CRC · California Residential Code

What are the rules for wood foundation walls and sill plate anchorage?

Q: What size anchor bolt does the CRC require for sill plates?

The CRC requires minimum 1/2‑inch (12.7 mm) anchor bolts or approved anchors providing equivalent anchorage per § R403.1.6 .

Q: How far must anchor bolts be embedded into concrete?

Bolts must extend not less than 7 inches (178 mm) into concrete or grouted CMU cells per § R403.1.6 .

Q: Can I use anchor straps instead of bolts?

Yes— approved anchors or anchor straps are permitted if they provide equivalent anchorage to the required 1/2‑inch bolts and are spaced/installed per manufacturer’s instructions and the code. § R403.1.6

Q: Is there a maximum spacing for anchors?

Typical maximum spacing is 6 ft o.c. for 1/2‑inch bolts; different spacing or bolt sizes may be required in other contexts or for seismic braced lines. § R403.1.6

Homeowner summary: The CRC requires foundation walls built of specified 2x6 lumber and sheathing and forbids exterior backfill until walls are braced or the floor is in place; sill plates (and sole plates on slabs) must be anchored to the foundation — typically with 1/2‑inch bolts embedded **7 inches** into concrete, spaced no more than **6 feet** apart, located in the **middle third** of the plate and with at least two bolts per plate section (with one within **12 inches** of each end). See **§ R404.2**, **§ R404.3** and **§ R403.1.6** for the governing text.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

In plain terms: wood foundation walls must be built from specified materials and sizes and cannot be backfilled until braced or the floor is in place, and sill plates (and sole plates on slabs) must be positively anchored to the foundation with specified bolt size, spacing and embedment. These requirements are set out in § R404.2 (wood foundation walls), § R404.3 (wood sill plates) and § R403.1.6 (foundation anchorage) of the California Residential Code.

The single most important rule: anchor all wood sill/sole plates to the foundation with approved anchors (minimum 1/2‑inch bolts or approved equivalent), spaced to the code limits, embedded 7 inches into concrete (and located in the middle third of the plate), and follow the special seismic requirements where applicable. § R403.1.6

Requirements in detail

1) Scope and basic material/identification rules (wood foundation walls)

Wood foundation walls must be constructed to the provisions of § R404.2 (including R404.2.1–R404.2.6) and the referenced figures. § R404.2
Load‑bearing lumber and wood structural panels must be identified by grade marks or an accepted certificate (DOC PS 1 / PS 2 or grade agency). § R404.2.1

2) Stud and sheathing requirements

Stud size: foundation wall studs must be 2‑inch by 6‑inch members. § R404.2.2
Required bending strength (F b) depends on stud spacing:
- at 16 in. o.c. use species with F b ≥ 1,250 psi; at 12 in. o.c. use F b ≥ 875 psi. § R404.2.2
Wood structural panel sheathing fastening follows Table R602.3(1) and § R404.2.6. § R404.2.6

3) Backfilling and bracing

Do not backfill wood foundation walls until the basement floor and first floor are constructed or the walls have been braced; for crawlspaces, interior bracing or interior backfill must be in place before exterior backfill. § R404.2.4
If not designed per AWC PWF, height of fill against the wall must not exceed 4 feet (see R404.2.3 and applicable plywood thickness requirements). § R404.2.3

4) Sill plate size and anchorage rule

Sill plates must be at least 2‑inch by 4‑inch nominal lumber. § R404.3
Anchorage for sill and sole plates is governed by § R403.1.6 (see below) and by the wall anchorage/connector requirements in § R602.11 where applicable. § R404.3

5) Foundation anchorage — the critical numbers (§ R403.1.6)

Minimum anchor type: 1/2‑inch diameter (12.7 mm) anchor bolts OR approved anchors/anchor straps providing equivalent anchorage. § R403.1.6
Maximum spacing: not greater than 6 feet (1829 mm) on center (unless equivalent anchors, or different spacing required by other provisions). § R403.1.6
Minimum embedment: bolts shall extend not less than 7 inches (178 mm) into concrete or grouted CMU cells. § R403.1.6
Bolt location across plate width: located in the middle third of the plate. § R403.1.6
Minimum number per plate section: not fewer than two bolts per plate section. One of those bolts must be located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. § R403.1.6
Anchor bolts may be set while concrete is still plastic or installed later with approved anchors; when placement is impeded, concrete consolidation (vibration) is required. § R403.1.6
Sill plates and sole plates must be protected against decay and termites where R304/R305 require it. § R403.1.6

6) Seismic and higher‑performance details (special cases)

In addition to § R403.1.6, Seismic Design Categories D0, D1, D2 (and certain townhouses in C) have extra rules in § R403.1.6.1: plate washers per § R602.11.1 over braced wall lines, closer spacing for interior braced wall plates and interior bearing wall sole plates (anchor bolts ≤ 6 ft o.c., located within 12 in. of plate ends). § R403.1.6.1
The CRC also references § R602.11 for details on plate washers/anchorage hardware; follow that section for washer dimensions and connector requirements. § R403.1.6 and § R404.3

Decision‑relevant summary table

Item	Required value / threshold	Code Reference
Stud size for wood foundation walls	2" × 6"	§ R404.2.2
Stud Fb at 16 in. o.c.	≥ 1,250 psi	§ R404.2.2
Stud Fb at 12 in. o.c.	≥ 875 psi	§ R404.2.2
Max unbraced backfill height (non‑PWF)	4 ft	§ R404.2.3
Minimum sill plate size	2" × 4" nominal	§ R404.3
Minimum anchor bolt diameter	1/2‑inch (12.7 mm) or approved equivalent	§ R403.1.6
Anchor spacing (typical)	≤ 6 ft o.c.	§ R403.1.6
Bolt embedment into concrete	≥ 7 in. (178 mm)	§ R403.1.6
Bolt location across plate	Middle third of plate width	§ R403.1.6
Min bolts per plate section	2 bolts, with one ≤ 12 in. from each end (or ≥ 7 bolt diameters)	§ R403.1.6
Seismic D0/D1/D2 extra measures	Plate washers, closer end spacing and braced‑line requirements per § R403.1.6.1	§ R403.1.6.1

Exceptions & special cases

If the wood foundation is designed and installed in accordance with AWC PWF (Prescriptive Wood Foundation standard), some prescriptive limits (like the 4‑ft backfill limit) may be replaced by the PWF design; see § R404.2.3.
Short wall sections that connect offset braced wall panels may have reduced anchorage requirements as allowed by exceptions in § R403.1.6 (see the exceptions in the anchorage text for short wall lengths). § R403.1.6 – Exceptions
Where anchor bolts cannot be placed through the top of the sill plate (retrofits / existing foundations), adhesive or expansion anchors and alternative connections are addressed in the CRC Appendix/retrofit guidance — see existing‑building anchorage guidance (e.g., A304.3 in existing code appendices) for permitted alternatives and required shear capacities.

If you need the exact washer dimensions or anchor‑strap load‑ratings used in Seismic Design Category D/E, those details are covered in related sections (for example § R602.11 and the CBC wood provisions) which should be consulted for exact plate‑washer sizes; the CRC references those sections rather than repeating full washer specs. § R403.1.6 and § R404.3

Common mistakes

Installing bolts with insufficient embedment (less than 7 in.) or placing bolts outside the middle third of the plate width — both violate § R403.1.6.
Spacing anchors wider than 6 ft o.c. without using an approved equivalent anchor strap system — noncompliant with § R403.1.6.
Using untreated lumber for sill/sole plates where decay/termite protection is required (per R304/R305) — CRC requires protection where those sections apply. § R403.1.6
Backfilling wood foundation walls before the floor is poured or walls are braced — prohibited by § R404.2.4.
Forgetting seismic requirements: omitting plate washers or not following the closer anchorage/washer rules in § R403.1.6.1 where the SDC necessitates them.

Worked example — applying the rule with numbers

Scenario: a continuous exterior sill/sole plate runs 20 feet (240 in.) along a foundation in a non‑seismic‑exception location (SDC A/B/C typical), using standard CRC anchorage.

Step 1 — anchor spacing rule: anchors can be at most 6 ft (72 in.) o.c. and there must be at least two bolts per plate section with one no more than 12 in. from each end. § R403.1.6

Step 2 — place required end bolts: put one bolt at 12 in. from each end → positions at 12 in. and 228 in. (240 − 12).

Step 3 — check intermediate spacing: the distance between the two end bolts is 216 in.; to keep spacing ≤72 in., add bolts such that consecutive bolt spacing ≤72 in. A compliant layout is bolts at:

12 in. (end)
84 in. (12 + 72)
156 in. (84 + 72)
228 in. (end) That is 4 bolts total, each 1/2‑inch diameter, embedded 7 in. into the concrete, and located in the middle third of the sill width. § R403.1.6

If this project were in Seismic Design Category D, plate washers and possibly closer spacing/washer at braced wall lines would be required — consult § R403.1.6.1 for the additional requirements.

Related provisions

§ R404.2 — Wood foundation walls (materials, stud size, backfill and fastening).
§ R404.3 — Wood sill plates (minimum size; cross‑reference to anchorage sections).
§ R403.1.6 — Foundation anchorage (anchor bolt diameter, spacing, embedment, location, decay protection).
§ R403.1.6.1 — Additional anchorage requirements in Seismic Design Categories D0/D1/D2 (plate washers, special spacing).
§ R602.11 / R602.11.1 — Plate washer and connector detail references called out for braced wall line anchorage (see CRC cross‑references).
Appendix/retrofit guidance for existing foundations (anchor alternatives and adhesive/expansion anchors): see the CRC/Existing Building Appendix material (e.g., A304.3 guidance).

Code references

Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:

CRC § 3.1 High relevance — show source text
Cold-formed steel framing shall be anchored directly to the foundation or fastened to wood sill plates in accordance with Section R505.3.1 or R603.3.1, as applicable. Wood sill plates supporting cold-formed steel framing shall be anchored to the foundation in accordance with this section.

Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with minimum [1] / 2 -inch-diameter (12.7 mm) anchor bolts spaced not greater than 6 feet (1829 mm) on center or approved anchors or anchor straps spaced as required to provide equivalent anchorage to [1] / 2 -inch-diameter (12.7 mm) anchor bolts. Bolts shall extend not less than 7 inches (178 mm) into concrete or grouted cells of concrete masonry units. The bolts shall be located in the middle third of the width of the plate. A nut and washer shall be tightened on each anchor bolt. There shall be not fewer than two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. Interior bearing wall sole plates on monolithic slab foundation that are not part of a braced wall panel shall be positively anchored with approved fasteners. Sill plates and sole plates shall be protected against decay and termites where required by Sections R304 and R305. Anchor bolts shall be permitted to be located while concrete is still plastic and before it has set. Where anchor bolts resist placement or the consolidation of concrete around anchor bolts is impeded, the concrete shall be vibrated to ensure full contact between the anchor bolts and concrete.

Exceptions:
1. Walls 24 inches (610 mm) total length or shorter connecting offset braced wall panels shall be anchored to the foundation with not fewer than one anchor bolt located in the center third of the plate section and shall be attached to adjacent braced wall panels at corners as shown in Item 9 of Table R602.3(1).
2. Connection of walls 12 inches (305 mm) total length or shorter connecting offset braced wall panels to the foundation without anchor bolts shall be permitted. The wall shall be attached to adjacent braced wall panels at corners as shown in Item 9 of Table R602.3(1).
R403.1.6.1 Foundation anchorage in Seismic Design Categories C, D 0 , D 1 and D 2 . In addition to the requirements of Section R403.1.6, the following requirements shall apply to wood light-frame structures in Seismic Design Categories D 0, D 1 and D 2 and wood light-frame townhouses in Seismic Design Category C.
1. Plate washers conforming to Section R602.11.1 shall be provided for all anchor bolts over the full length of required braced wall lines except where approved anchor straps are used. Properly sized cut washers shall be permitted for anchor bolts in wall lines not containing braced wall panels.
2. Interior braced wall plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section where supported on a continuous foundation.
3. Interior bearing wall sole plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section where supported on a continuous foundation.
CRC § 4-14 High relevance — show source text
1. Constructed in accordance with ASCE 32.
2. Erected on solid rock.
Footings shall not bear on frozen soil unless the frozen condition is permanent.

Exceptions:
1. Protection of free-standing accessory structures with an area of 600 square feet (56 m [2] ) or less, of light-frame construction, with an eave height of 10 feet (3048 mm) or less shall not be required.
2. Protection of free-standing accessory structures with an area of 400 square feet (37 m [2] ) or less, of other than lightframe construction, with an eave height of 10 feet (3048 mm) or less shall not be required.
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R403.1.5 Slope. The top surface of footings shall be level. The bottom surface of footings shall not have a slope exceeding 1 unit vertical in 10 units horizontal (10-percent slope). Footings shall be stepped where it is necessary to change the elevation of the top surface of the footings or where the slope of the bottom surface of the footings will exceed 1 unit vertical in 10 units horizontal (10percent slope).

R403.1.6 Foundation anchorage. Wood sill plates and wood walls supported directly on continuous foundations shall be anchored to the foundation in accordance with this section.

Cold-formed steel framing shall be anchored directly to the foundation or fastened to wood sill plates in accordance with Section R505.3.1 or R603.3.1, as applicable. Wood sill plates supporting cold-formed steel framing shall be anchored to the foundation in accordance with this section.

Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with minimum [1] / 2 -inch-diameter (12.7 mm) anchor bolts spaced not greater than 6 feet (1829 mm) on center or approved anchors or anchor straps spaced as required to provide equivalent anchorage to [1] / 2 -inch-diameter (12.7 mm) anchor bolts. Bolts shall extend not less than 7 inches (178 mm) into concrete or grouted cells of concrete masonry units. The bolts shall be located in the middle third of the width of the plate. A nut and washer shall be tightened on each anchor bolt. There shall be not fewer than two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. Interior bearing wall sole plates on monolithic slab foundation that are not part of a braced wall panel shall be positively anchored with approved fasteners. Sill plates and sole plates shall be protected against decay and termites where required by Sections R304 and R305. Anchor bolts shall be permitted to be located while concrete is still plastic and before it has set. Where anchor bolts resist placement or the consolidation of concrete around anchor bolts is impeded, the concrete shall be vibrated to ensure full contact between the anchor bolts and concrete.
CRC § 1.6 High relevance — show source text
Piers supporting girders for interior bearing walls shall have a minimum nominal dimension of 12 inches (305 mm) and a maximum height of 10 feet (3048 mm) from top of footing to bottom of sill plate or girder. Piers supporting girders for exterior bearing walls shall have a minimum nominal dimension of 12 inches (305 mm) and a maximum height of 4 feet (1220 mm) from top of footing to bottom of sill plate or girder. Girders and sill plates shall be anchored to the pier or footing in accordance with Section R403.1.6 or Figure R404.1.5.3. Floor girder bearing shall be in accordance with Section R502.6.

R404.1.9.3 Masonry piers supporting braced wall panels. Masonry piers supporting braced wall panels shall be designed in accordance with accepted engineering practice.

R404.1.9.4 Seismic design of masonry piers. Masonry piers in dwellings located in Seismic Design Category D 0, D 1 or D 2, and townhouses in Seismic Design Category C, shall be designed in accordance with accepted engineering practice.

R404.1.9.5 Masonry piers in flood hazard areas. Masonry piers for dwellings in flood hazard areas shall be designed in accordance with Section R306.

R404.2 Wood foundation walls. Wood foundation walls shall be constructed in accordance with the provisions of Sections R404.2.1 through R404.2.6 and with the details shown in Figures R403.1(2) and R403.1(3).

R404.2.1 Identification. Load-bearing lumber shall be identified by the grade mark of a lumber grading or inspection agency that has been approved by an accreditation body that complies with DOC PS 20. In lieu of a grade mark, a certificate of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted. Wood structural panels shall conform to DOC PS 1 or DOC PS 2 and shall be identified by a grade mark or certificate of inspection issued by an approved agency.

R404.2.2 Stud size. The studs used in foundation walls shall be 2-inch by 6-inch (51 mm by 152 mm) members. Where spaced 16 inches (406 mm) on center, a wood species with an F b value of not less than 1,250 pounds per square inch (8619 kPa) as listed in ANSI AWC NDS shall be used. Where spaced 12 inches (305 mm) on center, an F b of not less than 875 psi (6033 kPa) shall be required.

R404.2.3 Height of backfill. For wood foundations that are not designed and installed in accordance with AWC PWF, the height of backfill against a foundation wall shall not exceed 4 feet (1219 mm). Where the height of fill is more than 12 inches (305 mm) above the interior grade of a crawl space or floor of a basement, the thickness of the plywood sheathing shall meet the requirements of Table R404.2.3.

|TABLE R404.2.
CRC § 1.1. High relevance — show source text
DOC PS 1 Plywood grades marked:
1.1. Structural I C-D (Exposure 1).
1.2. C-D (Exposure 1).
2. DOC PS 2 Plywood grades marked:
2.1. Structural I Sheathing (Exposure 1).
2.2. Sheathing (Exposure 1).
3. Where a major portion of the wall is exposed above ground and a better appearance is desired, the following plywood grades marked exterior are suitable:
3.1. Structural I A-C, Structural I B-C or Structural I C-C (Plugged) in accordance with DOC PS 1.
3.2. A-C Group 1, B-C Group 1, C-C (Plugged) Group 1 or MDO Group 1 in accordance with DOC PS 1.
3.3. Single Floor in accordance with DOC PS 1 or DOC PS 2.
b. Minimum thickness15/32 inch, except crawl space sheathing shall have not less than3/8 inch for face grain across studs 16 inches on center and maximum 2-foot depth of
unequal fill.
c. For this fill height, thickness and grade combination, panels that are continuous over less than three spans (across less than three stud spacings) require blocking 16 inches
above the bottom plate. Offset adjacent blocks and fasten through studs with two 16d corrosion-resistant nails at each end.|

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R404.2.4 Backfilling. Wood foundation walls shall not be backfilled until the basement floor and first floor have been constructed or the walls have been braced. For crawl space construction, backfill or bracing shall be installed on the interior of the walls prior to placing backfill on the exterior.

R404.2.5 Drainage and dampproofing. Wood foundation basements shall be drained and dampproofed in accordance with Sections R405 and R406, respectively.

R404.2.6 Fastening. Wood structural panel foundation wall sheathing shall be attached to framing in accordance with Table R602.3(1) and Section R402.1.1.

R404.3 Wood sill plates. Wood sill plates shall be not less than 2-inch by 4-inch (51 mm by 102 mm) nominal lumber. Sill plate anchorage shall be in accordance with Sections R403.1.6 and R602.11.

R404.4 Retaining walls. Retaining walls that are not laterally supported at the top and that retain in excess of 48 inches (1219 mm) of unbalanced fill, or retaining walls exceeding 24 inches (610 mm) in height that resist lateral loads in addition to soil, shall be designed in accordance with accepted engineering practice to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Retaining walls shall be designed for a safety factor of 1.5 against lateral sliding and overturning. This section shall not apply to foundation walls supporting buildings.

R404.5 Precast concrete foundation walls.
CRC § 2308.6.1.1 High relevance — show source text
2308.6.1.1 Ceiling joists. Where ceiling joists also serve as floor joists, they shall be considered floor joists within this section.

2308.6.2 Wall studs. In exterior walls and bearing partitions, a wood stud shall not be cut or notched in excess of 25 percent of its depth. In nonbearing partitions that do not support loads other than the weight of the partition, a stud shall not be cut or notched in excess of 40 percent of its depth.

2308.6.3 Bored holes. The diameter of bored holes in wood studs shall not exceed 40 percent of the stud depth. The diameter of bored holes in wood studs shall not exceed 60 percent of the stud depth in nonbearing partitions. The diameter of bored holes in wood studs shall not exceed 60 percent of the stud depth in any wall where each stud is doubled, provided that not more than two such successive doubled studs are so bored. The edge of the bored hole shall not be closer than [5] / 8 inch (15.9 mm) to the edge of the stud. Bored holes shall not be located at the same section of stud as a cut or notch.

2308.6.4 Limitations. In designated lateral force-resisting system assemblies designed in accordance with this code and greater than three stories in height or in Seismic Design Categories C, D, E and F, the cutting, notching and boring of wall studs shall be as prescribed by the registered design professional.

In structures designed in accordance with the California Residential Code, modification of wall studs shall comply with the Cali- fornia Residential Code .

2308.7 Foundations and footings. Foundations and footings shall be designed and constructed in accordance with Chapter 18. Connections to foundations and footings shall comply with this section.

2308.7.1 Foundation plates or sills. Foundation plates or sills resting on concrete or masonry foundations shall comply with Section 2304.3.1. Foundation plates or sills shall be bolted or anchored to the foundation with not less than [1] / 2 -inch-diameter (12.7 mm) steel bolts or approved anchors spaced to provide equivalent anchorage as the steel bolts. Bolts shall be embedded not less than 7 inches (178 mm) into concrete or masonry. The bolts shall be located in the middle third of the width of the plate. Bolts shall be spaced not more than 6 feet (1829 mm) on center and there shall be not less than two bolts or anchor straps per piece with one bolt or anchor strap located not more than 12 inches (305 mm) or less than 4 inches (102 mm) from each end of each piece. Bolts in sill plates of braced wall lines in structures over two stories above grade shall be spaced not more than 4 feet (1219 mm) on center. A properly sized nut and washer shall be tightened on each bolt to the plate.

2308.7.1.1 Braced wall line sill plate anchorage in Seismic Design Category D. Sill plates along braced wall lines in buildings assigned to Seismic Design Category D shall be anchored with not less than [1] / 2 -inch (12.7 mm) diameter anchor bolts with steel plate washers between the foundation sill plate and the nut, or approved anchor straps load-rated in accordance with Section 2304.10.4 and spaced to provide equivalent anchorage.
CRC § 2308.7.1 High relevance — show source text
2308.7.1 Foundation plates or sills. Foundation plates or sills resting on concrete or masonry foundations shall comply with Section 2304.3.1. Foundation plates or sills shall be bolted or anchored to the foundation with not less than [1] / 2 -inch-diameter (12.7 mm) steel bolts or approved anchors spaced to provide equivalent anchorage as the steel bolts. Bolts shall be embedded not less than 7 inches (178 mm) into concrete or masonry. The bolts shall be located in the middle third of the width of the plate. Bolts shall be spaced not more than 6 feet (1829 mm) on center and there shall be not less than two bolts or anchor straps per piece with one bolt or anchor strap located not more than 12 inches (305 mm) or less than 4 inches (102 mm) from each end of each piece. Bolts in sill plates of braced wall lines in structures over two stories above grade shall be spaced not more than 4 feet (1219 mm) on center. A properly sized nut and washer shall be tightened on each bolt to the plate.

2308.7.1.1 Braced wall line sill plate anchorage in Seismic Design Category D. Sill plates along braced wall lines in buildings assigned to Seismic Design Category D shall be anchored with not less than [1] / 2 -inch (12.7 mm) diameter anchor bolts with steel plate washers between the foundation sill plate and the nut, or approved anchor straps load-rated in accordance with Section 2304.10.4 and spaced to provide equivalent anchorage. Plate washers shall be not less than 0.229 inch by 3 inches by 3 inches (5.82 mm by 76 mm by 76 mm) in size. The hole in the plate washer is permitted to be diagonally slotted with a width of up to [3] / 16 inch (4.76 mm) larger than the bolt diameter and a slot length not to exceed 1 [3] / 4 inches (44 mm), provided that a standard cut washer is placed between the plate washer and the nut.

2308.7.1.2 Braced wall line sill plate anchorage in Seismic Design Category E. Sill plates along braced wall lines in buildings assigned to Seismic Design Category E shall be anchored with not less than [5] / 8 -inch diameter (15.9 mm) anchor bolts with steel

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plate washers between the foundation sill plate and the nut, or approved anchor straps load-rated in accordance with Section 2304.10.4 and spaced to provide equivalent anchorage. Plate washers shall be not less than 0.229 inch by 3 inches by 3 inches (5.82 mm by 76 mm by 76 mm) in size. The hole in the plate washer is permitted to be diagonally slotted with a width of up to 3 / 16 inch (4.76 mm) larger than the bolt diameter and a slot length not to exceed 1 3 / 4 inches (44 mm), provided that a standard cut washer is placed between the plate washer and the nut.

2308.8 Floor framing. Floor framing shall comply with this section.

CRC § 3.1 High relevance — show source text

Anchors shall be installed in accordance with Figure A304.3.1(1), with the plate washer installed between the nut and the sill plate. The nut shall be tightened to a snugtight condition after curing is complete for adhesive anchors and after expansion wedge engagement for expansion anchors. Anchors shall be installed in accordance with manufacturer’s recommendations. Expansion anchors shall not be used where the installation causes surface cracking of the foundation wall at the locations of the anchor.

Where existing conditions prevent anchor installations through the top of the sill plate, this connection shall be made in accordance with Figure A304.3.1(2), A304.3.1(3) or A304.3.1(4). Alternative anchorage methods having a minimum shear capacity of 900 pounds (4003 N) per connection parallel to the wall shall be permitted. The spacing of these alternative connections shall comply with the maximum spacing requirements of Table A304.3.1 for [1] / 2 -inch (12.7 mm) bolts.

[BS] TABLE A304.3.1—SILL PLATE ANCHORAGE AND CRIPPLE WALL BRACING	Col2	Col3	Col4
NUMBER OF STORIES ABOVE CRIPPLE WALLS	MINIMUM SILL PLATE CONNECTION AND MAXIMUM SPACINGa, b, c	AMOUNT OF BRACING FOR EACH WALL LINEd, e, f	AMOUNT OF BRACING FOR EACH WALL LINEd, e, f
NUMBER OF STORIES ABOVE CRIPPLE WALLS	MINIMUM SILL PLATE CONNECTION AND MAXIMUM SPACINGa, b, c	A combination of exterior walls finished with Portland cement plaster and roofing using clay tile or concrete tile weighing more than 6 psf (287 N/m2)	All other conditions
One story	1/2 inch spaced 6 feet, 0 inch center- to-center with washer plate	Each end and not less than 50 percent of the wall length	Each end and not less than 40 percent of the wall length
Two stories	1/2 inch spaced 4 feet, 0 inch center- to-center with washer plate; or5/8 inch spaced 6 feet, 0 inch center-to- center with washer plate	Each end and not less than 70 percent of the wall length	Each end and not less than 50 percent of the wall length
Three stories	5/8 inch spaced 4 feet, 0 inch center- to-center with washer plate	100 percent of the wall lengthg	Each end and not less than 80 percent of the wall lengthg
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 47.88 N/m2. a. Sill plate anchors shall be adhesive anchors or expansion anchors in accordance with Section A304.3.1. b. All washer plates shall be 3 inches by 3 inches by 0.229 inch minimum. The hole in the plate washer is permitted to be diagonally slotted with a width of up to3/16 inch larger than the bolt diameter and a slot length not to exceed 13/4 inches, provided that a standard cut washer is placed between the plate washer and the nut. c.

CRC § 3.1 High relevance — show source text
NR = Uplift connector not required.
d. Foundation anchor straps are permitted in place of anchor bolts, if spaced as required to provide equivalent anchorage to the required anchor bolts and installed in accor-
dance with manufacturer’s requirements.
e. See Figure R603.3.1(4) for details.|For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s, 1 foot = 304.8 mm, 1 pound = 4.45 N.
a. Anchor bolts are to be located not more than 12 inches from corners or the termination of bottom tracks, such as at door openings or corners. Bolts are to extend not less than
15 inches into masonry or 7 inches into concrete.
b. All screw sizes shown are minimum.
c. NR = Uplift connector not required.
d. Foundation anchor straps are permitted in place of anchor bolts, if spaced as required to provide equivalent anchorage to the required anchor bolts and installed in accor-
dance with manufacturer’s requirements.
e. See Figure R603.3.1(4) for details.|For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s, 1 foot = 304.8 mm, 1 pound = 4.45 N.
a. Anchor bolts are to be located not more than 12 inches from corners or the termination of bottom tracks, such as at door openings or corners. Bolts are to extend not less than
15 inches into masonry or 7 inches into concrete.
b. All screw sizes shown are minimum.
c. NR = Uplift connector not required.
d. Foundation anchor straps are permitted in place of anchor bolts, if spaced as required to provide equivalent anchorage to the required anchor bolts and installed in accor-
dance with manufacturer’s requirements.
e. See Figure R603.3.1(4) for details.|

FIGURE R603.3.1(1)—WALL TO FLOOR CONNECTION

FLOOR JOIST

FLOOR SHEATHING

NO. 8 SCREWS SPACED PER TABLE R603.3.1

2025 CALIFORNIA RESIDENTIAL CODE 6-55

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

WALL CONSTRUCTION

TRACK

For SI: 1 inch = 25.4 mm.

For SI: 1 mil = 0.0254 mm, 1 inch = 25.4 mm.

FIGURE R603.3.1(2)—WALL TO FOUNDATION CONNECTION

NO. 8 SCREW THROUGH EACH FLANGE

4 NO. 8 SCREWS THROUGH EACH FLANGE

STUD BLOCKING INSIDE WALL TRACK (MINIMUM THICKNESS OF STUD)

ANCHOR BOLT OR OTHER CONNECTION AS REQUIRED

FOUNDATION OR SLAB ON GRADE

SILL SEALER AS REQUIRED

FIGURE R603.3.1(3)—WALL TO WOOD SILL CONNECTION

MINIMUM 3 ″ x 4 ″ x 33 MIL

METAL PLATE

4-10d OR 6-8d COMMON NAIL

NO. 8 SCREW THROUGH EACH FLANGE

MINIMUM 4 NO. 8 SCREWS

ANCHOR BOLT THROUGH WOOD SILL OR OTHER CONNECTION AS REQUIRED

6-56 2025 CALIFORNIA RESIDENTIAL CODE
CRC § 5.1 High relevance — show source text
The Col2

~~cor~~
SIP e

joints in top plates shall be offset not less than 24 inches (610 mm).

FIGURE R610.5.1—SIP WALL FRAMING CONFIGURATION

2x TOP PLATE

RECESSED INTO SIP CORE, WIDTH EQUAL TO SIP

CORE WIDTH

2x KING STUDS

RECESSED INTO THE SIP CORE, WIDTH EQUAL TO SIP CORE

For SI: 1 inch = 25.4 mm.

Notes:
1. Top plates shall be continuous over header.
2. Lower 2x top plate shall have a width equal to the SIP core width and shall be recessed into the top edge of the panel. Cap plate shall be placed over the recessed top plate and shall have a width equal to the SIP’s width.
3. SIP facing surfaces shall be nailed to framing and cripples with 8d common or galvanized box nails spaced 6 inches on center.
6-180 2025 CALIFORNIA RESIDENTIAL CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

WALL CONSTRUCTION

R610.5.2 Bottom (sole) plate connection. SIP walls shall have full bearing on a sole plate having a width equal to the nominal width of the foam core. Where SIP walls are supported directly on continuous foundations, the wall wood sill plate shall be anchored to the foundation in accordance with Figure R610.5.2 and Section R403.1.

FIGURE R610.5.2—SIP WALL TO CONCRETE SLAB FOR FOUNDATION WALL ATTACHMENT

SIP WALL

CONTINUOUS

SEALANT EACH

2x SOLE PLATE

MATCHING THE SIP

CORE THICKNESS

8d COMMON

NAILS AT 6 IN.

O.C. EACH SIDE

CAPILLARY BREAK

BETWEEN SIP AND

FOUNDATION

CONCRETE OR

MASONRY

FOUNDATION

WALL OR SLAB

FOUNDATION ANCHORAGE

PER SECTION R403.1.6

For SI: 1 inch = 25.4 mm.

R610.5.3 Panel-to-panel connection. SIPs shall be connected at vertical in-plane joints in accordance with Figure R610.8 or by other approved methods.

R610.5.4 Corner framing. Corner framing of SIP walls shall be constructed in accordance with Figure R610.5.4.

FIGURE R610.5.4 ~~—SIP CO~~ RNER FRAMING DETAIL

8d NAILS AT 6 IN. O.C. EACH SIDE

CONTINUOUS SEALANT

EACH SIDE

SIP SCREW AT 24 IN.

CONTINUOUS SEALANT

EACH SIDE

For SI: 1 inch = 25.4 mm.

R610.5.5 Wall bracing. SIP walls shall be braced in accordance with Section R602.10. SIP walls shall be considered continuous wood structural panel sheathing (bracing Method CS-WSP) for purposes of computing required bracing. SIP walls shall meet the requirements of Section R602.10.4.2 except that SIP corners shall be fabricated as shown in Figure R610.8. Where SIP walls are used for wall bracing, the SIP bottom plate shall be attached to wood framing below in accordance with Table R602.3(1).
CRC § 2306.1 High relevance — show source text
Where panels are applied on both faces of a wall and fastener spacing is less than 6 inches on center on either side, panel joints shall be offset to fall on different framing
members, or framing shall be 3 inches nominal or thicker at adjoining panel edges.
g. In Seismic Design Category D, E or F, where shear design values exceed 350 pounds per linear foot, all framing members receiving edge fastening from abutting panels shall be
not less than a single 3-inch nominal member, or two 2-inch nominal members fastened together in accordance with Section 2306.1 to transfer the design shear value
between framing members. Wood structural panel joint and sill plate nailing shall be staggered at all panel edges. See AWC SDPWS for sill plate size and anchorage
requirements.
h. Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
i. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
b. Panel edges backed with 2-inch nominal or wider framing. Install panels either horizontally or vertically. Space fasteners maximum 6 inches on center along intermediate
framing members for3/8-inch and7/16-inch panels installed on studs spaced 24 inches on center. For other conditions and panel thickness, space fasteners maximum 12 inches
on center on intermediate supports.
c. 3/8-inch panel thickness or siding with a span rating of 16 inches on center is the minimum recommended where applied directly to framing as exterior siding. For grooved
panel siding, the nominal panel thickness is the thickness of the panel measured at the point of fastening.
d. Framing at adjoining panel edges shall be 3 inches nominal or wider.
e. Values apply to all-veneer plywood. Thickness at point of fastening on panel edges governs shear values.
f. Where panels are applied on both faces of a wall and fastener spacing is less than 6 inches on center on either side, panel joints shall be offset to fall on different framing
members, or framing shall be 3 inches nominal or thicker at adjoining panel edges.
g. In Seismic Design Category D, E or F, where shear design values exceed 350 pounds per linear foot, all framing members receiving edge fastening from abutting panels shall be
not less than a single 3-inch nominal member, or two 2-inch nominal members fastened together in accordance with Section 2306.1 to transfer the design shear value
between framing members. Wood structural panel joint and sill plate nailing shall be staggered at all panel edges. See AWC SDPWS for sill plate size and anchorage
requirements.
h. Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
i.
CRC § 2.4 Medium relevance — show source text
Framing members that are both load-bearing and stabilization members shall meet the requirements of Section R602 and this section. Nonstructural stabilization members shall be not more than 32 inches (813 mm) on center. 2. Horizontal stabilization shall be installed at not more than 24 inches (610 mm) on center and in accordance with Figure BI103.2.4(1), BI103.2.4(2) or BI103.2.4(3). Horizontal stabilization shall be of any of the following with the stated minimum dimensions: [3] / 4 -inch (19.1 mm) bamboo, [1] / 2 -inch (12.7 mm) fiberglass rod, 1-inch (25 mm) wood dowel or nominal 1-inch by 2-inch (25 mm by 51 mm) wood.

FIGURE BI103.2.4(1)—LIGHT STRAW-CLAY WALL WITH LARSEN TRUSSES

DOUBLE TOP PLATE

VERTICAL SOLID BLOCKING

FLAT SOLID BLOCKING

LADDER (LARSEN) TRUSSES MADE WITH 2x4s AND GUSSETS PER SECTION BI103.2.4, ITEM 1

GUSSETS: [3] / 8 ″ x 3 ″ PLYWOOD OR 1x4 FASTENERS: 4–4d NAILS OR 4–1¾ ″ STAPLES

WOOD OR METAL STRAP BRACING (LIB) PER TABLE 602.10.4 WHERE APPLICABLE PER SECTION R602.10

LIGHT STRAW-CLAY INFILL

HORIZONTAL STABILIZATION OF LIGHT STRAW-CLAY PER SECTION BI103.4, ITEM 2

ANCHORAGE PER SECTION R403.1.6

2X SILL PLATE

CONCRETE OR MASONRY FOUNDATION PER SECTION R401

FRAMING FASTENERS PER TABLE R602.3(1)

For SI: 1 inch = 25.4 mm.

APPENDIX BI-4 2025 CALIFORNIA RESIDENTIAL CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX BI — LIGHT STRAW-CLAY CONSTRUCTION

FIGURE BI103.2.4(2)—LIGHT STRAW-CLAY WALL, SINGLE STUD WIDTH

DOUBLE TOP PLATE

FLAT SOLID BLOCKING

WOOD METAL STRAP BRACING (LIB) PER TABLE R602.10.4 WHERE APPLICABLE PER SECTION R602.10

2X STUDS PER SECTION BI103.2.4, ITEM 1

1x1 CLEAT CENTERED ON EACH STUD FACE BETWEEN HORIZONTAL STABILIZATION

HORIZONTAL STABILIZATION OF LIGHT STRAW-CLAY PER SECTION BI103.2.4, ITEM 2

LIGHT STRAY-CLAY INFILL

ANCHORAGE PER SECTION R403.1.6

2X SILL PLATE

CONCRETE OR MASONRY FOUNDATION PER SECTION R401

FRAMING FASTENERS PER TABLE R602.3(1)

FIGURE BI103.2.4(3)—LIGHT STRAW-CLAY WALL WITH BLIND STUDS

DOUBLE TOP PLATES

2X LET-IN PLATE

WOOD METAL BRACING (LIB) PER TABLE R602.10.4 WHERE APPLICABLE PER SECTION R602.10

2x6 MINIMUM STUDS PER SECTION BI103.2.4, ITEM 1

LIGHT STRAW-CLAY INFILL
CRC § 2.4 Medium relevance — show source text
Lab test for percent of clay, silt and sand via hydrometer method.
2. The Figure 2 Ribbon Test and the Figure 3 Ball Test in the appendix of ASTM E2392/E2392M.
d. Trace amounts of organic materials are acceptable.|©Douglas Piltingsrud and StrawClay.org. Used by permission.
a. Interpolation permitted. Extrapolation not permitted.
b. Water mixed with subsoil equals clay slip.
c. Subsoil Testing Methods:
1. Lab test for percent of clay, silt and sand via hydrometer method.
2. The Figure 2 Ribbon Test and the Figure 3 Ball Test in the appendix of ASTM E2392/E2392M.
d. Trace amounts of organic materials are acceptable.|©Douglas Piltingsrud and StrawClay.org. Used by permission.
a. Interpolation permitted. Extrapolation not permitted.
b. Water mixed with subsoil equals clay slip.
c. Subsoil Testing Methods:
1. Lab test for percent of clay, silt and sand via hydrometer method.
2. The Figure 2 Ribbon Test and the Figure 3 Ball Test in the appendix of ASTM E2392/E2392M.
d. Trace amounts of organic materials are acceptable.|

BI103.2.4 Stabilization of light straw-clay. Light straw-clay shall be stabilized as follows, or shall be in accordance with an approved design by a registered design professional:
1. Vertical stabilization shall be of structural or nonstructural wood framing in accordance with Figure BI103.2.4(1), BI103.2.4(2) or BI103.2.4(3). Framing members that are both load-bearing and stabilization members shall meet the requirements of Section R602 and this section. Nonstructural stabilization members shall be not more than 32 inches (813 mm) on center.
2. Horizontal stabilization shall be installed at not more than 24 inches (610 mm) on center and in accordance with Figure BI103.2.4(1), BI103.2.4(2) or BI103.2.4(3). Horizontal stabilization shall be of any of the following with the stated minimum dimensions: [3] / 4 -inch (19.1 mm) bamboo, [1] / 2 -inch (12.7 mm) fiberglass rod, 1-inch (25 mm) wood dowel or nominal 1-inch by 2-inch (25 mm by 51 mm) wood.
FIGURE BI103.2.4(1)—LIGHT STRAW-CLAY WALL WITH LARSEN TRUSSES

DOUBLE TOP PLATE

VERTICAL SOLID BLOCKING

FLAT SOLID BLOCKING

LADDER (LARSEN) TRUSSES MADE WITH 2x4s AND GUSSETS PER SECTION BI103.2.4, ITEM 1

GUSSETS: [3] / 8 ″ x 3 ″ PLYWOOD OR 1x4 FASTENERS: 4–4d NAILS OR 4–1¾ ″ STAPLES

WOOD OR METAL STRAP BRACING (LIB) PER TABLE 602.10.4 WHERE APPLICABLE PER SECTION R602.10

LIGHT STRAW-CLAY INFILL

HORIZONTAL STABILIZATION OF LIGHT STRAW-CLAY PER SECTION BI103.4, ITEM 2

ANCHORAGE PER SECTION R403.1.6

2X SILL PLATE

The	Col2

~~cor~~ SIP	e

Frequently asked questions

What size anchor bolt does the CRC require for sill plates?

The CRC requires minimum 1/2‑inch (12.7 mm) anchor bolts or approved anchors providing equivalent anchorage per § R403.1.6.

How far must anchor bolts be embedded into concrete?

Bolts must extend not less than 7 inches (178 mm) into concrete or grouted CMU cells per § R403.1.6.

Can I use anchor straps instead of bolts?

Yes—approved anchors or anchor straps are permitted if they provide equivalent anchorage to the required 1/2‑inch bolts and are spaced/installed per manufacturer’s instructions and the code. § R403.1.6

Is there a maximum spacing for anchors?

Typical maximum spacing is 6 ft o.c. for 1/2‑inch bolts; different spacing or bolt sizes may be required in other contexts or for seismic braced lines. § R403.1.6

When can I backfill against wood foundation walls?

Do not backfill until the basement floor and first floor are constructed or the walls are braced. For crawl spaces, interior bracing/backfill is required before exterior backfill. § R404.2.4

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California Residential Code