ADU conversions > Research — Intro
ADU conversions > Research
Source: ADU conversions > Research ↗
First, what's the tax impact?
Adding an accessory dwelling unit will likely increase the value of your home. If the value of your home increases, your property taxes will too. The county assessor, not the City of Portland, determines your property taxes.
Before starting your project, contact your county assessor. They can help you learn how your taxes may change.
Do you have the right space for an ADU conversion?
Some areas in your home might not meet requirements for a living space. Common issues can include:
- Ceiling height
- Emergency exit windows (also known as "egress windows")
- Insulation and ventilation
- Stairs ↗
These issues could make it expensive, difficult, or even impossible for you to convert a space into an ADU.
Different types of projects will have different construction standards. These standards help your new structure stay safe and durable for the people who will live in it. Below are the codes that each type of project must follow:
- Detached ADUs and ADUs within a detached or attached structure - Accessory Dwelling Unit Code Guide ↗
- This code guide has a few important revisions for building an ADU in a non-habitable space, and references the Habitable Spaces Code Guide ↗.
- For detached structures, there are more important rules about the size and location of the ADU. See the information guide for Detached Covered Accessory Structures Worksheet ↗ for more information.
- ADU conversion within a townhouse - Townhouse Code Guide ↗
Do you have questions about the building code? Schedule a free 15-minute appointment with a building code expert ↗.
What permits do you need?
You'll need a residential building permit to convert the space, and trade permits ↗ to supply the ADU with electricity, water, and heating. More information on these permits is in the section on getting the right forms ↗.
Can you build it on the property?
Start by understanding the zoning ↗ of the property. Some zoning rules may make your project more complex and costly.
If you can build it, find out where on your property you can build it. You'll have to follow zoning setbacks ↗ and rules about how much of the lot can be covered.
How to research your zoning:
- Go to PortlandMaps.com ↗.
- Enter your address.
- Navigate to Permits & Zoning.
- Click Zoning & Districts.
- There are four things to look for under Zoning & Districts:
- Base
- Overlay
- Historic District
- Historic Resource
The Base is where to find the setbacks and lot coverage requirements.