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 Allen
A room addition or ADU in Allen typically runs $45,000 to $130,000 for the construction scope, with garage conversions landing between $30,000 and $80,000 depending on finish level. You’ll want a contractor who knows what a post-tension slab on Blackland Prairie clay does after 25 years of drought cycles, because that one fact changes everything about how your addition gets framed. Our crews work in Allen every week, and we answer the phone at (877) 610-1318 when you call.
We’ve spent years working in and around Allen’s master-planned communities. We know the subdivisions, the builder packages, the HOA paperwork routines, and the specific ways these houses fail. That local knowledge is the difference between a room addition that settles cleanly and one that cracks its drywall within two seasons.
Key takeaways for Allen homeowners:
- Budget $45,000 to $130,000 for a room addition; $90,000 to $220,000 for a new detached ADU; $30,000 to $80,000 for a garage conversion.
- Post-tension slab evaluation should happen before any framing decision. This is not optional in Allen.
- HOA architectural review in communities like Twin Creeks and Watters Crossing can take weeks. Plan for it before you sign anything.
- Every change order on our jobs is in writing before work begins. That’s how we’ve operated since 1998.
Why Barrett & Sons Construction Is Allen’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998, and his sons run the crews. When we say we’ll be on your job in Allen, the person who shows up carries the Barrett name, not a subcontractor badge from three counties away. We pull permits on every eligible job, we put every scope change in writing, and we stand behind the work with our 90-Day Done Right Promise, written on the contract, not buried in fine print.
Our reputation in Allen is built on showing up when we say we will and doing what we said we’d do. Homeowners in Ridgeview Ranch and Twin Creeks have called us back for second and third projects. That’s the only review that matters to us. When you call our number, a live person answers, 24 hours a day. Not a voicemail box, not an out-of-state call center. You’ll talk to someone who knows Allen.
We also publish Tom’s name, address, and license number. Look us up before you sign anything. The Home Additions & ADU in Allen work we do is backed by paperwork you can verify, not promises you have to trust.
Our Home Additions & ADU Services in Allen
We’re the Home Additions & ADU team that actually frames the walls. Here are the services Allen homeowners call us for most.
ADU Design & Permitting
Building a detached ADU in Allen means navigating city permitting plus HOA architectural review in most master-planned communities. We handle the drawings, the permit package, and the HOA submission. Allen’s 75013 ZIP in particular has seen a wave of ADU interest from homeowners looking to house aging parents or adult children, and the permitting timeline is something we know well.
Garage Conversion ADU
A garage conversion in Allen runs $30,000 to $80,000, and it’s the most common ADU path we see because the structure already exists. In Allen’s 1990s tract homes, the garage slab is typically a separate pour from the house slab. That’s good news for a conversion, but you still want a slab elevation check before interior walls go up. We’ve done enough of these in Watters Crossing and Twin Creeks to know exactly where the trouble spots hide.
New Detached ADU
A new detached ADU in Allen runs $90,000 to $220,000 once you factor in foundation work, utility trenching, framing, and finishes. Allen’s Blackland Prairie clay means the foundation spec matters more than the square footage. We’ll size the slab and grade beams for soil that moves, and we’ll do it with a written scope before the first trench is dug.
Junior ADU & Interior Conversion
For homeowners who want a private suite without a full separate structure, a junior ADU or interior conversion makes sense. Maybe it’s a first-floor bedroom with a kitchenette and separate entrance, or converting a bonus room over the garage. We’ve done these in Allen homes where the existing layout already offers a natural separation. The trick is getting the plumbing and electrical right without disturbing the post-tension cables in the slab. We know how to do that.
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.
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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 Allen
We install brands you can look up, not mystery materials off a van. On Allen addition and ADU jobs we regularly use Simonton and Ply Gem Windows & Doors - Allen, and PGT impact-rated units when the project calls for storm resistance. Why does that matter to you? Because the weather that tracks northeast along the DFW storm corridor through Allen is real, and hail doesn’t care how nice your new sunroom looks. We stock local parts for these brands and can get replacements fast when you need them.
Common Home Additions & ADU Problems We See in Allen Homes
Allen’s housing stock is unusually uniform. Most homes in the 75002 and 75013 ZIP codes were built between 1993 and 2012, and in the older half of that range they’re hitting the renovation threshold all at once. Here’s what we run into constantly:
- Racked door frames in new additions. Allen sits on Blackland Prairie expansive clay. If you frame a room addition without a slab elevation survey, the new door frames will rack within two seasons. We measure first. Always.
- HOA stop-work orders. In Twin Creeks, Watters Crossing, and Ridgeview Ranch, skipping HOA architectural review gets a stop-work order faster than a framing crew can set a wall. We handle the submission so you don’t have to.
- Builder-grade insulation making new spaces drafty. A 1998-built house already fights Texas heat with outdated insulation. If your addition uses the same grade, the new room will be the hottest and coldest room in the house. We upgrade insulation as standard on Allen additions.
- Garage conversions with undersized electrical panels. A 1990s tract home in Ridgeview Ranch typically shipped with a 150-amp or 200-amp panel. Add a full ADU with a kitchen, and you’ll often need a panel upgrade before the conversion passes inspection. We check this before quoting, not after.
Pricing for Home Additions & ADU in Allen, TX
Allen prices are shaped by the same forces as the rest of Collin County, with a couple of local factors layered on top. The labor market is tight, the soil conditions push foundation costs up, and Allen Roofing and HOA-mandated exterior finishes in communities like Twin Creeks and Watters Crossing add real dollars to a project. Here’s what you can expect:
| Project Type | Typical Allen Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
These ranges reflect the markets we’ve quoted in Allen’s 75002 and 75013 ZIP codes. A simple bedroom addition or Bathroom Remodeling in Allen on a stable slab sits at the low end. A second-story addition with a bathroom and engineered beams pushes toward the top. Every quote we give is a written line-item estimate, and every change order is in writing before work starts. Call (877) 610-1318 for a free estimate and we’ll walk your specific property before putting numbers on paper.
We Also Serve Cities Near Allen
Our crews work across the northern DFW corridor, so if you’re in Allen proper or just outside it, we’re nearby. We regularly take on addition and ADU projects in Lucas, Plano, Murphy, and Fairview. Same crew, same written change orders, same permit discipline.
Serving Allen, TX - Our Local Coverage Area
We’re based in the Allen 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 Allen
Yes. Twin Creeks has an active architectural review committee, and you need approval before any structural work begins. We prepare and submit the elevation drawings and site plan for you. Skipping this step gets you a stop-work order, and in some Allen communities a fine, before the first wall goes up. Call (877) 610-1318 if you want help with the submission.
If your house is still under a builder warranty, a garage conversion can affect it, especially regarding the slab, roof structure, or electrical system. Many 1990s Allen homes are well past the warranty window, but newer builds in 75013 may still have active coverage. We recommend reading your warranty document before you sign a contract, and we’ll note any warranty-sensitive work in your written scope.
A structural engineer needs to evaluate the slab, and we arrange that as part of our pre-construction work. Post-tension slabs can often support a second story, but Allen’s expansive clay means you want a slab elevation survey and cable location scan first. In one Twin Creeks two-story built in 1997, our crew measured 1.5 inches of differential movement across the back corner before framing a second-story addition over the garage. We stabilized the slab with a pier-and-beam specialist, framed with engineered lumber and a steel beam, and got a clean inspection sign-off. That’s the sequence, and it works.
Expect 4 to 8 weeks for ADU permits in Allen’s 75013 ZIP, though HOA review can add another 2 to 4 weeks if your community has an architectural committee. We submit the permit package as soon as your scope is finalized in writing. The city processes are predictable, but the HOA timeline is the wildcard. Call (877) 610-1318 and we’ll tell you what to expect for your specific community.
Often, yes. Most Ridgeview Ranch homes from the late 1990s and early 2000s shipped with a 150-amp or 200-amp panel. A full ADU with a kitchen, mini-split HVAC, and laundry loads frequently pushes past the panel’s existing capacity. We check your panel load during the estimate, and if an upgrade is needed, it’s a written line item before you sign anything, not a surprise at rough-in.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Allen since 1998.