A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateTrusted ADU Builders for San Antonio Homeowners
Adding an accessory dwelling unit in San Antonio means navigating city code, choosing between stick-built and prefab, and managing a construction crew around your family’s daily life. Seedling ADU San Antonio handles all of it with a written price before any work starts, a crew that treats your home like it matters, and a 365-Day Done Right Promise on every project we complete. Led by Ben Ortega, our team builds detached ADUs, garage conversions, and home additions across San Antonio, from Terrell Hills to Timberwood Park. Call (210) 981-6358 to talk through your lot, your budget, and what’s actually possible.
ADU Construction
ADU Construction is the full process of adding a secondary living unit to your San Antonio property, from site prep and foundation work through framing, utilities, finishes, and final inspection. With San Antonio’s 2024 code updates allowing ADUs up to 1,200 square feet on most single-family lots, more homeowners in neighborhoods like Helotes and Fair Oaks Ranch are building rental units, in-law suites, and home offices. Our team at Seedling ADU San Antonio manages the entire build, including permits, trade coordination, and the written line-item price you receive before we ever break ground. Expect most ADU construction in San Antonio to land between $180 and $340 per square foot, with prefab options typically sitting at the lower end and fully custom builds at the higher end.
Permit-Ready Site Work
Before framing begins, we verify setbacks, easements, and utility tie-ins against City of San Antonio development codes. Our crew marks the exact footprint, confirms drainage slopes away from your foundation, and photographs the site so you can see what’s been done without walking the lot in work boots.
Foundation Through Drywall
We coordinate concrete, framing, rough electrical, plumbing, and insulation as one sequence, not a series of surprises. Your project lead keeps a daily log and calls you once at the end of each day, so you know what happened, what’s next, and whether anything changed since the morning.
Detached ADU
Detached ADU refers to a standalone secondary unit built entirely separate from your main house, usually in the backyard. This is the right choice for San Antonio homeowners who want rental income without sharing walls, a private space for aging parents in neighborhoods like Boerne or Scenic Oaks, or a quiet work studio removed from the noise of the main home. Seedling ADU San Antonio builds detached units from 400 to 1,200 square feet, including studio layouts, one-bedroom units with full kitchens, and two-bedroom family suites. Depending on finishes and whether you choose a prefab system like Boxabl or Plant Prefab, a detached ADU in San Antonio typically runs $220 to $340 per square foot.
Backyard Placement and Privacy
We walk your lot before drawing anything, checking how the unit will sit relative to the main house, neighbors, and existing trees. The goal is a unit that feels private for its occupants without making your yard feel smaller than it did before the build.
Utility Runs and Separate Metering
Detached units need their own water, sewer, and electrical connections, and we handle the trenching, tapping, and CPS Energy coordination. If you’re planning to rent the unit, we’ll set up separate metering so you’re not guessing who used what each month.
JADU
JADU stands for Junior Accessory Dwelling Unit, a smaller conversion typically built inside the existing footprint of your home, often by converting a garage, a large bedroom, or an underused bonus room into an independent living space with its own entrance and a small kitchen. In San Antonio, JADUs are usually capped at 500 square feet and are an efficient way to create rental income or a suite for a family member without adding a new structure to the lot. Seedling ADU San Antonio handles the layout, the plumbing and electrical work, and the fire separation requirements that come with an interior unit. A JADU conversion in San Antonio typically runs between $90,000 and $160,000 depending on the condition of the existing space and whether major utility rerouting is needed.
Interior Conversions That Stay Quiet
Because the work happens inside your home, we keep noise contained to the construction zone, use dust barriers at every opening, and run loud equipment only during reasonable daytime hours. Kids can nap on the other side of the house without a saw screaming through the wall.
Separate Entrance and Kitchenette
Code requires a JADU to have its own exterior entry or a clear path to one, plus an efficiency kitchen with a sink, small cooking appliance, and refrigeration. We design these spaces to feel complete and livable, not like a afterthought tacked onto a hallway.
ADU Plans
ADU Plans are the architectural drawings, site plans, and structural details required to get a building permit from the City of San Antonio and to guide the crew through the build. Every ADU project starts with a survey of your lot, a conversation about how you’ll use the unit, and a set of stamped drawings that reflect actual San Antonio code, not a generic template from another state. Seedling ADU San Antonio produces plans in-house for most projects, and we pair them with written pricing so you know the cost of building what’s on paper before you sign anything. Plan fees are included in your project quote; if you already have plans from another designer, we’ll review them and build from them at no added markup.
Site-Specific Drawings, Not Stock Plans
Your lot’s slope, setback lines, and existing utility locations all shape the plan, which is why we measure first and draw second. A plan that ignores a 2-foot grade change or a sewer line under the proposed slab will cost you weeks and thousands in change orders later.
Permit Submittal and Corrections
We submit your plans to the City of San Antonio Development Services Department, track the review, and handle any corrections that come back. You should never have to sit on hold with a city plan reviewer; that’s part of what you’re paying for.
ADU Contractor
ADU Contractor is the licensed professional responsible for executing the build, managing subcontractors, and making sure the finished unit meets code and passes inspection. In San Antonio, you’ll find plenty of general contractors who build ADUs as a side line; what you won’t always find is one who gives you a written price before the job and stands behind the finished work for a full year. Seedling ADU San Antonio is led by Ben Ortega and backed by the Cedarwell Care Promise, which means shoe covers and drop cloths inside your home, pet-safe products where there’s a choice, and a photo of the clean-up before the crew leaves every day. A contractor-managed ADU project in San Antonio typically costs 15 to 20 percent of total build cost in contractor fees, which is built into the per-square-foot pricing we quote.
Background-Checked, Uniformed Crews
Every person who walks through your gate or your front door has passed a background check and wears a Seedling uniform, so you always know who belongs on your property. If you have kids home after school or a dog in the yard, that certainty is not a small thing.
One Point of Contact, Always
You work with one project lead from first walkthrough to final walkthrough, not a different foreman each week. When something changes, which it will, you hear about it from the same person who’s known your project since the first measurement.
ADU Design
ADU Design is the process of shaping the unit’s layout, exterior style, and interior finishes to fit how your family will actually use the space, whether that’s aging parents, a college-age kid, or a long-term tenant. San Antonio lots vary widely, from the wide suburban parcels in Cibolo and Universal City to the tighter urban lots in Terrell Hills, and the design has to fit the lot, not the other way around. Seedling ADU San Antonio works with prefab systems from Abodu and Cover when a modern, factory-built unit fits, and with James Hardie siding and trim when a stick-built unit needs to match the main house. Design guidance is included in every project, not charged as a separate line item.
Materials That Match the Main House
If your home is limestone and stucco, we specify an exterior that sits comfortably next to it rather than fighting it. James Hardie plank and panel products give us the flexibility to match color, texture, and reveal patterns without maintenance worries down the line.
Interior Layouts for Real Life
A 500-square-foot unit needs a kitchen that works for one or two people, not a scaled-down version of your family kitchen. We design storage into every wall cavity we can, position windows for cross-breeze, and keep the bathroom close to the bed for nighttime trips without a hallway.
Backyard ADU
Backyard ADU is the term most San Antonio homeowners use for a detached unit built in the rear yard, set back from the main house and accessed by a side path or driveway. This setup suits families who want rental income near Alamo Heights or a private guest house on acreage in Floresville without changing the feel of the front of the property. Seedling ADU San Antonio builds backyard units that read as a natural part of the landscape, with foundations raised enough to handle San Antonio’s clay soil expansion and roof lines that shed summer storms without pooling. Expect a backyard ADU in San Antonio to run $220 to $340 per square foot, with higher-end finishes and site work pushing toward the top of that range.
Clay Soil and Foundation Choices
San Antonio’s expansive clay shifts through wet and dry cycles, which is why we specify pier-and-beam or properly engineered slabs for backyard units. A slab poured without soil testing can crack within two years, and that is the kind of thing our 365-Day Done Right Promise exists to prevent.
Access Paths and Yard Preservation
We plan the construction access route before we start so the path to the build site does not destroy the lawn you’re keeping. Drop cloths, plywood paths, and designated material zones keep the rest of your yard usable during the build.
Brands We Service
Seedling ADU San Antonio has hands-on experience with the prefab and modular ADU brands serious San Antonio buyers research before calling anyone. We work directly with Boxabl and Plant Prefab on a regular basis, coordinating site prep, foundation work, and utility hookups around the factory-set delivery schedule. When your unit arrives, our crew handles the crane or forklift coordination, the marriage of modules if applicable, and the finish work that turns a factory shell into a livable home on your lot.
For stick-built projects, we specify James Hardie siding and trim because it holds up to San Antonio’s heat, humidity, and occasional hail without the rot or warp issues we have seen with lower-cost fiber cement alternatives. Whether you have a Boxabl unit on order, a Plant Prefab you’ve been researching, or a fully custom build in mind, we can help you get it permitted, placed, and finished right.
Signs You Need a Pro Right Now
- You’ve received a quote with no line items. A bid that says “$180,000 for a 600-square-foot ADU” without breaking down site work, foundation, framing, mechanicals, and finishes is a bid you cannot compare or verify. A written line-item price is the baseline standard at Seedling ADU San Antonio, and it should be yours too.
- Your lot has drainage or slope issues. Water that pools near your foundation during San Antonio’s heavy spring and fall rains will only get worse when a new structure changes the grade. This is a fix-now, not a fix-later situation that affects both your existing home and the new unit.
- Your HOA or historic district has questions. Neighborhoods like Terrell Hills and parts of Alamo Heights have design review boards with their own ADU rules on top of city code. A contractor who builds first and asks later can leave you with a stop-work order and an expensive correction.
- You’re comparing prefab and stick-built and feeling stuck. The right answer depends on your lot’s access, your budget for finish work, and what CPS Energy will require for the panel upgrade. A pro who works with both paths can show you real numbers, not brochure numbers.
- Your garage is sitting empty and you’re losing rental income. A garage conversion JADU in San Antonio can rent for $1,000 to $1,400 per month depending on the neighborhood, which means every month of delay is money not coming in. Converting correctly the first time costs less than fixing a quick conversion later.
Our Process, Step by Step
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Walkthrough and lot review. Ben Ortega or a senior project lead walks your property with you, measures the buildable area, checks access for equipment, and talks through how the unit will actually be used. You’ll leave with a clear sense of what fits on your lot and what does not, based on real San Antonio code, not guesswork.
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Written plan and line-item price. We produce site-specific drawings and a written price that breaks down every phase: site work, foundation, framing, mechanicals, finishes, and permit fees. You review the number on paper before any tool is picked up, and nothing gets added later unless you approve it in writing first.
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Permit submittal and city review. We file with the City of San Antonio, respond to plan reviewer comments, and keep the process moving. You get a weekly status update by phone or email, whichever you prefer, until the permit is in hand.
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Construction with daily communication. Crews arrive in uniform, lay drop cloths and shoe covers where the work touches your home, and use pet-safe products where there is a choice. Your project lead calls once at the end of each day, and you receive a photo of the clean-up before the crew leaves.
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Final inspection and 365-Day Done Right handoff. We walk the finished unit with you, confirm every outlet, door, and finish against the plan, and pass the city’s final inspection before we consider the job done. Every project is covered by the 365-Day Done Right Promise in writing: if something is not done right, we make it right.
How Much Does ADU Builders Cost in San Antonio?
A typical ADU build in San Antonio runs $180 to $340 per square foot, which puts a 600-square-foot detached unit between roughly $108,000 and $204,000 depending on whether you choose a prefab system like Boxabl, a stick-built unit with James Hardie siding, or a fully custom design with higher-end finishes. A JADU conversion inside your existing home usually lands lower in total cost because there is no new foundation or exterior envelope to build, typically $90,000 to $160,000 for a complete livable unit.
What moves the price: lot access for equipment, clay soil conditions requiring pier foundations, how far utilities need to run from the main house, the level of finish you specify, and whether the existing electrical panel can handle the added load or needs an upgrade. To avoid overpaying, get a line-item price that separates site work from structure from finishes, ask what the contractor charges for change orders before you sign, and never accept a bid that’s vague about permit fees. Our free estimates include the full written breakdown, and we walk you through it line by line so you can compare our number against anyone else’s with confidence. Call (210) 981-6358 to schedule yours.
Our Service Area Near San Antonio
Seedling ADU San Antonio builds across the greater San Antonio metro, including ADU Builders in New Braunfels and ADU Builders in Selma, plus Boerne, Helotes, Fair Oaks Ranch, Terrell Hills, Universal City, Cibolo, Floresville, Timberwood Park, and Scenic Oaks. Most projects within the metro are scheduled within a week or two of your first call, depending on current permit volume. If you’re not sure whether we cover your address, call and ask. A live person answers, which is the whole point.
Serving San Antonio, TX - Our Local Coverage Area
We’re based in the San Antonio area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked Questions About ADU Builders in San Antonio
ADU Builders are contractors who specialize in designing and constructing accessory dwelling units, the secondary living spaces added to single-family properties. In San Antonio, ADU builders handle everything from initial site assessment and permits to pouring foundations, running utilities, and finishing interiors. Seedling ADU San Antonio focuses exclusively on ADUs, garage conversions, and home additions, so the crew showing up at your door is not learning how to build a small home on your lot.
Most San Antonio ADU projects take 6 to 10 months from first walkthrough to final inspection, depending on permit review times, weather, and whether you are building stick-built or placing a prefab unit. Prefab systems like Boxabl can compress the on-site construction phase significantly, though site work and utility hookups still take weeks. Your project lead gives you a written schedule at contract signing and updates it weekly, so the finish date never drifts silently. Call (210) 981-6358 to talk through a realistic timeline for your lot.
Expect to pay $180 to $340 per square foot for a detached ADU in San Antonio, with most projects landing between $130,000 and $220,000 total. A JADU conversion inside your existing home typically costs $90,000 to $160,000. Your written quote from Seedling ADU San Antonio breaks the price into line items so you can see exactly where every dollar goes before you commit. Free estimates are always part of the process; call (210) 981-6358 to schedule one.
Yes, we regularly work with Boxabl and Plant Prefab units, handling site prep, foundation, delivery coordination, utility hookups, and finish work. If you already have a unit ordered, we can step in and manage the installation and site work around the factory schedule. If you’re still deciding between prefab and stick-built, we can walk you through real pricing for both paths on your specific lot. Call (210) 981-6358 to talk through your options.
While ADU construction is a planned project, not an emergency service, we do answer the phone 24/7 with a live person, which matters when a storm hits mid-build or a window goes in wrong on a Friday afternoon. If something happens on your project that needs immediate attention, you can reach us any hour, any day. The Cedarwell Care Promise includes that live-answer commitment on every project. Call (210) 981-6358 and a person will pick up.
Every project we complete is covered by the 365-Day Done Right Promise in writing: if it is not done right, we make it right, covering every ADU, garage conversion, and home addition Seedling builds. Manufacturer warranties on prefab units and materials like James Hardie siding apply on top of our workmanship promise. The details are in your contract, not in a sales pitch, and you can read them before you sign anything.
Start by clearing the build area of stored items, pet toys, and anything you don’t want construction dust on, and let us know where your kids nap and your pets stay so we can plan around them. We handle the rest: site protection, material staging, dust barriers, and daily clean-up. A photo of the clean-up before the crew leaves is standard on every visit, so you never come home to a mess. Call (210) 981-6358 and we’ll walk you through the full prep list for your project.
Schedule Your ADU Builders Service in San Antonio Today
You’ll get a written price before any work starts, a crew that treats your home and family with care, and a one-year promise on every build. Call (210) 981-6358 today to schedule your free, no-obligation estimate and find out what’s possible on your San Antonio lot.
Written by Ben Ortega, Owner at Seedling ADU San Antonio, serving San Antonio and surrounding communities with ADU construction, garage conversions, and home additions.
