COSTS & PERMITS · ARCADIA · SAN GABRIEL VALLEY
How to Finance an ADU in California
We build them; we do not lend on them. This is the plain map of how homeowners actually fund a second unit, what lenders ask for, and the one sequencing mistake that costs people money.
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THE SHORT ANSWER
Most ADUs are funded from the equity in the existing house.
Because an ADU sits on a lot you already own, the most common routes all borrow against that ownership — a refinance, a home equity line, or a construction loan that converts to a mortgage when the unit is finished. Renovation loans, unsecured borrowing and grant programs exist too, and each has a different trade-off between rate, speed and how much paperwork you take on. What follows is the map, not a recommendation: the right route depends on your equity, your income and how the numbers look to a lender, which is a question for a lender.
Read this first
KWA Home is a contractor, not a lender, broker or financial adviser. We do not arrange financing, we do not earn anything from a loan, and we cannot tell you what a lender will approve. Verify current terms with your own bank or adviser.
THE ROUTES
Six ways people fund a second unit.
On smaller screens, swipe across the table to compare all columns.
| Route | How it works | Trade-offs |
|---|---|---|
| Cash-out refinance | Replace your existing mortgage with a larger one and take the difference as cash. | Usually the lowest rate of the equity routes, but it resets the whole mortgage and closes slowly. |
| Home equity line of credit | A revolving line secured against equity, drawn as construction progresses. | Flexible and fast to set up; typically a variable rate, and the line is tied to your home. |
| Home equity loan | A fixed lump sum secured against equity, repaid on a set schedule. | Predictable payments; you take the full amount up front whether or not the build needs it yet. |
| Construction-to-permanent loan | Funds the build in draws, then converts to a standard mortgage at completion. | Built for this purpose, but heaviest documentation, and draws depend on inspection milestones. |
| Renovation loan | One mortgage that covers purchase or refi plus the improvement, with the scope priced in from the start. | Useful when the ADU is part of a bigger purchase or remodel; requires the contractor and scope to be vetted early. |
| Unsecured borrowing, savings or family | Personal loan, savings, or a private arrangement. | Fastest and no lien, but usually the most expensive or the most personal. Generally suited to smaller scopes. |
Grant and assistance programs exist in California, including state housing agency support aimed at income-qualified homeowners for pre-development costs. Whether any given program is open depends on the funding cycle and your household income — check the current status directly rather than assuming it applies to you.
WHAT LENDERS ASK FOR
Four things, and two of them come from us.
1 · Equity
How much of the house you own outright. This is the number that usually decides which routes are even available.
2 · Income and existing debt
Standard affordability assessment. Lenders have their own ratios and thresholds.
3 · Drawings and a real scope
This is the part we supply. A lender will not price a project described as a backyard unit — they want plans and a written scope.
4 · A licensed contractor
Most lenders require licensed contractors for loan-funded work. Verify any license yourself on the CSLB register — including ours.
Some lenders will also consider projected rental income from the finished unit when assessing affordability, and some will not. Do not build your plan on the assumption that they will.
SEQUENCING
The mistake that actually costs money.
The expensive version of this project goes: get excited, start demolition, apply for money. Once a garage is stripped and a slab is opened, you have a deadline you cannot move and a lender who is now looking at an unfinished site.
The version that works goes: confirm feasibility → produce drawings and a written scope → know what the permit path looks like → arrange funding → build. It is slower at the start and faster overall, because nothing is waiting on money that has not arrived yet.
- Feasibility first. What fits on the lot, what utilities can carry, what the city will approve. Cheap to check, expensive to guess.
- Drawings and a written scope. The document a lender, an appraiser and a contractor can all work from.
- Permit path understood. Including how long review realistically takes where you live.
- Funding arranged against that scope. Not against an idea.
- Construction in stages. With progress draws tied to completed work rather than to dates.
COSTLY MISTAKES
Four patterns worth avoiding.
| Mistake | Why it hurts |
|---|---|
| Starting work before funding is in place | You lose the ability to walk away or re-scope, and a half-finished site is the weakest position to negotiate from. |
| Counting rent before the unit exists | Projected income is not income until there is a tenant. If the plan only works with rent, the plan is exposed. |
| Borrowing the full build cost up front | You pay interest on money sitting idle. Draws tied to progress usually cost less. |
| Choosing an unlicensed contractor to save cash | Most loan programs will not fund it, and unpermitted work is a liability at sale, refinance and in an insurance claim. |
THE COST OF MONEY
Interest is not the only line.
Beyond the interest rate, borrowing carries closing costs, points, appraisal and title fees, and in the case of construction lending, draw and inspection administration. On a project of this size those are real numbers, and they are the reason two loans with similar rates are not equal.
We will not quote you rates or payments — that is not our business and we would be guessing. Take your drawings and written scope to two or three lenders and compare the total cost over the period you intend to hold the loan, not the headline rate alone.
FAQ
Financing questions we hear.
Do you offer financing or payment plans?
No. We are a contractor. We can give you drawings, a written scope and a realistic program so a lender has something concrete to assess, but the borrowing is between you and your lender.
Can I use my home equity?
Often the most common route, because an ADU is built on a lot you already own. Whether it works for you depends on your equity position, income and the lender’s own criteria.
Will a lender count the rental income?
Some will consider projected rent when assessing affordability, and some will not. Ask directly before you rely on it, and do not assume it substitutes for income you already have.
Do I need drawings before I apply?
For most secured routes, yes — a lender needs plans and a scope to value the improvement. This is usually the first thing they ask for after the application.
What if I am funding it from savings?
Then your sequencing advantage is speed, and the same order still applies: confirm feasibility and scope before starting, so the money goes to a buildable plan.
Clear scope. Clear accountability.
Service scope
KWA Home is not an architecture or design firm.
Licensed professionals
We do not offer architectural design to the public, we do not stamp drawings, and we do not perform structural engineering — plans and any structural calculations are prepared and stamped by California-licensed design professionals.
Project responsibility
What we do is coordinate that work, submit the permit and build it, under CSLB #1145730. The responsible contracting entity and scope are named in your agreement rather than left implied.