere from 18 inches to two feet or more wide.
Two to four bars of reinforcing steel, commonly called rebar, are suspended in the trench and then it's filled with concrete to form a continuous solid beam of reinforced concrete around the perimeter of the home. This beam is called the footing or footer, and it creates the foundation of your home.
Next, a formed concrete wall, called a stem wall, is poured on top of the footing. The stem wall typically isn't reinforced with steel because it's not subjected to the movement or expansion of the soil underneath like the footing is.
After that, the under-slab plumbing gets added and then the interior area of the concrete floor, commonly referred to as the slab, is poured. The concrete slab isn't physically attached to the stem wall, so it's commonly known as a floating slab.
With a post-tension foundation, the contractor digs the perimeter trench in much the same way as in the conventional foundation. The contractor places form boards around the perimeter to define the shape of the house and the plumber installs the under-slab plumbing before any steel is added or concrete poured.
Rebar and fill sand are used in a similar way as conventional foundation, but a post-tension foundation also includes steel cables that form a grid pattern across the entire slab. They cables are encased on special sleeves that prevent them from binding the to concrete when it's poured. The concrete for the footing, stem wall, and slab is poured at one time, which is called a monolithic pour.
Once the concrete has cured, a hydraulic cable tensioner is used to pull about 20,000 pounds of tension on the grid of cables, which are then anchored into the concrete. The force of the cables puts the entire slab and foundation under a continuous compression load, which means the slab and foundation becomes effectively one unit
So which foundation is the better option? They're both good options. As long as the pros and cons are well understood and taken into account by the builder, either type of foundation should serve its purpose well into the future.
A home builder for 18 years, Tim is the "son" in Turner & Son Homes. He is the CEO of the company and partners with his dad, Ben, who has been building since 1964.
The current home on our property has been in existence for over 80 years. We love our property, and made our decision to build our new house there. Turner and Son was the first company we considered and we didn't have to look any further.
The Wells family
March 9, 2016