The foundation of a home is a particularly important area to inspect. The foundation is the main support for the home. If there are problems with the home's foundation, repairs not caught early may become extremely expensive.
The supporting structure of a home is mainly configured in three different ways. These three arrangements have similar features like concrete footings that support the home's weight, yet also differ greatly and need to be looked at on an individual basis.
Illustrated here is a "pad style foundation". This style of support system is built using concrete reinforced with steel rebar rods laid deep into the ground. Over the footings rests the home's foundation, which is made of concrete rebar. Tied into the foundation is the home's concrete-rebar slab, which supports some weight but is not designed to be a supporting feature in the home. When this type of home is built its footings, foundation, and slab are poured at the same time creating one solid piece. Note that the footings and foundations do extend into the center of the home, under the main weight bearing walls.
The next home was built over a crawl space. This style of support structure is consistent with the pad style, in that it is built with concrete-rebar footings and a cinderblock foundation reinforced with rebar. The difference is that the home is slightly elevated and the main floor of the home is built overtop of wooden joists, instead of a concrete slab. The wooden joists extend from foundation point to foundation point.
The last style of support structure we will look at is a home built with a basement having both a concrete slab and an enlarged crawlspace. Concrete-rebar footings are poured and cinderblock reinforced with rebar is used to build the foundation, which becomes the basement walls. A cement slab is poured at the bottom of the foundation, which is now the basement floor. The 1st floor of the house rests on the wooden joists that extend from foundation point to foundation point.
Though your cursory inspection of the foundation is very limited, it is important to look as close as you can. Problems with the foundation will affect many other areas of the home, and the costs of repairs will grow rapidly. Taking the time to look for clues throughout the house, should give you an indication of the homes overall soundness, saving you both time and money. During your inspection, if problems are discovered with the foundation only a licensed structural engineer can give you a written certification to the foundations soundness. Home inspectors cannot provide this service, so do not be fooled into having a home inspector certify structural problems.
Begin your inspection in the main areas of your home. Bound doors and windows, along with cracked walls are often indications of unseen ailments beneath your feet. Make a walking inspection of the perimeter of your home. The exposed foundation is usually the small inset band of concrete or masonry at the bottom of your house. Look along this band for any cracks, water damage, or crumbling, paying attention to any clues that can be found.