Accessory dwelling unit basics for Florida homes

ADU introduction

What an accessory dwelling unit actually is

An accessory dwelling unit, often shortened to ADU, is a secondary home on the same property as a main house. It has its own sleeping area, bathroom and cooking space, and usually its own entrance. The word accessory simply means it sits second to the primary residence, even though it can feel like a full home to the person living in it.

People use these small homes in many ways. Some build one for a parent who wants to live nearby but keep a separate door. Others plan a space for an adult child, a long term guest, a home office with a bathroom, or a rental. Each purpose shapes the layout, so the first useful task is to write down who will live there and what daily life should look like.

An ADU can take several physical forms. It might be a detached small house in the yard, a unit built above a garage, a suite attached to the main house, or a converted existing structure. The form you choose affects cost, privacy, utility runs and the rules that apply, which is why the earliest conversations are about the property and not the finishes.

This page is general education for homeowners in Florida. It does not describe the rules for your specific address, and it does not promise that any property can host a second unit. For our service overview, see accessory dwelling unit planning.

The question that comes before every other question

Before you sketch a floor plan, find out whether your property can have a second dwelling at all. Zoning, lot size, setbacks, utility capacity and community rules differ from one city to the next, and sometimes from one street to the next. Some communities welcome these units, some limit them heavily, and some do not allow them. We do not know your answer, and a general guide cannot know it either.

The right place to ask is your city planning or building department. Bring a clear description of what you imagine: where on the lot, how large, whether it will have a kitchen, who will live there and whether it might be rented. Ask them to explain which approvals are needed and in what order. Our page on general permit questions offers a useful list to bring along.

If your home is in a community with an HOA or an association, ask them as well. Associations can restrict secondary dwellings, rentals, exterior appearance and parking even where the city would allow the unit. Getting those answers in writing early prevents disappointment later. Our HOA approval basics page explains what the process often looks like.

Finally, ask your insurance contact how a second dwelling would be treated. Coverage questions are easier to settle before construction than after, and they may influence decisions about location on the lot and materials.

Designing a compact home that lives larger than it is

Small homes succeed or fail on layout. With limited area, every wall, door swing and hallway takes space from living. A good compact plan reduces circulation, lets rooms do more than one job and gives the eye long views so the space does not feel boxed in. A single open room that combines living and cooking, with a sleeping area set apart by a partition or a short wall, is a common starting idea.

Think about the paths people take in a normal day. Where does someone enter with groceries and where do they set them down? How do they get from the bed to the bathroom at night? Where does laundry happen and where do shoes go? Walking through these routines on paper reveals problems that a finished drawing can hide.

Furniture should be drawn into the plan, not added afterward. A sofa, a table that seats the right number of people, a bed with room to walk around it and a place for clothes will either fit or they will not. Measure real pieces rather than guessing, and remember that doors and windows interrupt wall space you might have counted on.

Storage is the thing small homes most often lack. Look for places where storage can hide in plain sight: under a raised bed platform, along the full height of one wall, over doorways or inside a bench by the entry. A closet that is slightly deeper than usual or a pantry cabinet that reaches the ceiling can matter more than an extra square foot of floor. Our guide to storage and closet systems compares ways to organize it.

Ceiling height and window placement do a lot of quiet work. A taller ceiling feels generous, and windows on two sides bring in balanced light. Our guide to planning for natural light can help you think about orientation and glare, which matter a great deal in a sunny climate.

• Write down who will live in the unit and for how long.
• List the daily routines the layout has to support.
• Draw real furniture sizes into the plan.
• Count windows and plan for light from at least two directions.
• Decide where storage lives before choosing the kitchen layout.

Kitchens and bathrooms in a small footprint

The kitchen in an ADU is often a single wall or an L shape with a small table or counter for meals. Because there is little room, appliance choices and cabinet design matter. Narrower appliances, drawers instead of doors and tall storage that uses wall height can give a small kitchen real capability. Our guide to small kitchen layouts compares the options in detail.

The bathroom should be planned just as carefully. A shower instead of a tub saves space, and a door that slides or opens outward can open up floor area. Waterproofing becomes especially important in a small wet room, because there is less margin for splashes to dry before they reach other surfaces. Slope to the drain, sealed corners and proper ventilation are basics that cannot be skipped.

If the unit may be used by someone who needs easier movement through the home, plan for that now rather than retrofitting later. Wider doorways, a shower with a low threshold and reinforced walls for future grab bars are choices that cost little to plan and a great deal to add afterward. Our accessible bathroom design guide covers these ideas as planning topics.

How utilities reach a second home

Utilities are where an ADU gets complicated. The new unit needs water, a way to drain waste, electricity and cooling, plus often internet and other low voltage services. Each of those has to come from somewhere, and the answer depends on where the unit sits relative to the main house and the street connections.

Water and sewer or septic questions come first. Can the new unit connect to the existing lines, or does it need its own? Is the existing system able to handle the added load? These are questions for qualified plumbing professionals and local utility officials, and the answers can shift the ideal location on the lot. A unit placed far from existing lines needs longer runs, which affects scope.

Electrical service is the next item. Your main panel may or may not have room for another dwelling, and some properties use a separate meter for the second unit. Ask an electrician how the connection would work and ask your city or utility what rules apply. As with all electrical and plumbing work, this is for qualified trades to design and install, and your job is to ask for a clear explanation.

Cooling needs special attention in our climate. A small unit still needs reliable air conditioning and humidity control, and the equipment must be sized for the space. Placement of outdoor units also matters for noise and appearance, and some communities have rules about where equipment may sit. Our overview of energy efficient remodeling basics explains how insulation and air sealing reduce the load.

Building for Florida weather

A second home on your lot has to deal with the same weather as the first. Heat, humidity, heavy rain, salt air near the coast and hurricane season all influence material choices, openings and how the structure is tied together. Detailing that works in other regions may not hold up here, so planning should be done with local conditions in mind.

Roof shape, wall construction and the way windows and doors are installed all matter. Ask your city what standards apply to a new dwelling, and ask your supplier and insurer what they expect from openings. Our overview of hurricane ready openings explains the questions in plain language.

Moisture control deserves its own attention. Floors that sit close to the ground, walls that face the sun all afternoon and a small interior that stays closed up while no one is home can create damp conditions. Planning for airflow, drainage around the building and materials that tolerate humidity helps the unit stay comfortable and healthy for its occupants.

Timing around storm season is also practical. Talk through how a project will be scheduled and secured during hurricane season, and what will be done to protect work in progress. Our planning page on hurricane season construction planning goes through those considerations.

Attached, detached or converted: choosing the form

Attached units share a wall with the main house and can often use existing connections for utilities. They save yard space but give less privacy, and they require careful treatment of the shared wall for sound and fire separation. Detached units offer more independence and can be placed to give both homes a private view, though they usually need longer utility runs and more site work.

Conversions are a third path. A garage, a pool house or an existing outbuilding may already have walls, a roof and a slab. The savings in structure can be real, but you inherit the limits of what exists, such as low ceilings, small openings or an uneven slab. Our garage conversion basics go through the questions that apply when the starting point is an existing garage.

If you cannot decide between a converted space and new construction, our comparison of garage conversion versus addition shows how the tradeoffs play out. The right answer depends on how much space you need, how you want to use your lot and what your city allows.

Privacy, parking and the neighbors

A second dwelling changes how a property is used, and neighbors notice. Windows that face an adjacent yard, an outdoor unit that hums near a bedroom and a new path for visitors all affect daily life. Thoughtful placement and landscaping can reduce friction and make both homes more pleasant.

Parking is often the practical limit. Some cities require additional spaces when a second dwelling is added, and some communities limit street parking. Ask what applies at your address before you commit to a plan, because a layout that leaves no room for a vehicle may not be approved.

Think about separation between the two homes as well. A shared walkway, a gate, a small patio or a screened planting can give each household a sense of its own entrance. Good separation helps both households, especially when family members live close together and want independence. Consider sound too: a bedroom window facing the main house kitchen, or a bathroom fan that vents toward a neighbor patio, can wear on everyone over time. Drawing sight lines from each window on the plan is a simple way to catch these issues before walls go up.

Lighting outside the unit is a small detail with a big effect. A path that is easy to follow after dark helps visitors and residents feel safe, and shielded fixtures keep glare out of neighboring windows. Mention outdoor lighting, house numbers, mail and trash storage in your planning notes so they do not become afterthoughts once the interior is finished.

Planning the process and the budget conversation

Because an ADU involves a site, utilities and approvals, the planning phase deserves real time. Gather a survey or site plan if you have one, a list of the utilities you know about, and a description of the unit you imagine. The more specific you are, the easier it is to identify the questions that matter.

Talk through scope and priorities before you talk about finishes. Decide what must be in the unit and what could wait, because a project often benefits from phasing. Our guide to setting scope and priorities helps you sort those choices without feeling pressured.

We do not quote prices in a guide like this, because they depend on the property, the design and the approvals needed. What we can say is that early clarity on scope, utilities and rules is the most reliable way to avoid surprises. A well defined plan is also easier to compare between professionals, which helps you choose with confidence.

Ask every professional you speak with the same set of questions: what approvals do they expect, how will utilities connect, what happens if the ground or existing structure surprises everyone, and how will changes to the plan be handled in writing. Our page on change orders explained describes why that last question matters. Comparing answers side by side will tell you more about each person than any brochure could.

Finally, think about the long view. A second home on your lot may serve one purpose today and another in ten years, so layouts that adapt, such as a room that can be an office now and a bedroom later, tend to age better. Planning for flexibility costs little on paper and can make the unit useful for far longer.

How a conversation with us works

You call and tell us about the property, the space you imagine and your priorities. We talk through layout, materials, storage, lighting and existing conditions, and we ask about anything that could affect the plan, including utilities and community rules you already know about. Then we build the plan and selections so you can see how the pieces fit together.

Before construction we go over the plan and the information needed before work begins. This guide is general, and your property will raise its own questions. If you are still deciding whether a secondary home is the right move, that is a perfectly good time to call.

Questions and answers