ADU builders
Affordable ADU contractor: where the real savings are
By the HyreADU research desk. Last checked .
The short answer
An affordable ADU contractor is one whose itemized bid is low because the project is simpler, not because lines are missing. The biggest savings come before you hire: reusing an existing structure, staying at or under 750 square feet to avoid impact fees in California, and using a preapproved plan.
Choices that lower the total
Reuse what exists. A garage or interior conversion keeps a slab and walls, though the slab must be checked. Mind the fee line. California bars impact fees on an ADU of 750 square feet or less (Gov. Code § 66311.5).
Connection and capacity charges are a separate matter. Use a preapproved plan. A detached ADU on a plan preapproved in the current code cycle gets a 30-day decision (Gov. Code § 65852.27).
Bids that only look affordable
A low total can hide a missing site work line, utility work “by owner”, or allowances too small to buy what you want. Ask each bidder to price the same drawings and the same lines.
Compare them in the ADU bid comparison. A low bid with a large deposit is a warning sign: California caps the deposit at $1,000 or 10 percent, whichever is less (Bus. & Prof. Code § 7159).
Check the fee math yourself
The ADU fee calculator shows how the 750 square foot line changes what your city may charge. The ADU cost calculator adds up the lines from your own bids.
What to do next: read the questions to ask an ADU builder, check what decides ADU cost, then tell us about your project. Matching is not live yet, so we reply with information, not a quote.
Get ADU optionsQuestions
What is the cheapest kind of ADU?
Often a conversion of existing space, because the shell exists. But a bad slab or missing egress can erase that. The site decides.
Are prefab ADUs cheaper?
Not by rule. Site work, the foundation, utilities and permits still apply. See modular ADU.
Are there grants for ADUs?
Some state and local programs have existed, and terms change. Check your city and the state housing finance agency directly.
Does HyreADU know cheap builders?
No. We publish no price rankings and have no partner builders.
Sources
- Gov. Code § 66311.5 (ADU fees and utility connections). Checked September 5, 2026.
- Gov. Code § 65852.27 (preapproved ADU plans). Checked September 5, 2026.
- Bus. & Prof. Code § 7159 (home improvement contracts). Checked September 5, 2026.
HyreADU is a publisher. It does not design, permit or build ADUs, has no partner builders, and gives no legal, tax or engineering advice. Rules vary by state and city; California rules are labeled as such.