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Building Code Reference

Got a CRC R507.3 correction?

Deck footings

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CRC R507.3 requires exterior decks to have footings sized to carry the imposed loads to the ground, with size determined by tributary area and soil bearing capacity per Table R507.3.1. Footings must extend at least 12 inches below undisturbed ground. Two situations are exempt: grade-bearing joists that bear directly on soil, and freestanding decks of 200 square feet or less with a walking surface no higher than 20 inches above grade.

How to fix it

  1. Calculate the tributary area for each footing

    Tributary area is the portion of the deck load that bears on a single footing. To find it, draw lines midway between each footing in both directions and sum the enclosed area. For a rectangular deck on four evenly spaced corner footings, each corner footing carries one quarter of the total deck area. For a 200 sq ft deck on four corners, each footing carries 50 sq ft of tributary area. Intermediate footings along a beam line each carry proportionally less. Write the tributary area calculation on your plans next to each footing location so the plan-checker can follow the math without guessing.

  2. State the assumed soil bearing capacity on the plans

    CRC Table R507.3.1 cross-references footing size against both tributary area and soil bearing capacity. For most residential sites in California without a geotechnical report, 1,500 psf is the standard presumptive soil bearing value. Call this out explicitly on the plans: 'Assumed soil bearing capacity: 1,500 psf per Table R401.4.1(1). No soils report performed.' If your site has fill, expansive clay, or known soft soils, a geotechnical report is needed before you can use a different bearing value.

  3. Look up the required footing size in Table R507.3.1

    With your tributary area and soil bearing value in hand, find the corresponding footing diameter (or dimensions) in Table R507.3.1. If your tributary area falls between two rows, interpolation is permitted but extrapolation beyond the table is not; using the row with the larger area is the simple, conservative choice. Record the required footing size for each footing location. For footings with different tributary areas across the deck, you may have more than one footing size — call each one out on the footing schedule.

  4. Show the 12-inch minimum depth on the footing detail

    R507.3 sets the minimum footing depth at 12 inches below undisturbed ground. Add a cross-section detail showing this dimension explicitly with a leader and dimension line. Undisturbed ground means native soil that hasn't been excavated and backfilled. If your site has any grading history, clarify how the depth is measured from the bottom of any disturbed material. In hillside areas or sites with recent grading, the inspector may require deeper footings or confirmation that the bearing surface is truly undisturbed.

  5. Create a footing schedule with all footings tagged

    Don't rely on the deck plan view alone to communicate footing requirements. Add a footing schedule table on the structural or civil sheet listing: footing mark (F1, F2, etc.), tributary area served, assumed soil bearing capacity, required footing diameter, and minimum embedment depth. On the deck plan, tag each footing with its mark so the plan-checker can trace from schedule to location without hunting. This table is the most direct way to satisfy R507.3 — it shows the sizing rationale and the result in one place.

  6. Document the freestanding exemption if you are using it

    If the deck qualifies for the freestanding exception, prove it on paper. Add a note stating that the joists bear directly on precast concrete pier blocks at grade with no beams or posts, the total deck area in square feet, and the walking-surface height within 36 inches of the edge. The thresholds: 200 sq ft total area and 20 inches maximum height at any point within 36 inches of the edge. If either is borderline, note how you measured it. A deck that's 199 sq ft and 19.5 inches at the high end should have both measurements confirmed on the drawing, not left implied.

  7. Show the grade-bearing joist detail if that exception applies

    Grade-bearing joists that sit directly on prepared grade are exempt from R507.3 footing requirements, but the plans need to show the configuration. Add a cross-section detail showing the joist bearing on soil, the bearing surface preparation (compacted native soil or a gravel layer), and the rot-resistant or pressure-treated specification for wood in contact with the ground. Simply noting 'grade-bearing framing' on the plan isn't enough. The detail has to show what the code intends: a joist sitting on grade, not on a post and footing assembly.

  8. Check for related deck corrections before resubmitting

    R507.3 corrections rarely come alone. The deck chapter flags tend to cluster. Before you resubmit, also review your plans against R507.9 (ledger connection to the house if attached), R507.4.1 and R507.5.2 (post-to-footing and beam-to-post connections), and R507.4 (post sizing). A plan-checker who's already flagging footings will likely flag missing connection hardware details on the same pass. If you're redlining the plans anyway, address the whole deck chapter in one shot rather than trading corrections letters across multiple review cycles.

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Why you got flagged

The most common corrections cite R507.3 because footing information simply isn't on the submitted drawings. Plan-checkers reviewing a deck addition need to confirm the footings are sized for the load — if the plans just show a 12-inch diameter concrete footing with no reference to tributary area or soil bearing value, that's a flag. The checker has no way to verify the footing is adequate without the numbers.

A second frequent scenario: the footing depth is shown, but the soil bearing value assumed for sizing isn't called out. CRC R507.3.1 ties footing size directly to both tributary area and presumptive soil bearing capacity. If your plans show a footing diameter but don't state the assumed soil bearing (typically 1,500 psf for residential sites without a soils report), the checker has to send it back.

Plans that show an isometric or 3D deck drawing without a separate footing schedule or Table R507.3.1 callout are another common trigger. The deck looks great in the drawing, but there's no place on the sheet that actually shows how the footing was sized. Plan-check departments want a clear table or detail, not an implied calculation.

A fourth situation comes up on elevated decks where the contractor assumes the 20-inch exception applies. If the walking surface is 21 inches above grade, even an inch over, the exemption disappears and full footing documentation is required. Getting the measurement wrong at submittal means the correction comes back.

The official code

2025 California Residential Code, Chapter 5 — Floors and Decks (R507.3 Deck Footings)

Read the source →

Common questions

Do I need footings for a small freestanding deck?
Not always. CRC R507.3 exempts freestanding decks that meet two conditions: 200 square feet or less in total area, and a walking surface no higher than 20 inches above grade. Both conditions must be true. If the deck is 180 sq ft but the far end is 22 inches above a sloped yard, the exception doesn't apply and footings are required. Measure the maximum height at the finished deck surface, not the average grade under the deck. The measurement point is the highest part of the walking surface relative to the ground directly below.
What soil bearing value should I use for deck footing sizing?
For most residential sites in California without a geotechnical report, 1,500 psf is the standard presumptive soil bearing value used to enter Table R507.3.1. If your site has known soil issues — fill, expansive clay, or anything flagged by prior grading — a soils report may be required to justify a different value. When in doubt, call out 1,500 psf on your plans and note that no soils report was performed. Plan-checkers know this is the conservative residential default. Using a higher bearing value without a report is where corrections come from.
How deep do deck footings need to be in California?
CRC R507.3 requires a minimum of 12 inches below undisturbed ground. That's the floor, not a target. Local building departments sometimes require deeper footings based on frost depth — not a common issue in coastal Southern California, but relevant at mountain elevations above 3,000 feet. Soil conditions and local amendments can also push the requirement deeper. Check your city's standard notes. Most Orange County cities accept 12 inches as sufficient for standard residential sites.
What is tributary area and how do I calculate it for deck footings?
Tributary area is the portion of the deck's surface that a single footing is responsible for supporting. For a rectangular deck on four corner footings, each corner footing carries roughly one quarter of the deck area. A footing in the middle of a beam carries a narrower strip. To calculate precisely: draw the midlines between adjacent footings in both directions, and the area enclosed in that grid cell is the tributary area for that footing. For a 200 sq ft deck on four corners, each footing carries 50 sq ft. Multiply by the design load (dead plus live) to get the footing load before checking the sizing table.
Why did my deck permit get a correction for footings when the concrete is already poured?
Plan-checkers review what's on paper, not what's in the ground. If the submitted drawings don't show footing sizes, embedment depth, or the sizing calculation, the correction gets issued regardless of what was actually built. The fix is to update the plans to reflect what was constructed: add a footing schedule, call out the dimensions and depth, note the soil bearing value assumed, and show how the tributary area was calculated. If the as-built footings are undersized or shallower than the code minimum, that's a separate issue to work out with your inspector.
Does R507.3 apply to attached decks the same way it applies to freestanding decks?
Yes, with one difference. The footing sizing and depth requirements apply to both. The only size-based exemption is for freestanding decks of 200 sq ft or less with a walking surface 20 inches or less above grade. Attached decks have no equivalent size exemption. Being attached to the house doesn't reduce the footing requirement. It just adds the ledger connection requirements under R507.9 as an additional item. If you're building an attached deck, plan to address both the ledger and the footings.

Related corrections

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