Crawl Spaces: An Overview

Crawlspaces have been a hot topic of discussion for many years. Should they be vented or not vented? Should they be sealed from all directions or just beneath the floor joist? What materials best serve for sealing a crawlspace? The list of questions goes on and on. In the following paragraphs we will try to explain the ands, buts, and wherefores associated to this subject and provide our clients with advice upon which they can rely.

So what's this crawlspace issue about anyway?

Everyone has an idea of what a crawlspace is when they see one, but that's about as far as it goes. To most a crawlspace is a dark, dank, dirt-floored area populated by all manner of creepy-crawly-slithery things which inhabit that area beneath a structure and above the bare ground. Its basic purpose is to separate the structure from the moisture-laden earth below and to keep out such weather that may occur. It may be enclosed or not depending on geography and the type and style of the structure. In the south crawlspaces are frequently open to some degree on frame structures. In colder, northern climates and almost universally beneath masonry structures, they are closed. Crawlspaces are an economical substitute for a full basement or even an on-grade slab which allows access for the installation and maintenance to the mechanical systems that are the lifeblood of a home. From a construction standpoint, crawlspaces are also handy ways to ensure the floor level of a new addition will be level with the floor of an existing home. Unfortunately, crawlspaces are also a primary source of moisture.

Open crawlspaces mean cold floors and heat loss in winter, and in summer, a place where warm air condenses on cooler surfaces leading to . .. mold, and worse. The old adage, "An ounce of prevention is worth a pound of cure" certainly applies to crawlspaces. If it's in your crawlspace, you can be reasonably sure it's in your house. Moisture is the most common element in the ruin of houses. It provides the perfect environment for molds, fungi, and insects that have your house on their menu. And due to a physical phenomenon, heat rises. Through the stack effect, warm moisture laden air rises invades an entire structure. While 35% to 40% inside relative humidity during the heating season and in areas where high humidity is common during summer months, it's not uncommon to find sign of excessive moisture such as condensation running down windows, moldy bathrooms or closets, or soggy attic insulation. Excessive moisture also manifests as large patches of exterior paint peeling from saturated siding.

Common manifestations from exposed crawlspaces:

Foul odors
Excessive humidity
Visible mildew or mold damage
Insects and rodents
Rotting wood in structural members
Visible condensation
Warped Hardwood flooring