A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across San Antonio
Adding a room, a second story, or a detached ADU on your San Antonio property starts with a written price, not a vague verbal guess. Benson ADU San Antonio builds home additions across the city and the surrounding Bexar County acreage, from Monte Vista bungalow bump-outs to full garage conversions off Scenic Loop Road. If you are wondering what a home addition costs here, expect to budget roughly $180 to $340 per square foot for most site-built work in San Antonio, with prefab ADUs like Abodu or Plant Prefab landing between $180,000 and $350,000 depending on size and site conditions. Call (430) 258-2928 to get a written estimate from Troy Eastman and our San Antonio crew.
Why Benson ADU San Antonio Is San Antonio’s Preferred Home Addition Contractor Company
Our Home Addition Contractor team handles the boring stuff most builders skip: written prices before demo, background-checked crew members who show up in uniform, and a 365-Day Done Right Promise stamped on every project. We are part of the Relay Home Co. family, founded in 2006, and our San Antonio customers regularly tell us the same thing: they never had to chase us for a call back. A live person answers our phone around the clock, seven days a week, and every work site gets before-and-after photo documentation so you can see exactly what was done while you were at work.
We build with materials homeowners can research themselves. That means James Hardie cladding on exterior walls that have to shrug off San Antonio’s beating afternoon sun and the occasional hail stone, plus prefab systems from Abodu, Plant Prefab, and Tuff Shed when a factory-built panel makes more sense than weeks of stick framing. Troy Eastman runs the San Antonio side of the business and personally walks acreage lots before we quote, because a county-permitted ADU on open land is a different animal from a city-permitted bump-out in Beacon Hill.
Garage Addition Contractors in San Antonio
Garage Addition Contractors in San Antonio do two kinds of work: building new attached garages on lots that never had one, and converting existing garages into conditioned living space. On the acreage around San Antonio, the more common scope is a detached garage addition that doubles as storage for equipment, a workshop, or a future ADU shell. Cost for a new 400-square-foot garage addition in San Antonio typically runs $60,000 to $110,000 depending on whether you need plumbing, insulation, and a separate electrical subpanel.
County Permitted Garage Shells
On Bexar County lots outside city limits, a detached garage with no living space is one of the easiest permits to pull. But if there is any chance you will convert it to an ADU later, we frame it with the future in mind: deeper footings, a floor plan that already meets egress rules, and conduit stubbed into the slab so you avoid cutting concrete later.
Garage-to-ADU Conversions
Converting an existing garage to a full dwelling means county inspectors treat the structure as a home, not a storage building. That triggers HVAC sizing, insulation values, egress windows, and a separate meter or submeter. We scope all of that in writing before quoting so the price you see is the price you pay.
Bathroom Addition Contractor in San Antonio
A Bathroom Addition Contractor in San Antonio is usually called for one of two reasons: an older three-bedroom home in Lavaca or King William that only has one bath, or an acreage ADU that needs a second full bath to make a rental pencil out. Adding a bathroom to an existing home in San Antonio runs $35,000 to $85,000 depending on foundation access, drain line routing, and whether you are adding to a pier-and-beam floor or a slab.
Pier-and-Beam Bath Additions
In central neighborhoods like Lavaca, King William, and Monte Vista, original pier-and-beam foundations change how we route drain lines. We level the joists, install a proper moisture barrier, and run new plumbing under the floor rather than jackhammering through a slab. That is why a bathroom addition on a pier-and-beam home often costs less per square foot for plumbing, even though the floor work itself takes a few extra days.
Acreage ADU Baths
On an open Bexar County lot, a second bathroom inside a detached ADU means thinking about septic capacity before we pour anything. A standard septic system sized for two bedrooms will not pass inspection for a two-bed ADU with two baths. We pull the percolation test and engineered septic plan first, then frame the bathroom footprint around what the county will actually sign off on.
Trusted Brands We Service in San Antonio
We install and service prefab systems from Abodu and Plant Prefab, plus Tuff Shed shells and James Hardie cladding, across San Antonio and the surrounding county. Because we are authorized with these brands, San Antonio customers get factory-backed warranties and our 365-Day Done Right Promise on top of them. We keep panel inventory and trim stock in our San Antonio yard, which means shorter lead times on garage shells, ADU panels, and exterior siding orders for neighborhoods from Cibolo Creek up to Bulverde.
Common Home Addition Contractor Problems We See in San Antonio Homes
- Bexar County septic and well setbacks red-tagging a project after excavation. A lot that looks buildable on a county plat can fail once the health department maps your well and drain field. We site-check wells and perc-test before we quote, not after demolition.
- Clay-heavy northwest lots rutting material trucks after a wet week. The soil around the I-10 and Scenic Loop corridor swells and turns to gumbo in rain. Long gravel or caliche driveway repairs after trucks tear up an open lot add real cost if it is not scoped up front.
- Treating an outbuilding-to-ADU conversion like a light interior remodel. County inspectors see a dwelling, not a shop. That means HVAC, insulation, egress windows, and a true foundation, all of which we factor in before writing a price.
- Underestimating grading and drainage on an open San Antonio acreage lot. Flat lots flood; sloped lots erode. We shoot grade with a laser level and pull drainage plans as part of every acreage quote, because a county inspector will check positive drainage away from the foundation.
Pricing for Home Addition Contractor in San Antonio, TX
| Project Type | Typical San Antonio Range |
|---|---|
| Detached garage addition (per sq ft) | $150 – $280 |
| Garage-to-ADU conversion | $120,000 – $220,000 |
| Bathroom addition (existing home) | $35,000 – $85,000 |
| Prefab ADU (Abodu or Plant Prefab, 400 – 750 sq ft) | $180,000 – $350,000 |
| Site-built detached ADU (open acreage lot) | $200,000 – $400,000+ |
What moves these numbers in San Antonio is not square footage alone. A lot outside city limits that needs a new septic field, a well setback variance, 28 tons of fill, and a 200-foot gravel driveway will price differently than a flat city lot on sewer. The way we handle that is simple: we walk the site, pull county records, and hand you a written price before any work begins. Call (430) 258-2928 for a free, no-pressure estimate from Benson ADU San Antonio.
We Also Serve Cities Near San Antonio
Our crews work across the greater San Antonio area including Converse, Universal City, Schertz, and Bulverde. If you are outside the city limits and dealing with Bexar County permitting, well setbacks, or long unpaved driveways, we scope those conditions in person before we quote. The same written-price guarantee applies everywhere we build.
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.
FAQs About Home Addition Contractor in San Antonio
No. Most acreage ADUs outside city limits fall under Bexar County jurisdiction, not City of San Antonio permitting. You skip city zoning review and impact fees, but you inherit county rules: engineered septic plans, percolation tests, and well setback requirements that do not apply on in-town sewer lots. Call (430) 258-2928 and we will pull the correct permits for your specific parcel.
Septic setbacks directly dictate where your ADU can physically sit. Bexar County requires a 100-foot separation between a well and a new septic drain field, plus additional spacing from property lines and existing structures. On smaller acreage lots that means the ADU footprint may need to shift, rotate, or shrink. We map the setbacks before we draw plans, so you do not get a red tag after excavation. For an exact site read, call us at (430) 258-2928.
Yes, and usually in a good way for plumbing. Pier-and-beam homes give plumbers direct access to drain lines from below, so routing a new bathroom costs less than jackhammering through a slab. The tradeoff is floor work: leveling joists, adding a moisture barrier, and sometimes sistering old framing. In Lavaca and King William, we budget for both and put it all in writing before the first material order. Get your free estimate at (430) 258-2928.
We shoot a laser grade line across the build site, mark the high and low corners, and design the foundation so water drains away from the slab, not toward it. On flat San Antonio lots that often means importing fill and building the pad up 6 to 12 inches. On sloped lots we may add a swale or French drain. County inspectors check positive drainage before signing off. Call (430) 258-2928 to have Troy Eastman walk your lot and quote the grading work as a line item.
Yes, and we recommend it when the acreage math works. A long unpaved driveway means material trucks, concrete mixers, and framing deliveries all have to reach the build site. We price driveway access up front, sometimes adding a temporary rock or caliche road so trucks do not sink into clay during wet months. On a 2-acre lot near Scenic Loop Road, our crew added a detached 750-square-foot ADU for an owner whose existing well sat 65 feet from the build site, closer than the required 100-foot setback. We re-sited the slab, hauled in 28 tons of fill to reach grade, and ran conduit back to the main panel so the shop and ADU shared one meter. The job was permitted through the county with septic-perc signoff before we poured. For your lot, call (430) 258-2928 and we will scope the full access plan in writing.
Written by Troy Eastman, Owner at Benson ADU San Antonio, serving San Antonio and the surrounding Bexar County acreage.
