Garage Conversion ADU in Schertz, TX: Cost, Permits & Reality
A garage conversion ADU in Schertz typically runs $120,000-$190,000 all-in, drawings through final inspection, depending on whether you’re converting an attached or detached garage, the slab condition, and which county jurisdiction your address falls under. That range reflects real projects across Schertz subdivisions from Northcliffe to the corridor near Cibolo Creek Ranch. The number moves because Schertz city limits don’t follow clean county lines, and that single fact controls more of your budget than almost anything else.
We’re Ellis ADU Studio, and we’ve designed and permitted garage conversions in Schertz long enough to know the difference between a house that’s actually in Schertz and a house that’s in Guadalupe County with a Schertz mailing address. Nadia Ellery leads our studio, and the phone number is (971) 497-2402. Call when you’re ready to talk through your specific address.
Key Takeaways for Schertz Homeowners
- Garage conversion ADUs in Schertz run $120,000-$190,000, with written pricing locked before work starts under Haven Standard Clause 1.
- Your exact address determines whether you’re permitting through Schertz, Bexar County, Guadalupe County, or Comal County, and the wrong assumption triggers stop-work orders.
- Expansive black clay soil under most Schertz lots means post-tension or deep pier slab engineering is standard, not optional, and it adds $8,000-$15,000 to a garage conversion.
- HOA deed restrictions in planned subdivisions like Northcliffe often matter more than the building permit itself.
- Attached garage conversions, garage partitions with bathroom adds, and garage JADUs are among the most requested ADU types in Schertz right now.
Why Jurisdiction Comes First in Schertz
Schertz is unusual among Texas suburbs because it spans three counties: Guadalupe, Bexar, and Comal. The city limits cut through subdivisions unevenly, so a homeowner on one side of a street may be permitted through the City of Schertz while a neighbor two lots away falls under unincorporated Guadalupe County. Both addresses might say “Schertz, TX” on the mail. Only one of them is actually in the city.
For a Garage Conversion ADU, jurisdiction controls slab engineering, septic setbacks if you’re not on city sewer, inspection sequencing, and which permit application you file first. We confirm the exact plat and jurisdictional status before any design work begins. If your address is in unincorporated Guadalupe County, for example, the county may require a septic system review that the city doesn’t, and the inspection schedule follows county protocols rather than Schertz’s. Getting this wrong after construction starts means a stop-work order, and stopped work costs money every week it sits.
Why Ellery ADU Studio Is Schertz’s Preferred Garage Conversion ADU Company
We’re a design-build studio, not a general contractor layering an ADU onto other work. Drawings, permit set, slab engineering, and construction are one contract at one written price. That structure matters in Schertz because the local permitting puzzle, with its county boundary complications and HOA overlays, is exactly where designer-versus-builder blame games start. In our model, there’s no one else to point at. Clause 1 of the Haven Standard says the price is written before work begins, and it means exactly that.
Schertz homeowners who’ve worked with us tend to mention the same things: the jurisdiction check happened before design started, the black clay soil was addressed in the permit set rather than discovered during excavation, and the HOA conversation wasn’t an afterthought. We also provide a documented photo record on every visit, so you see what’s happening in your garage, not a summary of how it went.
What We See in Schertz Garages: A Field Note
In the Northcliffe subdivision, we converted an attached two-car garage on an 8,200-square-foot lot where the county boundary placed the address under Bexar County rather than Schertz city permitting. The HOA still required board approval for the conversion even though the county issued the permit, so we staged the work to keep the garage door in place until the HOA letter arrived. Our crews used a post-tension slab plan and a mini-split system from a James Hardie accessory kit to handle the black clay soil movement and keep the unit rental-ready for a JBSA-Randolph airman on PCS orders. That’s a typical Schertz garage conversion: three layers of approval, one clear scope, and a tenant waiting on the other side.
Our Garage Conversion ADU Services in Schertz
Attached Garage Conversion
Attached garage conversions are the most common ADU type we build in Schertz, especially in 1990s and 2000s tract homes where the garage shares a wall with the main house. The shared wall reduces foundation costs and simplifies utility runs, since electrical and water lines are already nearby. In Schertz, the main variable is the slab: most attached garages sit on slabs poured before current expansive-clay engineering standards, so we often specify post-tension reinforcement or pier retrofits before framing begins.
Detached Garage Conversion
Detached garages in Schertz run into a different set of questions: septic setbacks if you’re not on sewer, utility trenching distance from the main house, and HOA rules about accessory structure appearance. Lots in the 7,000 to 10,000-square-foot range, common across Schertz, give you real room to work, but the distance between garage and main panel often drives trenching cost up by $2,000-$5,000. We scope that line item before quoting, so the written price reflects actual site conditions.
Garage Partition & Bathroom Add
Partitioning a two-car garage into an ADU plus a storage bay is popular with Schertz homeowners who want rental income without giving up the entire garage. The partition wall and bathroom add typically run $30,000-$50,000 over the base conversion, depending on plumbing rough-in distance and whether the slab needs cutting for drainage. Because so many Schertz garages have the water heater in the corner, we often relocate mechanicals as part of the same scope rather than patching around them.
Garage JADU
A garage JADU, a junior ADU of 500 square feet or less built within the garage envelope, is the leanest legal path to rental income in Schertz. JADUs avoid some HOA and county complications because the kitchen is efficiency-style and the unit stays within the existing footprint. Schertz homeowners near JBSA-Randolph often use a garage JADU for short-term furnished rentals to airmen and contractors on rotation, and the unit tends to pay for itself faster in this market than in most Texas suburbs.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
The JBSA-Randolph Rental Pipeline
Schertz sits directly adjacent to JBSA-Randolph, one of the busiest military installations in the country, and that creates a rental market no neighboring suburb can replicate. Military families on PCS orders cycle through Schertz constantly. Homeowners here, many of them active-duty or veterans themselves, build ADUs to collect rental income during deployments or to house the steady stream of incoming airmen and contractors who need short-term furnished housing. BAH-funded renters have predictable budgets and consistent move-in cycles, which means a well-built garage conversion in Schertz rents faster and more reliably than a comparable unit in Cibolo or San Marcos. That pipeline is why so many Schertz homeowners run the math and realize a garage conversion here isn’t just spare space, it’s a year-round revenue line.
Trusted Brands We Specify in Schertz
Ellery ADU Studio specifies and coordinates prefab and modular systems from brands including Abodu, Cover, and Dvele, and we also work with James Hardie accessory kits for garage conversions that need siding or trim integration with the main house. For Schertz specifically, we stock and order local parts for the systems we install, which keeps turnaround tight when a county inspection requires a specific component swap. If a prefab system fits your garage conversion scope, it’s included in the single written price, not bolted on as a change order later.
Common Garage Conversion ADU Problems We See in Schertz Homes
- Wrong jurisdiction assumption: A homeowner starts a garage conversion believing they’re permitted through the City of Schertz. They’re actually in unincorporated Guadalupe County. The city permit gets flagged, work stops, and the county wants a new application with different septic and inspection requirements. We confirm the plat and jurisdiction before design starts, every time.
- Expansive clay slab failure: The black clay soils across the San Antonio northeast corridor shrink hard during Schertz’s long, 100-degree summers and heave when winter rains return. A converted garage floor poured without post-tension or pier engineering can separate from the original foundation within two summers. This is a real failure we’ve been called in to fix, and it’s cheaper to engineer correctly from the first pour.
- HOA stall after permit approval: In planned subdivisions like Northcliffe, deed restrictions often block or slow garage conversions even after the building permit is issued. The HOA letter arrives late or with conditions no one anticipated. We stage the work to keep the garage door in place until HOA approval is documented, because it’s far easier to adjust a schedule than to undo a conversion.
- Septic setback conflicts: Schertz lots without city sewer have septic systems with minimum setback distances from any dwelling, including an ADU. A detached garage conversion on a lot near Cibolo Creek Ranch or in the unincorporated county fringe may require a septic system review and, in some cases, a new drain field. That’s a $10,000-$25,000 line item that generic ADU pricing pages never mention.
Pricing for Garage Conversion ADU in Schertz, TX
A typical attached Garage Conversion ADU in Schertz runs $120,000-$155,000 for a one-bedroom unit with a bathroom and efficiency kitchen. Detached conversions run $145,000-$190,000 due to utility trenching and slab work. A garage partition with bathroom add adds $30,000-$50,000 to the base conversion. A garage JADU runs $80,000-$110,000 for a 400-500 square foot efficiency unit. Post-tension or deep pier slab engineering for Schertz’s expansive clay adds $8,000-$15,000. HOA-related delays don’t change the price, but they can change the schedule, and we scope for that in writing before you sign. Estimates are free, and the written price covers drawings, permits, slab engineering, and construction under one contract.
Call (971) 497-2402 to schedule a free estimate. We’ll walk your garage, check the slab, confirm jurisdiction, and put the number on paper.
We Also Serve Cities Near Schertz
Our studio serves Schertz and the surrounding communities, including Cibolo, San Antonio, San Marcos, and Kyle. If your garage sits near the Cibolo Creek Ranch edge of Schertz or you’re just across the line into Guadalupe County, the jurisdiction questions change, but the design-build process stays the same. One contract, one written price, one team accountable for the whole thing.
Serving Schertz, TX - Our Local Coverage Area
We’re based in the Schertz area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Garage Conversion ADU in Schertz
It depends on your exact address, not your subdivision name. Cibolo Creek Ranch addresses can fall under Schertz city jurisdiction, unincorporated Guadalupe County, or in rare cases Bexar County, and the difference changes the application, inspections, and septic review requirements. We confirm the plat and jurisdictional status before design begins, so you don’t file the wrong permit and hit a stop-work order. Call (971) 497-2402 and we’ll check your address.
Yes, but the septic system becomes a design constraint. Septic setback distances from the drain field to the ADU must be met, and in some cases the county requires a septic system capacity review before issuing the permit. If the system is undersized for the added dwelling, a new drain field may be required, which runs $10,000-$25,000. We scope this in writing before you commit.
Not always. Many attached garages in Schertz sit on slabs that can be retrofitted with post-tension reinforcement or pier systems without a full replacement. But the existing slab must be evaluated: thickness, condition, and how much heave it’s already experienced. A full replacement is more likely in detached garages built before current engineering standards or where cracking is already visible. We include a slab assessment in every Schertz garage conversion estimate, at no charge.
The HOA wins, in practical terms. Deed restrictions are contractual obligations that run with the land, independent of municipal permits. Even if the city or county approves your ADU, the HOA can levy fines or take legal action for a conversion that violates covenants. In Schertz planned subdivisions like Northcliffe, HOA board approval often takes as long as the building permit, and we stage construction to keep the garage door in place until the HOA letter is documented. The written price and schedule account for that wait.
Yes. A garage partition with a bathroom add is one of our most common Schertz projects. You get a one-bedroom ADU in roughly 400-500 square feet of the garage, and the remaining bay stays as storage or parking. The partition wall, bathroom, and kitchenette add $30,000-$50,000 to the base conversion. The garage door can stay operational while work proceeds, which also helps with HOA compliance during the approval window. Call (971) 497-2402 for a free estimate on your specific garage.
Free Written Estimate for Your Schertz Garage Conversion
We don’t do verbal ballparks or “call for a quote” pricing. Every Schertz garage conversion we design gets a written price before any work begins, per Haven Standard Clause 1. The estimate covers the permit set, slab engineering for the clay soil, the drawings, and the construction, all in one contract. If you already have a written estimate from another company, we’ll give you a free second opinion on whether the slab scope, jurisdiction assumptions, and HOA risks are actually covered.
Call (971) 497-2402 to schedule your free estimate. Nadia and the team at Ellis ADU Studio will walk your garage, check the jurisdiction, and tell you the real number.
Written by Nadia Ellery, Owner at Ellis ADU Studio, serving Schertz since the studio’s founding.