Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Before
After
Before
After
Before
AfterFast, Reliable Home Additions & ADU Across Prosper
Home additions and ADU construction in Prosper runs $45,000-$130,000 for most room additions, while a new detached ADU typically lands between $90,000 and $220,000. We’re Barrett & Sons Construction, and we’ve been building in North Texas long enough to know exactly what happens when you open a wall in a Prosper home. If you’re planning an addition off Preston Road or out toward the newer sections of Windsong Ranch, call (877) 610-1318 and Tom will walk you through what your project actually involves before you sign anything.
Why Barrett & Sons Construction Is Prosper’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998. His sons run the crews. That’s not marketing language; that’s who shows up at your door in Prosper. Homeowners in 75078 don’t want a rotating cast of subcontractors who’ve never seen a post-tension slab before. They want the same faces on Monday who were there on Friday.
Our Home Additions & ADU team knows what Prosper’s fast-track construction cycle leaves behind. We’ve pulled permits in this town when multiple spec-build communities are going up at once, and we know how that tightens material lead times and inspection schedules. You get that knowledge in your written scope of work, not as an excuse later. Name, address, license number: all published. Call Tom and ask him yourself.
Our Home Additions & ADU Services in Prosper
Second Story Additions
Prosper’s two-story brick and stone veneer homes are prime candidates for second-story additions, but the original truss packages in fast-built subdivisions often weren’t engineered for later vertical expansion. We start with a structural evaluation, not a sledgehammer. In Star Trail, our crew opened a 2018 build for a second-story addition and found a partition wall carrying an unexpected load-bearing point from the original truss package. The post-tension slab had already moved 3/8″ at that interior wall, and the framing had never been engineer-signed for that condition. We pulled the permit correction, wrote a change order for the beam and footing reinforcement, and had the inspection sign-off before closing the wall. The addition went up straight, and the existing home stopped telegraphing cracks.
New Detached ADU
A new detached ADU in Prosper gives you rental income or space for aging parents without touching your main home’s footprint. But North Texas blackland prairie clay doesn’t care how clean your floor plan is. We budget for soil movement from day one: proper footings, moisture barriers, and slab design that accounts for expansion and contraction. Expect $90,000-$220,000 depending on square footage and finish level.
Garage Conversion ADU
Converting an attached garage in a Prosper home built since 2010 often means working around post-tension cables that don’t show up on the original builder plans. We map the slab before we cut. A garage conversion ADU in Prosper typically runs $30,000-$80,000, and the permit triggers a code review of the existing rough-in. That’s where fast-track framing defects surface. We handle it with a written change order, not a phone call asking for more money.
Junior ADU & Interior Conversion
A junior ADU built inside your existing Prosper home is the most cost-efficient way to add a legal dwelling unit. We convert bonus rooms, media rooms, and oversized second-floor spaces into full ADUs with separate entrances where setback rules allow. Prosper’s master-planned communities have specific HOA and zoning overlays that affect what counts as a legal ADU. We navigate those before you spend a dollar.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Prosper
We install materials you can look up, not mystery brands off a van. For ADU kitchens and baths we use Schluter waterproofing systems and Grohe fixtures because they hold up under North Texas humidity swings. If your addition includes roofing, GAF shingles are our standard. These are brands with published specs. If something fails, you know what you bought and we know what we installed.
Common Home Additions & ADU Problems We See in Prosper Homes
- Post-tension slab movement under fast-built homes. The clay in Prosper expands and contracts so aggressively that 5-8 year old homes already show measurable differential movement at interior partition walls. Open any wall for an addition without checking that movement, and your new framing fights the existing structure within two seasons.
- As-built rough-in that doesn’t match builder plans. When hundreds of lots go up per year, corners get cut. We regularly find rough-in framing and rough plumbing that was never engineer-signed and never matched the stamped plans. Writing an addition scope on the original plans alone is how you blow a schedule and a budget.
- Foundation heave transferring into the new structure. If you pour an ADU foundation with undersized footings or skip the moisture barrier on blackland prairie clay, the new structure heaves independently from the main house. We see this in conversions done by out-of-town crews who don’t know the soil.
- Warranty-window defects discovered mid-project. Prosper homes are young enough that builder warranties still apply. Opening a wall often uncovers defects the builder is still responsible for. We document everything and help you file the claim before we proceed. That protects your wallet and your addition.
Pricing for Home Additions & ADU in Prosper, TX
You’re not paying a flat rate. You’re paying for what we find when we open the wall. Here’s what current Prosper-market pricing looks like for the work we handle most:
| Service | Prosper Price Range |
|---|---|
| Home Addition | $45,000-$130,000 |
| Second Story Addition | $45,000-$130,000 |
| New Detached ADU | $90,000-$220,000 |
| Garage Conversion ADU | $30,000-$80,000 |
What moves the number? Soil testing, structural corrections, code upgrades triggered by your permit, and finish level. Every one of those gets priced in writing before we touch it. Call (877) 610-1318 for a free estimate that accounts for your street, your soil, and your house.
We Also Serve Cities Near Prosper
Our crews cover the full Prosper area and the towns around it. If you’re in Frisco, Celina, Little Elm, or Fairview and planning an addition or ADU, the same crew and the same written-scope discipline apply. Tom lives twenty minutes away. If something’s wrong, he wants to know about it.
Serving Prosper, TX - Our Local Coverage Area
We’re based in the Prosper 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 Prosper
Prosper addition quotes vary because the homes are young but the soil is aggressive. One contractor quotes off original builder plans, another quotes off an as-built inspection that reveals framing corrections, soil stabilization, and permit-triggered code upgrades. The spread you see is the difference between pricing the drawing and pricing the house. Call (877) 610-1318 and ask Tom to walk you through what’s actually in each number.
Usually yes. Even when you’re staying inside existing walls, Prosper’s building department requires engineered drawings for structural changes, electrical upgrades, and egress windows when you convert a garage to living space. A permit is mandatory for an ADU of any type. Tom’s team pulls permits on every eligible job. That’s not optional in Prosper.
The clay under Prosper shrinks in summer drought and swells with any real rain, so an ADU foundation must be designed for movement that a concrete slab in, say, East Texas would never see. We spec footings and moisture barriers for that soil profile, and we schedule concrete pours in early morning hours when slab surface temperatures stay manageable. If a contractor skips soil prep here, the ADU heaves independently from your house within a few years.
We stop work, document the defect with photos and measurements, and help you file a warranty claim before we proceed. In a town where most homes are under ten years old, this happens more than people expect. Your addition should not pay for the original builder’s mistake. Call (877) 610-1318 for an exact approach to your situation.
You can, but you shouldn’t. Windsong Ranch and most Prosper subdivisions are built on post-tension concrete slabs over blackland clay. Adding vertical load without checking slab condition risks existing cracks growing, doors binding, and the new second story fighting the foundation. We bring an engineer in before we frame anything. The inspection is cheaper than the fix.
Call Barrett & Sons Construction for Your Prosper Addition or ADU
If you’re planning a home addition or ADU in Prosper, start with a conversation. Tom Barrett answers his own phone. You’ll get a straight answer about what a permit-triggered inspection on your fast-built Prosper home will actually cost you, before the first stud gets opened. Written change orders, permits pulled, inspections signed, and the 90-Day Done Right Promise on every job. Call (877) 610-1318 to schedule your free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Prosper, TX since 1998.