Nearly 15% of American homes have a crawl space. This hollow and low-lying area acts as a buffer zone between the home and the earth beneath it. It combines the benefits of a basement and a slab foundation. Here, we will define what a crawl space is, highlight crawl space code requirements, pros and cons, and why contractors and architects still recommend them.
What’s a Crawl Space?
Crawl spaces derive their name from the fact that they’re only accessible through crawling. With just about 18 inches of clearance, they are not big enough to use as a living area. They seem like a poor compromise between a concrete slab foundation and a full basement. While that’s the case, they do offer the benefits of both including a durable base for your home and ample space for your electric panel and utility lines.
Code Requirements for Crawl Spaces
Vented crawl spaces must have at least one square foot of vent for every 500 sq ft of crawl space area. The requirement is different if the ground is covered with a 20-mil vapor barrier. Codes also expect the space between the joists and the ground to have outside ventilation.
Unvented crawl spaces must have a Class I vapor barrier with sealed overlapping seals. This barrier must go six inches up the wall and be sealed to the side walls. Homeowners are supposed to install a continuously operating exhaust system or provide access to their home’s conditioned air, including an air return via the ducts. Perimeter walls need to have air seals. Codes also expect the interior to have a fire barrier such as half-inch drywall.
While building code traditionally calls for crawl spaces to have open vents for air drying purposes, this actually is detrimental to your home because of the outside air, water, moisture, and pests this brings into the crawl space. The best solution is to seal the crawl space with vent covers, encapsulate it with a tick vapor barrier, and dehumidify the area for better air quality and moisture reduction.
How Crawl Spaces Are Built
Crawl spaces are typically built by elevating the home 18 inches off the ground. The foundation is constructed using block walls and footing, which support the home. Footings are made using concrete. However, some homeowners prefer to combine concrete blocks with bricks to improve curb appeal.
Wooden pillars are then set up on the inside of the crawl space, leaving a space that’s roughly one to three feet high at the base. Pipes and electric wires run through the interior of it. Other than these fixtures, the crawl space remains largely empty unless you decide to add some insulation.
Most crawl spaces have dirt floors, as this is cheaper than pouring concrete.
Cost of Building a Crawl Space
Building costs depend on the size of the home and the materials used. A bigger house requires more construction materials than a smaller one, and this will reflect in the crawl space foundation costs. A standard family house will cost you between $10,000 and $20,000.
Benefits of Having a Crawl Space
While crawl space foundations are difficult to install, they have many structural advantages over slab foundations including:
Durability: Crawl space foundations work well in a variety of situations. Homes built on crawl space foundations are likely to remain stable and upright when there’s an earthquake; this is not the case with slab foundations.
Level ground: Few lots are even. If you’re building a home on a sloping piece of land, a crawl space will allow you to create a uniform platform by varying the length of piers.
Flexibility: Crawl space foundations respond better to the hydrostatic force of soggy soils than slab foundations. These foundations are also suitable for building in expansive soils.
Flood protection: The 18-inch of space between your home and the ground creates a buffer against floods. This could mean the difference between a slight inconvenience and costly water damage.
Usable space: Another advantage of having a crawl space is that you can run your plumbing lines and electrical wires through it. If the area is properly encapsulated, you can also move items that take space down to the crawl space and free up your home.
Crawl Space Cons
The crawl space has its fair share of problems.
Reduced energy efficiency: An open crawl space can lower the energy efficiency of your home in winter. The large void of cold air that circulates under your home in winter means you’ll run the heater for long to warm up the crawl space. Insulating this space can bring down heating costs.
Pest infestation: Creepy crawlies like rodents and mice are drawn to the crawl space as it’s moist and dark. Down there, they can nest, breed, and flourish without being disturbed.
Moisture issues: With air getting in and out of the crawl space unfettered, the interior will get damp and this can have a damaging effect on your home. Mold will grow, beams will rot, and the air will become muggy.
When to Use a Crawl Space Foundation
Architects and building contractors may suggest a crawl space foundation instead of a slab foundation if you live in a flood-prone area or an area that’s likely to be hit by an earthquake. The same applies when building on an uneven piece of land or soil that’s not suitable for a concrete slab foundation. If you would like to encapsulate your crawl space or carry out repairs before seasonal changes occur, contact the experts at JES Foundation Repair. We’re happy to assess the condition of the crawl space and tell you what needs urgent attention.