Building an ADU is one of the smartest investments a Connecticut homeowner can make — but figuring out how to pay for it is often the first major hurdle. The good news is that financing options have expanded significantly in recent years, and most homeowners who have built equity in their property have multiple viable paths. Here is an honest breakdown of how to finance an ADU in Connecticut, including a state program that many homeowners do not know about.
How Much Equity Do You Need?
Most ADU financing options require you to have meaningful equity in your home — typically at least 20 percent remaining after you borrow. For example, if your home is worth $400,000 and you owe $200,000, you have $200,000 in equity. Most lenders will let you borrow up to 80 or 85 percent of your home’s value total, meaning you could potentially access $120,000 to $140,000 in additional borrowing capacity. That covers the typical ADU budget in eastern Connecticut.
If you purchased your home in the last few years and have limited equity, your options may be more constrained — though construction loans and certain state programs may still apply.
Option 1: HELOC (Home Equity Line of Credit)
The HELOC is the most popular way to finance an ADU, and for good reason. A home equity line of credit gives you a revolving credit line secured by your home equity, and you draw on it as construction costs arise rather than taking a lump sum upfront. This is ideal for construction projects where costs are disbursed in stages.
Pros: You only pay interest on what you draw. Flexible draw schedule matches construction payments. Generally lower closing costs than a full refinance. Interest may be tax-deductible if used for home improvement (consult your tax advisor).
Cons: Variable interest rate means your payment can increase if rates rise. Requires adequate equity. HELOC is typically a second lien on your property.
Best for: Homeowners with substantial equity who want flexibility and lower upfront costs.
Option 2: Home Equity Loan
A home equity loan gives you a fixed lump sum at a fixed interest rate, with a fixed monthly payment. Unlike a HELOC, you receive the entire amount at closing and begin repaying immediately.
Pros: Predictable fixed payment. Good for homeowners who want certainty about their monthly obligation. Locked rate protects you from rising interest rates.
Cons: You pay interest on the full amount from day one, even if construction is phased. Less flexible than a HELOC for multi-stage projects.
Best for: Homeowners who want simplicity and rate certainty and can absorb paying interest from the start.
Option 3: Cash-Out Refinance
A cash-out refinance replaces your existing mortgage with a new, larger mortgage and gives you the difference in cash. If your home is worth $500,000 and you owe $200,000, you might refinance into a $350,000 mortgage and receive $150,000 in cash at closing.
Pros: Single monthly payment, potentially at a competitive fixed rate. Simplifies your debt into one loan.
Cons: If current rates are higher than your existing mortgage rate, you are refinancing your entire balance at a higher rate — this can significantly increase your total interest cost over time. Closing costs are higher than a HELOC.
Best for: Homeowners whose current mortgage rate is already near or above current market rates, or who have a small remaining mortgage balance.
Option 4: Construction Loan
A construction loan is a short-term loan specifically designed to fund new construction or major renovations. Funds are disbursed in draws as construction milestones are completed. After construction is finished, the loan typically converts to a permanent mortgage (construction-to-permanent) or must be paid off through a refinance.
Pros: Designed specifically for construction projects. Can finance the full project cost. Works even with limited existing equity if the completed project will appraise high enough.
Cons: More complex underwriting process. Requires detailed construction plans and a licensed contractor. Higher interest rates during the construction phase. Two closing events if not construction-to-permanent.
Best for: Homeowners building a detached ADU or significant addition who need larger financing and have limited current equity.
Option 5: CHFA Time To Own Program
The Connecticut Housing Finance Authority (CHFA) offers assistance programs that some ADU builders in high-opportunity areas may qualify for. The Time To Own program provides down payment and closing cost assistance — in designated high-opportunity areas of Connecticut, this can reach up to $50,000 at 0% interest, forgivable over 10 years.
While the Time To Own program is primarily designed for home purchases, certain CHFA programs and local municipality programs provide renovation and ADU assistance grants. Connecticut’s Office of Policy and Management has also provided grants to municipalities specifically to facilitate ADU construction. Check with your town’s housing office and the CHFA website for currently available programs, as these change regularly and new funding rounds open periodically.
Additionally, some Connecticut towns participate in community development block grant programs that provide low-interest loans for accessory dwelling units, particularly when the unit will house a family member over 60 or a person with disabilities.
What Lenders Look For
Regardless of which financing path you choose, lenders will evaluate similar factors: your credit score (typically 680 or higher for preferred rates), your debt-to-income ratio (most lenders want this below 43 percent total), your home’s current appraised value, and the amount of equity remaining after the loan. Having a detailed construction contract and plans from a licensed contractor will strengthen your application — it demonstrates the project is real and budgeted properly.
Talk to Lagace Construction Before You Finance
One of the most important things you can do before approaching a lender is get a realistic cost estimate for your ADU project. Lagace Construction provides detailed project estimates for homeowners in Coventry, Tolland, Andover, Hebron, Colchester, Marlborough, Glastonbury, and throughout eastern Connecticut. A solid estimate gives you a specific number to finance against — and helps you avoid borrowing too much or too little.
Call us at (860) 933-2700 to schedule a consultation. We will help you understand what your project will cost so you can walk into the bank with confidence.
Lagace Construction — Building in Eastern Connecticut Since 2001. Licensed CT New Home Construction Contractor #NHC-0016939.
