The 100 Square Foot Rules


Nearly every contractor, construction manager, architect or facilities director is aware that there is a level of asbestos-containing material disturbance over which you need to be a registered asbestos contractor to conduct. Some are even aware this level is 100 square feet.

The misunderstanding of this requirement is for projects that disturb less than 100 square feet of asbestos-containing materials (ACM). It is widely thought that if less than 100 square feet of ACM is disturbed, any contractor can do the work because being a registered asbestos abatement contractor is not required. This is not entirely true.

While it is true that you don’t have to be a registered abatement contractor, you are still required to use properly trained workers, proper work practices, and proper housekeeping and cleanup procedures. How many non-abatement contractors know what the proper work practices are, let alone have any properly trained workers? Very, very few.

A direct quote from the Division of Occupational Safety and Health (DOSH) Web site:

What are the rules for work involving less than 100 sq. ft. of ACCM?

The employer must send a simple “report of use” to Cal/OSHA. Reports of use are also required for manufacturing and other general industry settings. All other occupational health and safety work rule requirements apply-especially those from 8 CCR 1529. For more information about “reports of use” and the database of carcinogen use reports, call 415-703-5190. Also, see 8 CCR 5203, the Carcinogen Report of Use Requirements.


In January 2002 Cal/OSHA modified their lead regulations to include a requirement to notify Cal/OSHA 24 hours in advance of the disturbance of 100 square or linear feet of lead-based paint or presumed lead-based paint (or other lead materials).

The regulation requires you to either assume lead paint exists or test it in all buildings, except school buildings constructed after 1993 or residences constructed after 1978.

Disturbance of 100 square feet of paint without proper notification, without proper inspection/assumption or without valid exemption (schools constructed after 1993; residences constructed after 1978) is a violation even if the paint contains no lead. Also, remember Cal/OSHA regulates paint containing “any detectable amount”. So even if it is not lead-based paint, Cal/OSHA still has jurisdiction and their regulations in 8 CCR 1532.1 apply. Mishandling of paints with low levels of lead can create health hazards and regulatory violations.

(Lead-based paint is defined as 1 mg. per square centimeter, 5,000 parts per million, or .5% by weight.)

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2 comments on “The 100 Square Foot Rules
  1. Brandt says:

    Are you saying anytime a plumber comes to your condo and puts a hole in the wall to fix a leak you have to have an asbestos test in San Diego California?

  2. No. You are free to assume the materials contain asbestos without collecting a sample. With the proper training and the use of the proper work practices (Cal/OSHA 8 CCR 1529 – Class III Work) this activity can easily be conducted by someone with as little as 4 to 16 hours of asbestos training.

    Also – don’t forget that the wall may (is likely to) contain silica, and could be coated with lead based paint – additional trainings most any plumber is likely to have already.

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