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How To Add An Accessory Dwelling Unit

How To Add An Accessory Dwelling Unit
This 480 sq. ft contemporary cottage lives large thanks to the e
Accessory dwelling units (ADUs) are in demand across the country (see an more on the subject here). Cities and counties are changing zoning regulations to allow them as homeowners scramble to build them. While most people are familiar with using ADUs as homes for aging parents or caregivers, a growing number of homeowners (especially those located in neighborhoods with a cool, walkable, urban vibe) are using them as long- and/or short-term rentals. “As long as land prices increase and people want to live in desirable city neighborhoods, this is a growing trend,” says architect François Lévy of the Austin, Texas-based architectural firm Lévy Kohlhaas. And Lévy is seeing an interesting new trend in the ADU boom in Austin: Some people are building a primary residence and an ADU on one lot and selling the two residences to two different buyers without subdividing the lot. This is allowed if one forms a condominium association and makes both homeowners members, Lévy says. He expects to see more of this in the future.

Whether you’re adding an ADU to your existing property or building a new home and planning to add an ADU later, here are ten ways to make building your ADU easier:

1. Set a budget and arrange financing
. Make sure that your financing is lined up and that your budget includes everything from design, construction, labor and materials to permitting fees, utility costs, legal fees and a contingency for anything else that may come up.

2. Hire an architect
if you’re building an ADU in a city like Austin that has a large number of complex zoning codes and constraints to deal with. Lévy, who is used to dealing with these regulations, says that the codes are sometimes written in a vacuum without full consideration of their impact on each other. “If you want to maximize the square footage of your developable area, you need to be pretty clever about understanding all of the ordinances and how to work with them,” he says. “You need someone (e.g. an architect) who is good at seeing how these codes interact.”

3. Know where you can build.
The local planning department can tell you whether your property is zoned to build an ADU or not. “Unincorporated areas of our county are organized by zoning categories,” explains Natalie Kuzmick, education and outreach technician for the Kitsap County Department of Community Development in Washington State. “Our allowed use table dictates if a proposed use can be developed in a particular zone.”
 
In Kitsap County, ADUs are permitted (P) in urban low-density and urban medium-density residential areas. However, areas that the county designates as Limited Areas of More Intensive Rural Development (LAMIRD) also require a conditional use permit [(C) on the chart below] or an administrative conditional use permit [(ACUP) on the chart below] in addition to a standard building permit application. These supplementary permits require additional fees and reviews, and neighbors are given written notice before the permit is issued. In addition, a conditional use permit requires a public hearing.
 
4. Comply with the zoning regs
in your county. You can’t just build whatever size ADU you want wherever you want. There are usually specific requirements about the maximum size of your ADU, where it can be built, etc. For example, in Kitsap County only one ADU is allowed per lot; the property owner must reside in either the primary residence or the ADU; the ADU can’t exceed fifty percent of the square footage of the habitable area of the primary residence or nine hundred square feet, whichever is smaller; all zone setbacks apply; the ADU must use the same side-street entrance as the primary residence; and the ADU requires additional off-street parking. Be ready to comply or to be denied a permit.

5. Be detail oriented.
Be prepared (or give your architect all of the information) to answer questions from the planning department about details such as your assessor tax parcel number; the type of permit being applied for; the number of existing and proposed dwelling units; the owner’s residence before and after construction; the square footage of the primary residence, the ADU, and the distance between the two; the property line setbacks; the type of construction; the number of parking spaces available; and whether you have obtained approval from the health department for your ADU. If your property is on a septic system, you could be required to install a new septic system to accommodate the ADU.

6. Dig up design ideas.
Find design ideas that you like and discuss them with your architect. One go-to resource is In-laws, Outlaws, and Granny Flats: Your Guide to Turning One House Into Two Homes, by Michael Litchfield. This book discusses the benefits of building an in-law unit, how to navigate planning and building departments, legal issues, floor plans, and a range of personal case studies. Other helpful books include The New Small House by Katie Hutchison, Small Houses (Great Houses) by the editors of Fine Homebuilding, and Accessory Dwelling Units: Case Study by the U.S. Department of Housing and Urban Development and Sage Computing Inc.

To browse a collection of plans suitable for use as accessory dwelling units (also called granny units or granny flats) like Plan 484-4, shown in the perspective and deck views, and at the top of this post, click here.

7. Draw a preliminary design.
Lévy suggests sketching out—or having your architect create—a preliminary design of your ADU that includes everything that you want to put in it. You and your architect can both refer to it, plus you can use it for the next step, which is meeting with a city planner to discuss the project.

8. Meet with a city planner.
It’s crucial to get all questions answered before submitting the building permit application. In Austin, Lévy recommends developing a preliminary ADU design and paying for a one-hour consultation to discuss it with a city planner. The key is to bring the preliminary design to the meeting, so that the planner has something to comment on. While Austin city planners can answer basic questions for free, such as the number of parking spaces you are required to have, detailed questions require a paid consultation. “It’s not a guarantee that you’ll get a permit,” but it should identify any areas where you may need to make adjustments, Lévy says. Some planning departments may allow you to consult with a planner for free.

9. Submit the final application, 
which usually includes documents such as the legal description of the property, site plan, plat map, project application, supplemental applications, additional permits (if necessary), address verification documentation, sewage disposal and water supply documentation, floor plans and photographs of the property. Review your submittal checklist and make sure that all requested documentation is included before you turn it in. FYI—some cities and counties offer an expedited review of your permit application for an additional fee, and it may be worth the cost under certain circumstances.

10. Go pro.
Hire the contractors (if you haven’t already) that you feel the most confident about working with. Ask your lawyer to review any contracts before you sign them. Start construction as soon as you receive your building permit. And don’t forget to celebrate having pulled a building permit. You deserve a little victory dance for that.

To browse a collection of 1-bedroom house plans click here.

How To Add An Accessory Dwelling Unit Inspiration

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