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James Hardie Home Additions & ADU: The Fort Lauderdale Owner’s Guide
James Hardie home additions and ADU construction in Fort Lauderdale typically runs $45,000 to $130,000 installed, depending on square footage, foundation work, and how much of the existing structure has to be tied in. We install and build with James Hardie siding, trim, and panel products on every addition and accessory dwelling unit we frame in Fort Lauderdale, and we can usually get your project scoped and priced within a week of the first call. The owners who land here usually have one of two situations: either they’re planning an addition and want Hardie products specified from day one, or they’ve got an existing James Hardie addition that’s showing its age in Florida humidity and they want to know if it’s a repair or a rebuild.
Key Takeaways
- Typical installed cost in Fort Lauderdale: $45,000 – $130,000 for a home addition; ADU construction runs $90,000 – $220,000.
- What fails first on Hardie exterior products here: improper flashing and seam treatment, not the board itself.
- We’re an independent Fort Lauderdale contractor, not a James Hardie dealer or affiliate. We buy Hardie products from regional suppliers and install them to Hardie’s published specs.
- You get a written price before work starts and a written 365-Day Done Right Promise on every project.
Which James Hardie Models This Applies To
When we talk about James Hardie on a home addition in Fort Lauderdale, we’re usually talking about three product families: HardiePlank lap siding, HardiePanel vertical siding, and HardieTrim boards. The compatibility question isn’t which product line your addition needs; it’s which product line matches what’s already on the house. Most Fort Lauderdale homes built or re-sided after 2005 use HardiePlank in either a 5/16-inch or 7/16-inch thickness, with either a smooth or Cedarmill texture. If your existing exterior is embossed to mimic wood grain, you need Cedarmill; if it’s flat, you need smooth. Matching the wrong texture creates a visible patch line that nobody wants on a project this expensive.
The OEM-versus-aftermarket decision doesn’t really apply here the way it does for a faucet or a hinge. James Hardie doesn’t license third-party equivalents for its products. If you’re building with Hardie, you’re buying Hardie board, Hardie fasteners (or their approved substitutes), and Hardie-recommended flashing. What you’re actually choosing is the installation standard. We stock 5/16-inch HardiePlank in Smooth and Cedarmill, 4×8 HardiePanel sheets, and primed HardieTrim boards on our Fort Lauderdale material orders. Trevor Nash will tell you the same thing he tells every homeowner: the board is only as good as the gap behind it.
Styles & brands we work with
Signs Your James Hardie Home Additions & ADU Is Failing
- Swollen, crumbling edges at the bottom course. This is almost always a clearance problem: Hardie requires a minimum 6-inch gap between siding and grade in South Florida, and less than that will wick moisture into the board edges within a few wet seasons. Fort Lauderdale Fort Lauderdale’s rainy summer months accelerate this fast.
- Paint peeling in vertical streaks, especially on the south-facing wall. Hardie’s factory primer is good, but if the installer didn’t caulk the butt joints correctly, water runs behind the paint film and lifts it. The board underneath is usually fine; the detailing failed.
- Gaps opening at the trim-to-siding junction. HardieTrim boards expand and contract at different rates than the board behind them. Gaps that appear at corners and window casings mean the installer didn’t leave the required 1/8-inch gap and fill it with a proper sealant.
- Rust-colored streaks below nails or screw heads. If a previous contractor used non-galvanized or insufficiently coated fasteners, the first rain system turns every fastener head into a small rust fountain. Hardie specifies 6d galvanized or 1-1/4 inch cement board screws; anything else is a future stain.
- Cracks running horizontally through the board, following a nail line. That’s fasteners driven too deep. Hardie board doesn’t compress like wood, so over-driven nails create stress points that crack under expansion cycles. We see this often on additions done by crews that framed with wood instead of Hardie’s recommended installation patterns.
See the difference
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AfterReplacement Cost & What’s Included
A full home addition or ADU project in Fort Lauderdale with James Hardie products typically lands between $45,000 and $130,000 for the addition itself; ADU construction climbs to $90,000 – $220,000 because it usually runs new utility lines, a separate meter, and its own foundation. For repair and remediation work on an existing Hardie installation, smaller scopes fall on the lower end or below: a Hardie re-siding of one wall with proper flashing runs $3,500 – $11,000 depending on access, height, and whether we’re pulling permits. The drivers are square footage, whether the framing underneath is sound, and whether we’re matching existing Hardie product or trimming back to a clean line and installing new.
Every Fort Lauderdale project gets a written price before any work starts. That number includes material, labor, dump fees, and permit coordination where the city requires it. It also includes our 365-Day Done Right Promise: if any part of the installation fails inside that year, we return and fix it at no charge. That’s written on the scope of work, not implied.
DIY or Call Us?
You can safely check a few things yourself: look at the bottom clearance between your Hardie board and the ground, look for rust streaks, and photograph any cracking you see. That’s useful information for a scope meeting. What you should not do is start pulling boards off a South Fort Lauderdale addition to see what’s behind them. Hardie installation involves cutting cement-fiber board, which produces silica dust that requires a respirator and proper containment; the work is loud, the fasteners are specific, and if you open the wall envelope incorrectly you’ll introduce more water than you fix. Trevor’s rule is simple: if you’re not sure whether that crack is cosmetic or structural, call us at (754) 551-2922 and we’ll send a uniformed technician to look at it. There’s no charge for the assessment before we price the job.
FAQs
James Hardie board itself carries a 30-year non-prorated limited warranty, and in Fort Lauderdale’s climate the board typically holds its structure for 25 to 30 years when installed with proper clearance, flashing, and paint. The installation details fail far sooner: bad flashing can show within two years, and poor fastener choice within five. Our 365-Day Done Right Promise covers the installation for the first year, and we build to Hardie’s published specs so the next two decades aren’t a cascade of repairs.
Yes, in most Fort Lauderdale cases: if the board is intact and the problem is flashing, caulk, or fastener corrosion, we can correct the details and replace only the damaged courses. If water has been getting behind the board long enough to compromise the framing or sheathing, the repair becomes a structural job and the price climbs. Call (754) 551-2922 to have us look at it before you assume the worst.
A full addition with Hardie materials on a Fort Lauderdale home typically takes 8 to 16 weeks from permitting to final walkthrough, depending on city review times and the condition of the existing structure. A one-wall Hardie remediation is usually 2 to 5 working days. We’ll give you a written timeline alongside the written price, and we show up in the arrival window we gave you.
We keep common HardiePlank lap siding sizes, HardiePanel sheets, and HardieTrim boards on our Fort Lauderdale material orders year-round, but we order project-specific quantities and colors for every job so you’re not paying for waste. When we price your addition or ADU, the material line item includes exactly what the job needs, sourced from regional James Hardie suppliers, alongside our other trade brands like KraftMaid, Cambria, and Silestone when the project calls for them.
Written by Trevor Nash, Owner, Penhallow Remodeling Fort Lauderdale at Penhallow Remodeling Fort Lauderdale, serving Fort Lauderdale and nearby areas.
