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Boral Home Additions & ADU: The Miami Owner’s Guide
Boral home additions and ADU construction in Miami typically runs $53,100 – $153,400 installed, depending on square footage, foundation work, and whether you’re adding living space or a fully independent unit. We stock Boral-compatible framing, sheathing, and trim materials on our trucks, so the materials are on-site the day we break ground. Most Miami homeowners find out their original addition or ADU wasn’t built to Boral’s spec when they see wall cracks at the roofline, a spongy subfloor, or doors that suddenly won’t close during the wet season.
Here’s the thing about Boral products in South Florida: they shed water exceptionally well when installed correctly, but the humidity and storm cycles punish bad installation fast. If your Boral addition was built by someone who cut corners on flashing or used the wrong fasteners, you’ll see the failure within three to five years. That’s the job we get called for most.
Which Boral Models This Applies To
Boral makes several product lines used in additions and ADUs, and compatibility depends on what was originally installed. For exterior sheathing and trim, Boral’s TruExterior siding and trim products show up on a lot of Miami additions built after 2010. If your addition has Boral roofing products, you’re likely looking at their concrete and clay tile lines, which have specific underlayment requirements that differ from what standard asphalt shingle installers are used to. The gotcha: Boral concrete tile roofs need a specific type of ridge vent and flashing detail that generic roofing suppliers don’t always carry. We run into this constantly in Coral Gables and Pinecrest, where original builders used Boral tile and later repair crews patched with whatever was on the truck. That patch fails first.
To identify what you have, check the exposed edge of your trim or sheathing for a Boral stamp, or look for the product code on any leftover material. We can also match by dimensions: Boral TruExterior comes in skip-trowel, wood-grain, and smooth finishes, and it’s a composite that doesn’t absorb water the way real wood does. If you’re not sure what you have, we identify it during the estimate. For OEM versus aftermarket: Boral’s own products are engineered as a system, so we use OEM for structural and water-shedding components, and quality aftermarket only for cosmetic pieces where spec doesn’t affect performance.
Styles & brands we work with
Signs Your Boral Home Additions & ADU Is Failing
- Crack lines at the roofline or wall corners. This usually means the framing behind your Boral sheathing is moving from moisture intrusion. In Miami, that’s almost always a flashing failure at the roof-to-wall junction, and it will get worse every hurricane season until it’s fixed.
- Soft spots in the floor near exterior walls. Water is getting past the Boral trim or sheathing and sitting on your subfloor. By the time you feel the softness, the subfloor is rotting and the repair is bigger than just the trim.
- Doors and windows that stick only during summer. High humidity swells poorly sealed framing. If your Boral addition was framed without proper moisture barrier details, the whole assembly swells from June through September, then shrinks again in the dry months.
- Mold or dark staining on interior drywall where the wall meets the floor. That’s capillary action pulling water up from a failed sill detail. Boral products don’t fail this way on their own; it’s the installation detail underneath that went wrong.
- Paint peeling on Boral trim within two years. Boral composite trim should hold paint for a decade if primed and painted correctly. Early peeling means someone skipped the end-seal on cut edges, and the trim is now wicking water from every seam.
See the difference
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AfterReplacement Cost & What’s Included
For a full Boral home addition or ADU build in Miami, plan on $53,100 at the low end (a simple single-room addition) up to $153,400 for a larger multi-room add-on or permitted ADU structure. The spread comes down to square footage, whether you’re cutting into the existing roofline, foundation type (slab versus raised), and finish level inside. A garage conversion with Boral exterior products lands between $35,400 and $94,400, depending on whether it’s a basic living space or a full ADU with a kitchenette and bathroom. If you’re just replacing failed Boral siding, trim, or sheathing on an existing addition, the pricing follows our siding and exterior repair ranges: typically $4,130 to $12,980 for trim and siding work on a single addition’s exterior.
Every estimate includes a written line-item price before work starts, so you know exactly what the materials cost and what the labor costs. We pull permits, pass the inspections, and back the work with our 365-Day Done Right Promise: if it’s not done right, we make it right. Written price, written guarantee, no change orders unless you ask for something different mid-project.
DIY or Call Us?
You can safely do a visual inspection: look for the cracks, stains, and sticking doors listed above. But replacing Boral sheathing, trim, or roof tile on an addition means working at height, cutting into your home’s water barrier, and matching products so the repair doesn’t create a new leak. That’s not a weekend job. We’ve watched too many Coral Gables homeowners try to patch a Boral tile roof seam themselves and end up with a bigger water problem inside the house than they started with. If you’re on a ladder with a pry bar looking at flashing, you’re already past the point where you should call us. Good work doesn’t need a sales pitch. Call (850) 801-8046 and we’ll get you a real number.
FAQs
A properly installed Boral addition should last 50-plus years for structural components, with Boral roofing tile often lasting 70 years or more, and Boral composite trim running 25 to 30 years before it typically needs repainting. The weak link in Miami is almost never the Boral product itself; it’s the flashing, fasteners, and moisture barrier details that someone either installed correctly or didn’t. Call (850) 801-8046 and we’ll tell you honestly how much life your current addition has left.
Yes, if the failure is caught early enough. Replacing failed flashing, resealing Boral trim edges, and repairing localized water damage often runs $4,130 to $12,980 in Miami with our pricing, and that’s a fraction of full replacement cost. If framing has already rotted or the foundation is moving, repair isn’t the right call. Call us and we’ll inspect before we ever quote.
A simple single-room addition typically runs eight to twelve weeks, while a full ADU with plumbing and electrical runs four to six months depending on permitting. Miami’s permitting office has its own timeline, and we don’t sugarcoat that. We’ll give you a written schedule before we start, and the Relay Visibility Guarantee means you get photo updates and real arrival times throughout the job.
We keep Boral-compatible flashing, fasteners, and common trim profiles on our trucks for repair calls, and for full additions we order Boral products per job so you get the right series match, not whatever was sitting in a warehouse. We also handle KraftMaid, Cambria, and Silestone materials for the interior finish work, so the whole project goes through one written estimate and one crew.
Written by Luca Romano, Owner & Lead Contractor, Sawyer Remodel Miami at Sawyer Remodel Miami, serving Miami and nearby areas.
