Financing an ADU

April 1, 2025

Financing ADUs: A Smart Strategy for Homeowners in San Diego County

Discover how San Diego County’s changing ADU regulations can create new income opportunities for homeowners—without tapping into savings.


San Diego County is undergoing significant changes to its Accessory Dwelling Unit (ADU) regulations in 2025 due to new state laws. These updates are aimed at increasing housing availability and making ADUs more accessible for homeowners. The key changes include:


  • More detached ADUs – Multifamily properties can now build up to eight detached ADUs.
  • Easier legalization – Unpermitted ADUs built before 2020 can now be approved.
  • Streamlined permitting – By 2026, local governments must simplify the ADU permitting process.
  • No owner-occupancy restrictions – ADUs can be rented out without requiring the owner to live on-site.
  • Conversion of non-habitable space – Up to 25% of existing multifamily units can be converted into ADUs.

The Growing Need for ADUs in San Diego County


The rising cost of living, expensive healthcare, and increasing home prices make it difficult for many homeowners to manage daily expenses. Nearly half of the households in San Diego County spend more than 30% of their income on housing costs. Moreover, the county faces a severe housing shortage, with estimates from the San Diego Housing Federation and the California Housing Partnership indicating a need for at least 134,500 additional homes for low-income renters.


To address this issue, San Diego County has set a target to build 171,685 new housing units by 2029, including 99,000 affordable units. As a result, many older homeowners with available space may consider adding an ADU to generate rental income.


The Cost of Building an ADU


The cost of constructing an ADU in San Diego County varies depending on size, design, and complexity. On average, ADU costs range between $180,000 and $300,000, with some projects reaching as high as $580,000 for larger or more intricate units. Given the substantial investment required, homeowners must explore financing options that allow them to generate income while preserving their savings.


Case Study: 


Financing an ADU For Senior Homeowners


Homeowners: Husband (76) and Wife (74)
Home Value: $850,000
Existing Mortgage: $80,000 (Monthly Payment: $850)
ADU Construction Cost: $220,000
Projected Rent from ADU: $2,500 per month


Option 1: Traditional Mortgage Refinance


One way to finance the ADU is by refinancing the existing mortgage to cover the construction costs.

  • The new loan includes the existing $80,000 balance plus the $220,000 construction cost.
  • Monthly mortgage payments increase, but the net rental income reduces to $1,800 per month after loan payments.
  • Homeowners’ monthly mortgage increases to $3,200 a month. 

Option 2: Use their Home Equity


Another option is utilizing a reverse mortgage to fund the ADU construction for homeowners above the age of 62, or age 55 if using a Jumbo Reverse Mortgage.


  • The reverse mortgage pays off the existing $80,000 mortgage.
  • The homeowners receive a line of credit of $272,000+, which they can use to cover the construction costs.
  • They only pay interest on the funds as it’s being withdrawn, once the ADU is completed No monthly mortgage payments are required, they must pay property taxes and homeowners insurance as long as they live in the home. 
  • Their total monthly spendable income has increased by eliminating their $850 mortgage payment and the $2,500 ADU rental to $3,350.
  • The ADU enhances the home's value by an estimated 15%, providing long-term financial security.

 

As San Diego County continues to face a housing shortage, ADUs present a valuable opportunity for homeowners to generate additional income while increasing property value. Financing an ADU requires careful planning, and homeowners should explore options such as refinancing or reverse mortgages to determine the best financial strategy for their needs.


Homeowners can create an additional revenue stream, reduce financial stress, and contribute to the much-needed housing supply in the region. If your client is considering adding an ADU to their property, Introduce them to Retirement In Reverse, your trusted referral partner.



Could This Strategy Benefit Your Clients? Let’s Find Out!

Do any of your clients fit this scenario? Retirement in Reverse would be happy to provide a customized, hypothetical scenario to help you assess if this strategy could be a valuable solution. Let’s explore how we can make it work for your clients!



Who would have ever thought you could use a reverse mortgage for this?

Today’s reverse mortgage is no longer the loan of last resort. It’s a flexible financial tool that can be used strategically for:

  • Charitable giving
  • Buy-sell agreements
  • Paying for long-term care or in-home support
  • Funding a business venture
  • Helping Grandkids Fund College Expense
  • Gift down payment to your Kids
  • Any many more….

It’s all about what the money costs. It’s just math.


Retirement In Reverse offers Objective, Competent Advice to help you make informative decisions for your clients.
Furthermore, we have 
No Conflict of Interest, as we do not sell Financial Product, nor enter into financial planning engagements. We share your commitment to your clients’ financial stability and quality of life.


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As a financial advisor, guiding your clients through the complexities of Social Security is key to securing their retirement. One of the most important decisions retirees face is when to start claiming their Social Security benefits. Although benefits can be claimed as early as age 62, delaying this decision often results in significantly higher monthly payments. However, this decision is not always straightforward, and factors such as health, employment status, and marital situation can all play a role in determining the optimal timing. Understanding the tax implications and exploring alternative income strategies, such as leveraging home equity, can help you provide valuable insights to your clients. Social Security benefits are taxable , and the amount owed depends on total income. Given the market conditions today, many retirees are considering ways to maximize their Social Security payouts while minimizing taxable income. Key Considerations for Claiming Social Security Will your client continue working? Claiming Social Security before full retirement age while working can result in reduced benefits. Are they married? Spousal benefits can be crucial in optimizing household income. What is their health status? Life expectancy is a key factor in deciding whether delaying benefits makes sense. Delaying Social Security benefits generally leads to higher lifetime payouts. However, waiting can create income gaps in the interim. For clients who want to postpone Social Security while maintaining financial flexibility, home equity can serve as an effective solution. Leveraging Home Equity for Retirement One strategy to help clients delay Social Security benefits is by utilizing home equity. With a reverse mortgage, clients can access their home equity to supplement retirement cash flow. Since reverse mortgage proceeds are not considered taxable income, they can provide a tax-efficient way to bridge the gap, allowing Social Security benefits to grow. Case Study: Steve and Alice Clients: Steve (66), Alice (63) Home Value: $1,150,000 | Mortgage: $0 Steve plans to retire at 70, and Alice will retire at 67. Both are in good health. Assets: Steve: IRA $125,000 | 401(k) $456,000 Alice: CalPERS pension $3,745/month | Retirement annuity $174,000 Joint investment accounts: $850,000 Monthly Expenses: Utilities: $350 Property Taxes: $635 HOA: $180 Car Insurance: $187 Food and Entertainment: $3,000 Total: $4,165/month Steve and Alice plan to defer Social Security, CalPERS, and 401(k) distributions until age 71. To help bridge the gap, they applied for a reverse mortgage that offers a $371,000 line of credit. The unused balance will grow annually at 6.25%. By age 71, Steve and Alice will have created a "perfect hedge" with an irrevocable line of credit that remains available for as long as they live in the home. With no required principal or interest payments, this strategy allows them to delay Social Security without sacrificing financial security. As a financial advisor, helping clients optimize their Social Security benefits while preserving their home equity can significantly enhance their retirement strategy. Although using home equity is not the right solution for everyone, for those looking to maximize their Social Security payouts and maintain steady income, it can be a powerful tool. By considering all available options, you can guide your clients to make informed, confident decisions that support their long-term financial goals. Could This Strategy Benefit Your Clients? Let’s Find Out! Do any of your clients fit this scenario? Retirement in Reverse would be happy to provide a customized, hypothetical scenario to help you assess if this strategy could be a valuable solution. Let’s explore how we can make it work for your clients! Retirement In Reverse offers Objective, Competent Advice to help you make informative decisions for your clients. Furthermore, we have No Conflict of Interest, as we do not sell Financial Product, nor enter into financial planning engagements. We share your commitment to your clients’ financial stability and quality of life.
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