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 Highlands
A home addition or ADU in Highlands typically runs $45,000 to $130,000 for a standard room addition, and $90,000 to $220,000 for a detached ADU, depending on size, foundation work, and floodplain requirements. Every permit runs through Harris County Engineering, and since Harvey, finished floors must sit at least 2 feet above Base Flood Elevation. That changes how we design, engineer, and build anything attached to your home. If you’re thinking about a second story off FM 2100 or a garage conversion near the San Jacinto River, call Tom Barrett and his sons at (877) 610-1318 for a free estimate and a straight answer on what your property will actually require.
Why Barrett & Sons Construction Is Highlands’s Preferred Home Additions & ADU Company
We’ve built Home Additions & ADU projects across Highlands for years, and the one thing we’ve learned is this: the county treats every permit like a floodplain case until proven otherwise. That’s not a headache for us. It’s the standard we build to every day. Tom Barrett publishes his name, address, and license number, and the same crew that pours your foundation is the crew that’ll be back if anything needs attention under our 90-Day Done Right Promise. No franchise, no strangers in a white van.
Highlands homeowners call us because we already know what Harris County Engineering will flag before they flag it. Elevation certificates, flood vents rated for Zone AE, wind-load strapping for 130 mph gusts, beam sizing for Beaumont clay foundation movement. We pull permits on every eligible job and we get them signed. That’s the difference between a project that closes out clean and one that stalls at final inspection.
Our Home Additions & ADU Services in Highlands
ADU Design & Permitting
This is where Highlands projects either succeed or quietly fail. Most contractors we follow behind never pulled the floodplain determination letter, or they drew the finished floor at the old slab elevation and Harris County rejected it. We handle the full permit sequence for you: floodplain review, elevation certificate coordination, structural drawings stamped for unincorporated Harris County, and every inspection from rough-in to final. You get a written scope and every allowance on paper before we dig.
New Detached ADU
A new detached ADU in Highlands gives you a separate address for aging parents, adult kids, or rental income without touching the main house. We frame these on pier-and-beam or elevated slab foundations set 2 feet above BFE, with flood vents and wind-rated sheathing installed from day one. Highlands lots range from tight post-war parcels to larger acreage off FM 565, and we design each ADU to fit the setback, drainage, and elevation realities of your specific property.
Room Additions
Whether it’s a primary suite, a second living area, or a home office, room additions in Highlands require an honest look at what your existing foundation can carry. Many of these 1950s and 1960s homes sit on slab-on-grade with settlement from Beaumont clay. We assess the load path before we draw anything. If the existing slab can’t take the tie-in, we pour a new elevated wing and connect it properly rather than bolting onto a cracked slab and hoping.
Garage Conversion ADU
Converting a garage to an ADU in Highlands often triggers the same floodplain review as new construction. Your existing garage slab may be below the 2-foot freeboard Harris County now requires, which means we may need to raise the finished floor, add flood vents, or both. We’ll tell you that on the first visit, in writing, with a real number attached. No surprises after demo starts.
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 Highlands
We install materials you can look up by name, not whatever rolls off a supply truck. On Highlands additions and ADUs, we regularly spec GAF roofing for wind-rated shingle systems, Schluter waterproofing in any bathroom or wet area we build, and Grohe fixtures where the budget allows. These are brands with published specs and manufacturer warranties that hold up under Harris County inspections and coastal wind exposure. We keep common parts in stock for Highlands jobs, so a punch-list item doesn’t stall your final inspection.
Common Home Additions & ADU Problems We See in Highlands Homes
- Slab additions poured at the old grade. Harris County rejects the permit because the finished floor sits below the 2-foot freeboard required for post-Harvey additions. The fix is an elevated foundation and a new drainage plan, not a variance request.
- Second stories tied into a settling 1960s slab. Beaumont and League City clay under Highlands moves with every wet-dry cycle. If the new framing isn’t independently supported or the existing slab isn’t reinforced, you’ll see cracks in the original structure within two years.
- Roof framing closed up before the wind-load inspection. Harris County requires hold-downs and strapping rated for 130 mph gusts. If drywall goes up before the county sees those clips, you’re tearing it back out on a change order.
- Permits “optional” from the last guy. We hear this weekly in Highlands. The county audits every pulled permit post-Harvey. An unpermitted addition becomes your problem when you sell, refinance, or file an insurance claim.
Pricing for Home Additions & ADU in Highlands, TX
Here’s what we tell Highlands homeowners on the phone, before any site visit: a room addition runs $45,000 to $130,000, a garage conversion runs $30,000 to $80,000, and a new detached ADU runs $90,000 to $220,000. Site prep and utility work for an ADU adds $12,000 to $45,000 depending on sewer line depth, drainage, and how far the structure sits from existing power. Floodplain requirements, foundation condition, and second-story framing all move the number. What doesn’t change: every scope item and allowance is in writing before work starts, and every change comes as a signed change order. Call (877) 610-1318 for a free estimate and a line-item quote you can actually compare.
| Project Type | Typical Range in Highlands |
|---|---|
| ADU Construction | $90,000 - $220,000 |
| Home Addition | $45,000 - $130,000 |
| Garage Conversion | $30,000 - $80,000 |
| ADU Site Prep & Utilities | $12,000 - $45,000 |
We Also Serve Cities Near Highlands
Barrett & Sons Construction serves Home Additions & ADU in Highlands and the surrounding communities along I-10 and the San Jacinto corridor. That includes Channelview, Baytown, Mont Belvieu, and Cloverleaf. If you’re a few miles east toward Baytown or west toward the Beltway, the same crew and the same pricing standards apply. You can call us direct at (877) 610-1318.
Serving Highlands, TX - Our Local Coverage Area
We’re based in the Highlands 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 Highlands
Yes. Harris County applies the same 2-foot-above-BFE finished floor requirement to garage conversions as it does to new detached ADUs. If your existing garage slab is below that elevation, the county will require an elevated floor assembly or a foundation modification before it signs the permit. Call (877) 610-1318 and we’ll pull your property’s specific floodplain determination so you know the exact number before you spend a dollar.
Harris County requires additions to meet a 130 mph wind-load rating, which means continuous load-path strapping, hold-downs at shear wall corners, and properly rated roof sheathing nails. The county inspects these connections before insulation and drywall cover them. We schedule the wind-load inspection as a separate stop so the inspector sees the clips and straps while they’re still exposed.
No. Homes in Highlands built in the 1950s through 1970s sit on Beaumont and League City expansive clay, and many of those slabs have moved, cracked, or settled by inches. Harris County will ask for a stamped foundation assessment before it issues a permit for a structural addition. We bring in a licensed engineer on every Highlands addition, and that report determines whether we tie in, reinforce, or pour new. It’s cheaper than tearing out a cracked tie-in later.
Your insurer will want the final elevation certificate, the signed Harris County inspection records, and documentation of flood-resistant construction if your ADU sits in a designated flood zone. We provide all three as part of every permitted Highlands project. Several of our customers have used that paperwork to reduce wind and flood premiums, because the carrier can verify the structure exceeds minimum code rather than just meeting it.
Highlands is unincorporated Harris County, so every permit runs through Harris County Engineering, which since Harvey has been auditing floodplain compliance on every pulled permit. The county requires a floodplain determination, an elevation certificate, and freeboard verification before final sign-off. City of Houston reviews the same engineering elements, but the county’s post-Harvey enforcement is more aggressive. We budget that time into our Highlands schedules so you’re not surprised when the permit review runs six to eight weeks instead of four.
If you’re planning a home addition or ADU in Highlands, don’t guess at the floodplain or the foundation. Call Barrett & Sons Construction at (877) 610-1318 for a free estimate. Tom or one of his sons will walk the property, explain what Harris County will require, and put every dollar of it in writing before you sign.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Highlands since 1998.