While looking at the walls and ceiling of the garage, look for signs of plumbing leaks. Check the ceiling for water-leakage stains. If the garage has an overhead door, be sure to close the door and then look at the ceiling. In the open position, the overhead door will block about 25 percent of the ceiling; if there are leakage stains in that section, you might not see them. Ceiling stains are often caused by leakage from a bathroom above the area. When you do the interior inspection of the house, all the plumbing fixtures (sinks, bowls, and tub-shower) should be operated. After that portion of the inspection is completed, if the garage ceiling showed signs of past problems, you should reinspect it for indications of current leakage.
In some cases there are exposed drainpipes or water pipes in the garage. If your home is located in the northern part of the United States, the water pipes should be insulated as a precautionary measure against freezing.
Depending on the location of the sewer or septic tank, there might be a pit in the garage floor covered with a metal plate. It might contain a cleanout and trap for the house waste line. Sometimes the water inlet pipe is also located in this pit. (These items are discussed in detail in chapter 13.) Lift the cover and look inside the pit. Often the builder neglects to remove the wood framing around the sides of the pit (used as a form when constructing the open area). Because of the dampness in the pit, a wood liner will eventually rot and might be termite-infested. (This is an area where termites are often found; see chapter 8 to learn how to determine their presence.) If there is wood in the pit, it should be removed, regardless of its condition.
The bottom of the pit should be relatively dry in all but very wet weather. If the bottom contains water, it is an indication that the level of the subsurface water (water table) in the overall area of the home is high. When this condition exists, there is a possibility that during rainy periods the water level can rise and seep into the garage through the pit or through cracks in the floor slab. (Water seepage into this area is discussed in detail in chapter 11.)
Cracks in the floor slab can be caused by shrinkage or differential settlement and are usually not a concerning factor. They should, however, be sealed because they can allow water to seep into the garage. An extensively cracked or heaved floor slab is of concern because it may indicate a water problem. Heaving and extensive cracking are very often caused by water pressure being exerted on the underside of the floor slab. This condition should be evaluated by a professional.
Note whether there is a drain in the floor slab. The floor should be pitched toward that drain. If there is no drain, the floor should have a slight pitch toward the automobile entry door. This will allow water from melting snow to drain to the exterior rather than puddle on the floor. Also, the floor slab should be slightly above the level of the driveway to reduce the possibility of water entry. It should be noted that a garage at the base of an inclined driveway is always vulnerable to water penetration. (This condition is discussed in the driveway section of chapter 4.)