An iffy crawl space © Daniel Friedman How to Inspect, Diagnose, & Repair Problems in Building Crawl Spaces

  • CRAWL SPACES - home - CONTENTS: How to inspect, diagnose, repair problems in building crawl areas and other under-floor spaces. Scope of crawl area inspections, limitations & advice on handling areas that are inaccessible or unsafe to enter for inspection.
  • POST a QUESTION or READ FAQs about diagnosing and fixing problems in building crawl spaces
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Building crawlspace inspection procedures & topics:

This building crawl space article series explains how to inspect, diagnose problems in, and repair building crawl spaces, including crawl space insulation & leaks or moisture control.

Information is provided about visual clues of crawl space problems, such as evidence of a history of leaks, mold contamination, insect damage, structural damage, flooding, as well as evidence of hazardous materials and conditions such as the probable presence of animal allergens, asbestos, or mold.

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Crawl Areas: Defect Recognition, Repair, Prevention for Building Crawl Space Leaks, Mold, Insulation & Ventilation

D Friedman inspecing with broken leg Aug 2003The page top sketch of the role of a dirt floor crawl space in building moisture and mold problems (above) is courtesy of Carson Dunlop Associates. Photo at left is of the author, Daniel Friedman, peering into an inaccessible crawl space while suffering from a broken leg. Photo courtesy of Arlene Puentes.

[Click to enlarge any image]

The list of concerns or problems in or due to building crawl spaces is long as would be a list of opinions about what to do with crawl spaces, wet crawl spaces, moldy crawl spaces, or crawl space insulation and ventilation.

Good building science combined with a lot of experience has led to some good information on how to correct crawl space problems. Here we list crawl space problem inspection, diagnosis, and cure. Here are some things to watch out for in a building crawl space:

  1. Crawl spaces may be unsafe to enter due to risk of asbestos, chemicals, collapse, hantavirus, mold, rodents, sewage, snakes or even electrical shock hazards.

    See CRAWL SPACE SAFETY ADVICE where we explain when you should not even enter a crawl space.
  2. Crawl spaces may be a source of building water, moisture, leaks, mold -
    see CRAWL SPACE DRYOUT - home - this is the key article on dealing with wet or damp crawl spaces and related problems in buildings.


    For a crawl space contaminated by burst drain piping or sewage backups or spills

    For avoiding foundation collapse in areas prone to flooding, also
    see FLOOD VENTS & FLOOD PORTS. WATER ENTRY in BUILDINGS is the home page for our series of articles on the causes and cures of high indoor moisture, wet basements, wet crawl spaces, and moisture related problems like attic condensation and mold.

    Also see Mold in Fiberglass Insulation.
  3. Crawl spaces may be a cause of building energy loss or increased heating bills, especially if the crawl space is improperly insulated and/or vented.

    See CRAWL SPACE DRYOUT - home where we also discuss the change in thinking between the old-school idea of venting crawl spaces to the current best practice of converting crawl areas to a conditioned space, explained further
  4. Crawl spaces are often a reservoir of hidden structural, rot, insect, mold, water, contaminant, or other problems, largely because most crawl areas are difficult to enter and are rarely inspected.
    carpenter ants, powder post beetles, & other wood destroying organisms are a special risk in crawl areas, especially if fiberglass insulation was run from crawl space floor right up the wall and onto building framing or flooring.
  5. Crawl spaces may be cluttered with debris impeding inspection and inviting pests or rodents. Crawl spaces are required to be kept clear of debris; some such as wood scraps increase the risk of termite risk. For example from the 2012 IRC:

    The under-floor grade shall be cleaned of all vegetation and organic material. All wood forms used for placing concrete shall be removed before a building is occupied or used for any purpose. All construction materials shall be removed before a building is occupied or used for any purpose. [1]

Key Crawl Space Inspection, Diagnosis, Repair articles

Mold remediation completed in a problem crawl space © Daniel Friedman

Contaminated insulation in a crawl space © Daniel Friedman


Key Crawl Space Water Entry Diagnosis and Cure Articles

List of additional building crawl space inspection and defect articles

An iffy crawl space © Daniel Friedman


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CRAWL SPACES at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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