How to Finance an ADU in Denver: HELOCs, Construction Loans, and What Actually Works

Financing an ADU in Denver: Why It Is More Straightforward Than It Looks

The most common thing we hear from Denver homeowners who want to build an ADU is that they are not sure they can afford it. The second most common thing we hear, once we have walked through their situation, is that they actually can.

Most Denver homeowners who have owned for five or more years have substantial equity — often $300,000 to $600,000 or more given the market appreciation of the last decade. An ADU project that costs $200,000 to $250,000 is within reach for many of them once they understand their financing options. The challenge is not usually the equity. It is understanding how to access it for a construction project specifically.

The Four Main Financing Options for Denver ADU Projects

Option 1: HELOC (Home Equity Line of Credit)

A HELOC lets you borrow against your home's equity up to a lender-determined limit, typically 80 to 85 percent of your home's appraised value minus your outstanding mortgage balance. You draw funds as needed during the draw period (usually 10 years), pay interest only on what you have drawn, and then enter a repayment period.

HELOCs work well for ADU projects when the total project cost is within the available credit limit and you prefer the flexibility of drawing in stages as the project progresses rather than taking a lump sum upfront. The interest rate is variable, which is a consideration in rate environments where increases are possible.

In Denver's current market, a homeowner with a home valued at $750,000 and a $400,000 mortgage balance has roughly $187,500 to $237,500 in accessible HELOC capacity (at 80 to 85 percent LTV). For a $200,000 ADU project, that may be enough. For a larger detached unit, it may need to be paired with another financing source.

Option 2: Cash-Out Refinance

A cash-out refinance replaces your existing mortgage with a new, larger mortgage and gives you the difference in cash. If you have a $400,000 balance on a home worth $750,000, a cash-out refinance at 80 percent LTV could give you $200,000 in cash ($600,000 new mortgage minus $400,000 existing balance) while keeping your new loan below 80 percent LTV.

Cash-out refinances made more sense when rates were lower. In the current rate environment, replacing a lower-rate existing mortgage with a higher-rate new mortgage increases your monthly payment on the full balance. Run the full numbers — not just the cash extracted — before choosing this route. For homeowners with low existing mortgage rates, a cash-out refinance is often the most expensive way to access equity.

Option 3: Construction Loan

A construction-to-permanent loan (or standalone construction loan) is designed specifically for building projects. Funds are disbursed in draws as construction milestones are met, interest is paid only on drawn amounts during construction, and the loan converts to a permanent mortgage upon completion.

Construction loans typically require more documentation than standard mortgage products — the lender will want your contractor's license, the project plans, and a budget breakdown before approving. The approval process takes longer, usually 30 to 60 days. But for larger ADU projects — particularly detached units over $250,000 — a construction loan may be the most appropriate financing structure.

Option 4: Personal Loan or Home Improvement Loan

For smaller ADU projects — garage conversions and smaller attached units — some homeowners use personal loans or unsecured home improvement loans. These do not require an appraisal or touch the mortgage, which simplifies the process. The trade-off is higher interest rates and shorter repayment terms that increase monthly payments. This option is best suited for projects under $75,000 where the homeowner wants to avoid touching their mortgage structure.

Does ADU Rental Income Help You Qualify?

This is one of the most common questions Denver homeowners ask, and the answer depends on the lender and the loan type.

For construction loans specifically, most lenders do not count projected rental income from the ADU being built toward your qualification income — the income does not yet exist. Some lenders will count existing rental income from a currently occupied unit on the property.

For HELOCs and cash-out refinances, the underwriting is based on your existing income and debt profile — the ADU project itself does not factor into the calculation. If you already have rental income from the property, that is counted.

Once the ADU is completed and rented, the rental income can be documented and used to qualify for future refinancing or additional financing. Many Denver homeowners find that the ADU's rental income improves their overall financial picture for future borrowing. See our ADU cost breakdown to understand the full project budget you would be financing.

Colorado-Specific ADU Financing Programs

Colorado has made ADU development a policy priority in recent years, and several programs have emerged to support financing:

The Colorado Housing and Finance Authority (CHFA) has explored ADU-specific lending products, and some local credit unions in the Denver metro have introduced ADU construction loan programs with streamlined approval processes. The Colorado Office of Economic Development and International Trade has periodically offered grant and loan programs for ADU development, particularly for income-restricted units.

These programs change and are sometimes limited in availability — check with a local mortgage broker who specializes in residential construction lending for the most current options. A Denver-based lender with ADU construction experience is a meaningfully better partner than a national lender unfamiliar with Colorado's specific market and regulatory environment.

Which Financing Path Makes Sense for Your Project

For most Denver homeowners with substantial equity and a project in the $150,000 to $250,000 range: a HELOC is often the most flexible and cost-effective option if the credit limit supports the full project. For larger projects or homeowners with limited HELOC capacity, a construction-to-permanent loan is usually the right structure. Cash-out refinance is only worth considering if your existing mortgage rate is already at or above current market rates.

Start with a conversation with two or three local lenders who have financed ADU projects in Denver before — the specifics of your equity position, rate environment, and project scope will determine the right answer. Understanding Denver's ADU permit and zoning requirements before you start the financing conversation helps you have a more precise budget discussion with your lender.

Learn more about Denver Dream Builders' ADU construction services.