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
Adding square footage in Allen, TX typically costs $45,000 to $130,000 for a room addition and $90,000 to $220,000 for a full detached ADU. We schedule free estimates across Allen’s 75002 and 75013 ZIP codes, and Tom Barrett or one of his sons will walk your property personally before a single number lands in front of you. If you’ve been sitting on a floor plan sketch or a text from your son about “building something in the backyard,” call (877) 610-1318 and let’s talk about what your lot can actually support.
Why Barrett & Sons Construction Is Allen’s Preferred Home Additions & ADU Company
We’ve watched Allen grow from a quiet railroad stop into one of the most competitive housing markets in Collin County. What that means for your home is simple: if you own a tract house in Twin Creeks or Ridgeview Ranch built between 1993 and 2012, you’re sitting on the same builder package as three hundred of your neighbors. The framing, the slab, the window headers are nearly identical block to block. That sameness is exactly why our Home Additions & ADU team knows what we’re walking into before we open the first wall. We’ve seen your house before, even if we haven’t seen your house before.
Tom Barrett founded this company in 1998 and his sons still run the crews. When we tell you we’ll be in Allen on Tuesday, it’s the same person who measured your hallway on the phone. The permit inspector works for you, not for us, and we’re glad for it. Every job gets permits pulled and inspections signed, and every price change comes as a written change order before work moves forward. If a contractor ever tells you permits are optional in Allen, hang up and call us.
Our Home Additions & ADU Services in Allen
ADU Design & Permitting
Allen’s zoning and setback rules for accessory dwelling units are their own animal, particularly in the 75013 corridor where lot lines tighten up. We handle the full design and permit package, including site surveys, utility tap coordination, and HOA submission work if your neighborhood requires it. You won’t be the person sitting in the Collin County permit office trying to figure out why your form came back with a pink slip.
Garage Conversion ADU
In Allen’s master-planned subdivisions, a garage conversion is often the smartest dollar-per-square-foot play on the block. Most 1990s tract homes have oversized two-car garages that convert cleanly, though we always check the slab thickness and drainage before promising your in-laws a finished studio. A typical Allen garage conversion runs $30,000 to $80,000 depending on plumbing, electrical, and whether we’re adding a kitchenette.
New Detached ADU
Lots in eastern Allen, especially near Lucas and Fairview, often have the yard depth for a true detached unit. These run $90,000 to $220,000 and are a different animal from a garage conversion: new foundation, new utility trench, new roofline. On Blackland Prairie clay, we pour with foundation movement in mind from day one. You don’t want a brand new ADU with drywall cracks before the paint cures.
Junior ADU & Interior Conversion
If your needs are smaller, say a bedroom suite above the garage or a finished space off the utility room, a junior ADU can run $45,000 to $130,000. We see these a lot in Allen from homeowners whose adult kids moved back, or whose parents need a first-floor setup with no stairs. Interior conversions avoid most setback restrictions but still require permits and a hard look at how the plumbing stack runs through the slab.
While we’re inside your walls, plenty of Allen homeowners ask us to handle Kitchen Remodeling in Allen at the same time, since the dust is already flying. If we’re adding a kitchenette to your ADU, it also makes sense to talk about Bathroom Remodeling in Allen for the main house while the crew is on site.
What happens when you call
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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 Allen
We install and stand behind materials you can look up. For Allen additions and ADUs, we regularly frame and trim with Simonton windows, and we spec Ply Gem and PGT when impact ratings or North Texas hail resistance matter. We don’t pull mystery brands off a van and call them premium. If you want to Google the window before we hang it, that’s the point.
Common Home Additions & ADU Problems We See in Allen Homes
- Slab movement before the addition even starts: Allen sits on Blackland Prairie expansive clay, and homes in Twin Creeks and Watters Crossing routinely show seasonal door racking and drywall splits. We assess current slab movement before designing any attached addition, because framing tied to a moving slab fights itself within two years.
- Post-tension cable strikes: Allen’s 1990s and 2000s tract homes sit on post-tension slabs, and cutting into one without locating the cables is a five-figure mistake. We locate before we saw, every time.
- HOA design review delays: Many Allen neighborhoods, especially in 75013, require architectural committee approval before a visible addition or detached ADU moves forward. We pull the HOA submittal package together early so it doesn’t stall your permit timeline.
- Original roof and fascia failure at exactly the wrong time: Homes built around 1995 to 2005 in Ridgeview Ranch are hitting simultaneous age on their original roofing, soffits, and fascia. If your addition ties into an existing roofline, we’ll tell you honestly whether the old section needs to be addressed now rather than after the new drywall is up.
Pricing for Home Additions & ADU in Allen, TX
Expect a room addition in Allen to run $45,000 to $130,000, and a detached ADU $90,000 to $220,000. Garage conversions land at $30,000 to $80,000. What moves the number: whether you’re tying into existing plumbing, how far the utility trench runs, whether the HOA forces architectural changes, and how much slab work the clay demands. We give you a written line-item quote before you sign anything, and every allowance and scope change arrives as a written change order before we pick up a tool. No surprise invoice at the end. Call (877) 610-1318 for a free estimate.
We Also Serve Cities Near Allen
Our crews live in the area and regularly work in Lucas, Plano, Murphy, and Fairview. If you’re in one of those towns and your addition or ADU needs the same foundation-aware approach we use in Allen, we’ll schedule your estimate the same way: Tom or one of his sons on site, measuring your lot and telling you the truth.
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
We typically schedule estimates in Allen within a few business days, and if you’re flexible on timing we can often get someone out faster. Call (877) 610-1318 and we’ll put you on the calendar. The estimate is free and the person who shows up is the same person who will make decisions about your project.
Yes. We cover every neighborhood in Allen’s 75002 and 75013 ZIP codes, including Twin Creeks, Watters Crossing, and Ridgeview Ranch. Each subdivision has its own HOA quirks and its own slab history, and we’ve worked with enough of them to know what to expect before we submit the first form.
A room addition in Allen runs $45,000 to $130,000, which is close to Plano but often higher than rural corners of Lucas or Murphy because of Allen’s permitting and HOA review overhead. The foundation work on Blackland Prairie clay is the big equalizer across the whole area. We’ll give you a written quote that breaks the number down line by line.
Every eligible job includes permits pulled and inspections signed. If your ADU or addition needs a Collin County or City of Allen inspection, we schedule it and we’re on site when the inspector walks. The permit inspector works for you, not for us, and we wouldn’t have it any other way.
Every Barrett & Sons job comes with our written 90-Day Done Right Promise: if something’s not done right, Tom comes back and makes it right, one call. That’s in addition to manufacturer warranties on materials like Simonton, Ply Gem, and PGT windows. No fine print, no chasing a national call center.
If you’re ready to stop sketching and start digging, call (877) 610-1318. We’ll schedule your free estimate in Allen, walk the lot with you, and put the real numbers in writing before you commit to anything.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Allen and surrounding North Texas communities.