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Crawlspace Mold: How to Find, Test, & Prevent Mold in Crawl Spaces MoldAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• How to find, test, prevent, or remove mold from building crawl spaces

This document gives advice on how to find and deal with mold in building crawl spaces. This is a chapter of "How to Look for Mold" which describes how to find mold and test for mold in buildings, including how and where to collect mold samples using adhesive tape - an easy, inexpensive, low-tech but very effective mold testing method.

This crawl space inspection procedure for mold helps identify the presence of or locate the probable sources of mold reservoirs in buildings, and helps decide which of these need more invasive, exhaustive inspection and testing. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

CRAWLSPACE MOLD: finding the problem mold, allergens, or other particles in crawl spaces

The photograph at page top shows extensive fungal growth on the underside of subflooring and on wood framing supporting a wood floor over a very damp crawl space. Depending on the mold genera/species, if an airborne fungus is present at high levels in a crawl space, spores of that mold may move easily to upper levels in the building.

We very often find that insulation in crawl spaces has become a problem mold reservoir. Some of these molds move easily from the crawl area up into the living space.

For example, Penicillium sp. or Aspergillus sp. spores, which can be as small as about one micron in diameter, are so tiny and light that they can move much like a gas in a building. These tiny spores rise in upwards-moving air currents as warm air, rising to upper building levels, creates a slightly lower air pressure in lower building areas such as basements and crawl spaces.

Depending on the tightness of construction, and the presence or absence of hot air or central air conditioning systems which themselves may increase indoor air particle movement, the rate of movement of particles from a moldy crawl space can vary widely.

In some instances I have found rather high levels of airborne mold spores and mold spores in settled dust that tracked directly to the moldy crawl space. In other instances I found that there was not much air and particle movement upwards from a crawl space or basement, until specific triggering conditions occurred. These included opening of a basement door, or in the case of crawl spaces, opening upper floor windows or turning on a whole house exhaust fan. These conditions led to a significant increase in movement of crawl space (or basement) mold from lower building areas into the living space.

First aid for moldy crawl spaces

• Do not enter or work in a moldy area without wearing proper respiratory and other personal protection.
• Evaluate the history of water entry, dampness, ventilation, listing the factors conducive to fungal growth such as:
• Present or past wet conditions, whether "once", episodic, or recurrent water entry
• Marginal or no ventilation. Actually I prefer to stop trying to vent crawl spaces since when we want venting it's usually inadequate, and depending on weather conditions venting a crawl space can actually increase its moisture level and make matters worse. A preferred approach is to dry out, enclose, and seal a crawl space under a building, making it into conditioned space.
• Exposed dirt. If the crawl space has a dirt floor, put down 6-mil plastic over the dirt to reduce moisture movement from the soil into the crawl space. Also see MOLD ON DIRT FLOORS
• Presence of fiberglass or other fibrous insulation
• Fix outside conditions that are causing wet crawl space conditions such as roof gutter or downspout spillage by the building foundation.
• Fix inside conditions that wet crawl spaces, such as plumbing leaks or improper ventilation.
• Look for visible mold:
• Inspect the exposed sides of all framing, joists, girders, posts
• Inspect the exposed under-side of subflooring of the floor overhead. See my warning about mold growth on pine boards discussed at Attic inspections above.
• Special screening tests may assist in evaluating the condition in inaccessible crawl spaces.
• Prevent mold movement into the living area: As with a moldy basement, keep openings between the crawl space and living space closed as much as possible.
• Remove wet or mold-suspect insulation.
• Test representative samples of mold before going to a major expense to be sure you're not just looking at cosmetic mold on framing lumber, or at something else that is not even mold. If a large area of visibly moldy material is present (more than 30 sq .ft.) professional cleaning and remediation are probably in order. In that case, a building inspection and preparation of a mold remediation plan is a good idea - that work should be performed by someone who has no conflicts of interest - in other words, not by the mold cleanup company or their agent. Follow any costly mold remediation job with a clearance inspection and test before you make final payment.
• Review MOLD PREVENTION GUIDE Correct the Causes of Mold and Prevent Indoor Mold or other indoor environment problems

Mold in fiberglass insulation in a crawl space

More Reading:
Insulation Mold how where and why to test building insulation for mold contamination
Fiberglass in Indoor Air, HVAC ducts, and Building Insulation
The Mold Information Center - What to Do About Mold in Buildings

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

More Information on Finding, Recognizing, and Proper Testing for Mold, More on Building Diagnostic Inspections and Repairs

Mold and Allergen Recognition and Identification - Not All "Black Mold" is Harmful; Some Suspect Stuff is Not Mold

• How to Find and Test For Mold in Buildings - Looking for Mold - A 'how to' photo and text primer on finding and testing for mold in buildings
• Recognizing Mold: What mold looks like mold identification photos to help identify mold - choosing what to sample in buildings
• Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
• Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
• Mold Action Guide: an easy step by step outline of what to do about mold
• How to find mold without hiring anyone, for do-it-yourself'ers
• Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
• Mold Test Kits - How to Collect and Send Your Own Mold Sample to our mold testing lab
• How to find a mold inspector or test consultant: Directory of IAQ,Sick Building, Mold Allergen Testing, Building Investigation Service Providers
• Meruliporia: the house eating fungus or "poria"
• Mold Investigation Tips for Home Inspectors how to find mold, where to look, what is likely to be important. Advice to building inspectors intending to inspect or test for toxic or problematic mold indoors, mold inspection methods, and mold test methods which are valid or invalid
• Mold Risk Levels in Buildings Based on Visual Inspection - simple visual clues help decide on action
• Mold in Fiberglass Insulation© 2005 comments about a field study in process, & more about health hazards from fiberglass insulation - DJF
• Frequently Asked Questions About Mold -- check this FAQ list & IAQ Site Map to see if you can find a quick answer to your mold concern
• When to hire a professional to inspect for toxic mold or other allergens
• Contact Us to arrange mold/IAQ building on site inspection and testing.

InspectAPedia ^TM Home & Site Map - Building Inspection, Diagnosis, & Repair, Environmental Inspection & Testing - Research Website

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Home Inspection Construction Consulting Services & advice for home buyers

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

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