Crawl space

Source: Wikipedia, the free encyclopedia.
"Crawlspace" redirects here. For other uses, see Crawlspace (disambiguation).
A typical crawl space with a vapor barrier keeping some moisture from coming in from the dirt floor

A crawl space or crawlspace is an unoccupied, unfinished, narrow space within a building, between the ground and the first (or ground) floor. The crawl space is so named because there is typically only enough room to crawl rather than stand; anything larger than about 1 to 1.5 metres (3 ft 3 in to 4 ft 11 in) and beneath the ground floor would tend to be considered a basement.

Mechanical crawlspace under a pool in an apartment complex (California)

Uses

A crawl space is often built when building a basement would be impractical. A crawl space can also substitute for a concrete slab foundation that would hinder building inspections.[1]

The crawl space's functions include providing access to repair plumbing, electrical wiring, and heating and cooling systems without the need for excavation. Building insulation can also be installed in a crawl space.[2] The crawl space can provide a protective buffer between the damp ground and the wooden parts of a home and, with adequate sealing, help with radon mitigation. Crawl spaces are also sometimes used for storage of items such as canned goods that are not particularly susceptible to destruction by mildew or unstable temperatures.

A crawl space foundation can be used to elevate the lowest floors of residential buildings located in Special Flood Hazard Areas above the Base Flood Elevation. The Federal Emergency Management Agency recommends that the floor of the crawlspace be at or above the lowest grade adjacent to the building.[3]

Disadvantages

Crawl spaces are not usually an option in cold regions, such as the

HVAC equipment in unconditioned crawl spaces tends not to operate as efficiently as it would in a conditioned space such as a basement.[4]

Designs

Crawl spaces can be actively or passively vented, or closed. An advantage of a vented crawl space is that harmful gases such as

relative humidity above 80% can support mold growth and rot wooden structural materials such as floor joists.[6] Humidity in some sealed crawl spaces is controlled using a dehumidifier
.

A wooden crawl space access panel, opening to the exterior of the house, that has begun rotting away from dampness

Encapsulation is sometimes used to prevent the passage of air from the crawl space to the living environment, to save energy and improve

U.S. Department of Energy study of homes in the southeastern United States found that closed crawl spaces with sealed foundation wall vents, sealed polyethylene film liners and various insulation and drying strategies had significantly reduced space conditioning energy use compared to traditional wall-vented crawl spaces with perimeter wall vents and unsealed polyethylene film covering the ground surface.[7]
As a further encapsulation measure, crawl space access doors are sometimes located inside the home, or an airtight, insulated access door is built in the perimeter wall.

A crawl space can be susceptible to

flooding, a risk that is sometimes mitigated by such measures as using rain drainage such as rain gutters to conduct rainwater away from the house and sloping the earth away from the house.[8]

Crawl space wall materials may include, e.g., solid concrete or

concrete masonry units.[9]

References

  1. ^ a b "What to do when pests become homewreckers - The Washington Post". The Washington Post.
  2. ^ "Basement & Crawlspace Air Sealing and Insulating Project". www.energystar.gov.
  3. ^ "Crawlspace | FEMA.gov". www.fema.gov.
  4. ^ "Slab, Crawlspace or Basement? Do You Know What Type of Foundation to Choose-- BYHYU 069". BUILD YOUR HOUSE YOURSELF UNIVERSITY-- BYHYU.
  5. PMID 3980214
    .
  6. ^ "Home Energy Magazine :: The SCARY Crawl Space". homeenergy.org.
  7. OSTI 850459. {{cite journal}}: Cite journal requires |journal= (help
    )
  8. ^ "Fact sheet" (PDF). www1.eere.energy.gov. Retrieved 2020-11-13.
  9. ^ "Unvented, Insulated Crawlspaces | Building America Solution Center". basc.pnnl.gov.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Crawl_space&oldid=1207882327"