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 Richardson
A detached ADU in Richardson typically runs $90,000 to $220,000, while a home addition or second-story addition lands between $45,000 and $130,000 depending on foundation work, permitting path, and site access. Barrett & Sons Construction has built additions and Bathroom Remodeling - Richardson and ADUs across Richardson’s 75080, 75081, 75082, and 75085 ZIP codes since 1998. Call (877) 610-1318 for a free, written estimate from Tom Barrett’s crew, not a call center.
The biggest cost swing on any Richardson addition isn’t the lumber or the framing. It’s what’s under your feet. The black clay under 75080 and 75081 shrinks hard in August and heaves after spring rain, moving slabs enough to crack brick veneer and bind door frames on original 1960s ranches. That means a foundation engineered for soil movement is not an upgrade here. It’s the bare minimum. We scope it before quoting because any contractor who skips it leaves you with a change order the size of the original budget.
Why Barrett & Sons Construction Is Richardson’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998 and his sons run the crews. That’s not marketing language. You’ll see Tom on-site in Richardson for scope walks, and you’ll get a written change order before any price moves. We’re the Home Additions & ADU team that pulls permits on every eligible job and signs off inspections because the inspector works for you, not for us. That’s the whole point.
Richardson homeowners call us because the national outfits quote a price on the phone and show up with a different one at the door. We quote in writing, with allowances in writing and scope in writing, before a single nail moves. If you live in 75080 near Arapaho Road or 75082 near Breckinridge Park, you’re twenty minutes from us. If something’s wrong after the job, Tom comes back. That’s the 90-Day Done Right Promise, written on every contract we sign.
Our Richardson customers see us at the hardware store on Saturday. That changes how we build. We answer our own phone at (877) 610-1318, and when you call about an addition off Campbell Road, the person who answers knows what the clay does to a slab on that side of town.
Our Home Additions & ADU Services in Richardson
ADU Design & Permitting
Richardson sits split between city-permitted and county-permitted lots, and the wrong permit path fails inspection on day one. We verify whether your property falls inside Richardson city limits before we draw a single line. For lots on acreage outside the city, that means Dallas County building codes, septic setback reviews, and sometimes well-distance minimums that move your ADU footprint twenty-five feet before you ever see a foundation form.
Garage Conversion ADU
A garage conversion in Richardson runs $30,000 to $80,000, and the older the home, the more rough-in work hides behind the drywall. 1960s and 1970s tract homes in 75080 and 75081 rarely have insulation in garage cavities, and the slab under the garage door opening was never graded for living space. We scope those unknowns as a written allowance before quoting, so you never get a surprise invoice after demolition.
New Detached ADU
New detached ADUs in Richardson average $90,000 to $220,000. The foundation is the line item that separates a good build from a rework. Blackland Prairie clay moves, and a standard slab poured without a geotechnical report will crack within two seasons. We engineer for helical piers or an over-excavated, properly reinforced slab based on the soil report, not a guess. On acreage lots, we also handle grading, drainage swales, and utility runs from the main house, which most city-lot contractors never touch.
Junior ADU & Interior Conversion
A junior ADU built inside the existing footprint of a Richardson ranch avoids the foundation question entirely, which is why it’s become the fastest path to a rental unit or in-law suite in 75080. We convert existing bedrooms, bonus rooms, or attached garages into code-compliant living spaces with separate entries, kitchenettes, and updated electrical panels sized for the added load. In Richardson’s older stock, that almost always means reworking original 1960s rough-in that doesn’t meet current IRC standards.
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 Richardson
Barrett & Sons installs brands you can look up, not mystery materials off a van. On Richardson additions and ADUs, we regularly use Techo-Bloc and Cambridge pavers for patios, walkways, and driveway approaches, and Quikrete products for foundation and masonry work, plus Windows & Doors in Richardson. We stock local components for Richardson jobs so you’re not waiting on a freight truck from three states away when the framing crew is ready. That keeps your addition moving and your schedule honest.
Common Home Additions & ADU Problems We See in Richardson Homes
- Black clay slab movement. Richardson’s 75080 and 75081 sit on expansive black clay that shrinks in summer drought and heaves after wet seasons. A room addition anchored to an existing 1964 slab without soil-movement engineering will crack at the corner within two years.
- Wrong permit path on acreage. Lots outside Richardson city limits go through the county, not the city. Contractors who don’t verify before pulling permits create a failed inspection sign-off and weeks of delay.
- Undersized second-story framing. A second-story addition on a 1960s or 1970s ranch requires opening the existing subfloor to check joist spacing and load-bearing walls. Skip that step and you’ll be writing a change order for steel reinforcement after drywall is already hung.
- Long utility runs on open lots. Detached ADUs on acreage around Richardson often need electrical, water, and sewer or septic runs of one hundred feet or more. Contractors who don’t scope trenching, conduit, and backfill in the original quote add thousands in change orders before trim work begins.
Pricing for Home Additions & ADU in Richardson, TX
A home addition in Richardson runs $45,000 to $130,000. A detached ADU runs $90,000 to $220,000. A garage conversion lands between $30,000 and $80,000, and a second-story addition falls in the same $45,000 to $130,000 range. The gap between the low and high end comes down to four things: foundation engineering for black clay, city versus county permitting, utility run distance on acreage lots, and how much original rough-in work hides behind the walls of a 1960s ranch. Here’s the breakdown:
| Project Type | Richardson Market Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
| Second Story Addition | $45,000 - $130,000 |
Every Barrett & Sons quote includes a written scope, written allowances, and written change orders before any price changes. Call (877) 610-1318 for your free estimate. We’ll walk your Richardson property, check the slab, verify the permit path, and give you numbers you can actually plan around.
We Also Serve Cities Near Richardson
Richardson sits at the center of our North Dallas service area. We handle Home Additions & ADU projects in University Park and Highland Park, where older luxury housing stock demands careful foundation work, plus Garland and Dallas, where permit requirements and lot conditions shift block by block. Wherever you are, the same crew shows up and the same written promise applies.
Serving Richardson, TX - Our Local Coverage Area
We’re based in the Richardson area and know this community well, offering Richardson Roofing and more. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Home Additions & ADU in Richardson
Richardson’s western ZIP codes sit on Blackland Prairie black clay that shrinks during summer droughts and heaves in wet seasons, so a detached ADU foundation must be engineered for that movement. That typically means a geotechnical report, helical piers or an over-excavated reinforced slab, and a drainage swale graded away from the building. A standard slab poured without those steps will crack and shift within two seasons, and the rework doubles the original rough-in cost. Call (877) 610-1318 and we’ll explain what your specific lot needs before you sign anything.
It goes through Dallas County, not the City of Richardson, if the property sits outside incorporated city limits. The wrong permit path fails inspection when a city inspector shows up for county-permitted work, which delays sign-off and costs money. We verify jurisdiction before we quote, so your permit path is settled on paper before demolition starts. Call (877) 610-1318 for a free estimate with the permit path confirmed.
Septic drain field setbacks and well-distance minimums routinely move an ADU footprint twenty to thirty feet from the spot a homeowner first picks. In one Richardson acreage job, the well setback forced the ADU twenty-five feet farther back than the client originally hoped. We check those distances during the scope walk and adjust the site plan before quoting, so the ADU lands where the county says it can. Call (877) 610-1318 and we’ll walk your lot with you.
A 1960s Richardson ranch sits on a slab that has moved for sixty years, and the original framing and rough-in don’t meet current IRC standards. That means opening the existing subfloor to check joist spacing, reinforcing the load path, and often reworking plumbing and electrical before the second story goes up. In a 1990s or 2000s home in 75082, that work is usually faster and cheaper. Call (877) 610-1318 for a written scope that shows exactly where the money goes on your house.
Long material hauls and equipment access on open acreage get scoped before quoting. That means confirming the driveway or access path can carry a concrete truck, scheduling material drops in stages so lumber doesn’t sit exposed on damp black clay, and running utilities from the main house over distances most city-lot contractors never consider. We write every one of those line items into the original estimate, so the price on paper matches the price at the end. Call (877) 610-1318 to schedule your free acreage walk-through.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Richardson since 1998.