A detached ADU is a standalone structure on your property — designed from scratch, built from the ground up, and completely separate from your main home. It's the most flexible option for homeowners who want a true independent living space on their lot.
Because it's a new build, a detached ADU gives you total control over the design: layout, size, placement on the lot, finishes, and how the space connects (or doesn't) to your primary home. It's also the best option for lots where the existing garage can't be converted or built upon.
Detached ADUs in DFW typically range from $100,000 to $300,000+ depending on size, design complexity, site conditions (slope, access, utility proximity), and finish level. Larger or premium builds can go higher, but most DFW projects fall in this range.
What Goes Into Building a Detached ADU
Lot Requirements for a Detached ADU in DFW
| City | Max Size | Min Lot Size | Owner-Occupancy |
|---|---|---|---|
| Fort Worth | Varies by district | 6,000 sq ft typical | Not required |
| Dallas | Per ADUO overlay | Per overlay district | Not required |
| Mansfield | Per zoning code | Per district | Not required |
| Aledo / Parker Co. | Varies by jurisdiction | Larger lots typical | Not required |
| Denton | 800 sq ft or 75% | 7,000 sq ft | Not required |
| Burleson | Per zoning code | Per district | Not required |
| Arlington | Per zoning code | Per district | Check locally |
| Southlake | Larger lots typical | 15,000+ sq ft | Not required |
All zoning details subject to change. We verify your specific address before design begins.
How Long Does It Take to Build a Detached ADU?
Site survey, floor plan development, structural engineering, and material selections.
New construction takes longer to permit than conversions. City timelines vary significantly.
Site prep, foundation, framing, rough-in, exterior, and interior finish.
Total: 5–9 months from first conversation to final walkthrough.
Is a Detached ADU a Good Investment?
Detached ADUs command the highest rents of any ADU type because they offer the most privacy, the most independence, and the most amenities. The payback period is longer than a garage conversion, but the long-term return — in both rental income and property value — is the strongest of any ADU build type.
Frequently Asked Questions About Detached ADUs
What's the difference between an ADU and a guest house?
Functionally, they're similar — both are separate living spaces on your property. "ADU" (Accessory Dwelling Unit) is the legal/zoning term. "Guest house" is the lifestyle term. Zoning rules apply to both.
How much does a detached ADU cost in DFW?
Most detached ADUs in DFW cost $100,000–$300,000 depending on size, site conditions, and finish level. It's a ground-up build, so costs are higher than conversions but you get a brand-new, purpose-built structure.
What size ADU can I build on my property?
It depends on your city and lot size. Denton allows up to 800 sq ft or 75% of primary dwelling. Fort Worth varies by zoning district. Mansfield, Burleson, and Aledo each have their own requirements. We research your specific property before design begins.
Do I need separate utilities for a detached ADU?
Most cities require or strongly recommend separate utility connections for detached structures. This includes water, sewer, electrical, and gas. Some cities allow shared meters; others require separate. We handle this during the design phase.
Can I put an ADU anywhere on my lot?
No — setback rules dictate how close to property lines, the main house, and other structures the ADU can be. Placement also depends on utility access, drainage, and tree preservation requirements. We factor all of this into the site plan.