Learning About Crawl Spaces

Water has damaged this crawl space and allowed for mold growth

Crawl space foundations can be found in many parts of the country. Sometimes an entire building is constructed with a crawl space foundation.

In other situations, a crawl space foundation is used for an addition on a house with a different foundation. In all cases, crawl space foundations can have problems with far-reaching effects.

Understanding these problems and their solutions will help you to make the right decisions about your crawl space foundation.

Common problems with crawl space foundations

Excess moisture. When warm, moist outside air enters a vented crawl space, condensation takes place on the cooler surfaces inside the crawl space. Prolonged wetting of framing lumber, insulation and ductwork causes mold, wood rot and rust. Fiberglass batt insulation installed between crawl space joists can become so wet that it falls onto the crawl space floor.

Mold. Mold spreads by means of airborne spores, and it thrives in damp, dark environments where cellulose (wood fiber, paper, fabric) is present. Once mold takes hold in a crawl space, it damages building materials and poses a health hazard to building inhabitants (see Indoor air pollution, below).

Indoor air pollution. Crawl space air can easily make its way into your home’s living space, through gaps and cracks in building materials and through larger holes made for plumbing pipes, electrical lines and ductwork. If your crawl space has mold and musty odors, you probably have indoor air pollution in your living space that can cause serious health problems.

Comfort & energy problems. Wet fiberglass insulation, improperly installed insulation and missing or inadequate insulation are very common in crawl spaces. All of these conditions make your home colder than necessary in winter and uncomfortably warm on hot summer days. As a result, you spend more on heating and cooling.

Sagging and/or spongy floors. Most crawl spaces include a long beam that is supposed to provide mid-span support for the first floor joists. If this beam is undersized or supported by posts that have settled or shifted, the first floor is likely to sag or be excessively springy. In short, the floor isn’t capable of supporting the people and furniture in the house.

Professional encapsulation is the solution to most crawl space problems

Properly sealing a crawl space can't prevent mold growth and odors

“Encapsulation” is the term that building scientists use to describe a method of sealing the crawl space so that it’s completely separate from the outdoor environment. Even wet, moldy, dirt-floored crawl spaces can be repaired in this way.

A well-trained crew can complete a typical crawl space encapsulation in a single day. Technicians install high-strength plastic moisture barriers over wall and floor surfaces, incorporating waterproofing and dehumidifying features if necessary. Crawl space vents are sealed, and openings are fitted with airtight covers that can be opened or removed if access to the crawl space is necessary.

Damaged insulation is removed, and new rigid foam insulation is installed against crawl space walls. Unlike fiberglass insulation, rigid foam doesn’t absorb moisture, compress, lose R-value or fall out of place after installation.

Structural upgrades can level & strengthen sagging floors

By installing SmartJack® posts, your contractor can level and reinforce sagging floors above a crawl space. This specially designed steel post rests on a precast concrete base beneath the mid-span support beam, and can be adjusted gradually to level a sagging floor and provide permanent additional support.

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