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Austin ADU Home Addition Design Permit Documents Motif Architects

South Congress Accessory Dwelling Unit


Demolition Package and New Design


Austin, Texas




Motif Architects

Hausman Homes


  • ADU code research

  • Economical Finishes


  • As-built Survey

  • Demolition drawings

  • Architectural Design

"A cozy and compact accessory dwelling unit serving all functions."

This accessory dwelling unit truly blends into the lively setting of South Congress. A contemporary home that complements the old and kindles a new spirit.       

"Located in a historic district near South Congress - the Live Music Capital of the World.”


Weaving a home within a compact space needs architectural imagination and thoughtful approach. Nestled in the shopping and cultural district of South Congress in Austin, Texas, known of its music and art venues, eclectic retailers and famed restaurants, the two story auxiliary dwelling with a one-car garage is a perfect abode, comfy with all features.

Motif Architects were approached by the client, a music lover, to add a unit into his property that had an existing century old home. The property, being in a historic neighborhood required reviews for the new architecture addition from the board of approvals. After a series of discussions, generating drawings and evaluating options to reduce material and cost, the team arrived at an elegant design, neatly tucking the modern into an antique street-scape. Protecting the existing trees and complimenting the existing home, the architects developed a two level dwelling unit, with additions enriching the exterior and interior.

Design Concept

Combining a skillion and lean to roof, the resulting vertical space of the crisscrossing roof of the dwelling became the perfect niche for clerestory windows. The ground floor serves as a complete garage attached to a restroom. A staircase running along the western façade leads to the dwelling spaces above. A corner deck attached to the entrance makes an expansive transition from the stairway to the main door.


Designed to be flexible, it opens into a full size open living and kitchen with an island counter. Vaulted ceilings with natural light streaming in from the clerestory windows makes the space; rich and vibrant. The primary bedroom with an attached walk-in closet and bathroom is suited well into the abode.

At night, capture the twinkling stars that peek through the clearstory windows above!       

Austin ADU Home Addition Design Permit Documents Motif Architects
Home Expansion

Discussing with the client on the overall renovation, browsing through trending elements and design styles, they arrived at an elementary vision to craft a dwelling unit appropriate for its neighborhood.

The new Accessory Dwelling Unit was designed to accommodate many uses, including a mother-in-law suite, office space and studio apartment for the stay at home college student.

The garage space is very generous, allowing room for one vehicle and storage space.

Austin ADU Home Addition Design Permit Documents Motif Architects
Exterior Features

The exterior was faced using vertical board and batten along with ship lap fiber cement board siding. Intricate details etched along the frames of matte black vinyl windows, wooden soffits on deck, and standing seam metal roofing add to the unique character defining this cozy home. From a metal coiled garage door to composite wooden stairs to matte black and stainless steel handrails and guardrails add to the modern outlook. Integrating acoustics was one of the key features; soundproofing the apartment from the garage using acoustical materials like QuiteRock gypsum board.

Interior Features

Interior spaces follow an adaptable option, enabling to use the unit as an office space, a suite for the mother-in-law, or as an apartment for rent in the future. Costs were minimized by sharing plumbing walls, reducing infrastructure, exposing mechanical ductwork, providing a pony dividing wall between the living space and the bedroom, reducing the building height and applying economical finishes. The client desired for a ‘light and airy’ feel, which channeled into an array of windows all around the unit. The master bath integrates all modern features of hardware, shower systems, floating vanities, back lit mirror and elegant tile finishes.

Austin ADU Home Addition Design Permit Documents Motif Architects
Accessory Dwelling Unit (ADU)

An Accessory Dwelling Unit (ADU) is a separate dwelling unit on the same property as a single-family home that is smaller in size and regulated by the City of Austin’s Land Development Code. Some of the requirements for ADUs in the City of Austin are as follows:


Zoning is a set of municipal laws or regulations that govern how property can and cannot be used in specific geographic locations. Everything you need to know about zoning is on the City of Austin website and this zoning guide. Zoning will 

Clients are also encouraged to read through the deed restrictions (your title rep can get those quick) of each individual neighborhood because some neighborhoods are zoned do not allow duplexes, but will allow ADU’s.

Example: Minimum lot size for ADUs on SF-3 (Single Family) zoned lots is 5,750 square feet. (zoning laws are subject to change.)

Tree Protection

The city of Austin has an ordinance that prohibits the unlicensed destruction of heritage trees greater than 19 inches in diameter. 

Example: Special consideration was taken to protect the existing trees on the property. 

Floor Area Ratio (FAR) Size Limitation

Floor Area Ratio (FAR) is a mathematical formula that determines how many square feet can be developed on a property in proportion to the lot area. The property area is multiplied by the FAR factor; with the result being the maximum floor area allowed for a building on the lot. Local Zoning Codes will assign a designated FAR based on the zoning district and building use. The larger the FAR, the larger the building can be.

In Austin, your accessory dwelling unit can be a maximum size of 1100 square feet or 15% of the lot size, whichever is smaller.


  • Austin SF-3 zoning = 0.15 FAR. If the lot is 60'-0" x 100'-0" = 6,000 S, thus 6,000 SF x 0.15 (FAR) = 900 SF allowed

  • If you’re lot size is 9,000 square feet than 15% of your lot size is 1,350 square feet. 1,350 is larger than the maximum, 1,100 allowed, so the max you can build is 1,100 square feet.

Building Coverage

Building cover for the site may not exceed 40%. Essentially meaning the city doesn’t want houses filling up more than 40% of the lot if you’re looking down from an aerial view. If the ADU has a second story, the second story must be less than 550 square feet.

Example: Maximum size of an ADU is 1,100 square feet or 0.15 FAR whichever is smaller.

Austin's McMansion Ordinance 

The Residential Design and Compatibility or "McMansion" regulations, were designed to minimize the impact of new construction, remodels, and additions to existing buildings on surrounding properties in residential neighborhoods by defining an acceptable building area for each lot within which new development may occur. 

The standards were adopted to protect the character of Austin's older neighborhoods by ensuring that new construction, remodels, and additions are compatible in scale and bulk with existing neighborhoods. To see if they apply to a particular property or neighborhood, please refer to the City of Austin's website for additional resource.

Example: In best effort to show compliance, Motif includes diagrams and exhibits to graphically illustrate the code interpretation. Disclaimer: consult with a professional for advice and guidance. 


The main house and the accessory dwelling unit must be separated by 10 feet front to back and side to side. It must also comply with building setbacks, easements and other title requirments

You must provide one parking space for your accessory dwelling unit in addition to the primary structure of parking you already have on your property. If you live within a ¼ mile of a transit stop, you do not need to provide additional parking. 

Example: The ADU is located exact 10'-0" from existing house. Front façade of ADU is staggered, to run parallels with the rear (skewed) property line and 25'-0" building setback. The project also complies with the utility setback on each side of the fence.

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