Wet crawl space unsafe to enter (C) Daniel FriedmanCrawl Space Mold, Rodents, Asbestos Clean-up Procedures

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How to clean out a crawl space contaminated with mold, rodents, asbestos, or sewage.

Here we discuss safety precautions and cleaning approaches for a dirty or contaminated building crawl space. We explain that first you should inspect the crawl space for visible signs of unsanitary or unhealthy contaminants. Cleanup methods need to include steps to prevent spreading contamination to other building areas. We include discussion of using vacuum cleaners and power washers in crawl areas. .

This article series describes the steps needed to get into, inspect, clean, and then dry out a building crawl space. We give a step by step crawl space entry, inspection, cleanout, dryout and keep dry guide explains how to get into or inspect a crawl space even if there is no ready access, how to assess crawl space conditions, how to stop water that is entering the crawl area, how to dry out the space, how to clean up and if necessary disinfect or sanitize the crawl space, and how to keep out crawl space water and moisture in the future.

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How Clean Up the crawl space: remove asbestos, mold, rodent droppings, unsanitary soils, insulation

Asbestos in crawl area (C) Daniel Friedman

Is there asbestos insulation in the crawl space? Often we find a crawl area in which the asbestos pipe insulation is not just hanging (photo at left) but has fallen onto the crawl space floor.

[Click to enlarge any image]

Asbestos pipe or HVAC duct insulation that has been disturbed, damaged, or deteriorated, including asbestos that has fallen to the floor should be removed and cleaned up by a professional. Asbestos pipe insulation that is in good condition, that is not damaged, might be left in place or perhaps left in place and encapsulated.

Do not enter such an area without protective equipment; take care that you do not track hazardous materials out of the crawlspace and into other building areas.

Do not track asbestos debris back into other building areas.

Mold on framing in a crawl space (C) Daniel Friedman

Is there evidence of mold contamination such as areas of wood, paper, or other material covered with mold or mold-suspect material.

If the crawl area has more than 30 sq.ft. of contiguous toxic or allergenic mold it should be cleaned by a professional mold remediation company.

Beware: often the most serious mold we find in crawl spaces is not the mold you see on wood framing but rather the mold you don't see in fiberglass insulation in a damp or wet area.
See Mold in Fiberglass Insulation for details.

Watch out: If the crawl space has a large area of mold (more than 30 sq ft) or if you suspect it may be contaminated with rodent droppings, chemicals, pesticides, (or electrical hazards)


Do not enter such an area without protective gear.

Rats, mice & other crawl space rodent hazards

Evidence of mice or rats in a crawl space (C) D FriedmahBeware also of rodent-infested crawl areas; there may be bacterial or viral hazards from these animals, or from their urine and feces, and in some areas there may be a Hantavirus hazard.

Hantavirus pulmonary syndrome (HPS) is a deadly disease from rodents. Humans can contract the disease when they come into contact with infected rodents or their urine and droppings.

HPS was first recognized in 1993 and has since been identified throughout the United States. Although rare, HPS is potentially deadly. Rodent control in and around the home remains the primary strategy for preventing hantavirus infection. - [3] US CDC

If it is necessary to remove rodent feces or urine-stinking soil (try using a "black light" to spot urine stains) your cleaning company may decide to actually remove the top few inches of contaminated soil in the most offensive areas, followed by sanitizing, sealing, and poly vapor barriers on crawl space floors and lower walls.


Also see LIGHT, GUIDE to FORENSIC USE for help in spotting mold or similar contaminants on buildng surfaces

Watch out: don't remove so much soil that footings are undermined at foundation walls or supporting columns. If necessary, bring in and compact clean fill and gravel to fill low areas.

Is there or was there a crawl area sewage spill?

Sewage backup under a homeWatch out: entering a crawl space where there has been a sewage spill is hazardous, risking exposure to bacteria and other pathogens even if currently the crawl area is dry.

It's obvious that crawling around through sewage is not healthy unless you are wearing adequate protective gear.

But you may not realize that those same sewage pathogens may be carried on dry airborne dust.


Should we Use a Vacuum Cleaner to Clean up the Crawl Space?

Do not use a household vacuum cleaner nor an ordinary shop-vac to clean up crawl space dust and debris. Those machines will temporarily but significantly increase the level of airborne dust and debris.

Since that dust and debris may contain harmful particles, tossing it into the air increases the risk of cross contamination from the crawl space into other building areas such as a basement or even upper floors in the building.

To vacuum and clean surfaces in a crawl area use a HEPA-rated vacuum cleaner that will trap very fine particulates, and select a vacuum cleaner model that does not have air bypass leaks that escape from the equipment when they should be passing through the filter.

Do we need to Set up Dust Containment and Negative Air to Clean Up the Crawl Space?

Containment barrier for mold remediation (C) Daniel FriedmanNegative air machines and dust barriers are procedures used by professional mold remediation companies, asbestos removal experts, and building flood damage restoration companies. These measures reduce the risk of blowing contaminated dust and debris into other building areas - an event which could be a health risk, especially to occupants who are in fragile health. Photo courtesy of Anabec, Inc.

Even an amateur, do-it-yourself cleanup project would benefit from these methods.

But you should recognize when your cleanup project needs the help of a professional. Here are some examples of conditions that mean you should hire a professional to clean up a crawl area:

There is asbestos material that needs to be removed

  • The area contains a large reservoir of harmful mold, more than 30 square feet of contiguous moldy material
  • The area has been contaminated with sewage and sewer backups
  • The people who plan to do the cleanup are not fit, healthy, and properly dressed and equipped
  • Other building occupants are at particular risk of health effects from stirred-up building dust that may contain mold, fiberglass insulation fragments, bacterial, viral, or other hazards. Examples are the elderly, infants, asthmatics, people suffering from COPD, or people suffering from MCS.



Should we use a Power Washer to Clean up the Crawl Space?

Post-Cleanup using a baking soda spray processIf there is room to work, a power washer is a very effective way to clean surfaces, but the increase in water and moisture in the crawl space can make mold or other building-related moisture conditions worse.

In some circumstances such as a crawl area or basement that can be well ventilated, in dry weather, that is well drained, and where other measures are taken to avoid sending a surge of moisture upstairs, power washing might be possible.

Alternative dry-spray surface cleaning methods called media blasting include use of dry-ice spray and baking soda or other abrasive particles, even sand or walnut shell fragments.

See MOLD CLEANUP by MEDIA BLASTING. Our photo shows the ceiling over a basement after cleaning by media blasting.




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