ADU Loans: How to Finance an ADU

By Bill Lyons | Updated on February 2, 2024

In this article, we’ll explore various methods and loans for financing ADUs to help you capitalize on this growing trend. 

What Is an ADU?

An ADU is a secondary living space located on the same property as the primary residence. Also known as an in-law suite, ADUs are separate living quarters equipped with the same essential amenities as the main house, including a kitchen, bathroom, and sleeping area. These units can be attached to the main home, such as converting a garage or basement, or they can be detached structures like standalone living spaces in the backyard. 

ADUs offer a flexible housing solution, serving various purposes for homeowners. They can provide additional living space for family members, offer rental income opportunities, or serve as a studio or home office. The versatility and relatively compact size of ADUs make them a popular choice for maximizing the utility of the property without the need for extensive construction or property expansion. 

In general, Fannie Mae ADUs and ADU financing from lenders are treated similarly to other types of home loans. 

Why Build an ADU?

Building an ADU can offer homeowners a range of benefits, including: 

• Additional income: One of the primary advantages of constructing an ADU is the potential for generating rental income. Homeowners can rent out the ADU to tenants, providing a steady revenue stream and helping to offset mortgage or maintenance costs. 
• Multigenerational living: ADUs offer a solution for accommodating multigenerational households. Whether housing aging parents, adult children, or other family members, the separate living space provides privacy and independence while keeping the family close. 
• Property value: Adding an ADU can enhance the property’s overall value. The extra living space and potential for rental income make the property more attractive to potential buyers, potentially increasing its market value. 
• Flexibility: ADUs can serve various purposes, adapting to homeowners’ changing needs or desires. From a home office or workshop to a guest suite or personal space, the flexibility of ADUs allows for versatile use based on the homeowner’s changing lifestyle. 
• Quick construction: ADUs often have quicker construction timelines compared to major home expansions. This efficiency is particularly advantageous for homeowners looking to add living space without undergoing extensive and time-consuming construction projects. 
• Affordability: ADUs are relatively affordable to build compared to traditional home expansions. They often utilize existing space, such as garages, reducing the need for additional land. This affordability makes ADUs an accessible option for homeowners looking to increase living space without a substantial financial burden. 

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How Much Does Building an ADU Cost?

The cost of building an ADU can vary based on several factors, including the project’s size, scope, and location. Different cities may have varying permit fees and construction costs, so it’s crucial to consider these aspects.

The most substantial expense in building an ADU is typically the construction costs. This includes materials, labor, and contractor fees. The size and complexity of the ADU, as well as the quality of materials used, will significantly impact these costs. 

Your contractor can also help obtain the necessary permits for building an ADU, which comes with fees. These fees can vary depending on the city and type of permits required.

Connecting the ADU to utilities like water, sewer, and electricity also comes with costs. Depending on the existing infrastructure on the property, these connections may require additional work and expenses. 

Consider setting aside a contingency fund for unexpected expenses that may arise during construction. Unforeseen issues or changes to the original plan can impact your budget, and having a contingency fund helps manage these situations. 

5 ADU Financing Options

Financing an ADU requires careful consideration of your available options to ensure a financially sound and feasible type of investment. Here are five loans for ADUs you might consider: 

Cash-out refinance

A cash-out refinance involves replacing the existing mortgage with a new one that has a higher principal amount. The homeowner receives the difference between the old and new mortgage in cash, providing the necessary funds for the ADU construction. 

One significant advantage of this approach is the potential for lower interest rates typically associated with mortgage loans. Additionally, the interest paid on mortgages may be tax-deductible, offering potential financial benefits. 

However, it’s essential to consider that opting for a cash-out refinance increases the overall debt on the property, and some lenders may have stringent requirements for qualification. 

Home equity loan (HELOAN)

Another financing avenue for building an ADU is a home equity loan. HELOANs allow homeowners to borrow a lump sum based on the tappable equity accumulated in their property. HELOANs operate as second mortgages, with fixed payments over a predetermined term. 

The fixed interest rates provide stability for budgeting, and homeowners receive the entire loan amount upfront, simplifying financial planning for the ADU project. 

However, it’s crucial to note that interest payments are applied to the entire loan amount, and approval for a HELOAN may depend on the homeowner’s creditworthiness and the equity available in the property. 

Home equity line of credit (HELOC)

A home equity line of credit is an alternative option for financing an ADU. Similar to a home equity loan, a HELOC allows homeowners to leverage the equity in their property. However, a HELOC functions more like a credit card with a revolving line of credit. 

Homeowners can borrow as needed, paying interest only on the amount used. This flexibility can be beneficial for managing construction costs, allowing homeowners to draw funds incrementally as the ADU project progresses. It may also help those who aren’t quite sure what their construction costs are and may need additional funds to complete the project. 

While HELOCs often come with variable interest rates, offering flexibility, borrowers should be mindful of potential fluctuations in interest payments. 

DSCR loan

For those considering renting out the ADU, a debt service coverage ratio (DSCR) loan might be a good option. DSCR is a financial metric that assesses a property’s ability to cover its debt obligations, including the mortgage loan. This type of mortgage loan doesn’t consider the borrower’s personal income. Instead, it solely focuses on the property’s ability to generate sufficient income to cover its debts. 

For ADU financing, a DSCR loan considers the potential rental income generated by the ADU. This type of loan is specifically designed for income-generating properties, making it ideal for ADUs intended for rental purposes. 

It’s important to note that DSCR loans aren’t used for personal-use ADUs, which means these loans aren’t available for those who want to build an ADU for a home office or for their parents or children to live in. However, if your family members are paying rent, a DSCR loan might be a feasible option. 

These ADU loans require a clear plan for renting out the additional unit to demonstrate the ability to cover loan payments. Your lender will need to see information regarding how much you plan to rent the ADU for and calculate ROI, so you’ll need to perform market research. DSCR loans offer a unique approach for those looking to offset ADU construction costs through rental income, but they require strategic planning. 

Additionally, if you plan to rent out your ADU, you’ll essentially become a landlord with various responsibilities, such as tenant relations, property maintenance, and adherence to landlord-tenant laws. 

Construction loan

A construction loan is a specialized ADU financing option tailored for individuals undertaking construction projects, making it a suitable option for building an ADU. This type of ADU loan is designed to provide funds specifically for the construction phase of the project. 

Initially a short-term loan, a construction loan allows homeowners to access the necessary capital to cover construction costs. One notable feature is that during the construction period, homeowners can make interest-only payments, reducing their financial burden. Once the construction is complete, the loan is typically converted into a permanent mortgage. 

The advantages of a construction loan include its tailored focus on construction needs, ensuring that the funds are used efficiently for building the ADU. However, interest rates for these ADU loans may be higher compared to traditional mortgages. Additionally, since these loans are only used for the construction of the ADU, you don’t have any available funds left over for the design or any other additions you want to make to the ADU to make it feel more like a home. 

Reach Out to Learn More About Loans for ADUs

Financing the construction of an ADU involves careful consideration of the various mortgage options tailored to individual needs and circumstances. Consider why you’re building the ADU — is it for accommodating family or personal use, or are you planning to use it to generate rental income? Cash-out refinances, HELOANs, HELOCs, DSCR loans, and construction loans each offer unique advantages and considerations. When choosing the best ADU financing method, you should weigh factors like interest rates, repayment terms, and eligibility criteria. 

Explore the best financing solutions for your ADU project with Griffin Funding. With our expertise in mortgage lending and commitment to client success, we can provide valuable insights, answer questions, and assist you in understanding your ADU loan options. Apply for a loan online today or download the Griffin Gold app to learn more about our mortgage options and leverage smart financial tools that can benefit both current and aspiring homeowners.

Bill Lyons

Bill Lyons is the Founder, CEO & President of Griffin Funding. Founded in 2013, Griffin Funding is a national boutique mortgage lender focusing on delivering 5-star service to its clients. Mr. Lyons has 22 years of experience in the mortgage business. Lyons is seen as an industry leader and expert in real estate finance. Lyons has been featured in Forbes, Inc., Wall Street Journal, HousingWire, and more. As a member of the Mortgage Bankers Association, Lyons is able to keep up with important changes in the industry to deliver the most value to Griffin's clients. Under Lyons' leadership, Griffin Funding has made the Inc. 5000 fastest-growing companies list five times in its 10 years in business.