ADU Construction DFW

Costs vary with size, site work, utilities, and finishes.

Garage conversions are typically the most budget-friendly, while new detached units cost more due to foundation, trenching, and separate systems.

Hidden cost drivers include electrical service upgrades (many projects move to 200-amp panels), sewer tie-ins, grading, and inspection fees.

National remodeling guidance highlights utility upgrades, site work, and finishes as the most underestimated line items, and longer timelines can delay rental income.

What we do: after a feasibility visit, we provide a line-item estimate (foundation, framing, MEP, finish packages) and a schedule so you can weigh rental goals vs. finish level.

A realistic DFW ADU development timeline is:

• Feasibility 1–3 weeks
• Design/engineering 3–8 weeks
• Permitting 4–12 weeks
• Build 12–24+ weeks

Permitting time depends on your city’s review queue and whether you need variances.

We map these steps up front and update you at each milestone to avoid surprises.

You’ll need building, mechanical, electrical, and plumbing permits, and sometimes zoning approvals or variances, depending on your lot.

In Dallas, overlay adoption comes first; then standard submittals and inspections.

In Fort Worth, it moves through normal building permits, with the accessory-use rules applied.

We prepare drawings, submit applications, coordinate comments, and attend inspections for you.

Are ADUs allowed in the City of Dallas?

Yes—but only within areas that adopt an ADU Overlay (ADUO).

Dallas does not allow ADUs citywide by right.

A neighborhood (50+ single-family structures) can petition for an overlay; if adopted, owners may apply for ADU permits.

Key Dallas ADUO standards include:

• Size: Detached ADU min 200 sq ft; max is the greater of 700 sq ft or 25% of the main home. Attached ADU max is the greater of 700 sq ft or 25% of the main use.

• Setbacks (when <15 ft tall): may be as close as 3 ft to side/rear lines if in the back 30% of the lot; taller units follow base-zoning setbacks.

• Parking: 1 off-street space required, waived within 1,200 ft of a DART stop; reductions are possible if 75% of owners in the overlay agree or City Council approves.

• Stories: max one story.

• Owner-occupancy: if one unit is rented, the owner must live in the main house or the ADU (with limited absence allowed).

• Utilities: up to two electrical meters per lot; rental units must be in the city’s single-family rental program.

For process steps (neighborhood meeting, signatures, CPC/City Council hearings), Dallas’ ADU page summarizes how overlays get created.

What about Fort Worth—can I build an ADU there?

Fort Worth’s code recognizes habitable accessory structures and allows them to be used as an accessory dwelling unit, subject to building code and development standards.

These units may not be used as a separate, independent residence in one-family districts (i.e., they remain accessory to the primary house).

Accessory buildings must meet side/rear setbacks and lot-coverage rules of the base zoning; height generally cannot exceed the primary structure.

Final approval runs through standard permitting and inspections.

(Translation: Fort Worth is generally friendlier to ADU-style, habitable accessory buildings than Dallas, but your exact path—rental, metering, and layout—must conform to the “accessory” rules of your zoning district. We verify that in feasibility.)

I’m in Plano—are “backyard cottages” (ADUs) allowed?

Plano adopted changes in 2019 that opened the door for backyard cottages (ADUs) on more single-family lots, including smaller minimum lot sizes (~6,000 sq ft), at least one additional off-street parking space, and design/placement limits (behind the primary, not taller than the main house).

City staff expected only modest production (about 250 units in 10 years).

Always confirm the latest requirements with Planning/Building Inspections, as the city has updated multiple development codes since 2019.

Studios and 1-bedroom layouts in the 400–700 sq ft range rent well; larger two-bedroom layouts (700–1,000+ sq ft) fit multigenerational needs.

In Dallas ADU Overlay areas, remember the 700 sq ft / 25% of the main home cap, whichever is greater, when sizing concept plans.

Often, yes—subject to slab condition, structural upgrades, egress, insulation, fire separation, and utilities.

Garage conversions are typically the fastest, most cost-efficient way to create code-compliant living space.

In Dallas, your neighborhood must be inside an adopted overlay before a garage apartment can be permitted as an ADU.

Fort Worth treats it as a habitable accessory building (not an independent residence) with standard setbacks and building code compliance.

Absolutely. Great for workdays and guest stays on weekends.

Short answer: neither is automatically cheaper. In DFW, the better value depends on your lot, the scope you want, and what’s included in the quote. Here’s how to think about it:

What “Prefab Pricing” Usually Does and Doesn’t Include

Prefab makers often advertise a box price that covers the factory-built unit and basic installation.

Read the fine print: reputable vendors show that totals usually exclude some or all of the costly site items—long utility trenching, difficult craning, tree removal, unusual engineering, permit/impact fees, and sales tax.

Those add-ons can close the gap with a site-built ADU.

Typical extra line items to budget for (either path):

• Foundation
• Grading
• Utility trenching and tie-ins
• Electrical service upgrades
• Permit/plan-check fees and inspections

Delivery, crane/set-in, and tight backyard access can add thousands more for prefab installs.

When prefab can be cheaper

• Simple lots + easy access. Minimal trenching, a short crane reach, and straightforward foundation work keep extras down.
• Schedule = money. Factory timelines can shorten on-site labor and interest carry, which helps the overall cost of capital.
• Standard finishes. If you’re happy with a set floor plan and spec package, prefab’s predictability can control change orders.

When a site-built (custom) ADU can be cheaper

• Garage conversions. Reusing structure/utility runs often beats a shipped module on cost. Many public ADU guides show conversions as the most budget-friendly path.
• Tricky sites. Irregular setbacks, long utility distances, or narrow access can erase prefab savings (crane + staging) while a custom build adapts in place.
• Integration/value. Custom ADUs can match your main house better (design, materials), which some pros say helps resale and rental appeal.