The Other Types of Crawl Spaces

Most Popular Thickness

12 Mil DrySpace™

The 12 Mil DrySpace™ is by far our most popular crawl space vapor barrier due to the all around versatility for light storage and superior moisture protection.

Spray Foam Insulation

Where NOT to use it -

Closed cell spray foam is a great product for sealing out every little air leak. But, it will hinder your ability to inspect the structure if it is installed in the rim (band) joist area of the crawl space. This issue will come into play when selling a home or getting a termite inspection.

Mold and Mildew

Quick Facts -

• Mold can only be identified under a microscope
• There are more than 100,000 different kinds of Mold
• Bleach is NOT recommended to kill Mold on porous surfaces

Closed Crawl Space

A closed crawl space is one that was built without foundation Vents

Within the last few years the building code has allowed homes built on a crawl space to be built as a "closed crawl space". This means foundation vents are not required as long as other requirements are met. This type of crawl space is more energy efficient than an open crawl space.

The crawl space still needs ventilation

If a crawl space is built without foundation vents it is still required to have ventilation. The two most common configurations are:

1. Ventilation using the air from the home- via openings in the floor

or

2. Ventilation using the forced air (furnace) system of the home

Continuous vapor barrier on the floor

There needs to be a continuous vapor barrier, rated at less than 1 perm, laid on the floor with all seams lapping at least 12".

Insulation

There are two insulation methods allowed in a closed crawl space:

1. Insulating the perimeter foundation wall

or

2. Insulating the floor joists (crawl space ceiling)

Cons-

1. Generally, the vapor barrier is loosely installed preventing proper moisture control from the earth floor.
2. There is no moisture protection from the crawl space walls.
3. Odor can still be a problem with a closed crawl space.
4. Generally speaking storage is not an option.

Concrete Crawl Space

A crawl space with a concrete floor either with or without foundation vents

This type of crawl space is not as common but has its advantages. For one, this type of construction is more energy efficient than an open crawl space if constructed without foundation vents.

Ventilation

The concrete crawl space uses mainly two different types of ventilation:

1. Foundation Vents

and/or

2. Ventilation using the forced air (furnace) system of the home

Durable storage option

Although most crawl spaces are too short for this option after the home is built, it offers a lasting means for durable storage.

A bit more costly

Gaining the durable storage does come with a price, usually adding several thousand dollars to the construction costs.

A cap on the odor

A crawl space with a concrete floor has far fewer odor problems than an open crawl space.

The Cons-

1. Some are constructed with foundation vents
2. Most are poured as a "mud pad". A mud pad is a rough poured concrete slab that's sole purpose is to cap the earth under it- usually without a vapor barrier between the concrete and the earth. Therefore, there is little to no protection for the crawl space against moisture penetration through the (non vapor barrier) floor and the walls.
3. If conditions change and a water problem shows up it can be very expensive to install a drain system in an existing concrete floor crawl space due to the height.
4. When installing a concrete floor in a crawl space after the home is built will cause very high moisture in the crawl space due to the drying and curing process. This will go away, but will need to me managed to prevent any new issues.
5. Not a DIY Project

Concrete Encapsulation

Similar to a concrete crawl space, this type incorporates no foundation vents and uses foundation insulation to control  energy loss.

This type of crawl space takes advantage of both the "closed" and the "concrete" crawl space strengths. In this design sealing the walls with an insulation to control energy costs also protects the crawl space from moisture penetration from the foundation walls.

Share the air

The most common source for ventilation in this design is to add a conditioned air supply to the crawl space. This ensures the crawl space is at its peak of energy efficiency.

The Insulation

The two types of insulation used in this design are rigid foam and closed cell spray foam. Both types of insulation offer a level of moisture protection from the foundation wall.

Balance the budget

Although this design offers many comforts it also is very costly. As time goes by the cost of spray foam insulation will undoubtedly come down, but for now it is on the high end of the options. Added to that is the cost of a good quality vapor barrier under the concrete and of course the concrete itself. This method calls out to do the math and determine if you will get back your investment. Individual situations will determine what's right for your home and family.

A conditioned crawl space

This design is considered a conditioned crawl space. This is ONE OF the energy efficient and comfortable crawl space designs.

The Cons-

1. Cost
2. Not a DIY project

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