While there are both advantages and disadvantages to a concrete slab foundation there are many more advantages than there are disadvantages providing the foundation has been laid correctly. Perhaps the biggest disadvantages are a loss of heat through the floor and the fact that access to such as electrical wiring is impossible if they are under the concrete without digging up the floor.
However as said there are far more good points when it comes to having concrete slab foundations. Perhaps the biggest plus for the concrete slab is the stability that it can provide and since foundations are all about stability, this is a huge plus and excellent reason for choosing this method above others such as footing and piers.
Solid Foundation Essential, Concrete Slab Foundation Solid as it Gets
Providing the ground on which the concrete foundation is going to be poured is dry then you will not have any problems with one of the downsides to the slab, seepage. While some shifting can occur with the concrete foundation studies have shown that the shifting is less than with other methods which of course is another very desirable feature of the slab foundation.
Perhaps one of the biggest advantages of the concrete slab is that in comparison to other foundations it is relatively cheap to install. However it is essential that you get it right the first time of pouring and that you have prepared the underlying material on which you are going to be pouring the concrete correctly. The underlying material must have been prepared and the concrete poured correctly to avoid any unevenness otherwise it could turn costly if it has to be dug up and re-laid.
Basics of a Concrete Slab Foundation
A properly installed concrete slab foundation which will be trouble free will begin with a four to six inch layer of gravel which is called the capillary break, the idea of this is the gravel will stop any seepage that does occur from reaching right through. Following this there should be a 10ml vapour barrier which is in the form of plastic sheeting and it is important that this sheeting overlaps in all directions preferably about a foot.
To keep the plastic in place you will then need a two to four inch layer of sand and this will act as a firm base for the actual concrete slab. The concrete slab foundation itself needs to be no less than six inches deep in the centre and at least 12 inches and preferably 14 around the perimeter of the room and can include wire mesh or steel rods to add to stability.
To get benefit from the concrete slab it must be poured correctly and all the components listed above are included, if any are missing then the concrete slab can be undermined. It is also essential that the concrete is left to dry correctly and that only the expected amount of shrinkage cracks appear in the concrete.
If you are moving into a home that has a concrete slab foundation then it is essential that you take the advice of a concrete engineer regarding the foundation before buying what could turn out to be a very costly mistake. This of course will cost you money but it could end up costing so much more if the foundation turns out not be solid and you have to payout for the cost of rebuilding.