Can You Fill A Crawlspace?

A crawlspace is a common foundation type for houses in dry climates and on a topographic slope. Crawlspaces have many practical advantages over other foundation types due to the space they leave between the house and the natural grade line; however, this space can sometimes cause some issues for the house owners.

You can fill the space of a crawlspace foundation, but it is not recommended at all. Crawlspaces provide many benefits, and filling it would defeat the purpose of the foundation and add even more problems for your home.

Read on if you’d like to learn more about crawlspaces, their pros and cons, the common problems that arise from having a crawlspace, and the solution to these problems.

What is a crawlspace?

A crawlspace is a space between the house and the ground. This space is designed along with a foundation to make up what is called a crawlspace foundation type.

The height of a crawlspace widely varies depending on the topography of the lot and the elevation of the house. As the name implies, most crawlspaces only have enough space to allow people to crawl under the house to access utilities.

Crawlspaces are used depending on the needs of the house. Crawlspaces provide certain benefits that other foundation types do not. We’ll be going into these benefits.

Pros and cons of a crawlspace

Crawlspace foundations provide an array of pros and cons compared to other foundational types. What makes crawlspaces different from other foundation types is their exposure to the environment, which accounts for most of its pros and cons.

Below is a list comparing the pros and cons of a crawlspace foundation.

Crawlspace Foundation
Crawlspace foundations provide easier access to utilities.Crawlspace foundations expose utilities to outside elements( weather, wildlife, and etc.)
Crawlspace foundations are less prone to damage due to earthquakes.2. Moisture can accumulate inside a crawlspace.
Crawlspaces help prevent flooding.3. Crawlspaces are more expensive to construct compared to slab-type foundations.
Crawlspaces can provide means for ventilation.4. Crawlspaces can cause heat loss.

Why you shouldn’t fill your crawlspace

As you can see from the listed pros and cons from the previous articles. Compared to other foundation types, the majority of the benefits of a crawlspace foundation stems from the extra space that it provides between the house and the ground.

In the first place, an architect and a contractor would not have had a crawlspace foundation built if they did not think that it would be the best foundation type for that structure.

Unless there have been changes in the conditions of your house or the environment surrounding your house, there is no real reason you should fill your crawlspace.

Can you fill a crawlspace by pouring concrete?

No, this is not a practical solution for filling a crawlspace. Concrete is heavy, entailing that it would need some structural support, and filling a crawlspace with concrete would remove the benefits of having a crawlspace without giving you the benefits of a concrete slab foundation.

Lastly, concrete needs good conditions to be applied properly, crawlspaces are less than ideal for concrete to be poured in, and the conditions inside a crawlspace aren’t ideal for curing either.

Can you fill a crawlspace with soil?

No, this is not a practical solution either. Building materials should rarely come in contact with soil, especially materials like wood. Rain could also easily displace the soil and remove it from the crawlspace, which ends up just wasting time, money, and effort it took to fill the crawlspace up in the first place.

Also, the type of soil underneath houses are often compact and are also engineered. It’s extremely unlikely that it can be pulled off within the tight space of a crawlspace.

Problems that would make you think you need to fill your crawlspace (with solutions)

This is gonna be a brief overview of crawlspace maintenance to give you a background in it. Crawlspace maintenance generally revolves around making sure that the environment within your crawlspace does not cause any deterioration.

This involves controlling moisture, prevent wildlife from entering, proper ventilation, proper insulation, and proper lot usage. It’s always more cost-effective and efficient to go for prevention, and maintenance is an important part of that.

Since you probably searched for this article, you probably have some problem related to your crawlspace that would make you think you would need to have it filled in.

Unfortunately, that is rarely the answer to most problems related to a crawlspace. Below is a list of common problems with a crawlspace foundation and a brief solution for these problems.

  1. Structural failure

If your house or foundation is experiencing structural failure, then filling up a crawlspace will not do anything for you. The weight of the house is transferred through the foundation columns and is distributed to the ground through the footings of the foundation. Filling a crawlspace adds more weight on the foundation footings, and that type of weight is not distributed evenly, which is dangerous.

The solution for this would be to hire an engineer and contractor immediately to find out how to best reinforce the structural system of your house.

  1. Heat loss

If heat is escaping through your crawlspace, that means you have a problem with the insulation between your house and the crawlspace. There are many ways to insulate a space, but the general gist is that it’s an extra barrier that prevents heat from going through, allowing heat to instead stay inside the house.

Insulation methods could range from using paddings, foams(loose-fill), blankets, material choice, and many more.

  1. Moisture

Moisture usually stems from too much humidity, water in the air within a certain space. This is why crawlspaces are usually only constructed in dry climates that do not experience that much humidity. Problems such as mold arise because of too much humidity.

Reducing humidity in a crawlspace involves improving insulation, adding water traps, dehumidifiers, etc. This could be achieved through vapor barriers and proper ventilation to prevent entry and promote the exit of humidity within your crawlspace.

  1. Pest Control

Pest infestations are a  problem that exclusively affects homeowners with crawlspaces. Pests are often attracted to crawlspaces because it mimics their habitats which are usually dark and moist crevices.

The solution here is to call pest control if an infestation is already present in your crawlspace and properly seal up your crawlspace to prevent pests from entering/exiting your crawlspace.

These are 4 of the most common problems often faced by homeowners when it comes to their crawlspaces. The general gist is that most problems faced by homeowners do not need such an extreme solution, such as filling up the crawlspace itself.

Research on proper maintenance and viable solutions for your crawlspace problems should be the way to go.


Crawlspaces are a foundation-type best suitable for dry climates. They provide a wide array of benefits but also require regular maintenance. Common problems with crawlspaces can easily be solved by applying the appropriate measures.

Filling in your crawlspace is not one of those measures. A filled-up crawlspace defeated the purpose of having a crawlspace in the first place and instead may cause even problems down the road.

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