Fencing (C-13) · Lesson 2 of 6

Chain-Link Post Footings: Caltrans Standard Plan A85

"Chain-Link Post Footings: Caltrans Standard Plan A85" is lesson 2 of 6 in the Fencing (C-13) Learning Hub. It opens with "Footing Size Comes From a Table" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Footing Size Comes From a Table
  2. Reading the Line-Post Table
  3. The Width Rule and the End and Corner Posts
  4. Cut the Post to Length
  5. Concrete and Finishing

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Check the width rule" through "Cementitious material".

What you'll be able to do

  • Explain the main idea of "Chain-Link Post Footings: Caltrans Standard Plan A85" in plain language you can use on the exam.
  • Apply this step with confidence: "The Width Rule and the End and Corner Posts".
  • Apply this step with confidence: "Cut the Post to Length".
  • Apply this step with confidence: "Concrete and Finishing".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Chain-Link Footing: Caltrans Standard Plan A85Width B and depth D come from the table by fence height and post sizeONE LINE-POST FOOTINGGRADE2.88 in. OD line postpost length 128 in.concretefooting,crowned topD = 36 in.(3 ft)B = 12 in.Above-grade height not to scaleTHE NUMBERS (200 FT, 8 FT FENCE)Table A85, non-slatted, 8 ft:2.88 in. OD, B = 12 in., D = 3 ftWidth rule: 3 x 2.88 = 8.64 in.OKPost length = 36 + 96 - 4 = 128 in.200 / 10 = 20 spaces: 19 line + 2 end= 21 footingsOne hole: 3.1416 x 0.5² x 3 = 2.36 cu ft21 x 2.36 = 49.5 cu ft = 1.83 cu yd1.83 x 470 lb = 861 lb cementitious470 lb per cu yd is the minimum inStandard Specifications 80-1.02.RESULT: 21 footings, 12 in. x 36 in., 861 lb cementitious materialSource: 2025 Caltrans Standard Plan A85 (p. 155) and A85A Note 1; Standard Specifications 80-1.02, 80-3.02B.CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Footing Size Comes From a Table

Footing width and depth are not guesses. The 2025 Caltrans Standard Plan A85 (Chain Link Fence, p. 155), one of the books the CSLB C-13 Study Guide lists for the exam, gives a Typical Member Dimensions table that sets the footing width B (in inches) and depth D (in feet) for each fence height and post type. The same plan also gives the post and brace sizes, so the footing and the post are chosen together.

Step 2: Reading the Line-Post Table

Pick the row whose maximum fence height covers your fence, then the slatted or non-slatted group. Non-slatted fabric: 5 ft uses a 1.90 in. OD post with B = 8 in. and D = 2 ft 6 in.; 6 ft uses 2.38 in. OD, B = 10 in., D = 2 ft 6 in.; 8 ft uses 2.88 in. OD, B = 12 in., D = 3 ft; 10 ft uses 3.50 in. OD, B = 14 in., D = 3 ft 6 in. Slatted fabric catches more wind, so the posts and footings grow: 5 ft uses 4.00 in. OD, B = 12 in., D = 3 ft; 6 ft uses 4.50 in. OD, B = 14 in., D = 3 ft; 8 ft uses 5.56 in. OD, B = 18 in., D = 3 ft 6 in.; 10 ft uses 6.63 in. OD, B = 20 in., D = 4 ft. These are minimums, and larger sizes may be used on approval.

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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