Techniques for Foundation Construction

Foundation Construction

• The live and dead loads of the house rest on the foundation. How the weight is distributed determines the functioning and life span of the building. The foundation technique is decided primarily from soil conditions since ultimately the load is transferred to the soil. Appropriate construction techniques can compensate for poor soil. Subgrade preparation and concrete mix, reinforcement and control joints are all components of the solution when choosing the right foundation type for the site.

Footing and Foundation Wall

• The footing and foundation wall is used widely in regions with freezing temperatures. Freeze-thaw action causes settling in the soil, creating potentially damaging cracks in the concrete. Footings set below the frost line avoid the risk. An additional advantage of the technique is that it creates room for a full basement. The design of this foundation is essentially a T-shaped retaining wall. The walls are placed on the footings, and the slab is poured between the walls.

Slab-on-Grade

• Slab-on-grade foundations are constructed with a single layer of concrete, several inches thick. The edges are thickened to form an integral footing, and the concrete is reinforced with wire mesh to strengthen it. The slab rests on a well-drained gravel bed. Slab-on-grade foundations are especially common where soils don't freeze. Slab-on-grade foundations are a cost-effective choice, although costs increase when conditions require the slab to be thicker with more steel reinforcement.

Insulated Slabs

• In cold climates, slabs may be insulated with rigid polystyrene board -- usually foam board -- placed against the exterior foundation wall and laid horizontally on the ground at its base. The boards retain heat from the house to keep the ground from freezing. The house has to be heated for this insulation technique. Another method of insulation is a "floating" slab. The floating slab rests on a layer of sand with rigid insulating boards placed against interior walls and underneath the sand.