Research
When a retaining wall needs a permit
19 cities, counties and state codes plus 4 model codes, each with its permit height, measuring point, surcharge clause and source.
Written by HyreYard Research Desk Primary-source research and fact checking
The finding
There is no national 4-foot retaining wall law. Four feet is the IRC R105.2 permit exemption, measured from the bottom of the footing, and it disappears when the wall supports a surcharge.
Of the 23 codes we read on September 5, 2026, 9 do not use a plain 4-foot exemption. Phoenix and San Diego use 3 feet from the top of the footing; Menlo Park uses 2 feet. Ask your building department how it measures.
Read these limits first
Call 811 before anyone digs a footing. Utility lines can sit inside the depth of a wall footing.
Freestanding landscape walls only. A wall that retains or bears on a house foundation, undercuts a footing or holds up a building is a foundation condition. It belongs to a different trade and is out of scope here, even when the residential code prints the same height.
Not a design. Above the local threshold, or with any surcharge (a slope above, a driveway behind, a pool, a fence on top, tiered walls), the next step is an engineer or a licensed contractor who pulls the permit. HyreYard does not build walls.
Not a national table. It covers the codes, bulletins and department pages we opened on September 5, 2026, mostly in HyreYard’s seven research states plus Denver, Douglas County and New York City. A city missing from the table is not a city with a 4-foot rule.
Where does the 4-foot rule come from?
IRC 2024 R105.2. IRC 2024 R105.2 Building item 3; R404.4; R312.1.1. The exemption covers walls not over 4 feet, measured from the bottom of the footing to the top of the wall, unless the wall supports a surcharge.
IRC R404.4. Separately, walls not braced at the top that retain more than 48 inches of unbalanced fill, or walls over 24 inches that resist loads beyond soil, need accepted engineering practice, with a 1.5 safety factor against sliding and overturning. R404.4 “does not apply to foundation walls supporting buildings.”
IBC 2024 §105.2 and §1807.2. The commercial code also exempts 4 feet from the bottom of the footing, unless there is a surcharge or the wall impounds Class I, II or IIIA liquids. Design covers overturning, sliding, foundation pressure and water uplift. Segmental units: ASTM C1372.
HyreYard analysis. “Walls under 4 feet don’t need a permit” drops the measuring point, the surcharge clause and local amendment.
A 3-foot exposed face on a 12-inch footing is a 4-foot wall measured from the bottom of the footing, and a 3-foot wall from the top. Phoenix uses the top; the IRC uses the bottom.
Which places set a number other than 4 feet?
Phoenix, AZ: 3 feet, top of footing. Phoenix Building Construction Code Admin. 105.2.2; TRT/DOC/00181 (rev. July 2013, still the published guideline).
In Phoenix, a surcharge or Class I, II or III-A liquids removes the exemption. Surcharge includes a house, building, road, pool, or a fence on the wall or within 3 feet uphill. A wall-and-fence combination needs structural calculations at any height.
San Diego, CA (city): over 3 feet needs a permit. City of San Diego Information Bulletin 220 (Oct 2024); Information Bulletin 221 (Dec 2023); SDMC §142.0340.
Five other listed conditions also trigger one. San Diego County, CA (unincorporated) uses 3 feet too, with four other conditions that must all be true. The two are separate rules.
Menlo Park, CA: 2 feet, top of footing. Menlo Park Municipal Code Ch. 12.06, amending CBC §105.2 Building item 4. Half the model number, measured from a different point. A surcharge or impounded Class I, II or III liquids removes the exemption.
Pierce County, WA: 4 feet without a surcharge, 2 feet with one. Pierce County Planning & Public Works, “Residential Retaining Walls Permits and Exceptions,” rev. 26 Mar 2024 (2021 International Codes).
In Pierce County, a surcharge within a 45-degree angle of the bottom of the footing counts. HyreYard reading: this turns the IRC’s 24-inch engineering trigger into a permit trigger, so a 30-inch wall with a driveway behind it needs a permit.
North Carolina 2024 Residential Code: 5 feet of unbalanced backfill. R404.4 requires a registered design professional when one wall holds more than 5 feet of unbalanced backfill, or several walls add up to more than 5 feet of vertical relief within 15 feet horizontally.
North Carolina engineers property-line walls at any height. That is looser than the model on height and stricter at the property line. It replaced a 4-foot (48-inch) rule in the 2018 code.
Denver, CO (zoning permit): 12 inches. Zoning permit for new retaining walls over 12 in, with landmark exceptions. This is a zoning permit; the interpretation we read did not state the building-code threshold.
Tucson: no 4-foot number on the PDSD exemptions page we retrieved. Engineered plans may be required if the wall “functions as a retaining wall by holding back soil or changing ground level.” We did not fill in 4 feet.
HyreYard classification of 23 codes, retrieved September 5, 2026. A 4-foot bar does not mean a plain 4-foot rule: Seattle, Austin and Portland keep 4 feet and add conditions that can remove the exemption.
Which clauses remove the exemption?
The number is the easy half. The clauses beside it decide whether a wall under that number still needs a permit.
Measuring point. The IRC and IBC measure from the bottom of the footing, including the buried part. Phoenix and Menlo Park use the top of the footing. North Carolina uses unbalanced backfill, and Cary’s handout measures from grade at the face. 12 non-model rows here do not use the IRC’s bottom-of-footing point.
Surcharge. A slope above the wall, a driveway, a parking pad, a pool, a fence on top or another wall uphill. In Portland a backslope steeper than 3:1 is already a surcharge, so the 4-foot number can be irrelevant on a hillside lot.
Austin adds flood hazard: a 3-foot wall in the floodplain loses the exemption.
Tiers. North Carolina sums vertical relief within 15 feet horizontally. Two 3-foot walls that make 6 feet of relief are the engineered case, not two exempt walls.
Neighbors and critical areas. Seattle requires all three: 4 feet or lower, outside an Environmentally Critical Area, and no damage to adjoining property. The city gives a property-line wall as an example that can fail the third test.
HyreYard analysis. The useful question is not “is it under 4 feet.” It is what the city measures, what counts as surcharge, and whether a grading permit sits beside the building permit. A bid silent on those three is hard to compare.
The model codes, and California’s adopted versions
| Jurisdiction | Permit height | Measuring point | Surcharge / extra | Citation |
|---|---|---|---|---|
| IRC 2024 (model code) | 4 ft, unless supporting a surcharge | Bottom of footing → top of wall | Any surcharge removes the R105.2 permit exemption, at any height. | IRC 2024 R105.2 Building item 3; R404.4; R312.1.1 |
| IBC 2024 (model code) | 4 ft, unless surcharge or Class I, II or IIIA liquids | Bottom of footing → top of wall | Surcharge or impounding Class I, II or IIIA liquids removes the 105.2 exemption. | IBC 2024 §105.2 Building item 4; §1807.2; §1015.2 |
| California Building Code 2025 | 4 ft, unless surcharge or Class I, II or IIIA liquids | Bottom of footing → top of wall | Surcharge or impounding Class I, II or IIIA liquids removes the exemption. | 2025 California Building Code §105.2 Building item 4 |
| California Residential Code R105.2 | 4 ft, unless supporting a surcharge | Bottom of footing → top of wall | Surcharge removes the exemption at any height. | California Residential Code R105.2 Building item 3 (2022 edition as published) |
Model language and state adoptions retrieved September 5, 2026. California’s building and residential codes are listed separately because they are the adopted state models that cities then amend.
19 cities, counties and state codes
| Jurisdiction | Permit height | Measured from | Compared with the IRC | Surcharge or extra trigger |
|---|---|---|---|---|
| Florida Building Code, Residential, 8th Ed. (2023) · source | Not set statewide; permit exemptions are local | Unbalanced backfill | Height not stated in the page we retrieved | Additional lateral loads (the 24-in clause) include surcharge. Permit administration is county-level under F.S. 553.73. |
| North Carolina Residential Code 2024 · source | Engineering at 5 ft of unbalanced backfill | Unbalanced backfill | Looser than the model | Property-line walls are engineered at any height. Tiers are summed inside 15 ft. Building-support walls are out of this page’s landscape scope: they are a foundation… |
| Phoenix, AZ · source | 3 ft, unless surcharge or Class I, II or III-A liquids | Top of footing → top of wall | Stricter than the model | Surcharge includes a house, building, road, swimming pool, or a fence on the wall or within 3 ft horizontally of the uphill side. Hillsides and preservation locations… |
| Tucson, AZ · source | Not stated as a 4-ft number on the PDSD exemptions page we retrieved | Not stated / other | Height not stated in the page we retrieved | Not stated as a surcharge clause on the exemptions page. Holding back soil is itself the trigger for treating the wall as a retaining wall. |
| Los Angeles, CA · source | 4 ft in the standard LADBS figure, with conditions that take the exemption away | Bottom of footing → top of wall | 4 ft plus extra triggers | P/BC 2026-002: no permit for Figure 1 only. Permit required for Figure 2 and Figure 3 (slough wall). Figure 1 is not allowed where the existing slope below or beneath… |
| San Diego, CA (city) · source | Over 3 ft, or any of five other listed conditions | Top of footing → top of wall | Stricter than the model | Permit required if: (1) over 3 ft; (2) sloping backfill steeper than 1.5:1; (3) surcharge (driveways, walkways, structure footings, fences); (4) impounds flammable… |
| San Diego County, CA (unincorporated) · source | Walls that retain not over 3 ft of soil, with four other conditions all true | Top of footing → top of wall | Stricter than the model | Exemption (County Code 91.1.105.2 building item 7): retains not over 3 ft of soil, not more than 6 ft total height, level backfill, no other structures within 6 ft,… |
| Menlo Park, CA · source | 2 ft, unless surcharge or Class I, II or III liquids | Top of footing → top of wall | Stricter than the model | Surcharge or impounding Class I, II or III liquids removes the 2-ft exemption. |
| Seattle, WA · source | 4 ft, and two other conditions must also be true | Bottom of footing → top of wall | 4 ft plus extra triggers | No construction permit only if all three: (1) 4 ft or lower from bottom of footing to top; (2) the parcel has no Environmentally Critical Area; (3) the wall will not… |
| Pierce County, WA · source | 4 ft without surcharge; 2 ft with surcharge | Bottom of footing → top of wall | Stricter than the model | Technical bulletin (2021 International Codes): walls over 4 ft (with or without surcharge) and walls over 2 ft that support a surcharge require permitting per IRC… |
| Portland, OR · source | Over 4 ft, or any surcharge, including an ascending slope steeper than 3:1 | Bottom of footing → top of wall | 4 ft plus extra triggers | Title 24.10.072 B.2: retaining walls not over 4 ft are exempt except where the wall supports ascending slopes exceeding 3:1 or supports a nonsoil surcharge. Brochure… |
| Austin, TX · source | 4 ft, unless surcharge or located in a flood hazard | Bottom of footing → top of wall | 4 ft plus extra triggers | Residential R105.2 item 3: unless supporting a surcharge or located within a flood hazard. Commercial 105.2 item 4 adds Class I, II or IIIA liquids and repeats the… |
| Houston, TX · source | 4 ft, unless surcharge or Class I, II or IIIA liquids | Bottom of footing → top of wall | Matches the model 4 ft | Surcharge or impounding Class I, II or IIIA liquids removes the exemption. |
| San Antonio, TX · source | 4 ft or less all along its length, unless surcharge or Class I, II or IIIA liquids, measured from grade at the front, not from the footing | Exposed face / grade to grade | Same number, different measuring point | Sloping retained soil steeper than 3:1; building foundations, parking, roads/driveways, sign/monument footings within 1.5× the exposed height; solid fences attached… |
| Cary, NC · source | Implements NCRC R404.4: 5 ft unbalanced backfill / 5 ft cumulative within 15 ft | Exposed face / grade to grade | Looser than the model | Tiers: if any point of grade within 15 ft behind the wall is more than 5 ft above grade at the front of the wall base, a design professional and a Cary building… |
| Charlotte County, FL · source | Engineered drawings required if the retaining wall is more than 4 ft | Not stated / other | Matches the model 4 ft | Not stated on the residential-wall page. Zoning height and location still apply; contact Zoning. |
| New York City, NY · source | Less than 4 ft, no surcharge, no Class I, II or III-A liquids | Top of footing → top of wall | Same number, different measuring point | Any surcharge, or impounding Class I, II or III-A liquids, removes the 1 RCNY 101-14 exemption. |
| Denver, CO (zoning permit) · source | Zoning permit for new retaining walls over 12 in, with landmark exceptions | Not stated / other | Stricter than the model | Not stated in the zoning interpretation. |
| Douglas County, CO · source | Over 4 ft, or any surcharge; tiers over 4 ft or spaced less than 2× the lower wall | Bottom of footing → top of wall | 4 ft plus extra triggers | Surcharges listed: sloping retained soil, structure footings, vehicle loads, nearby structures, stockpiled materials, patios, swimming pools, driveways. Guideline:… |
Municipal and county pages retrieved September 5, 2026. Ellipses are a display limit; the full text is in the linked source. The Florida and North Carolina rows show a short label, with the full wording under Sources. “Not stated” is a gap in the page we retrieved, not a 4-foot guess.
San Diego, CA (city) and San Diego County, CA (unincorporated) are not the same 3-ft rule. Do not copy one onto the other. A grading permit, where adopted (IRC Appendix J), does not include the wall structure.
What to take to the building department
Bottom of footing, top of footing, exposed face, or unbalanced fill. The same wall is a different height in Phoenix and in the IRC.
Slope above, driveway, parking, pool, fence on top, another wall uphill, floodplain, critical area, property line. In some of these cities those clauses remove the exemption at any height.
Houston, North Carolina and Seattle run a grading permit separate from the wall permit. An exemption from one is not an exemption from the other.
A wall that undercuts a footing or holds a building is a foundation condition. It is not a landscape retaining wall. That is a different drawing and a different trade.
Above the local threshold, or with any surcharge, the next step is an engineer or a contractor who will pull the permit. This table frames the question; the local code answers it.
How we built this table
Each row is a code section, information bulletin or department page we opened on September 5, 2026, stored with the URL. Model IRC/IBC rows are the baseline cities amend.
Coverage is 19 places plus 4 model or state-model rows, mostly in TX, AZ, WA, CA, OR, FL and NC. A missing city is not a 4-foot city.
Where the published exemptions page did not print a height, we stored null. We did not fill the model number in.
North Carolina already changed 4 feet to 5 feet of unbalanced fill between the 2018 and 2024 residential codes. Re-check the department before you treat a row as current.
Questions
Do I need a permit for a retaining wall?
Is there a national 4-foot retaining wall law?
What is a surcharge on a retaining wall?
Does a 3-foot wall need a permit?
Do tiered retaining walls count as one wall?
The wall holds up part of the house. Is this the right page?
Does HyreYard build retaining walls?
Written and audited by
HyreYard Research Desk
Primary-source research, data analysis and fact checking
We are a research desk, not a landscaping company. We read the statute, the municipal code, the water-district rule or the federal soil file ourselves, and we publish the figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify. This desk is new.
The counts below are what we can already stand behind, and every one of them is counted from the studies on this site.
- 255
- source documents cited, each linked
- 112
- government (.gov) domains among them
- 258
- citations carrying a retrieval date
- 10
- research studies published
How this desk works
- Primary sources only. A rule comes from the statute, ordinance, board or agency that issued it, cited by section, with the URL and the retrieval date. We do not cite a blog that cites a code.
- Coverage is a number. A table titled to fifty states has fifty sourced rows. A table of cities is titled to the cities we actually read. Gaps are published as gaps.
- Company counts stay inside seven states. Texas, Arizona, Washington, California, Oregon, Florida and North Carolina. Texas is the largest roster on the weakest evidence, a self-reported NAICS sales-tax permit, because Texas licenses no landscaper. National claims rest on federal or state agency data, never on our counts.
- Fact, calculation, analysis and recommendation stay labeled. "According to…" is a source. "HyreYard analyzed… and calculated…" is ours. "This suggests…" is interpretation. We do not present our reading as something the source stated.
- We do not landscape, irrigate, plant, cut trees or pull permits, and we take no payment for placement, ranking or a favorable mention. Nobody buys a position on this site.
Data as of Codes and bulletins retrieved September 5, 2026. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
Price the face. Ask the city about the height.
HyreYard does not build walls. The calculator will put face area and a drainage line on the same page as the bid. This table is the permit question the bid has to survive.
This page is general information about adopted codes and department pages, retrieved on the dates shown.
It is not legal advice, is not a structural design, and is not a determination about any named lot. HyreYard does not perform landscaping, engineering or permit work.
Walls retaining or bearing on a house foundation are out of scope.