ADU contracts from feasibility to keys, signed phase by phase
An accessory dwelling unit is a whole house on somebody else's lot, sold to homeowners who have never built anything. They sign a design agreement, wait out the permit, then sign a construction contract, a payment schedule and a stream of change orders. SignMaster keeps each phase moving with documents they can sign on their own phone, and a sealed record of every approval for when the final payment comes due.
Updated November 9, 2026 · 3 min read
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What each phase of an ADU needs signed
| Phase | Documents |
|---|---|
| Feasibility and design | A feasibility or site study agreement, then a design agreement covering plans, engineering, the permit submittal and what the fees pay for |
| Permitting | The owner's signature on city and utility applications, and any service upgrade request |
| Construction | The home improvement contract, the progress payment schedule, the selections sheet and change orders |
| Prefab or manufactured units | The unit purchase agreement and a separate site work and installation contract |
| Closeout | Final inspection sign-off, the punch list, warranty and keys |
California: building an ADU is home improvement
“Building an ADU is considered a home improvement project under the Contractors State License Law.”
So the home improvement rules apply. CSLB says a written home improvement contract is required, covering the scope of work, timeline, payment schedule, materials and finishes, your license number and the notice of cancellation rights. Contractors can't ask for or accept a down payment of more than $1,000 or 10 percent of the total contract price, whichever is less, and progress payments must reflect the actual work completed or materials delivered.
CSLB also tells homeowners they have three days from signing to cancel, five if they're 65 or older and seven in disaster zones, to be careful about paying for plans or permits before work starts, and that a B general building contractor can build an ADU while a C-47 can install a manufactured one. Read the California home improvement contract requirements before you finalize your template.
A payment schedule built from the work
CSLB's sample schedule for an ADU splits the price into phases: 5% mobilization, 10% demolition and site prep, 10% foundation, 15% framing, 15% rough MEP, 15% roof and exterior wrap, 10% insulation and drywall, 10% flooring, tile and cabinets, 5% finish MEP and carpentry, 3% final inspection, and 2% at keys, once the punch list is done.
Put your own schedule into the contract template as calculated fields: each phase's percentage times the contract price, so the dollar amounts fill themselves in. Then the homeowner signs one document with the numbers already worked out.
Milestones the homeowner approves
- 1
Finish the phase
Framing is done and inspected. Scan the signed inspection card in the iPhone and iPad app.
- 2
Send the milestone sign-off
A one-page form with the phase, the inspection, photos and an Approve field. The homeowner taps Approve from work.
- 3
Invoice against the record
Your invoice goes out with a sealed approval behind it, and the template's Responses table lists every milestone approved so far.
- 4
Handle changes the same way
A window upgrade or a utility trench rerouted around a tree becomes a signed change order before the work, as CSLB recommends.
Pricing
ADU builders with a designer, a project manager and an office usually start on Crew: $49 a month for 5 people, plus $8 a month per extra seat. Solo is $15 a month for an owner-operator. Every paid plan sends unlimited envelopes. New workspaces get 14 days of Crew free. Compare plans.
What SignMaster doesn't do
- It doesn't draw plans, run feasibility studies or file permits.
- It doesn't take down payments or progress payments.
- It doesn't decide which notices your state's home improvement law requires.
- Signing requests go by email; you can copy a link and text it.
Questions? Answers.
Is an ADU contract a home improvement contract in California?
CSLB says building an ADU is a home improvement project under the Contractors State License Law, so a written home improvement contract is required and the down payment and progress payment limits apply.
Can both homeowners sign the construction contract remotely?
Yes. Each signs from an email link on their own phone or computer, in the order you set, and nobody needs an account.
Can the homeowner approve each phase before I invoice it?
Yes. Send a short milestone form with an Approve field. Their approval, name and time are printed on the page and sealed with the certificate.
Can I send the design agreement before the contract?
Yes. Send each phase's documents as their own envelope from a template, so the design agreement is signed long before the construction contract.