shower-size-standard
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The shower size standard in the sources we opened is a permit rule, not a single national size. The three California handouts we read each require a finished interior of at least 1,024 square inches, and each requires that the space enclose a 30-inch diameter circle. The person typing shower size standard usually wants one number to plan around. The answer is 1,024 square inches of finished floor that also holds a 30-inch circle, with 36 by 36 inches as the common comfort size from This Old House.
Quick answer
- All three handouts require a minimum finished interior of 1,024 square inches for a shower stall. Each also requires the space to encompass a 30-inch diameter circle.
- All three handouts set a 22-inch minimum clear opening at the shower entry. Pleasanton also requires the door to swing out of the enclosure.
- All three set the maximum shower temperature at 120 F. Pleasanton and Los Altos Hills require any new or replaced mixing valve to be pressure balancing.
- This Old House gives 36 by 36 inches as the most common standard size and recommends at least that much for a more comfortable experience.
- These handouts are general guides for three California jurisdictions. They do not set a standard for every address in the United States.
What the three California handouts require
Each handout is a permit guide for bathroom remodels, written by a city or town building department. The three differ in the code edition they cite. The City of Pleasanton handout is based on the 2022 California Residential Code. The Town of Los Altos Hills handout cites the 2013 codes. The City of Pleasant Hill handout says: “Applicable codes are the 2019 editions of the California Residential Code (CRC)”. Those dates matter, because a remodel permit follows the code in force when the permit is filed. The table below lists what each handout states about shower size and the related rules. Where a handout does not address an item, the table says “not stated.”
| Requirement | Pleasanton (2022 CRC) | Los Altos Hills (2013 codes) | Pleasant Hill (2019 CRC) |
|---|---|---|---|
| Minimum finished interior | 1,024 sq in | 1,024 sq in | 1,024 sq in |
| Circle that must fit inside | 30-inch diameter | 30 inch diameter | 30-inch diameter |
| Door or entry opening | 22 inches minimum, door swings out | 22 inch unobstructed opening | 22-inch clear egress opening |
| Wall finish | Nonabsorbent to 6 feet above floor | Non-absorbent to 6 feet above floor | Waterproof up to 72 inches above drain inlet |
| Maximum water temperature | 120 F at mixing valve | 120 F at mixing valve | 120 F at shower |
| Curb or threshold size | 2 inch minimum, 9 inch maximum | Minimum 2 inches, maximum 9 inches | The curb may encroach on the size requirement |
The table shows that the core size rule is the same in all three. The differences are in the details: the handouts describe the door, the wall finish and the curb in different ways. A reader in one of these cities should use the handout for that city and the code cited in it. A reader elsewhere should not treat these handouts as the law for their address.
The 1,024 square inch finished interior
The Pleasanton handout states the rule in one sentence: “Shower stalls shall be a minimum finished interior of 1,024 square inches and be capable of encompassing a 30-inch diameter circle.” The Los Altos Hills handout gives the same rule with a code citation to CPC 408.6. The Pleasant Hill handout says: “All shower compartments shall have a minimum finished interior of 1024 square inches and shall be capable of encompassing a 30-inch diameter circle [CPC 408.6].”
The word “finished” is the important part. Each handout measures the interior that remains after the wall is complete, not the framed opening. None of the three gives a wall thickness, a tile setting or a waterproofing thickness. A stall framed to a size close to the minimum can finish below it once the wall is built, so the framing plan should allow for the finished dimension. This post does not give a number for that allowance, because the sources do not state one.
Turning the area into dimensions is simple arithmetic. A square interior of 32 by 32 inches gives exactly 1,024 square inches. A square of 30 by 30 inches gives 900 square inches, which is below the handouts’ minimum. A 36 by 36 inch square gives 1,296 square inches. These figures are our calculations from the stated dimensions, not figures stated by any of the sources.
Why the 30-inch circle matters
The circle test is separate from the area test. A stall must have room for a 30-inch diameter circle inside it, so a long narrow space can pass the area rule and still fail the circle rule. The handouts do not describe a narrow stall in more detail, so the circle is the simplest check to apply to any shape.
The Pleasant Hill handout makes one exception that a reader should know about. It says: “The curb may encroach on these size requirements.” That means a curb built into the stall may project into the space the rule measures. The handout does not say how far a curb may project, and the Los Altos Hills handout gives a separate limit for the curb height only: a minimum of 2 inches and a maximum of 9 inches. Check the exact curb rule with the building department before you frame the curb.
This Old House gives a separate, typical planning figure. It describes a 30-by-30-inch square stall as the minimum size under the building code, and says it “can feel tight for many adults”. Its standard square stall is 36 by 36 inches. The circle rule and the planning size point to the same conclusion: a stall that only just meets the minimum leaves little room for a user to turn.
Doors, openings and egress
All three handouts set a 22-inch opening for the shower entry, but they phrase it differently. The Pleasanton handout says: “Any doors shall swing out of the enclosure and have a clear opening of 22 inches minimum.” Los Altos Hills says: “Shower doors shall open so as to maintain not less than 22 inch unobstructed opening for egress.” Pleasant Hill says that thresholds “shall be of sufficient width to accommodate a minimum 22-inch clear egress opening from the shower”.
The swing direction is a separate rule that the Pleasanton handout states and the other two do not. A door that swings out of the enclosure cannot block a user who is trying to leave, and it does not fold into the stall. The handouts do not describe the door type, so a sliding, hinged or pivot door can meet the rule if the clear opening is at least 22 inches. The sources do not say which door type performs best, and this post does not rank them.
The entry clearance in front of the stall is a separate question. This Old House says that “a minimum of 24 inches of clear space is required in front of the shower entrance”. That figure comes from a trade publication, not from the three California handouts. The handouts do not state a clearance in front of the entry, so the 24-inch figure should be checked with the local building department before it is applied in a permit drawing.
Water temperature and the mixing valve
All three handouts limit the shower temperature to 120 F. The Los Altos Hills handout says that “Any new or replaced mixing valve in a shower (including over a tub) shall be pressure balancing set at a maximum 120 F.” The Pleasanton handout sets the same valve rule. The Pleasant Hill handout says: “The maximum water temperature to a shower or tub/shower combination is 120 F.” It adds that the water heater thermostat cannot serve as the control.
The Pleasanton handout states the thermostat point in plain words: “The water heater thermostat cannot be used to meet these provisions.” A reader who only adjusts the water heater to lower the temperature has not met the rule in these handouts. A replacement valve is the case the handouts address directly, and any new or replaced mixing valve falls under the requirement.
The handouts also list a valve standard. Pleasant Hill says valves shall provide scald and thermal shock protection and be pressure-balanced, thermostatic, or combination mixing that meets ASSE 1016 or ASME A112.18.1/CSA B125.1. A permit reviewer will check the valve label, so keep the product documentation with the permit file. These handouts do not address the valve installation steps, which the installer’s instructions cover.
Wall finish and height
Pleasanton says that “Shower stalls and bathtubs with shower heads installed shall have walls finished with a nonabsorbent surface for a minimum of 6 feet above the floor.” Los Altos Hills uses the same 6-foot figure. Pleasant Hill gives a related rule that reaches higher: “All surfaces shall be waterproof up to 72 inches above the drain inlet”. Seventy-two inches is 6 feet, so the figures agree on height, but Pleasant Hill measures from the drain inlet and the other two measure from the floor.
This Old House gives a ceiling figure that is separate from the handouts. It says the height “should typically measure at least 80 inches from the finished floor to the showerhead.” That is a planning figure in a trade guide. The three handouts do not give a ceiling height for a shower, so a reader should check the local building department for any ceiling rule. For the head’s own mounting height, see how high to mount a shower head.
Typical sizes people build
The permit minimum is not the size most people choose. This Old House says its most common standard shower size is 36 by 36 inches, and that dimensions range from the code-minimum 30 by 30 inches up to 60 by 36 inches for walk-in designs. It recommends “at least a 36-by-36-inch shower for a more comfortable experience.”
The gap between the permit minimum and the comfort size is the practical point for a remodel. At 1,024 square inches, a stall meets the rule and holds a 30-inch circle, but a user has little room to turn. At 36 by 36 inches, the stall has 1,296 square inches and room for the typical comfort size named by This Old House. A project that can reach 36 by 36 will usually pass the permit rules with margin, provided the finished interior is measured after the wall is built.
This Old House also notes that the square stall, rectangular stall, walk-in and tub-shower layouts each have their own typical sizes. The table in its guide lists those sizes by layout. This post uses only the 36-by-36 figure and the 30-by-30 minimum from that guide, because the permit rule is the main subject here. For the head itself, see what size shower head to get.
How to use these numbers before you build
Start with the permit office. Each handout says it is a general guide. The Pleasanton handout says it “is not to be considered all-inclusive”. It also says the applicable code governs. Ask the building department which code edition applies to the permit you will file.
Next, measure the finished interior, not the framed opening. Confirm the interior is at least 1,024 square inches and that a 30-inch circle fits inside it. Then check the door or opening for a clear width of at least 22 inches. If the door is a hinged type, confirm that the swing clears the toilet and vanity, and that a door which swings out of the enclosure is allowed by your plan.
Finally, check the water system. Confirm the mixing valve is a pressure-balancing or equivalent valve set to 120 F, and that the water heater thermostat is not being used as the temperature control. Keep the valve documentation with the permit file. Where a handout states a rule for the wall finish, follow it for every wall that the shower water can reach.
How we chose
This post covers the shower size rule that a reader would meet in a permit context. We opened four pages on 2026-10-28: the City of Pleasanton’s residential bathroom alteration handout, the Town of Los Altos Hills residential bathroom remodel handout, the City of Pleasant Hill bathroom remodel guideline, and This Old House’s guide to standard shower sizes. The first three are municipal documents and the fourth is a trade publication. We cited a rule only when the page states it in its own words, and we checked each quoted sentence against the saved text of that page.
We did not rank the handouts. Each one cites a different code edition, and the wording of the rules differs in detail. Where they differ, this post shows both wordings in the table or in the quoted text. We did not choose one city’s wording over another’s. We also did not treat the trade publication as a code source. It is used only for the typical size and the planning figures it states.
A Contra Costa County page and a number of other pages returned a verification screen or an access error, so they are not used in this post.
What we could not verify: what the sources do not say
- None of the sources gives a single national shower size. The three handouts apply to three California jurisdictions, and the trade publication is not a code.
- The handouts do not give a wall thickness, tile setting or waterproofing thickness, so they do not say how much space a finished wall takes.
- Pleasant Hill says the curb may encroach on the size requirement but does not state how far. The post does not give that figure.
- The handouts do not set a clearance in front of the shower entry. The 24-inch figure in This Old House is a trade guide figure and is not verified as a code rule.
- The handouts do not describe the shower door type, the glass thickness or the hardware, so they do not say which door type is best for a given stall.
- The sources do not give a ceiling height rule from the permit handouts. The 80-inch figure comes from This Old House only.
- The handouts address the mixing valve but not its installation steps. Follow the valve manufacturer’s instructions for the install.
FAQ
What is the shower size standard for a permit?
The three California handouts require a minimum finished interior of 1,024 square inches, with a 30-inch diameter circle that fits inside the space. A square stall of 32 by 32 inches meets the area figure exactly, which is our arithmetic and not a figure stated in any handout.
Is a 30 by 30 inch shower legal?
In the sources we opened, a 30 by 30 inch stall gives 900 square inches, which is below the 1,024 square inch minimum in each California handout. Check the local code before you frame anything smaller than the handouts require.
How wide does the shower door opening need to be?
All three handouts set a 22-inch minimum clear opening. Pleasanton also adds a swing-direction rule for the door.
What temperature must the shower water be?
The three handouts set a maximum of 120 F. They say the water heater thermostat cannot be used to meet the rule, and a new or replaced mixing valve must be pressure balancing or equivalent and set to 120 F.
What size do most people build?
This Old House says its most common standard size is 36 by 36 inches. It recommends at least that size for a more comfortable experience, and gives 30 by 30 inches as the code minimum that can feel tight.
Bottom line
For a permit, the shower size standard in these sources is a finished interior of at least 1,024 square inches that holds a 30-inch circle. Measure after the wall is built, keep the door opening at 22 inches or more, and set the mixing valve to 120 F. For comfort, 36 by 36 inches is the common size named by This Old House. Confirm the code edition and the local rules with your building department before you start work.
Sources
- City of Pleasanton, Building and Safety Division, “Residential Bathroom Alteration Requirements” (revised 01/2023), https://www.cityofpleasantonca.gov/assets/our-government/community-development/handouts/residential-bathroom-alteration-handout-2023.pdf (opened 2026-10-28). Used for the 1,024 square inch rule, the 30-inch circle, the 22-inch door opening and swing, the 6-foot wall finish, the 120 F valve rule and the thermostat note.
- Town of Los Altos Hills, “Residential Bathroom Remodel”, https://www.losaltoshills.ca.gov/DocumentCenter/View/138/Residential-Bathroom-Remodel-PDF (opened 2026-10-28). Used for the 1,024 square inch rule, the 22-inch opening, the 6-foot wall finish, the 120 F valve rule and the curb height limits.
- City of Pleasant Hill, “Bathroom Remodel Requirements” (August 2020), https://www.phillca.gov/DocumentCenter/View/19321/BATHROOM-REMODEL-HANDOUT (opened 2026-10-28). Used for the 2019 code reference, the 1,024 square inch rule, the 30-inch circle, the curb note, the 22-inch egress opening, the 72-inch waterproof height and the 120 F limit.
- This Old House, “Standard Shower Sizes: A Complete Guide to Dimensions and Requirements”, https://www.thisoldhouse.com/bathrooms/standard-shower-sizes (opened 2026-10-28). Used for the 36-by-36-inch common size, the 30-by-30-inch minimum, the 80-inch height and the 24-inch entry clearance as planning figures.
