ADU Financing in Florida: How to Pay for a Granny Flat

Educational content only. This article is for informational purposes and does not constitute financial, legal, or lending advice. Loan programs, rates, and eligibility requirements change frequently. Consult a licensed mortgage professional before making any borrowing decision. Mortgage Capital | NMLS# 1859012 | Licensed in Florida.

ADU financing Florida homeowners need usually comes down to one question: does the lender count the unit before or after it is built?

That single distinction changes what you can borrow. Our ADU loan page covers the products.

What counts as an ADU

A second, smaller dwelling on a lot that already has a house.

It has its own kitchen, bathroom and entrance.

It can be attached, built over a garage, or free-standing in the back garden.

Local code decides what is permitted, and in Florida that varies enormously by city.

The rules are local, not statewide

Florida has encouraged accessory units as a housing-supply measure, but permission still comes from your municipality.

Miami-Dade has allowed them in much of its unincorporated area for years.

Broward and Palm Beach cities differ street by street, and some prohibit them outright.

Check zoning before you price anything, because a lender will not fund an unpermittable unit.

Option one: a HELOC

You draw as the build progresses and pay interest only on what you have drawn.

That fits construction spending better than a lump sum does.

The rate is variable, which is the cost of the flexibility.

See our HELOC page.

Option two: a home equity loan

A fixed lump sum at a fixed rate, repaid on a set schedule.

Better when you have a firm contractor bid and know the exact number.

You pay interest on the whole amount from day one, so it suits a single-draw project.

See our home equity loan page.

Option three: a cash-out refinance

You replace your mortgage with a larger one and take the difference.

This only makes sense if the new rate is close to your existing one.

Homeowners holding a 3% mortgage should not give it up to build a garden unit.

See our cash-out refinance page.

Option four: a renovation loan

This is the one most homeowners have not heard of, and often the right answer.

A renovation loan lends against the home's value *after* the work is finished.

So you are not limited by the equity you hold today.

See our renovation loan page.

Why after-completion value matters so much

A homeowner with $60,000 of equity cannot borrow $150,000 against today's value.

If the finished ADU raises the appraised value to support it, a renovation loan can.

The appraiser values the property as though the plans were already built.

That is the mechanism that makes these projects possible for people who are not already wealthy.

The FHA 203k route

The standard 203k covers structural work, which an ADU generally is.

It works on a purchase or a refinance, so you can buy a house and fund the unit in one loan.

It carries FHA mortgage insurance and a consultant requirement, which adds cost and time.

See our 203k calculator.

Can the future rent help you qualify?

Sometimes, and this is worth asking about specifically.

Some renovation and construction programmes allow a portion of projected ADU rent, supported by a market rent schedule from the appraiser.

Many do not count it at all until there is a signed lease and filed tax returns.

The answer varies by programme, so ask before you assume the unit pays for itself.

What it costs to build in Florida

Costs vary widely with size, finish and whether you are attaching to existing structure.

Impact fees, utility connections and engineering are frequently underestimated line items.

Florida wind-load requirements raise structural cost against inland states.

Get a permitted contractor bid before a lender conversation, not after.

Insurance and taxes change

Your homeowners policy must be updated to cover the additional structure.

If you rent the unit, you may need a landlord endorsement on top.

The county reassesses the improvement, so your tax bill rises.

Your Save Our Homes cap protects the original assessment, but new construction is added at current value.

What it does to resale

A permitted, well-built ADU generally adds value and widens your buyer pool.

An unpermitted one does the opposite and can stop a buyer's financing entirely.

Appraisers treat unpermitted square footage cautiously or ignore it.

Permit the work. It is the difference between an asset and a liability.

Who these actually suit

Multigenerational families housing a parent while keeping separate space.

Homeowners wanting rental income without buying a second property.

Owners of large lots in cities where zoning already permits it.

The Florida Housing Finance Corporation publishes state programme information on its official site.

Sequencing the money

Zoning confirmation first, because it costs nothing and it can end the project.

Then a contractor bid with permit-ready drawings, since no lender funds a sketch.

Then the loan application, with the bid and drawings attached.

Draws are released against inspections as the work completes, not as a lump sum up front.

Building this order into your plan avoids paying for design work on a project that was never permittable.

Where to start

Confirm zoning with your municipality first. Everything else depends on it.

Get a contractor bid, then we will tell you which product reaches that number.

The renovation route is usually the answer when equity is the constraint. Start with a conversation.