Reinforcing Steel (C-50) · Lesson 4 of 7

Cover and Clear Spacing: Do the Bars Fit in the Member?

"Cover and Clear Spacing: Do the Bars Fit in the Member?" is lesson 4 of 7 in the Reinforcing Steel (C-50) Learning Hub. It opens with "Cover: The Concrete Between the Steel and the Outside" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Cover: The Concrete Between the Steel and the Outside
  2. Tolerance and Support
  3. Clear Distance Between Bars and Bundles (Caltrans 52-1.03D)
  4. The Fit Check: Room, Spacing, Count
  5. Clean, Placed and Inspected Before the Pour

The worked example in the course applies this lesson to a realistic job in 4 steps, from "Minimum center-to-center spacing" through "Most bars that fit in one layer".

What you'll be able to do

  • Explain the main idea of "Cover and Clear Spacing: Do the Bars Fit in the Member?" in plain language you can use on the exam.
  • Apply this step with confidence: "Clear Distance Between Bars and Bundles (Caltrans 52-1.03D)".
  • Apply this step with confidence: "The Fit Check: Room, Spacing, Count".
  • Apply this step with confidence: "Clean, Placed and Inspected Before the Pour".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
COVER AND CLEAR SPACING: DO THE BARS FIT?2025 Caltrans Std Spec Sec. 52-1.03D | 2025 CRC R403.1.3.5.3 and R608.5.4.1 | CBC Table 1705.3GRADE STRIP SECTION, 30" WIDE2"2"room = 26"2.5" c-c11 x #8 bars at 2.5" c-c (min.)clear cover 2" (Caltrans 52-1.03D)COVER AND SPACING RULESCaltrans 52-1.03DDefault clear cover: 2"Parallel bars: c-c at least 2.5dbMetal supports: 1" clear cover2025 CRC R403.1.3.5.3Against earth: 3"Exposed forms: #5 and smaller 1-1/2",#6 and larger 2"Not exposed / stay-in-place: 3/4"Minus tolerance: smaller of 1/3 cover, 3/8"1Room between cover faces = 30" - 2(2") = 26"2#8 bar: db = 1.000" (Sec. 52-1.04), so minimum c-c = 2.5 x 1.000 = 2.5"3Bars that fit: (26 - 1.0) / 2.5 = 10 spaces, so 10 + 1 = 11 bars (11 bars use exactly 26")4Plan calls for 12: 11 x 2.5 + 1.0 = 28.5" is more than 26" - does NOT fit in one layerRESULT: at most 11 #8 bars fit in one layer; 12 do notCover is measured to the outside of the steel. Bars drawn at the minimum c-c spacing.CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Cover: The Concrete Between the Steel and the Outside

Caltrans Section 52-1.03D says that unless otherwise shown, reinforcement must have a 2-inch clear cover measured from the surface of the concrete to the outside of the reinforcement. For footings and stem walls in Seismic Design Categories D0, D1 and D2, 2025 CRC R403.1.3.5.3 says steel in concrete cast against the earth has a minimum cover of 3 inches; concrete cast in removable forms exposed to the earth or weather needs 1-1/2 inches for No. 5 bars and smaller and 2 inches for No. 6 bars and larger; concrete in removable forms not exposed to earth or weather, and concrete cast in stay-in-place forms, needs 3/4 inch.

Step 2: Tolerance and Support

For wall reinforcement, R608.5.4.1 adds that the minus tolerance for cover may not exceed the smaller of one-third of the required cover and 3/8 inch: for 3 in. of cover that is the smaller of 1 in. and 0.375 in., so 2-5/8 in. is the least you may accept. Bars must be secured in the forms with tie wire or another bar support system so they cannot move during the pour (R403.1.3.5.3). Caltrans 52-1.03D says to hold bars by wiring at intersections and splices and by precast mortar blocks or ferrous metal chairs, spacers, hangers or supporting wires strong enough not to crush; do not use aluminum, plastic or wood supports, and do not place bars on layers of fresh concrete as the work progresses.

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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