Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Friendswood
Home additions and ADU construction in Friendswood run between $45,000 and $130,000 for a typical project, with detached ADUs landing in the $90,000 to $220,000 range. That’s a wide spread, and the single biggest variable here isn’t square footage. It’s whether your lot sits in a post-Harvey FEMA flood zone and whether your existing structure crosses the 50% substantial improvement threshold. We’ve been building additions and ADUs in Friendswood long enough to know that the person answering the phone needs to understand Clear Creek floodplain rules, Beaumont clay, and acreage site access before quoting anything. Call (877) 610-1318 and you’ll talk to someone who does.
Why Barrett & Sons Construction Is Friendswood’s Preferred Home Additions & ADU Company
We’re Tom Barrett and his sons. Tom founded Barrett & Sons Construction in 1998, and he’s been on Friendswood job sites ever since, walking slabs, reviewing flood-zone maps, and writing change orders before work proceeds, not after. Our crews aren’t dispatched strangers. The people who show up at your house carry the Barrett name, and Tom’s own sons run the crews on most jobs.
Friendswood homeowners have dealt with enough out-of-town contractors who quote one price on the phone and hand over a different bill at the door. That doesn’t happen with us. Every scope, every allowance, every price change arrives as a written change order before a single nail moves. We publish Tom’s name, his license number, and his address. Look it up. The permit inspector works for you, not for me, and we treat every Friendswood inspection that way.
We know the difference between a 1960s slab-on-grade ranch in 77546 near Clear Creek and a post-Harvey elevated-slab home on the city’s edge. That knowledge changes how we design foundations, scope drainage, and sequence a project. Ask anyone on your street, or call (877) 610-1318 and ask us directly.
Our Home Additions & ADU Services in Friendswood
Our Home Additions & ADU team handles everything from a single room addition to a fully permitted detached ADU with its own utilities. In Friendswood, the site conditions drive the scope more than the floor plan does. Here’s how we approach the most common projects.
New Detached ADU
A detached ADU in Friendswood means building on the same Beaumont clay that has shifted slabs all over town. We design for it from the ground up: helical piers where soil movement warrants them, properly sized footings, and drainage that moves water away from the foundation before it ever touches it. If your lot is on septic, the ADU’s bathroom count, bedroom count, and placement all hinge on the existing drainfield’s capacity and setback requirements. We’ll flag that before you spend a dollar on plans.
Garage Conversion ADU
Converting a garage to living space in Friendswood means opening up concrete that has been sitting on expansive clay for decades. Cracks are common. Rotted sill plates from Harvey moisture intrusion are common. We inspect before we quote, and if we find structural issues when the slab is open, you get a written change order, not a surprise invoice. A garage conversion in Friendswood typically runs $30,000 to $80,000 depending on whether we’re adding a bath, re-leveling the slab, or re-flashing the band joist.
Room Additions
A primary suite or family room addition on a 1970s ranch in Friendswood isn’t a simple bolt-on. The existing slab may have moved, the roofline tie-in needs to handle summer heat and humidity cycles, and the new foundation has to be designed so it doesn’t fight the old one. We pull permits on every eligible job and we understand the city’s post-Harvey substantial improvement rule well enough to warn you before your “simple” addition legally halts your project.
ADU Site Prep & Utilities
Long material hauls, equipment access, septic setbacks, and trenching for power and water all change the price of a Friendswood ADU. Our Home Additions & ADU in Friendswood work starts with a site walk that accounts for where the concrete pump can reach, where the septic lines run, and how the lot drains after a heavy Gulf rain. We scope site prep in writing before quoting, because that’s where change orders hide if nobody looks first.
What happens when you call
- 1
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.
Trusted Brands We Service in Friendswood
We build with materials you can look up. On Friendswood hardscape-adjacent ADU projects and driveway approaches, we use Belgard, Techo-Bloc, and Cambridge pavers depending on the look and the load. Foundation work gets Quikrete and Oldcastle products where appropriate. When you’re choosing finishes for a new ADU kitchen, we’ll show you KraftMaid and Cambria options, not mystery brands off the back of a van. Every one of those names is verifiable, and we stand behind the install with a 90-Day Done Right Promise written on the contract.
Common Home Additions & ADU Problems We See in Friendswood Homes
- Missing the substantial improvement threshold. A homeowner on a 1975 ranch in the AE zone asks for a full kitchen gut-and-remodel. Mid-project, someone realizes the combined value of the work crosses 50% of the structure’s assessed value. Work halts. The whole house now legally needs elevation to the new Base Flood Elevation. We walk every older Friendswood job with a FEMA flood-zone map in hand precisely to avoid this tripwire.
- Clay-soil foundation movement on older slabs. Friendswood sits on Beaumont clay that swells in wet seasons and shrinks in dry ones. Slabs on 1960s-to-1980s homes can shift an inch or more, which means doors bind, cladding cracks, and a new addition’s foundation has to be designed not to fight the old slab.
- Harvey moisture intrusion that was never properly dried-in. We find rotted sill plates and compromised band joists in homes that were “repaired” quickly after 2017. If you build a new ADU or addition on top of that, you’re locking moisture in. We check before we close walls.
- Acreage access and long material hauls. If the concrete pump can’t reach your rear setback, or the lot has no established access for equipment, the price changes. Contractors who quote Friendswood acreage like suburban infill end up writing change orders. We scope access and haul distance up front.
Pricing for Home Additions & ADU in Friendswood, TX
Here’s where Friendswood projects land. A room addition on a standard city lot typically runs $45,000 to $130,000. A garage conversion ADU ranges from $30,000 to $80,000. A new detached ADU, with its own foundation, utilities, and site prep, sits between $90,000 and $220,000 depending on size, finishes, and how much site work the lot demands.
| Project Type | Typical Range in Friendswood |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
What moves the number: flood-zone elevation requirements, soil conditions, septic capacity, material haul distance, and equipment access. We give you a written line-item quote before work starts, and any change arrives on paper before it arrives on your bill. Call (877) 610-1318 to schedule a free estimate.
We Also Serve Cities Near Friendswood
Our crews work throughout the Clear Creek and Bay Area communities. In addition to Friendswood, we handle home additions and ADU projects in Webster, Pearland, League City, and Alvin. If you’re a few minutes down the road and wondering whether we cover your street, call us. Chances are we already have a crew nearby.
Serving Friendswood, TX - Our Local Coverage Area
We’re based in the Friendswood 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 - Home Additions & ADU in Friendswood
Yes. Friendswood requires permits for detached ADUs, and on a septic lot the county health authority and city building department both get a say. The existing drainfield’s capacity and setbacks drive the ADU’s size, bedroom count, and placement. We scope the septic review before you pay for plans, because a drainfield that can’t handle a second bathroom changes everything. Call (877) 610-1318 for an exact read on your lot.
Possibly, and you need to know before you start. If the combined value of the addition plus any post-Harvey repairs exceeds 50% of the structure’s assessed value, the city’s substantial improvement rule legally requires elevating the entire structure to the new Base Flood Elevation before inspection sign-off. That’s a six-figure trigger, not a line item. We walk the FEMA map and the assessor’s numbers with you before you commit to drawings. Call (877) 610-1318 to have us run the numbers.
Expect to pay meaningfully more for site work: longer trenched utility runs, septic and well setbacks, grading and drainage on an open lot, and equipment access for concrete and framing delivery. The structure itself costs about the same as a city-lot build, but site prep on acreage can add tens of thousands depending on how far the utilities have to run and how the lot drains. We scope it in writing before we quote.
Usually yes, but the slab has to be addressed. On a 1978 brick ranch off Winding Way Drive in 77546, our crew started a garage conversion ADU with a new bath rough-in. The existing slab had shifted a full inch over the years on Beaumont clay, so we scoped helical piers under the new subfloor and a channel drain at the garage door. Once the concrete was open, we found rotted sill plates from Harvey moisture intrusion that had never been properly dried-in. We wrote a change order for full replacement and re-flashed the band joist before closing walls. That’s the difference between a garage conversion that lasts and one that binds its doors within two years.
The substantial improvement rule. Contractors who don’t work Friendswood regularly quote a “simple” room addition on a 1970s ranch without checking the assessed value against the 50% threshold. Mid-project, the job legally halts until the whole house is elevated. We’ve watched it happen. We check first, every time.
Call (877) 610-1318 to schedule your free estimate. A live person answers, 24/7, and we’ll give you a straight answer about your lot, your flood zone, and what your addition or ADU will actually cost in Friendswood.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Friendswood since 1998.