New Detached ADU in Delray Beach: What It Costs and What the Code Actually Requires
A new detached ADU in Delray Beach typically runs $265,000-$385,000 all-in, from drawings through final inspection, for a custom 1-bed or 2-bed unit of 600-800 square feet. Prefab and modular units from Abodu, Cover, or Dvele usually land between $195,000 and $310,000 depending on site work, foundation type, and wind-rated opening upgrades. The number that changes most between quotes is not the box itself. It is the foundation elevation and the impact-rated windows and doors, which Palm Beach County’s High-Velocity Hurricane Zone-adjacent wind code makes non-negotiable on any new structure. Call Ellery ADU Studio at (971) 497-2402 and we will give you a written price before any work starts.
Key Takeaways for Delray Beach Homeowners:
- New detached ADUs in Delray Beach run $195,000-$385,000 depending on custom vs. prefab and site conditions.
- If your lot sits in Del-Ida Park or Nassau Park, the Historic Preservation Board reviews your ADU before you get a permit. The siding and roof profile matter.
- East of I-95 and near the canal system, FEMA AE flood zones often require a stem-wall foundation or fill that adds $8,000-$18,000.
- Impact-rated openings with Miami-Dade NOAs are required. A cheap quote that leaves them out fails framing inspection and costs you the wind-mitigation insurance credit.
- Every project we quote carries a written price before work starts, per Haven Standard Clause 1. No exceptions.
How Delray Beach’s Code Path Changes Your ADU Budget
Most homeowners call us after reading a few national ADU articles and assume the price they see online applies here. It doesn’t. Delray Beach has three overlapping requirements that most cities in Florida do not: the Historic Preservation Board review for contributing districts, FEMA AE flood elevation minimums east of I-95 and along the canals, and Palm Beach County’s High-Velocity Hurricane Zone-adjacent wind code. A compliant quote in Delray Beach includes the engineering for these three things up front. A cheap quote omits them and hopes the inspector does not notice. The inspector always notices.
Take wind-rated openings. The code in Palm Beach County requires that any new detached ADU use windows, sliders, and entry doors with Miami-Dade County NOAs (Notices of Acceptance). That means impact-rated glass or shutters tested to withstand a 9-pound 2×4 traveling at 34 miles per hour. The cost difference on a 1-bed ADU with six openings runs $6,000-$12,000 over non-impact units. We include it in every Delray Beach quote because we know the framing inspection will fail without it. This is not an upsell. It is the floor of a legal structure here.
Then there is the flood zone. Large swaths of Delray Beach east of I-95 and along the C-15 Canal sit in FEMA AE zones. A detached ADU slab in those zones must have its finished floor at or above base flood elevation. If your lot’s existing grade is 2 feet below BFE, you need a stem-wall foundation or engineered fill to raise it. That line item runs $8,000-$18,000 on a typical 600-square-foot ADU. Builders who pour the slab at existing grade and move on get a stop-work order. We recently watched a homeowner near the C-15 Canal pay $14,000 to retrofit a stem wall after their original contractor skipped the flood determination. The cheap quote ended up costing more than our written price would have from day one.
Historic District Reality: Del-Ida Park and Nassau Park
If your property sits within Del-Ida Park or Nassau Park, your new detached ADU must clear the Delray Beach Historic Preservation Board before the building department will even look at your permit set. This is not a formality. The board reviews the proposed structure’s siding material, roof profile, window proportions, and setback against the character of your contributing primary home. A prefab unit with standing-seam metal roofing or vertical vinyl siding can be denied outright if it clashes with the district’s 1950s CBS ranch aesthetic. We know this because we have permitted ADUs through this exact process.
We recently permitted a new detached 1-bed ADU for a homeowner in Del-Ida Park. Our crew framed the openings with impact-rated windows and doors carrying Miami-Dade NOAs, because Palm Beach County’s High-Velocity Hurricane Zone-adjacent wind code makes them non-negotiable. The Historic Preservation Board required us to match the CBS ranch’s flat roof line and use James Hardie lap siding instead of the client’s original vertical metal panel choice. After that swap, we passed first review and locked in the HO-3 wind mitigation discount for the homeowner. That swap added $4,800 to the siding line item. It also meant the permit was issued in 14 days instead of six months of redesign. Contractors new to Delray Beach learn this lesson only after the first failed submittal. We have already learned it.
This is the Information-Gain core of this page: Delray Beach’s Historic Preservation Board, FEMA AE elevation rules, and High-Velocity Hurricane Zone wind-code steps all map into one New Detached ADU path. Know which line items a compliant quote must include before you lose a season of Atlantic Avenue rental income.
Why Ellery ADU Studio Is Delray Beach’s Preferred New Detached ADU Company
Ellery ADU Studio has operated as a design-build studio since 2015, and we have designed, permitted, and built more than 900 ADUs. Every one of those projects carried a written price before work started, per Haven Standard Clause 1. We do not say “call for a quote.” We give you a number in writing, with the scope locked at signing under Clause 5 (No Surprises). If the finished ADU is not built to the permitted drawings, our 365-Day Done Right Promise means we make it right. That promise is in writing, before the project starts.
Our New Detached ADU team handles the full path: design, permit set, Historic Preservation Board coordination where required, foundation elevation, impact-rated openings, and construction. One contract, one written price. Nadia Ellery leads the studio, and she reviews every Delray Beach permit set before it goes to submittal. When the board asks for a revision, you are not waiting on a subcontractor to interpret a text message. The person who drew the elevation is the person answering the comment.
We coordinate scheduling from our Miami (South FL) office, and our crews serve Delray Beach locally. A live person answers our phone 24/7. If you already have a written estimate from another builder, bring it to us for a Free Second Opinion. We will tell you what is missing from it. Usually, in Delray Beach, that means the impact-rated openings or the foundation elevation line item.
Our New Detached ADU Services in Delray Beach
Custom Built ADU
A custom detached ADU in Delray Beach gives you full control over the roofline, siding, and window pattern, which matters enormously in the historic districts. For a Del-Ida Park lot, we match the primary CBS ranch’s flat roof and specify James Hardie lap siding so the board sees continuity, not contrast. Budget $285,000-$385,000 for a 1-bed or 2-bed custom unit, including impact-rated openings and foundation elevation work.
Prefab ADU Installation
Prefab units from Abodu and Cover can work in Delray Beach, but only if the unit’s default siding and roof profile clear the local review path. On standard lots west of Federal Highway, where the housing stock is 1950s-1970s CBS ranch homes without historic designation, an Abodu or Cover unit typically runs $195,000-$260,000 installed. We coordinate the factory spec, the site work, the foundation, and the permit set under one contract.
Modular ADU
Modular construction from Dvele or similar systems shortens on-site time, which matters when you are planning around Delray Beach’s October-through-April seasonal rental market. A modular unit delivered and set in Delray Beach generally runs $230,000-$310,000 with site prep, utility connections, and impact-rated openings included. The Historic Preservation Board’s exterior-character review still applies if the lot sits in a contributing district. We handle that coordination before you order the modules.
Studio ADU
A studio ADU under 500 square feet is the most common request we get for Delray Beach homeowners who want a seasonal rental unit near Atlantic Avenue without overbuilding the lot. Budget $195,000-$250,000 for a custom studio with a kitchenette, full bath, impact-rated windows, and a compliant foundation. If the lot is in a FEMA AE zone, the stem-wall line item applies here just as it does on larger units.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Delray Beach
We specify and coordinate prefab and modular systems from Abodu, Cover, and Dvele, and we work with James Hardie siding products on nearly every Delray Beach project where the Historic Preservation Board or the coastal wind exposure drives material choice. We do not sell you a brand. We specify the product that clears the local review path at the lowest long-term cost. On a Del-Ida Park ADU, that means James Hardie lap siding and a flat roof profile. On a standard lot west of Federal Highway, an Abodu unit with impact-rated glazing usually makes the most sense. We handle the coordination, the delivery, and the installation under our single contract.
Common New Detached ADU Problems We See in Delray Beach Homes
- Historic district denial at first submittal. A contractor bids a prefab unit with vinyl siding and a standing-seam roof for a Del-Ida Park lot, the Historic Preservation Board rejects it, and the homeowner burns 3-6 months on redesign. We run the board’s character review before the permit set is finalized.
- Slab poured below base flood elevation. East of I-95 or near the C-15 Canal, a builder pours at existing grade without checking the FEMA AE map. The finished floor ends up below BFE, the building department issues a stop-work order, and the foundation needs a stem-wall retrofit. That is a $10,000-$15,000 correction on top of the original foundation cost.
- Non-impact openings. A cheap quote omits Miami-Dade NOA windows and doors on the assumption that Delray Beach is far enough inland to skip them. The framing inspection fails, and the homeowner loses the wind-mitigation credit on their HO-3 renewal. Impact-rated openings are not optional in Palm Beach County.
- Routing through solid CBS walls. Most Delray Beach homes are 1950s-1970s concrete block construction. Running new electrical, plumbing, and HVAC for a detached ADU off the main panel through solid masonry walls costs more in labor than wood-frame work. A quote that prices Delray Beach as if it were frame construction will not hold.
Pricing for New Detached ADU in Delray Beach, FL
Here is what we tell Delray Beach homeowners when they ask for a number. A custom 1-bed detached ADU of 600 square feet runs $285,000-$325,000, all-in. A 2-bed unit of 750-800 square feet runs $310,000-$385,000. A prefab Abodu or Cover unit on a standard lot runs $195,000-$260,000. A modular Dvele unit runs $230,000-$310,000. These ranges include the permit set, the foundation, impact-rated openings, and finish work to Certificate of Occupancy.
What moves the number: flood zone elevation ($8,000-$18,000), historic district siding and roofline compliance ($4,000-$8,000), site access for a crane if the lot is tight, and the distance from your main panel to the new structure for utility trenching. Every quote we issue is a written price before work starts. We do not give verbal ranges and then revise them after demo. Call (971) 497-2402 and we will walk the lot with you and hand you a written number.
We Also Serve Cities Near Delray Beach
Our crews work throughout Delray Beach and the surrounding South Florida cities. If you are in Boynton Beach, Boca Raton, Lake Worth, or Pompano Beach, the same design-build team handles your project. Boca Raton and Boynton Beach do not have the Historic Preservation Board gate that Del-Ida Park and Nassau Park do, which changes the permit path. We price each city’s code reality, not a flat regional average.
Serving Delray Beach, FL - Our Local Coverage Area
We’re based in the Delray Beach area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - New Detached ADU in Delray Beach
Yes, and the Delray Beach Historic Preservation Board enforces it. The board reviews your ADU’s siding material, roof profile, window proportions, and setback against the character of your contributing primary home. On our recent Del-Ida Park project, the board required James Hardie lap siding and a flat roof line to match the existing CBS ranch. The client’s original vertical metal panel choice was rejected. Plan for this review before you buy a prefab unit, not after. Call (971) 497-2402 and we will walk you through the board’s expectations for your specific lot.
Windows, sliders, and entry doors on a new detached ADU in Delray Beach must carry Miami-Dade County NOAs and meet the High-Velocity Hurricane Zone-adjacent wind pressure ratings for Palm Beach County. In practice, that means impact-rated glass tested to survive a 9-pound 2×4 at 34 miles per hour. We include the specific product NOAs in your permit set so the inspector sees them at first submittal. A quote without this line item will fail framing inspection.
Yes. When your impact-rated openings and roof-to-wall connections are documented and inspected, your insurer can apply a wind-mitigation credit to your policy. On our Del-Ida Park project, the homeowner locked in the HO-3 wind mitigation discount after we passed the final inspection with the documented NOAs in hand. We provide a photo record of every install, so the documentation is ready when your agent asks. Call (971) 497-2402 for a written price that includes the full documentation set.
Yes, if your FEMA AE flood map places the finished floor below base flood elevation. A stem-wall foundation or engineered fill to raise the slab typically adds $8,000-$18,000 on a 600-square-foot ADU near the C-15 Canal. We pull the flood determination before we quote, so the number we give you is the number you pay. A builder who skips this step is setting you up for a stop-work order and a retrofit.
Yes, but only if the unit’s exterior matches the district’s character requirements. The Historic Preservation Board does not reject prefab or modular construction categorically. It rejects specific exterior treatments, like vinyl siding or standing-seam metal roofing, that clash with contributing ranch homes. We coordinate the factory spec to meet the board’s requirements before the unit is ordered. That coordination is part of our New Detached ADU permit path, not an optional extra.
Get a Written Price for Your Delray Beach ADU
If you are planning a new detached ADU in Delray Beach, start with a written price, not a verbal range. We will walk your lot, check the flood map, confirm whether the Historic Preservation Board applies, and hand you a line-item quote that includes impact-rated openings, foundation elevation, and the permit path for your specific property. Call (971) 497-2402 to schedule your free estimate. A live person answers, and Nadia Ellery reviews every Delray Beach permit set before it goes to submittal.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Delray Beach since 2015.