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Hazards Associated with Building Demolition

hazardous materials

Hazardous Materials

Construction and demolition (C&D) materials consist of the debris generated during the construction, renovation, and demolition of buildings, roads, and bridges. C&D materials often contain bulky, heavy materials that include:

  • concrete
  • wood (from buildings)
  • asphalt (from roads and roofing shingles)
  • gypsum (the main component of drywall)
  • metals
  • bricks
  • glass
  • plastics
  • salvaged building components (doors, windows, and plumbing fixtures)
  • trees, stumps, earth, and rock from clearing sites

Primary Hazards

primary hazards

The hazards unique to demolition include all of the following:

  • Changes from the structure's design introduced during construction;
  • Approved or unapproved modifications that altered the original design;
  • Materials hidden within structural members, such as lead, asbestos, silica, and other chemicals or heavy metals requiring special material handling;
  • Unknown strengths or weaknesses of construction materials, such as post-tensioned concrete;
  • Hazards created by the demolition methods used such as exposure to excessive dust, noise and vibration.

Primary Types of Accidents

The most common types of accidents that result from the hazards associated with demolition are:

  • falls from elevated work surfaces
  • exposure to hazardous air contaminants
  • being struck by falling or collapsing structures
  • electrical shock
structural instabilities

Structural Instabilities

It’s important that the engineering survey identify framing, floors, walls of the structure and any adjacent structures that might be unstable. Key engineering and work practices controls for the hazards associated with structural instabilities during demolition include:

  • Shore/brace walls and floors as needed to maintain safe work areas during demolition activities.
  • Have a competent person continually inspecting the work area to detect hazards resulting from weakened or deteriorated floors, walls, or loosened material. A competent person is able to recognize existing and predictable hazardous conditions and has the authority to take prompt corrective measures to eliminate the hazardous condition.
  • Demolishing an unstable wall.
  • Do not allow falling debris/stored materials or heavy equipment to exceed the safe carrying capacity of the floor.
  • Conduct demolition work from the topmost floors down; do not cut/remove load-supporting members until upper or supported loads have been removed.

Unsecured Hazard in the Work Area


During demolition, unsecured objects like glass and structural members may fall while workers are under them. Key hazard control strategies for the hazards associated with unsecured hazards in the work area during demolition include:

  • Use debris netting, sidewalk sheds, canopies, or catch platforms to reduce hazards from falling objects.
  • Make sure employee entrances to multistory structures are completely protected by sidewalk sheds or canopies, or both, providing protection from the face of the building for a minimum of 8 feet.
  • Canopies should be at least 2 feet wider than the building entrances or openings capable of sustaining a load of 150 pounds per square foot.



It’s important to reduce or eliminate the hazards from utilities that are not properly located and secured. To reduce the hazards associated with utilities:

  • Verify the location of all other utility lines.
  • Ensure lines have been shut-off, capped, or otherwise controlled outside the building before beginning work.
  • Notify utility companies before controlling their utility lines.

Assessing for Hazardous Substances


During demolition, exposure to hazardous substances is likely. To prevent and reduce the hazards associated with the exposure to hazardous substances, do the following:

  • Conduct worksite inspections prior to the start of operations to assess for the presence, contents, and condition of tanks and equipment that might contain hazardous chemicals, gases, or flammable materials.
  • If the condition of tanks or equipment is suspect, avoid disturbing them until after the assessment is done and a plan of action is developed to reduce exposure or eliminate the hazardous substances.

Eliminating Hazardous Substances

To eliminate the hazardous substances that have been identified prior to and during demolition, do the following:

  • Purge lines, tanks, and equipment containing hazardous chemicals, gases, or flammable materials.
  • Use air monitoring equipment such as a combustible gas indicator, toxic gas monitor, or oxygen monitor to determine if any hazardous conditions remain.
  • When necessary, provide additional controls to protect response and recovery workers (e.g., forced ventilation, respiratory protection, etc.).

Walkways and Access


To prevent slips, trips and falls, provide and use safe walkways to reach any point without having to walk on exposed beams. Walkways should be at least 18 inches wide and formed by using 2-inch thick wood, with stringers installed as needed for support.

To ensure safe access to the structure, use only inspected and designated stairways, passageways, and ladders, designated as means of access to the structure of a building. Other access ways must be entirely closed at all times.


In a multi-story building, when a stairwell is being used for access or egress, it must be properly illuminated by either natural or artificial means, and completely and substantially covered over at a point not less than two floors below the floor on which work is being performed. Access to the floor where the work is in progress must be through a properly lighted, protected, and separate passageway.

Safe Work Practices When Working in Confined Spaces

confined space

Demolition contractors often come in contact with confined spaces when demolishing structure at industrial sites. These confined spaces can be generally categorized in two major groups:

  1. those with open tops and a depth that restricts the natural movement of air
  2. enclosed spaces with very limited openings for entry

Examples of these spaces include storage tanks, vessels, degreasers, pits vaults, casing, and silos.

The hazards encountered when entering and working in confined spaces are capable of causing bodily injury, illness, and death. Accidents occur among workers because of failure to recognize that a confined space is a potential hazard. It should therefore be considered that the most unfavorable situation exists in every case and that the danger of explosion, poisoning, and asphyxiation will be present at the onset of entry.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Which of the following is a hazard unique to demolition operations?

2. Which of the following are common accidents during demolition operations?

3. Which of the following is a key engineering control for hazards associated with structural instabilities during demolition?

4. During demolition, canopies should provide at least _____ of protection from the face of the building.

5. Walkways on demolition projects should be at least _____ and formed by using _____ wood, with stringers installed as needed for support.

Have a great day!

Important! You will receive an "error" message unless all questions are answered.