Building Moving and Demolition (C-21) · Lesson 4 of 6

Demolition Order of Work: Survey, Utilities, Sequence, and the 25 Percent Rule

"Demolition Order of Work: Survey, Utilities, Sequence, and the 25 Percent Rule" is lesson 4 of 6 in the Building Moving and Demolition (C-21) Learning Hub. It opens with "The Written Survey Comes Before Any Worker Starts" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. The Written Survey Comes Before Any Worker Starts
  2. Utilities, Chemicals, and Asbestos Are Handled First
  3. Fix What the Survey Found Before You Cut
  4. Work Top Down and Keep Floor Openings Small
  5. Brace Tall Walls and Protect the Standpipe

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Total of the planned openings" through "Paperwork and order of work".

What you'll be able to do

  • Explain the main idea of "Demolition Order of Work: Survey, Utilities, Sequence, and the 25 Percent Rule" in plain language you can use on the exam.
  • Apply this step with confidence: "Fix What the Survey Found Before You Cut".
  • Apply this step with confidence: "Work Top Down and Keep Floor Openings Small".
  • Apply this step with confidence: "Brace Tall Walls and Protect the Standpipe".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Demolition: The 25 Percent Floor-Opening LimitONE FLOOR (PLAN VIEW), 5 px = 1 ftA: 20 x 12240 sfB: 15 x 16240 sfC: 10 x 12120 sfred strip = 2 ft x 20 ft= 40 sf over the limitFloor 40 ft x 60 ft = 2,400 sfopenings cut for dropping debris (Sec. 1735(f)(2))THREE CHECKSFLOOR OPENINGS (1735(f)(2))2,400 sf x 25% = 600 sf maximumAs drawn: 280 + 240 + 120 = 640 sf26.7%: 40 sf OVERFix: A to 20 x 12 -> 600 sf = 25.0%STANDING WALL (1735(m))Over 1 story or 12 ft: brace it13 ft wall: bracing requiredStable at the end of every daySTANDPIPE (CFC 3307.5.1)5 floors, working on floor 4:remove standpipe no lower thanfloor 3 (one floor below work)Top story first. Openings no more than 25% of the floor. Brace walls over 12 ft.A qualified person surveys first, in writing, kept on site for the whole project (Sec. 1734(b)).Sources: Cal/OSHA Title 8 Sections 1734, 1735(f), 1735(m); California Fire Code Section 3307.5.1.CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: The Written Survey Comes Before Any Worker Starts

Cal/OSHA Title 8 Section 1734(a) puts demolition under the immediate supervision of a qualified person with authority to secure maximum safety. Section 1734(b)(1) requires that qualified person to survey the structure before employees start, covering the condition of the framing, floors and walls and the possibility of an unplanned collapse, and to check any adjacent structure where employees may be exposed. Section 1734(b)(2) says the survey must be in writing, kept on the job-site, available to the Division on request, and maintained for the duration of the demolition project.

Step 2: Utilities, Chemicals, and Asbestos Are Handled First

Section 1735(a) requires utility companies to be notified and all utility service shut off, capped, or otherwise controlled at the building or curb line before demolition starts, unless electricity or water is needed during demolition, in which case it is relocated as needed and protected from damage. Section 1735(b) requires testing and purging where hazardous chemicals, gases, or flammable materials are apparent or suspected in pipes or tanks, and Section 1735(c) requires a survey of pipe insulation, steel fire protection, and duct work for asbestos, with compliance with Section 1529 if it is present. California Building Code (CBC) Section 3303.6 adds that service utility connections are discontinued and capped under the rules of the governing authority, and CBC Section 3303.2 says demolition shall not start until pedestrian protection is in place.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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