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We understand ADU costs in Florida.
When it comes to building an Accessory Dwelling Unit (ADU), understanding all the costs is crucial.
At A&O, we’re about transparency and clarity, especially when it comes to the costs involved in building an ADU. We don’t just design and permit ADUs, we also build them, giving us firsthand insights into every hidden cost that can spring up along the way.
The process of building an ADU is layered, from initial planning to the final stages of construction. Our experience in ADU design build has taught us how to anticipate and manage unforeseen costs that often slip past the design and permitting phase. It’s our responsibility to foresee these potential pitfalls, armed with a wealth of experience and knowledge about real-world ADU costs.
In this article, we’ll delve into the comprehensive costs of building an ADU, discussing all the variables that can influence the final price in the Florida, area. We’re here to give you a realistic view of what to expect financially when embarking on your ADU project.
How much does it cost to build an ADU in Florida?
For budgeting purposes, figure on the ADU cost per square foot running $245-413+ per square foot for your all-in cost to build a turn-key detached ADU, for units ranging from 276-1200 sqft. Roughly 80-85% of those costs are for the vertical building construction (the construction of the structure itself, e.g. the building and standard finishes).
To get to the all-in cost to build a granny flat, also factor in the ADU costs from design ($12K), permitting (~$2-14/sqft in fees depending on city), and typical sitework ($25K). Also assume an average of $30-50K+ of costs for additional work like utility upgrades, which will be specific to your property requirements. We review over 75 factors for each property to assess all the relevant costs for your ADU project.
TABLE: Cost To Build New Construction Detached ADU in Florida.
How much it costs to build a detached ADU will be most heavily impacted by the size unit, how many units you are building, site conditions (e.g. grading, utility locations) and local requirements for permitting (e.g. building plan check & permitting fees, school fees). Vertical build costs will be affected by final finishes; our pricing always includes a standard level of finish, including appliances and fixtures. See more about our standard features.
It’s crucial to acknowledge the recent surge in build costs, which can often lead to sticker shock for many homeowners. The Construction Cost has increased a total of 37% from January 2021 to January 2024. This hike means that an ADU which cost around $120,000 to build in January 2021 would now require an investment of approximately $150,000 in 2024.
As of June 2024, our cost estimates for ADU’s in Florida have been adjusted to reflect these changes. Our goal is to provide you with a realistic understanding of the expenses involved, rather than leaving you with unexpected costs later. You can find more detailed information on our pricing approach and our price guarantee. Being well-informed from the start can help you plan effectively for your ADU project.
How much does it cost to build multiple ADUs?
The cost of building multiple ADU’s varies widely depending on factors like size, design complexity, site constraints and utility upgrades. Generally, you can expect some cost savings through shared components, such as a single foundation and exterior finishes. However, each unit will still require its own kitchen, bathroom, HVAC, and electrical systems, which are significant cost drivers.
As a rough estimate, plan for the second unit to cost about 85% of the first unit. Overall, while there are efficiencies in mobilization and project management, the cost per square foot will not decrease as much as simply adding square footage to a single ADU. For a detailed cost assessment, consulting with ADU construction companies is essential.
What is the total cost to build an ADU?
ADU Feasibility Study: $7,500
Our comprehensive ADU Feasibility Study goes far beyond basic reports that others offer (we cover that level of information for free in our Discovery Process & Proposal). This in-depth study provides an accurate assessment of the scope & costs for your ADU project. It includes essential elements such as surveys, utility mapping & planning, design, renderings, and a complete analysis and budget tailored to your property and floor plan.
Construction Drawings: $7,500+
Our in-house drafting team produces a full set of ADU plans required by the city, known as construction documents (CDs). This comprehensive package includes architectural design, structural engineering, Title 24 compliance, building code reviews, and necessary revisions to ensure your ADU meets all standards for permitting. Standard one-story plans start at $7,500, with additional costs for multi-story units or complex designs.
Additional Design: $2,500+
(Applies in some situations) Our in-house design team can support you with custom design work if you need to modify one of our standard ADU floor plans or design a completely custom plan. This service is ideal if you’re adding a garage, building multiple ADUs, or dealing with special foundation scenarios. Custom design work typically extends the design timeline by 2-6 weeks, depending on the complexity of the changes.
Property Reports: TBD
(Applies in some situations) Depending on your jurisdiction, as well as where you intend to locate the ADU on your property, additional reports may be required to properly plan for the ADU. These could include a boundary survey, title report, soils report, and grading plans. We’ll determine the need for these reports during our discovery process with you and incorporate them into your project proposal.
Permitting Management: $2,500+
Each ADU project requires an application package with all required forms for plan check. Effective advocacy plays a crucial role in navigating the permitting process. Our in-house permitting team handles these steps from start to finish, ensuring a seamless and efficient experience. Additional permitting management costs could apply if you are in the coastal zone, an HOA, or in jurisdictions requiring in-person submittals.
Permits & Fees: $5,000+
While many ADU fees have been waived, several are still applicable. A good rule of thumb is to budget around $10/sqft in ADU permit fees, though this varies greatly by city and unit size. For ADUs over 750 square feet, impact fees proportional to the ADU’s size relative to the main house may apply. School fees and sewer connection fees are also part of the overall cost.
Basic Site Work & General Conditions: $35,000
For a level lot with adequate access for construction equipment, basic site work is needed to prepare a buildable pad for the ADU. This includes trenching & connecting utilities, finish grading, and general conditions like required site protection, temporary facilities, and necessary testing for soils compaction and energy efficiency.
Vertical Building Construction: $200,000-400,000+
The vertical building cost is for the accessory dwelling unit itself, including the slab-on-grade poured foundation, structure, standard finish materials, and warranty. View our floor plans for vertical build construction prices and our home features for a list of everything included in the build.
Finish Material Upgrades: TBD
(Optional) Standard finish materials are included in our vertical build prices. Wood cabinets, quartz countertops, appliances, flooring and fixtures are all included in our standard packages. You can also choose to upgrade any of these selections from our full design catalog, which includes tiled showers, islands, and premium appliances.
Additional Sitework: TBD
(Applies in some situations) Additional sitework costs may come up based on your specific property features or jurisdictional requirements. These are the sitework cost drivers we help you plan for, including demolition of existing flatwork, structures & trees, grading, retaining walls, and stormwater mitigation (required in some cities). When required, soils reports also necessitate additional sitework.
Additional Utilities: TBD
(Applies in some situations) Most properties require a separate electric meter for the ADU, and other special electrical requirements may apply. Some new detached ADUs are required to have solar, though many are exempt based on size and climate zone. We’ll also look for any additional sewer and water requirements, or plan for septic if needed. Typically we see all these costs ending up between $15-30K+ depending on property specifics.
Additional Vertical Building: TBD
(Applies in some situations) Depending on your property & zoning specifics, you may require a special foundation type or fire rated construction, both of which increase the cost to build the unit. Choosing non-standard exterior finishes – like siding or tiled roofing – will also add some cost. HOAs may also mandate some exterior upgrades so that the ADU matches your main home.
The A&O Price Lock.
Even though Florida has eased the process, ADU design & permitting still takes on average 2-4 months (and sometimes much longer if a city is backed up). During that time, the cost of the ADU build is typically in flux, as most builders won’t give a final cost until closer to breaking ground. If you’re financing the ADU, this can be a disaster, as your loan value might not cover the final build cost.
To offer homeowners more certainty in their ADU budget, we offer a Price Lock as part of our feasibility & design process. This guarantee ensures that your ADU cost is fixed by the time we submit the plans for city permits, enabling you to confidently plan your finances for the ADU construction.
We go to great lengths during Feasibility & Design to make sure and uncover sitework roadblocks upfront. Our extensive experience in accessory dwelling units has enabled us to develop a sophisticated ADU cost calculator, providing you with an accurate and realistic project estimate early on. It’s important to note that our initial proposal might appear higher compared to other bids not anticipating these requirements. This is because we aim to present a comprehensive and realistic cost, encompassing all potential expenses we are aware of, to avoid surprise costs during construction.
What drives most of the cost of the ADU?
The construction itself is by far the most expensive part of adding an ADU. As you can see in this example, sitework & the structure make up 94% of the overall project costs; plans & permits are just 6%. This means your contractor is a vital part of the project, since they will drive the vast majority of the costs (and hopefully not incur overages). Additionally, we suggest design/build as a more predictable model, especially since we provide a fixed price for the build upfront.
Why does it cost so much to build an ADU?
We often are asked why Accessory Dwelling Unit building costs seem higher when compared to a Single Family Residence (SFR) on a cost per square foot basis. In short, the answer is that SFRs are often twice the size of an ADU, resulting in a lower price per square foot. ADUs have a higher cost per square foot because they bear many of the same “fixed” costs of any residential building project.
Whether building an ADU or a SFR, there are certain base costs which occur no matter the size of the structure. These include:
- Design & Construction Documents: Relatively speaking, drafting hours and costs are in the same ballpark for an ADU or a basic SFR. An ADU still requires a full set of building plans… even pre-approved plans are not something you can walk into a building department as-is; they must be customized to your property.
- General Conditions: Dumpsters, temporary toilets, project supervision, and site protection are required regardless of the build size and will be part of your ADU costs.
- Kitchen, Bath & Laundry: Kitchens are the most expensive room of a building, including cabinets, countertops, plumbing & sink, plus appliances. Bathrooms and laundry facilities are also costly with plumbing & finish materials. A small one bedroom ADU still needs a kitchen and a bathroom, while a modest SFR might need just an additional bath yet support 4X the square footage.
- Vendors: Whether a vendor is installing a small amount of material for an ADU or a large amount for a SFR, there is a base cost for simply showing up and setting up their tools.
Thus, there is a minimum base cost to build a residential unit, no matter how small the unit may be. That means that an ADU cost per square foot can be as high as $500+ for very small units.
