On a United Signature ADU, payments follow the work instead of running ahead of it. A deposit at contract signing pays for design and starts the ordering of materials. Once construction begins, you receive an invoice after each trade finishes its scope and that work is verified, and the pattern repeats until the unit is complete.
Our article on staged billing as a way to defer ADU costs introduced this structure as one of several timing levers. This guide goes further: what actually happens between a trade finishing and an invoice arriving, how each bill meets your credit line, construction loan or savings, where change orders fit, and which contract terms deserve a slow read before you sign.
The Two Kinds of Payment on a United Signature ADU
The Deposit and the Work It Funds
The first payment is due after the contract is signed. According to the company FAQ, it covers your design and lets the project start with the ordering of materials. United Signature buys the materials you selected, stores them at its warehouse and delivers them to your property as each trade needs them, so the deposit is working before anyone digs on site.
The exact deposit amount is set out in your contract. Treat it as the one payment that comes before visible construction, and plan its source first, because nothing else moves until it is paid.
Trade-by-Trade Invoices After Construction Starts
After the build begins, billing switches to a progress rhythm. Each trade, such as foundation, framing or electrical, is invoiced once its scope is complete and verified. This continues through the final trade, so the number of invoices you see depends on how the project is divided, not on a calendar.
What “Completed and Verified” Means in Practice
A trade is complete when its contracted scope is finished, not when the crew leaves for the day. Framing, for example, is not done while sheathing or blocking is still missing in one corner of the building.
Verification is the check that confirms it. In practice that usually means the project manager walks the work against the plans and the contract, and, where the city inspects that stage, the inspection result becomes part of the record. Foundation forms and footings, framing, and the plumbing, electrical and mechanical rough-ins are the stages most often tied to a city sign-off on an ADU.
Photos, a short note on what was checked, and any open items give you a paper trail for each invoice. If something fails, the trade corrects it first, and verification follows the correction. That order is the whole point of the system: you pay for work that has been confirmed, not for work that is promised.
A Sample Sequence of Trade Invoices on a Detached Unit
The trade list varies with the design, but a new backyard cottage often produces invoices in roughly this order.
Site preparation and excavation, including any trenching for utilities.
Foundation, once forms, reinforcement and concrete are in place and checked.
Framing, sheathing and roof structure.
Windows, exterior doors, roofing and the weather barrier that closes the building in.
Plumbing, electrical and mechanical rough-ins.
Insulation and drywall.
Cabinets, flooring, fixtures and interior finish work.
Final utility connections, punch-list work and completion.
An attached unit or a garage conversion skips some of these trades and adds others, such as demolition or fire separation between units. If you want to see how these stages translate into weeks and months, our guide to the phases of an ADU timeline lays out the schedule side of the same sequence.
Lining Up Invoices With the Money Behind Them
When a Credit Line Pays the Bills
With a home equity line, the cleanest approach is to draw for each invoice when it arrives and pay it the same week. Interest then runs only on money already spent on finished work. Our explainer on how a HELOC funds an ADU covers line size, the draw period and rate risk in detail.
When a Construction Lender Releases the Funds
A construction lender has its own draw schedule and sends its own inspector. Before work starts, compare the builder’s trade sequence with the lender’s milestones and agree on how each invoice maps to a draw. Where the two lists differ, settle in writing which invoices will be grouped into a single draw and who covers any short gap between a verified trade and the lender’s payout. The lender’s side of that process is explained in ADU construction loan draws and inspections.
Savings, or a Mix of Sources
Cash works best when it sits in an account you can reach within a day or two, not in investments you would have to sell on short notice. Many owners pay the deposit from savings, then let a loan carry the trade invoices, or the reverse. Whichever order you choose, write down which source pays which invoice so nothing is left uncovered in the middle of the build.
How Change Orders Enter the Payment Plan
A change order is a written amendment to the contract: it describes the added or removed work, its price and any effect on the schedule. Both you and the builder sign it before the change is made.
Ask when each change order is billed. Some are invoiced with the trade they affect, others as a separate line once that work is verified. If a lender is involved, it may need to approve changes that alter the budget, and upgrades you choose mid-project often have to come from your own funds rather than the loan. Keeping a running list of approved changes next to the original contract makes the final invoices easy to reconcile.
Contract Clauses to Read Before You Sign
The trigger for each invoice: which trade, which scope and what verification step comes first.
How verification is documented and shared with you, and how quickly payment is due after you receive an invoice.
How allowances work if you have not picked every fixture yet, and how differences are credited or billed.
Lien releases: in Washington, subcontractors and suppliers can have lien rights on the property they improve, so ask how releases are handled as trades are paid.
What the last payment is tied to, such as the final inspection, the punch list and the handover of warranty documents.
Why Paying in Phases Protects the Homeowner
Progress billing keeps the money you have paid close to the value standing on your lot. If a project pauses for weather, a permit correction or a design change, you are not far ahead of the work.
It also creates natural checkpoints. Every invoice is a moment to ask questions, look at the photos and confirm that the quality is what you expected. The FAQ names your project manager as the point of contact and escalation point if anything goes wrong, and the payment rhythm gives you regular reasons to use that contact.
Building Your Cash-Flow Calendar Around the Schedule
At signing, ask for the expected sequence of trades and a rough idea of when each one should finish. Put those dates on a calendar next to your loan milestones, your paydays and any savings transfers. Leave a cushion for invoices that arrive together when two short trades finish in the same week.
If you are still deciding how to pay, start with our overview of ADU funding options. United Signature presents financing at the start of the consultation, and the partner offers available now are listed on the financing page for ADU projects.
FAQ
Do I pay for materials before they reach my property?
The deposit covers the ordering of materials, which United Signature stores and then delivers as each trade needs them. Trade invoices come later, after the installed work is verified.
What happens to the invoice if a city inspection fails?
The trade corrects the issue first. Because billing follows verified work, that trade is not treated as complete until the correction passes, so its invoice comes after the fix rather than before.
Can the payment schedule be adjusted to fit my lender’s draws?
Often it can be aligned, but this has to be settled before construction starts. Bring the lender’s draw schedule to the contract discussion so both sides agree on how invoices and draws correspond.
Is the last payment due before the punch list is finished?
Check your contract. The final invoice relates to the last trade and completion of the project, so confirm in writing how punch-list items, the final inspection and warranty documents connect to that payment.
Who can explain an invoice I do not understand?
Your project manager. The company FAQ describes that person as the source of truth and escalation point during construction, which includes questions about what a bill covers.