Framing and Rough Carpentry (C-5) · Lesson 3 of 5

Sill Plate Anchor Bolts: Spacing, End Distance, and Counting

"Sill Plate Anchor Bolts: Spacing, End Distance, and Counting" is lesson 3 of 5 in the Framing and Rough Carpentry (C-5) Learning Hub. It opens with "What the Anchor Bolts Do" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. What the Anchor Bolts Do
  2. The Bolt Specification (2025 CRC R403.1.6)
  3. The End Rule Applies to Every Plate Section
  4. Seismic Plate Washers, Added Anchorage, and Decay Protection
  5. How to Count the Bolts for a Plate Piece

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Convert to inches and remove the end allowances" through "Plate washers".

What you'll be able to do

  • Explain the main idea of "Sill Plate Anchor Bolts: Spacing, End Distance, and Counting" in plain language you can use on the exam.
  • Apply this step with confidence: "The End Rule Applies to Every Plate Section".
  • Apply this step with confidence: "Seismic Plate Washers, Added Anchorage, and Decay Protection".
  • Apply this step with confidence: "How to Count the Bolts for a Plate Piece".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Anchor Bolt Layout: Count Every Plate Section16 ft section = 4 bolts14 ft section = 3 boltsPlan view of a 30 ft sill plate (two pieces)56 in.56 in.56 in.72 in.72 in.End bolts 12 in. from plate endsEnd bolts 12 in. from plate ends THE RULES (CRC R403.1.6) 1/2 in. bolts, 7 in. into concrete 6 ft max o.c.; middle third of plate Each section: 2 bolts minimum End bolt 3-1/2 to 12 in. from each end THE COUNT (24 in. for end bolts) 16 ft: (192 - 24) / 72 = 2.33, 3 spaces, 4 bolts 14 ft: (168 - 24) / 72 = 2.0, 2 spaces, 3 bolts Total = 4 + 3 = 7 anchor bolts 7 bolts: 4 in the 16 ft piece and 3 in the 14 ft piece Each plate piece needs its own end bolts (not one 30 ft run) SDC D0-D2 braced wall lines: 7 plate washers, 3 x 3 x 0.229 in. Spacing 56 in. and 72 in. are both within the 6 ft (72 in.) maximum Source: 2025 CRC R403.1.6, R403.1.6.1 and R602.11.1CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: What the Anchor Bolts Do

The sill (or sole) plate is the first framing member on the foundation, and the anchor bolts are what tie the whole house to the concrete. In an earthquake or high wind they resist the building sliding sideways off the foundation and being lifted off it. Every wall above is only as secure as this connection, so the 2025 California Residential Code (CRC) R403.1.6 fixes the bolt size, depth, spacing, and end distance, and inspectors count them before the wall framing is allowed to start.

Step 2: The Bolt Specification (2025 CRC R403.1.6)

Wood sill plates, and the wood sole plates of exterior walls and braced wall panels on monolithic slabs, are anchored with minimum 1/2 in. diameter anchor bolts spaced not greater than 6 ft (72 in.) on center, or with approved anchors or anchor straps that give equivalent anchorage. Bolts extend at least 7 in. into concrete or grouted cells of concrete masonry units and are located in the middle third of the width of the plate. For a 2x6 sill (5-1/2 in. wide) that puts the bolt centerline between about 1-5/6 in. and 3-2/3 in. from either edge. A nut and washer are tightened on each bolt. Where a bolt resists placement or the concrete around it is not consolidating, the concrete is vibrated to ensure full contact with the bolt.

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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