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

Demolition Debris: Tons, the 65 Percent Diversion Rule, and Truckloads

"Demolition Debris: Tons, the 65 Percent Diversion Rule, and Truckloads" is lesson 6 of 6 in the Building Moving and Demolition (C-21) Learning Hub. It opens with "Turn Floor Area into Tons of Debris" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Turn Floor Area into Tons of Debris
  2. What the 65 Percent Rule Says
  3. Count the Diversion by Weight, Not a Mix of Methods
  4. The Waste Stream Reduction Alternative
  5. Convert Tons to Truckloads Within the Weight Limit

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Total debris" through "Truck payload and loads".

What you'll be able to do

  • Explain the main idea of "Demolition Debris: Tons, the 65 Percent Diversion Rule, and Truckloads" in plain language you can use on the exam.
  • Apply this step with confidence: "Count the Diversion by Weight, Not a Mix of Methods".
  • Apply this step with confidence: "The Waste Stream Reduction Alternative".
  • Apply this step with confidence: "Convert Tons to Truckloads Within the Weight Limit".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Demolition Debris: Weight, 65 Percent Diversion, Loads4,800 sf of floor x 45 lb/sf = 216,000 lb = 108 tons of debrisCONCRETE 50 tWOOD 18 tLANDFILL 34 tMETAL 6 t65% = 70.2 tDIVERTED 74 t = 68.5% of 108 t: meets 65% with 3.8 t to spareWEIGHT CHECK (CALGreen 4.408.1)65% x 108 t = 70.2 t must be divertedDiverted: 50 + 6 + 18 = 74 t74 - 70.2 = 3.8 t marginCount by weight OR volume, not bothHAULING (80,000 lb gross limit)80,000 - 32,000 tare = 48,000 lb= 24 t payload per truck108 / 24 = 4.5, so 5 loads in allLandfill only: 34 / 24 = 1.4, so 2 loadsWeigh it, sort it, prove it: 74 of 108 tons diverted, 5 truckloadsSources: 2025 CALGreen Sections 4.408.1, 4.408.2; Caltrans Transportation Permits Manual Sec. 104 (80,000 lb);CSLB C-21 Study Guide (debris lb per sf of floor space). The 45 lb/sf and 32,000 lb tare are example inputs.CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Turn Floor Area into Tons of Debris

The CSLB C-21 Study Guide sample question shows the estimator's method: a two-story building with 2,000 square feet of floor space per story generating 40 pounds of debris per square foot of floor space yields 2 x 2,000 x 40 = 160,000 pounds, or 80 tons (roof excluded). Multiply the floor area of every story by the pounds-per-square-foot rate from your own survey of the building, then divide by 2,000 pounds per ton. The pounds-per-square-foot rate is a job-specific input, so a heavier building (concrete, masonry, a basement slab) needs a higher rate than a light frame house.

Step 2: What the 65 Percent Rule Says

2025 California Green Building Standards Code (CALGreen) Section 4.408.1 (residential) requires recycling and/or salvaging for reuse a minimum of 65 percent of the nonhazardous construction and demolition waste, or meeting a more stringent local waste ordinance. Section 5.408.1 says the same for nonresidential projects. Excavated soil and land-clearing debris are exempt under the listed exceptions. Hazardous materials such as asbestos and lead paint waste are not part of the nonhazardous count and are handled under their own rules.

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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