In some areas of the country, with deep layers of expansive soil, in-ground piers are used to support the grade beams of foundations. Wafflemat can be used to create voids under the slab and between the grade beams of this type of foundation, thereby completely isolating the slab from the underlying expansive soil. Note that Wafflemat can be used as a direct substitute for carton forms that are used to form voids.
Wafflemat With Structural Slab On Piers
Some areas in the US have deep expansive soil that will often require the use of a deep foundation design using drilled concrete piers, with concrete beams interconnecting the tops of the piers, with a flat slab on grade tied to the beams, and with replacement of some of the underlying expansive soil to reduce the potential vertical rise of the expansive soil. The result of this design is that the upward forces of soil expansion are transmitted directly to the underside of the thin floor slab.
Using Wafflemat with this foundation design provides voids in the slab for absorption of the volume change of expanding soil. The closely spaced ribs of the Wafflemat System also provide a more rigid floor than the thin floor slab.
Structural Slab On Piers:
Using Wafflemat With Structural Slab On Piers
|With Wafflemat:||Without Wafflemat:|
|Absorbs volume change of expansive soil,thereby reducing uplift forces||Expansive soil pushes the foundation upward|
|Much more rigid floor slab||Thin flexible floor slab, more easily subject to cracking|
|Non-expansive fill is usually not required||Non-expansive fill is used to attempt to reduce uplift forces of expansive soil|