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What Are the Best Materials for a Crawl Space Floor?

By Dana DeCecco
Updated May 16, 2024
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The best materials for a crawl space floor are gravel, crushed stone or concrete, with the best of those choices being concrete. Concrete will keep out moisture and bugs. Construction work that might need to be done in the crawl space will be much easier with a finished concrete floor. The concrete should be poured after the footer installation and the foundation walls are in place. Concrete crawl space floors will be difficult to install after framing has begun.

Even though the best crawl space floor is concrete, most crawl space floors are not. The typical floor is simply dirt. The main reason for building a home over a crawl space is to save money. The full basement is a better option, but the additional cost might not fit in to the builder's budget. Crawl spaces are adequate if a proper vapor barrier and ventilation are installed.

To install a concrete slab in a new construction, various steps need to be taken. After the footers and foundation walls are complete, a French drain system should be installed on the exterior of the foundation. If any portion of the foundation is under grade, these areas must be waterproofed.

Before the concrete pad is poured, all of the plumbing or electrical groundwork must be done. At this point, a six mill plastic vapor barrier must be set on the earth in the crawl space area. A preferable method for this is putting about 3 inches (7.62 cm) of crushed stone or gravel down before setting the vapor barrier.

After the vapor barrier is in place, steel reinforcing can be added but is not necessary. Half-inch (1.27-cm) steel rebar can be added on 24-inch (61-cm) centers or wire mesh can be set in place before the concrete is poured. The additional steel reinforcement will insure insure the best crawl space floor.

The concrete slab should be poured 4 inches (10.16 cm) thick. A floor drain can be installed but might not be necessary. In many cases, water heaters and furnaces are installed in the crawl space.

If the existing crawl space floor is dirt, some improvements might be undertaken to give the homeowner the best floor possible. A six mill plastic vapor barrier should be installed. About 3 inches (7.62 cm) of stone or crushed gravel can be applied over the plastic to hold it down and allow work to be done in the crawl space without tearing the plastic.

Frequently Asked Questions

What is the best material for a crawl space floor?

A 6-mil polyethylene vapor barrier is the finest material for a crawl space floor. This type of material is sturdy and long-lasting, and it keeps moisture and humidity from entering the crawl space that may cause mold or mildew to grow. It also keeps dust and grime from building up. It is very simple to install, as it can be rolled out and taped to the floor joists.

What other materials can a crawl space floor be made of?

Aside from the 6-mil polyethylene vapor barrier, other popular materials for a crawl space floor include concrete, gravel, and crushed stone. Concrete is the most long-lasting and robust alternative, although it can be challenging to install. Gravel and crushed stone provide good drainage, but they are difficult to maintain and do not prevent moisture and humidity as well.

Is there anything else to consider when choosing a 6-mil polyethylene vapor barrier for a crawl space floor?

Yes, in addition to being a long-lasting and effective crawl space floor material, the 6-mil polyethylene vapor barrier also serves as insulation. This can help keep the crawl area cooler in the summer and warmer in the winter, making you more comfortable. It also lowers the amount of energy required to heat and cool the room.

Is a 6-mil polyethylene vapor barrier simple to install?

Yes, a 6-mil polyethylene vapor barrier is relatively simple to install. It may be rolled out and taped to the floor joists, and it is also simple to cut to fit around pipes or other crawl space objects. Furthermore, the 6-mil polyethylene vapor barrier is lightweight and easy to carry and install.

Is a vapor barrier necessary in a crawl space?

Yes, having a vapor barrier in a crawl space is critical. The vapor barrier keeps moisture and humidity out of the crawl space, where mold and mildew can form. It can also help to save energy by insulating the home and blocking out dust, grime, and other airborne pollutants.

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Discussion Comments

By Talentryto — On Feb 05, 2015

@spotiche5- Sand might be an option for you to use on your crawl space floor. It is easy to put down and absorbent if you have excess moisture that you need to control. It is also quite affordable, and you don't need a lot of sand to improve your crawl space floor.

By Ocelot60 — On Feb 05, 2015

@spotiche5- If you don't want to use loose stones, concrete, or gravel, you should try some square concrete paving stones. These large slabs of concrete are movable, so you can place them in the areas that you need them most. They are also much less costly than having concrete poured, and they are less messy than gravel or small pieces of stones and concrete.

Concrete paving stones also come in several sizes, so you can find the kind that works best for the area you want to improve in your crawl space. While the smaller ones are easier to work with, the larger ones are less likely to move out of place once you put them down.

By Spotiche5 — On Feb 04, 2015

Does anyone have some good tips for improving a crawl space floor on a budget? I really don't want to use gravel or crushed concrete, but I can't afford to have concrete put down.

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