Framing and Structural Components: the numbers behind the frame
20% of the B exam. You can frame a house. This section asks for the California limits you normally leave to the plans and the inspector: notch depths, bolt spacing, stair geometry, guard heights.
What CSLB says it covers
- Subfloor and wall framing — sills, joists, bearing, studs, plates, notching and boring, fireblocking.
- Roof framing — rafters, ridges, ties, bearing.
- Seismic hardware requirements and installation — anchor bolts, hold-downs, cripple walls, bracing.
- Siding and stucco — weather-resistive barriers, laps, weep screeds.
- Decks and stairs — risers, treads, headroom, handrails, guards.
The numbers that get asked
| Rule | Number |
|---|---|
| Notch in a stud, exterior or bearing wall / nonbearing partition | 25% / 40% of width |
| Bored hole in a stud (over 40% in a bearing wall: stud doubled) | 60% max; 5/8 in to edge |
| End joints in a double top plate, offset | 24 in min |
| Bearing for joists, beams, girders: wood or metal / masonry or concrete | 1½ in / 3 in |
| Sill anchor bolts: diameter, embedment, spacing | ½ in, 7 in, 6 ft o.c. |
| Anchor bolts per sill piece; bolt from each end | 2 min; 12 in max |
| Stair riser max / tread min | 7¾ in / 10 in |
| Stair headroom | 6 ft 8 in |
| Handrail required | 4 or more risers |
| Guard required on open side more than … above grade | 30 in |
| Guard height, California (decks, porches, landings) | 42 in |
| Weep screed flange / above earth / above paving | 3½ in / 4 in / 2 in |
California Residential Code values as restated in San Diego County PDS 081 Minimum Construction Specifications (framing, bearing, anchor bolts, weep screed) and the City of San Ramon deck, porch, stair and guardrail handout (2025 code cycle). Checked 29 September 2026.
Where people lose points
- 25 or 40. Notch limits depend on the wall: 25% of the stud width in exterior and bearing walls, 40% in nonbearing partitions. Bored holes go to 40% in a bearing stud, and up to 60% only if the stud is doubled.
- Percent of the actual width. A 2×6 stud is 5½ inches wide. 25% is 1⅜ inches, not 1½.
- Guards are 42 inches; stair guards may be 34. On decks, porches and landings the guard is at least 42 inches above the walking surface. On the open side of a stair it may be 34 inches, measured from the line of the tread nosings. Questions swap the two.
- “Four risers” is about handrails, “30 inches” is about guards. A handrail is required on a flight with four or more risers. A guard is required where the open side is more than 30 inches above the floor or grade within 36 inches horizontally.
- Bolt spacing has two rules. 6 feet maximum between bolts, and a bolt within 12 inches of each end of every sill piece, with at least two per piece. The count questions depend on both.
How the questions tend to read
A framing condition and a number, or a count built from one. Two examples of our own (not actual exam questions):
A 20-ft sill plate is bolted to a new foundation. Using the fewest bolts allowed, how many anchor bolts does it need?
4. The end bolts sit no more than 12 inches from each end, which leaves 18 ft between them. At 6 ft maximum spacing that is 3 spaces, so 4 bolts. The trap is 20 ÷ 6 = 3.3, rounded to 3 or 4 without placing the end bolts first.
How deep may you notch a 2×6 stud in an exterior bearing wall?
1⅜ inches. 25% of the actual 5½-inch width. 2.2 inches is the 40% limit for nonbearing partitions, and 1½ inches is 25% of the nominal 6.
How to study it
- Read one county's minimum construction specs. San Diego County's PDS 081 puts most of these numbers on a few pages, with the code section beside each. Your own county may have its own version.
- Draw it. A stair section with riser, tread, headroom, handrail and guard; a sill with bolts and end distances. Numbers stick to a sketch.
- Learn percentages as fractions of real lumber. 25% of 3½ (2×4) is ⅞ in; 25% of 5½ (2×6) is 1⅜ in.
- Budget. About 3 hours in a two-week plan and 5 in a four-week plan (B study plan).
Common questions
How high does a deck guard have to be in California?
At least 42 inches on decks, porches and landings, required where the open side is more than 30 inches above grade (California Residential Code, as restated in the City of San Ramon's 2025-cycle handout).
What is the maximum stair riser height for a house in California?
7¾ inches, with treads at least 10 inches and headroom at least 6 ft 8 in.
Last reviewed 29 September 2026 against the CSLB General Building (B) study guide 13E-B (03-2026), San Diego County PDS 081 Minimum Construction Specifications and the City of San Ramon deck, porch, stair and guardrail handout (2025 California code cycle). Code section numbers change between editions, so this page cites the rules, not the numbering. Confirm with your building department. We are not affiliated with CSLB or PSI.