What is a Crawl Space?

L. Hepfer

A crawl space is an area constructed between the ground and the bottom of a house, creating a permanent foundation and used in place of a basement. It does not have the depth of a regular basement, making it difficult for a person to be able to stand up when inside the small space.

Gravel is one of the best materials for a crawl space floor.
Gravel is one of the best materials for a crawl space floor.

This space is constructed with block walls for the home to sit on. It may also have concrete flooring, although some have gravel instead. The area can be accessed either from the outside or the inside of the home, similar to a basement, depending on what the home owner chooses when building the home. Double-wide manufactured homes, modular homes, and stick built homes can all have crawl spaces as a permanent foundation.

Crawl space mold can cause respiratory issues for people living in the house.
Crawl space mold can cause respiratory issues for people living in the house.

There are advantages and disadvantages that should be taken into consideration before deciding on a crawl space instead of a regular basement when building a home. One of the advantages is having the house off the ground, as opposed to a concrete slab foundation. This is necessary when the house is being built in a damp area or an area that may be prone to the infestation of termites. A basement keeps the house off the ground as well, but a crawl space is much more inexpensive. It also makes it more convenient to service plumbing and duct work because it is more accessible than a house with a finished basement.

As crawl spaces seldom have proper ventilation, they can be a breeding ground for mold.
As crawl spaces seldom have proper ventilation, they can be a breeding ground for mold.

Moisture is a huge disadvantage when building a crawl space, and proper precautions must be taken to avoid the damage that moisture can cause. Any water that accumulates in the space will travel upward, entering the floorboards, drywall and insulation. This can cause severe health and safety issues for those living inside the home. Properly installed insulation can keep moisture at a minimum, helping to prevent mold and health problems. A vapor barrier placed properly will create a thin concrete barrier over the gravel floor, keeping the moisture and any rodents out.

A crawl space consisting of its floor and walls fully finished in concrete is best overall. With this setup, rodents cannot burrow tunnels underground and enter the home. Concrete can also block out mold, various odors, poor air quality and keep high energy bills at a minimum.

Toxic mold can grow on any organic materials, including leather, fabrics and wood.
Toxic mold can grow on any organic materials, including leather, fabrics and wood.

You might also Like

Readers Also Love

Discussion Comments


You know, maybe I've seen too many scary movies and television shows about crime, but I don't think I could bring myself to live in a home with a crawl space. Crawl spaces are creepy, and in the movies there are always bodies or something else scary hidden down there.

Could you imagine if you had to do crawl space repair and you discovered something creepy? If you owned the house, it would be pretty difficult to move.


@indemnifyme - That makes sense. But like you said, things can go wrong with both crawl spaces and basements. As long as I lived in an area that wasn't at a very high risk for flooding, I would probably choose a basement.

At least with a basement, you can finish it and use it along with the rest of the house. I've never heard of anyone using their crawl space for anything, except maybe hide and seek like some of the other commenters mentioned.

Plus, I wouldn't want to have to worry about crawl space ventilation. It seems like crawl spaces are at a higher risk of developing mold than a plain old basement is.


I used to work in the insurance business, and based on my experience handling basement-related claims, I will probably choose a crawl space if I ever buy a house!

There are so many things that can go wrong with basements. Your pipes can back up into the basement, or your basement can flood because of a bad storm. And if the basement floods, the rest of the house is definitely going to be affected.

With a crawl space, it seems like as long as you have a waterproof crawl space barrier, the moisture will stay in the crawl space. Sounds like it would be much easier to deal with.


@Ivan83 - The crawl space freaked me out as a child, too. We could access it through vents outside, though we rarely ever did.

One time, our dog had a litter of puppies that made their way into the crawl space. The dog pen had one of the crawl space vents in it, and they tore the vent cover off and scampered into the darkness.

We could hear them running and playing under the floor of the house. It was really creepy until we realized what had happened. At first, we thought we might have a giant rat infestation down there!


The house that I’m renting has a crawl space, though I’m not sure why. It’s located on a hill, so moisture accumulation should not have been an issue. Also, the landlord has someone come and spray for termites every year, so I don’t think he built it to avoid termite infestations.

My husband and my dad crawled under there right after we moved in to install some cable. They ran it from our television set down through the floor and out of the house to the antenna. They came out covered in dirt and cobwebs, and they were glad that they were under there in winter time, when most critters were dormant.


@backdraft - There are certainly moisture liners that you could install yourself if you are pretty handy. But I would encourage you not to mess around! Home repairs are expensive but this is not an area to skimp. Mold can cause permanent problems with your home and even health problems for the inhabitants.

I would encourage you to at least have the area evaluated by a professional - someone who specializes in doing inspections for people considering buying homes. Someone who does not perform the repairs personally; that way you know you will be getting unbiased advice. The inspection wouldn't be terribly expensive and you would then known what would be the best steps to take.


We have had trouble dealing with crawl space moisture that leads to mold in the summer time. I think it has to do with moisture coming in from the roof and getting trapped in the space. Either way, we get green drips down our walls every July.

Does anyone have any ideas how we can dry that space out without having to hire some kind of professional to do it? I think any repairs we do will have to be DIY.


Growing up our family home had a crawl space. That was always the number one hiding spot for hide and seek. It was number one because everyone was afraid to look there. Imagine how scary it was to hide in there. You were liable to never be found.

Post your comments
Forgot password?