A crawl space, also called a storage area or cellar, is an unheated, unfinished, short-length space inside an old building, usually below the second floor and sometimes no above the first floor. The term ‘crawl space’ is also used when talking about basements that are unoccupied. A crawl space can be used for a variety of things: storage of goods, storing waste, a workshop, a garden shed or even a house-remodeling project. Typically, though, a crawl space has no utilities and is often dark, cold and damp.
Usually a crawl space has concrete walls and floors and is sealed off from the outside by a foundation or a roof above. Sometimes this is just a cement slab with a concrete slab floor. A concrete slab is simply a large sheet of cold-pressed concrete (sometimes reinforced with steel) that is used in many different applications to seal and protect openings and cracks. Concrete slabs can be used in many different situations, including: garages and driveways, patios, pool decks and walkways, pools, hot tubs, garages, workshops, as well as crawl spaces. It’s also possible to pour a concrete slab directly into a concrete pit or hole – known as a ‘pit hole’ – to seal and protect a pre-existing pit.
When a slab is used in a crawl space, it provides a barrier against moisture infiltration, but does not provide insulation. Moisture can penetrate through gaps in a slab and will eventually find its way into the building, creating humidity problems in the air. This will then encourage mold growth in the walls and other areas of the building. It’s not known whether the moisture that leaks into a crawl space comes from condensation on the exterior of the foundation or from infiltration of water through the soil beneath the foundation wall.
Mold growth in crawl spaces that are sealed and covered with a slab will likely have a negative impact on the structure of the home as well as the health of the occupants. It’s not known yet whether the moisture that leaks in crawl spaces leads to the formation of mold but the potential for basement mold is real. The moisture that leaks in crawl spaces eventually reaches the interior of the house through windows, doors and floorboards. Even poorly insulated walls are likely to contribute to moisture problems in the home.
If a leak is detected and repaired quickly, the problem may not be resolved. In some cases, it may be necessary to remove the concrete slab on the outside of the crawl space and reconstruct the basement on the same site. Other times, waterproofing the perimeter of the space and installing drains and dehumidifiers will be enough to solve the problem without the need to replace the entire house.
One thing to keep in mind about crawl spaces is that there are several different types of molds that can be found on earth beneath your foundation walls. While most are harmless, others may present a serious problem. Black ants are common indoor visitors to the crawl space and can do damage to drywall and wood framing. Earthworms are a pest that can also affect wood framing. Mold, on the other hand, can lead to serious structural damage. With this in mind, it’s important to have a thorough inspection of the basement twice a year, and be ready to tackle problems like black ants, termites and mold as they arise.