Advantages and Disadvantages of Concrete Slab Foundation

What is Concrete Slab Foundation

A concrete slab foundation is basically a layer of concrete that is poured over a prepared surface of soil or gravel over which a structure of a building is constructed. It is more suited for climates that don’t have issues of freezing or thawing of ground and the connected movement of soil. So, these are frequently employed in warmer climates, thus negating the requirement of heat ducts beneath the floors. They are most often used in areas comprising of clay soil. However, slab foundations are securely anchored to the ground to prevent damage to the structure due environmental reasons like severe weather or shifting of soil. 

The purpose of slab foundation is to distribute weight that is kept over it, thus providing a flat, level and stable surface. For instance, some walls are load bearing and in the absence of a foundation of some kind to rest upon, would sink into the soil to some extent and respond to movement of soil. It is for this reason that the soil underneath the slab foundation needed to be prepared prior to pouring concrete. The soil is generally leveled and overlaid with gravel and humidity barriers. A number of factors including the load the slab would need to bear need consideration for calculating the thickness of slab.

Advantages of Concrete Slab Foundation

Slab foundations have many advantages that include:

• The main advantage of slab foundations is the cost. It is the least expensive foundation option available. It helps keeping the cost of labor, excavation and forms to the minimum. Its cost is considerably less than making a full basement or even crawl space beneath the building.
• They are robust. The structure rests straight on the poured concrete and doesn’t depend on beams or other supports for sustaining the structure.  
• There is no problem of termites.  In case of concrete slab foundation, there won’t be any wood touching the ground which is very likely to be exposed to termites.
• They offer superb solution for tract homes because of their cost effectiveness.
• Slab foundations are first class for flooring in case of sheds, garages or barns.
• These can be made faster that other kinds of foundations.

Disadvantages of Concrete Slab Foundation

Despite the advantages they offer, slab foundations also have some disadvantages that need to be considered: 

• You can’t access the area beneath the slab for being used for utility lines and cable work. 

• There is apprehension of the building getting flooded in case the slab foundation is positioned at a low elevation.
• Since the building rests on poured concrete slabs, it is not feasible to extend the building.
• Over a period of time slab foundations would settle and pose problems of the reliability of the building.
• Cost of heating houses with slab-foundation is generally higher as a lot of cold enters the house through the floor.
• Water and natural gas lines which are laid at the time of pouring the slab will finally break down over time and necessitate replacement. These pipes need to be checked regularly for signs of a leak. The signs include drop of water pressure, dampness on floors and exterior walls getting discolored. Alternatively, these must be run on walls, incurring additional expense of securing and weatherizing.