ADU Constructionin Desert Hot Springs, CA
ADU construction in Desert Hot Springs starts with the sewer question: the City says ADUs are not permitted on septic lots under 1 acre. On sewered lots, approval is ministerial with the building permit, the City acts within 60 days of a complete application, and eight pre-approved detached plans exist. The City waived its local impact fees in 2023.
Desert Hot Springs lots were laid out for spa cottages, not for second homes in the back, and that history decides who can build here. The Census Bureau's 2024 five-year estimates count 12,474 homes (plus or minus 538), about 63.9 percent of them single-family detached (7,969), with a median build year of 1990. Median gross rent is $1,412 (plus or minus $125) and the median home is worth $354,800 (plus or minus $16,386). The City incorporated on September 17, 1963, and the General Plan says the town did not fully develop until the 1960s. Several categories carry wide margins of error, so treat each share as an estimate.
This page covers the septic limit, the sewer switch, pre-approved plans and fees, size and setbacks, garage conversions, fire, solar, dust and fault rules, and the schedule. The City's pages answered our tools, but its code host did not, so code text comes from GoCodebook, a third-party mirror, and the rules built on it should be confirmed with the Building & Safety Division and the City's ADU page. Prices and phases are on our ADU construction page.
Desert Hot Springs Planning and Building rules that apply to ADU construction
Where adu construction permits come from in Desert Hot Springs: City of Desert Hot Springs Community Development Department, Building & Safety Division.
- ADU program (City ADU page): hotline (760) 329-6411 ext. 505, planning@cityofdhs.org; eight Pre-Approved detached ADU plans from YNG Architects in four styles (Contemporary, Pueblo, Mediterranean, Spanish), from a 385 square foot studio to 1,040 square feet, are only for NEW detached ADUs, not conversions or attached units. Pre-approved plan applications are paperless PDFs (prefilled plan set, site plan, grant deed with all pages, and a hold harmless statement signed by the owner; the page also links a list of C-16 licensed fire sprinkler contractors), each plan has a fee estimate sheet, and on June 6, 2023 the City Council waived all local development impact fees for ADUs.
- ADUs and septic: the City's ADU page says ADUs are not permitted on lots on septic that are less than 1 acre. The zoning code (17.08.090, third-party mirror) separately requires Riverside County Environmental Health and the Regional Water Quality Control Board to approve an ADU that uses a private sewage system and a percolation test completed within the last 5 years (10 if recertified). Check septic versus sewer first on any older lot.
- ADU standards (municipal code 17.08.090, third-party mirror): approved ministerially with a building permit, with action in 60 days of a complete application when a single-family home exists; an ADU inside existing space meets building and fire codes only; detached ADUs up to 1,200 square feet or 50 percent of the main house (whichever is less); attached up to 50 percent of the main house or 850 square feet (1,000 with more than one bedroom); setbacks of no more than 4 feet side and rear; height 16 feet (18 feet near major transit, plus 2 feet to match roof pitch); at most one parking space per ADU or bedroom and none within a half mile of transit or when part of the main house; no fire sprinklers unless the main house needs them; no impact fee under 750 square feet.
- ADU rental rules: the owner signs the City's ADU Rental Term Affidavit and shows valid California ID (an agent needs a notarized affidavit and every owner must sign), promising any rental will be for terms longer than 30 consecutive days, and Section 17.08.090 says an ADU can never receive a short-term vacation rental permit. Junior ADUs (17.08.100) are capped at 500 square feet inside the house, need an efficiency kitchen and a recorded deed restriction, and require the owner to live in the house or the JADU.
Can you build an ADU in Desert Hot Springs if your lot is on a septic tank?
Not on a lot under 1 acre, according to the City. Its ADU page says ADUs are not permitted on lots on septic that are less than 1 acre in size. That line bites harder here than in nearly any valley city, because the General Plan counts roughly half of households, a 2019 figure, on septic systems, and the oldest spa-era lots were platted small. Learn whether your lot is on septic or sewer before paying for drawings.
The zoning code reads differently. Section 17.08.090, as GoCodebook mirrors it, requires Riverside County Environmental Health and the Regional Water Quality Control Board to approve an ADU that uses a private sewage system, plus a percolation test completed within the last 5 years, or 10 if recertified, and it names no acreage. We found nothing that reconciles the page with the code. State law lets cities use only objective standards and sets no minimum lot size (Government Code 66314(b)(1)), so the written question for Planning is whether the 1 acre line applies to your parcel. The ADU hotline is (760) 329-6411 extension 505, or planning@cityofdhs.org.
How do you move a Desert Hot Springs lot from septic to sewer before building an ADU?
Through Mission Springs Water District, which owns the pipe. The District's Sewer Service Installation page says that where a lateral is available the owner must connect: apply to the District for sewer service, hire a contractor to abandon the septic tank and tie into the lateral at the property line, get a Sewer Opening Permit from the City (or the County), and hand the District the signed inspection card. The District also runs a Financial Assistance Program for qualified owners. Its office is at 66575 Second Street, phone (760) 329-6448.
History explains the patchwork. The District formed by an election in 1953, built the Horton plant in 1972 and has since added the Nancy Wright Regional Water Reclamation Facility, and the General Plan says it has converted parcels to sewer since 2005. Whether a lateral reaches your street is a District question we did not answer for any address. We print no hook-up charge, because the only figure we found sits in a dated General Plan, and we do not know how the City treats a street with no lateral.
Does Desert Hot Springs offer pre-approved ADU plans, and are ADU impact fees waived?
Yes to both. The City lists eight pre-approved detached ADU plans by YNG Architects in four styles (Contemporary, Pueblo, Mediterranean and Spanish), from a 385 square foot studio to 1,040 square feet. They are for new detached units only, not conversions or attached units. Applications are paperless: a prefilled plan set, a site plan, the grant deed with every page and a hold harmless statement signed by the owner, and each plan has its own fee estimate sheet. The City also links a list of C-16 fire sprinkler contractors.
On June 6, 2023 the City Council waived all local development impact fees for ADUs. That helps, but it is not the whole bill. State law already bars impact fees on a unit of 750 square feet or less, and charges set outside City Hall, such as water and sewer capacity, utility service and any school fee, stay separate lines. A pre-approved plan also does not erase the septic question or the site work, so the plan fits only a lot that passes the sewer test first.
How big can an ADU be in Desert Hot Springs, and how close to the property line?
Section 17.08.090 sets the numbers. An ADU is approved ministerially with a building permit, and the City acts within 60 days of a complete application when a single-family house already stands on the lot. A detached unit may reach 1,200 square feet or 50 percent of the main house, whichever is less. An attached unit may reach 50 percent of the main house or 850 square feet, or 1,000 with more than one bedroom. Side and rear setbacks are no more than 4 feet, height is 16 feet, or 18 near major transit plus 2 feet to match the roof pitch.
Parking is light. The code asks for at most one space per ADU or bedroom and none within a half mile of transit or when the unit is part of the main house. A new unit needs no fire sprinklers unless the main house does, and none of the impact fee applies under 750 square feet. State law adds a 15 business day completeness check and deemed approval if the 60 days pass in silence (Government Code 66317, as amended in 2026), and the text is on the state's legislative site.
Can you convert a garage in Desert Hot Springs, and what happens to an old casita?
Yes, and the rules are lighter. The code says an ADU inside existing space meets building and fire codes only, state law allows up to 150 square feet of added entry space and requires no replacement parking when a garage is converted, and the City's pre-approved plans do not cover conversions at all. A converted garage usually brings a new bathroom, so the septic question returns. Plan check settles the framing, insulation, cooling and electrical service.
Old backyard units follow a state path. A backyard unit built without a permit before January 1, 2020 has a state path: Government Code 66311.7 stops a city from refusing the permit over code violations unless the fix is needed for health and safety, and an owner may ask for a confidential third-party inspection. How Desert Hot Springs runs that path was not on any page we read. A guest house is a different animal: the code (17.08.120) caps it at 500 square feet, bars a kitchen, cooking facilities or wet bar, bars renting it and needs an Administrative Use Permit, so a casita with a stove is an ADU question.
Do Desert Hot Springs ADUs need fire sprinklers, solar panels, a dust plan or a fault setback?
Sprinklers are not simple. The ADU rule says none unless the main house needs them, yet the City's fire code, Chapter 15.22, requires sprinklers in one- and two-family dwellings under the Residential Code regardless of size, and fire apparatus roads must be 24 feet wide with 13 feet 6 inches of vertical clearance. Fire services come from Riverside County Fire under a cooperative agreement with CAL FIRE, so ask the Fire Marshal how a rear unit and its access are treated. On solar, the state's HCD ADU Handbook says the Energy Code requires panels on a newly built detached ADU, not on conversions.
Dirt has rules here. A grading permit, or a building permit that disturbs more than 5,000 square feet, needs a City-approved fugitive dust control plan before earth-moving, and South Coast AQMD Rule 403.1 applies to Coachella Valley sources on top of Rule 403. A pad, a utility trench and a staging area add up quickly. Last, Section 17.40.090 bars development within 50 feet of an active or potentially active fault, and the Mission Creek fault runs near downtown, so a lot near it needs a Planning answer before any design.
Can you rent a Desert Hot Springs ADU, how long does one take and who builds it?
You can rent it, with limits. The owner signs the City's ADU Rental Term Affidavit and shows valid California ID, promising any rental will run longer than 30 consecutive days, and Section 17.08.090 says an ADU can never receive a short-term vacation rental permit, which matters in a spa and resort town. A junior unit is capped at 500 square feet inside the house, needs an efficiency kitchen and a recorded deed restriction, and the code asks the owner to live in the house or the unit, though the state rule since 2026 asks that only when the unit shares a bathroom with the house.
Our planning ranges are 4 to 10 weeks of design, the City's 60 day clock, 2 to 6 weeks of scheduling and site prep, 3 to 5 months for a garage conversion or 5 to 9 months for a detached unit, and 1 to 3 weeks of final inspections. Work may not run between 5:00 p.m. and 7:00 a.m., or 6:00 p.m. and 6:00 a.m. in daylight saving time, and not on Sundays. Utilities come from several hands: Mission Springs Water District writes will-serve letters, and the City's fee sheets also name Southern California Edison and SoCal Gas.
MDG Builders, CSLB #1040337, designs the unit, files it and coordinates licensed subcontractors for grading, concrete, framing, plumbing, electrical and cooling, and you can ask each for a license number and a certificate of insurance. State law limits a down payment to the lesser of $1,000 or 10 percent of the price.
ADU photos from Desert Hot Springs and nearby homes
ADU scenes tied to Desert Hot Springs, from sewer trenches and slabs to finished studios and backyard cottages, across the desert neighborhoods of the Coachella Valley. Tap a photo to enlarge it.
What adu construction costs around Desert Hot Springs
The ADU construction page puts a garage conversion into a studio or one-bedroom unit at about $100,000 to $200,000 and a new detached unit of 400 to 800 square feet at about $200,000 to $400,000. Three independent sources stand behind those ranges. Berkeley's survey of owners who finished or applied for an ADU in 2018 and 2019 reports a Los Angeles County median of $100,000, the Terner Center put Los Angeles at $148,000 in 2020, and Remodeling magazine's 2025 Cost vs. Value report lists $178,536 for a Los Angeles ADU, recovering 39.9 percent at resale. None is a Desert Hot Springs quote. Set against a median home value of $354,800 (plus or minus $16,386), the low end of a detached range is more than half of the median home value here, so the numbers deserve a hard look. A septic abandonment, a long sewer or electrical run and dust control can each add a line a regional range misses, and permit, plan check and utility charges are separate lines in a written proposal. The ADU cost guide shows how the ranges are built, and the ADU versus JADU guide covers the junior unit. For nearby valley cities, see Palm Springs, Cathedral City and Indio. A bath in the unit is on the Desert Hot Springs bathroom page, an attached project on the room addition page, windows on the window page, and the Desert Hot Springs area page lists every trade we cover in the city.
| What it covers | Typical range |
|---|---|
| Garage conversion to a studio or one bedroom | $100,000 to $200,000 |
| New detached ADU, 400 to 800 sq ft | $200,000 to $400,000 |
| UC Berkeley survey, Los Angeles County median, 2018 and 2019 projects | $100,000 overall. $90,000 garage. $180,000 detached. |
| Terner Center and Berkeley CCI, 2020 | $148,000 Los Angeles estimate. $167,000 statewide average. |
| Remodeling Cost vs. Value 2025, Los Angeles | $178,536 job cost |
| Electrical and plumbing, Angi Los Angeles, January 2026 | Electrical $2,600 to $7,800. plumbing $3,900 to $10,400. |
| City permit and plan check fees | Not priced here |
Other work we manage in Desert Hot Springs
Desert Hot Springs ADU questions, answered
How do I build an ADU in Desert Hot Springs?
Confirm your lot is on sewer or over 1 acre, then apply to Building & Safety. ADUs are approved ministerially with the building permit, and the City acts within 60 days of a complete application. You need plans, Title 24 energy calculations and any utility letters. The City also offers eight pre-approved detached plans.
Can I build an ADU on a lot with a septic tank in Desert Hot Springs?
The City says no on septic lots under 1 acre. The zoning code separately requires Riverside County Environmental Health and Regional Board approval and a recent percolation test for an ADU on a private sewage system. We could not reconcile the two, so ask Planning in writing before drawing.
How big can an ADU be in Desert Hot Springs?
A detached ADU can reach 1,200 square feet or 50 percent of the main house, whichever is less. An attached unit is capped at 50 percent of the house or 850 square feet, or 1,000 with more than one bedroom. A junior unit stops at 500 square feet and must sit inside the house.
How much does it cost to build an ADU in California?
Garage conversions to a studio or one bedroom run about $100,000 to $200,000 in our ranges, and a new detached unit of 400 to 800 square feet about $200,000 to $400,000. Berkeley, Terner Center and Cost vs. Value data for Los Angeles stand behind them, not a local survey, so only a written proposal after a site visit sets your price.
Do I need to provide parking for my ADU?
Rarely. The City's code asks for at most one space per ADU or bedroom and none within a half mile of transit or when the unit is part of the main house, and state law requires no replacement parking when a garage is converted. Ask Planning how your lot counts.
What is the difference between an ADU and a JADU?
A junior ADU is smaller and lives inside the house. It is capped at 500 square feet, needs an efficiency kitchen, a recorded deed restriction and its own entrance. A full ADU can be detached, attached or converted, up to 1,200 square feet here, and carries its own kitchen and bathroom.
Do I have to live on the property to rent an ADU?
Not for an ADU under state law, but the City requires an affidavit that any rental will run longer than 30 consecutive days and never allows a short-term vacation rental. The City asks a junior unit's owner to live on site, though the 2026 state rule asks that only when the bathroom is shared.
How long does it take to get an ADU permit?
The City acts within 60 days of a complete application, and state law since 2026 adds a 15 business day completeness check and deemed approval if the deadline passes. A correction round adds time, and we found no published City average. Design before filing runs about 4 to 10 weeks in our plans.
Does the City of Desert Hot Springs charge impact fees for an ADU?
Not its own. On June 6, 2023 the City Council waived all local development impact fees for ADUs. State law also bars impact fees on units of 750 square feet or less. Water and sewer capacity, utility service and any school fee are separate, so each agency needs a direct question.
Tell us about your Desert Hot Springs ADU plans
Tell us your part of town, whether the lot is on septic or sewer, whether you want a garage conversion, a pre-approved detached plan or a junior unit, and roughly how big the lot is, and the first visit starts with the sewer question and the 60 day clock.