July 13, 2024


Elegant home interior

The Ultimate Guide to Building an ADU

This article will give you an overview of how to build an ADU. This includes the cost, construction methods, design specifications, and safety standards. This guide will make your life easier and ensure you create quality, safe, affordable units.

Cost of building an ADU

The cost of building an ADU is dependent on several factors. First, you must get approval from your city or county. If your proposed ADU is not compliant with building codes, you may have to obtain a variance. Then you will have to create architectural plans and complete permitting process. You may also get surveying and engineering services. These professionals must make load-bearing calculations.

The cost of building custom design build accessory dwelling unit varies based on your dwelling type. Depending on your specific situation, you could spend anywhere from $25,000 to $150,000 to build an ADU. Depending on how many amenities you add, the cost may increase.

Construction methods

One of the most popular ways to build additional living space is with an accessory dwelling unit. This type of unit can be a different story or an addition to the side of a house. In addition, you may share utilities with the original place or have separate utilities installed. 

The first step in building an ADU is to submit your building plans to City Hall. The program will need to include structural and architectural projects and Title 24. Once the plans are approved, you can begin construction.

Safety standards

An accessory dwelling unit is a separate structure attached to or detached from your primary residence. It may be a manufactured home or an efficiency unit. It may also be built by building a new detached structure or converting a permitted interior space of an existing dwelling. It must meet specific standards.

To build an ADU, you must first meet the minimum size, setbacks, and location requirements. If it is attached to your main dwelling, the ADU must be no larger than 50 percent of the main dwelling. If the ADU is detached from the main dwelling, it must have its primary entrance and at least one bedroom.

Building an accessory dwelling unit is complicated. Therefore, California increased the size limits for this type of addition. An ADU should not exceed 500 square feet. Depending on the jurisdiction, you may also need to provide parking.

Design Specifications

There are several design guidelines for accessory dwelling units. These guidelines determine the appropriate materials for the building and the team’s location. Moreover, these guidelines determine how large the group can be in the primary dwelling unit. Besides, these guidelines also require that the window and door openings face the side street.

As of August 2016, New York City’s City Council approved amendments to the Zoning Ordinance, which allows the construction of accessory dwelling units (ADU) on residential lots if they meet specific requirements. Below you will find the Planning Commission and City Council action history for this planning initiative.


If you plan to build an accessory dwelling unit on your property, it is essential to understand the regulations that apply to this type of structure. Many cities have specific restrictions regarding the size of this accessory unit in the primary residence. A professional builder will know more about your area’s codes and regulations.

When building an accessory dwelling unit, it is important to follow local regulations for height limits. For example, if you live in a zoning district that limits the height of primary structures, you must build an accessory unit that is no higher than that.