You probably already know if your home has a crawl space. Some of the most common types of houses that feature crawl spaces include: manufactured homes, prefab homes, modular homes, traditional or older homes. If your home has a crawl space, it may extend beneath the entire floor plan of your house and is likely accessible from the outside. In some cases, your crawl space may only extend below part of your house, especially if your home is built on a grade or has a partial basement. The best and only way to measure the size of your crawl space is to get into the space itself. This is also the most effective way to ascertain the extent of a potential rat, mouse or pest problem in your crawl space. This is best done by a professional, but some homeowners are comfortable checking for themselves.