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Motif Articles: Wildlife Urban Interface and how it effects your home in Austin

Austin is a city that embraces nature and wildlife, but it also faces the challenges of living near the wildland-urban interface (WUI), where urban development meets natural areas. The WUI is a zone of high fire risk and potential conflict between humans and wildlife.

As Austin grows and expands into the WUI, new homes need to be designed with these factors in mind. In this blog post, we will discuss some of the best practices and regulations for building new homes in Austin's WUI.

What is the WUI code and why is it important?

The WUI code is a set of rules adopted by the Austin City Council in 2020 to regulate the construction and maintenance of structures in the WUI. The WUI code is based on the 2015 International Wildland-Urban Interface Code (IWUIC), with some local amendments. The WUI code applies to new construction, additions, alterations, repairs, and relocation of structures within the designated WUI zones, which cover about 20% of Austin's land area [1].

The WUI code is important because it aims to protect lives, property, and natural resources from wildfires and other hazards in the WUI. The WUI code also helps to preserve the ecological integrity and aesthetic value of Austin's natural areas. The WUI code sets standards for building materials, design features, landscaping, defensible space, fire protection systems, and emergency access.

Wildland-Urban Interface requirements

On April 9, 2020 the Austin City Council voted to approve the new 2015 International Wildland-Urban Interface Code (WUIC), making Austin the first major city in the state of Texas to adopt such a code; implementation is slated to begin on January 1, 2021. More than 60 percent of current structures in Austin are found within 1.5 miles of the Wildland-Urban Interface (WUI), with more joining that percentage every day.

For example, our Big Horn project on Lake Austin required IWUIC compliance per the City of Austin. At first glimpse, we were confused on some of the requirements however, after meeting with the plan reviewer, talking to the owner and contractors... we actually liked the idea and value that the newly adopted code. All-in-all, it made a bunch of since once you wrap your head around the concept.

Class C Construction - Examples of compliance in Austin

If your new home is is located within the Wildland-Urban Interface (WUI), it maybe required to meet the Class C Ignition Resistant (IR) Construction requirements of the 2015 International Wildland-Urban Interface Code (IWUIC).

Our Big Horn project on Lake Austin had very low hydrant flow. Infact it was so low, it was deemed pretty much pointless. To add to the complexity, the City of Austin's Fire Department would not allow third party testing (as noted below)... however the water district only allowed third party testing (do you see the problem here).

Regardless of the testing, the district was aware of the low flow, so the results wouldn't of been in our favor.

Also, because the lot walls within Lake Austin contours, the City of Austin has jurisdiction over Travis County.. so the permitting process and other code adoptions that City of Austin has - applied to this project.

Understand Fire Area, Fire Flow and the Code Requirements in Austin.

Fire Area: If the Fire Area of a new home in the City of Austin exceeds 3600 SF, the 2021 International Fire Code (IFC) Table B105.1(2) requires at least 1750 GPM Fire Flow for the fire hydrants closest to the property.

Our project was only 3495 SF however the approx. fire area was calculated around 4540 SF, due to the large overhangs and three tiered patio deck.

Fire Flow: Providing water to the responding fire department is a crucial aspect of the overall fire protection and life safety strategy of an entire community. When a new building is developed or an existing building is renovated, it is important to make sure that the proper amount of water is available to the responding fire department to allow for both suppression of the fire in the building, and protection of any exposed buildings. Because of this, NFPA 1, The Fire Code, requires a minimum amount of water be provided based on the type of construction of the building as well as fire flow area.

Fire flow is defined as the flow rate of a water supply, measured at standard residual pressure, that is available for the responding fire department for manual firefighting, typically this is water that is available at the surrounding fire hydrants, but it can be supplied with another approved source such as a static water supply like a tank or pond, or even using a fire department tanker shuttle service.

Options: If the Austin Fire Department has no flow data on file for this area. The available options for compliance with 2021 IFC are as follows:

  • Request a fire flow test at nearest hydrant from the assigned Emergency Services District. Sometimes the available fire flow may not be the same value as the Flow Rate displayed on the ESD hydrant flow test. The City of Austin reviewer will calculate the available fire flow and notify you of the amount of fire flow available and what options are available to comply with the 2021 IFC. Important: AFD Does not accept third party fire flow tests. All fire flow tests must be conducted by AFD or witnessed by AFD unless it comes from another fire department or ESD.

  • If the available fire flow (as shown by the flow test) is less than the required fire flow of at least 1750 GPM, your options for compliance with the IFC 2021 are as follows:

    1. Reduce the fire area of the home to under 3600 SF.

    2. Provide a full fire sprinkler system designed per 2019 NFPA 13D or 2021 IRC Sec. P2904.

Refer to the City of Austin's Municode / NFPA Website for additional information with regards to location, code and application type

How to design new homes in compliance with the WUI code?

If you are planning to build a new home in the WUI zone, you need to follow the requirements of the WUI code. Some of the key aspects of the WUI code are:

  • Building materials: The WUI code specifies the types of materials that are allowed or prohibited for exterior walls, roofs, windows, doors, vents, decks, fences, and other components of structures in the WUI. The materials must be fire-resistant, non-combustible, or ignition-resistant, depending on the location and exposure of the structure. For example, wood shingles or shakes are not allowed for roofs in the WUI [1].

  • Design features: The WUI code requires certain design features that reduce the vulnerability of structures to fire and embers. For example, roofs must have a minimum slope of 2:12 (17%), eaves must be enclosed or protected with fire-resistant materials, vents must be screened or covered with mesh or baffles, and openings must be sealed or caulked [1].

  • Landscaping: The WUI code regulates the type and placement of vegetation around structures in the WUI. The landscaping must create a defensible space that reduces fuel load and fire spread. The defensible space consists of three zones: Zone 1 extends 5 feet from the structure and must be free of flammable materials; Zone 2 extends from 5 feet to 30 feet from the structure and must have low-growing plants that are spaced apart; Zone 3 extends from 30 feet to 100 feet from the structure and must have thinned trees and shrubs that are pruned and maintained [1].

  • Fire protection systems: The WUI code requires structures in the WUI to have adequate fire protection systems, such as sprinklers, smoke alarms, fire extinguishers, and water supply. The fire protection systems must be installed and maintained according to the applicable codes and standards [1].

  • Emergency access: The WUI code requires structures in the WUI to have sufficient emergency access for firefighters and residents. The emergency access includes driveways, roads, gates, bridges, signs, and address numbers. The emergency access must be designed and constructed according to the specifications of the fire department [1].

"We look forward to providing a code that helps ensure businesses and residences abutting our wildland areas are ready for, and protected from, the next wildfire. Because it’s not a matter of “if” that happens, but “when” " –AUSTINTEXAS.GOV

Are you ready to get started on your lake house design?

At Motif Architects, we are passionate about creating homes that blend with nature and protect from fire. That's why we are excited to design a new home in Austin's Wildlife Urban Interface (WUI), where urban development meets natural areas.

We will follow the WUI code and wildlife considerations to ensure that the home is safe, sustainable, and respectful to the environment. We will use fire-resistant materials, create defensible space, avoid attracting wildlife, and enhance the aesthetic value of the site. We look forward to working with you on this unique and rewarding project.

This article is building code information and should not be seen as code advice. You should consult with an architect, builder or code expert before you rely on this information. The blog published by Motif Architects PLLC is available for informational purposes only and is not considered legal and or building code advice on any subject matter. By viewing blog posts, the reader understands there is no architect-client relationship between the reader and the blog publisher. The blog should not be used as a substitute for legal or building code advice from a licensed professional architect / interior design, and readers are urged to consult their own legal counsel on any specific legal questions concerning a specific situation.

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