Before you pay for ADU plans, check these four things

1. Find out who reviews your property

Start with the address and assessor parcel number, then confirm the city or county responsible for planning and building permits. The place name in your mailing address is not always the reviewing city.

Keep the official map and permit-record links together. If the address, parcel, or existing building information doesn't agree, flag that question before a design relies on it.

2. Look at the building or site you actually have

A new backyard ADU and a garage conversion start with different questions. For a conversion, the existing walls, foundation, roof, ceiling height, and utilities matter just as much as the proposed rooms. For new construction, look at access, available space, utilities, and the relationship to the main house.

• What do the records show?
• What can you see, and what is still hidden?
• Which dimensions need to be checked?
• Will a surveyor, engineer, or another specialist need to be involved?

3. Look beyond the drawing fee

Plans are one part of the budget. Consultant fees, agency fees, utility work, demolition, site work, construction, and a contingency for unknowns all need a place in it.

You won't have an exact construction price at this stage. The point is to understand the main costs well enough to decide whether to keep going, reduce the scope, or reconsider the idea. Ask what a proposal includes and which costs you will pay separately.

4. Decide what you need the ADU to do

Is it for a family member, a tenant, or flexibility later? Think about privacy, access, the number of bedrooms, and how much yard you want to keep. A short list of priorities is more useful than a folder full of layouts that solve different problems.

Write the idea in one sentence. For example: convert the existing garage into a one-bedroom home while keeping a usable outdoor area. That gives a project review or drawing proposal something specific to address.