Why ADU financing is its own topic
An ADU costs like a small house and behaves like an investment. Standard mortgages were not designed for it — but several loan types were, or adapt well. Here are the four Maryland homeowners actually use, from the due-diligence research behind this site.
1. Renovation loans (RenoFi-style, after-value lending)
Renovation lenders like RenoFi base the loan on your home's after-renovation value — what the property will be worth with the ADU — instead of today's value. That matters because a traditional home-equity loan only lets you borrow against what you own right now, which rarely covers a full ADU. Excell Homes, a DMV ADU builder, partners with RenoFi for exactly this reason.
Sources: Excell Homes / RenoFi partnership (published).
2. HELOC or cash-out refinance
The familiar route: borrow against the equity you already have, either as a line of credit you draw as construction bills arrive (a HELOC) or by refinancing into a larger mortgage and taking cash out. Simple, widely available — but limited to your current equity, which may not stretch to a full detached build. Industry-typical option; terms depend on your lender and your equity position.
3. FHA 203(k) — the one that counts rental income
The FHA 203(k) rehabilitation loan can finance an ADU addition, and — the part most homeowners miss — it can count projected ADU rental income toward your qualifying income. That is a real lever for borrowers whose salary alone would not carry the loan. Broad Branch DMV documents this use for the DC area.
Sources: Broad Branch DMV (broadbranchdmv.com, published).
4. Fannie Mae HomeStyle & Freddie Mac CHOICERenovation
Both government-sponsored loan programs allow renovation financing that can cover ADU construction as part of a home purchase or refinance. They are conventional loans with renovation features — worth asking your lender about by name if the FHA route does not fit.
What to ask your lender
Bring these questions: Does the loan count future rental income? (most do not — the 203(k) is the exception). Is it based on current or after-renovation value? (after-value unlocks bigger projects). How are construction draws handled? (renovation loans release money in stages as work completes). What does it do to my monthly payment? (run the payment against realistic rent — see rental income and ROI math).
And the order of operations: confirm the ADU is feasible on your lot before you apply for the loan. Lenders fund projects; feasibility tells you whether you have one.
Check it yourself — or talk it through
We are builders, not loan officers — verify every program's current terms with a lender or the program's own site. For the building side: call (240) 222-5082 and we will walk your lot free and give you a written price you can take to your lender.