What is a Crawl Space Foundation?

Crawl space foundation

A crawl space is a foundation that is built higher than ground level. This is to protect the house from water levels or to enable someone to crawl under the dwelling for work on the foundation, piping, mechanical or any other things that may need attention. According to the National Association of Home Builders Survey, crawl space foundations account for approximately 14% of the homes in the United States. 

Sometimes people will build an open crawl space using pier footers to support the weight of the structure. Other times people will use blocks around the entire perimeter of the structure to raise the height of the floor. But the area is still a tight squeeze that is hard to get in, hard to move around in and hard to get out. The purpose of the crawlspace is to enable piping and ductwork to go through the crawl space area in the building process. It also could be a space for storage but you need to take moisture problems into consideration before storing anything that could be damaged.

In some colder clients a scratch coat (Thinner layer of concrete) is used with a vapor barrier on the floor of the crawlspace to help alleviate moisture problems that often occur. The building's officials were wise to require measures to cut back on the moisture. That has been a recurring problem in crawl space foundations. To address this situation a crawl space is required to also be ventilated. The drawback to ventilation is that it can lead to animals and insects getting into the crawlspace area.

Entrances to get into a crawl space can be the size of an attic entrance. Sometimes a 2’X2’ opening is about all that is needed.  Just because it’s a small area there still needs to be attention paid to the structural integrity of the floor joists and beams. If you don’t catch a moisture problem quickly you may have a large job trying to replace foundational wood or floor joists.

There are pros and cons to every installation procedure. One pro is that when a crawl space is open to a full basement, the warm air from the basement can find its way to the crawlspace and heat the floor of the room above. But, there is an added cost to heating the crawl space area itself. 

Pricing on crawl spaces is between the cost of a full basement and lesser cost of the slab on grade foundations. Today we see slab on grade construction going on more and more. With the advent of insulating techniques the slab on grade is fast becoming the trend in foundations other than full basements. 

Having had the opportunity to enjoy crawling in these spaces, I would prefer any other foundation. It is not pleasant when you have to crawl in one and the things you find in crawl spaces are even less pleasant. However they are a viable form of foundations that have been around for years and years.

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