GAF Home Additions & ADU Nationwide

GAF Home Additions & ADU: The Fort Lauderdale Owner’s Guide

Home additions and ADU construction in Fort Lauderdale typically runs between $45,000 and $130,000 for a standard addition, while a full detached ADU lands in the $90,000 to $220,000 range depending on size, foundation work, and finishes. We install GAF roofing and weatherproofing systems on every addition and ADU we build in Fort Lauderdale, and we’re usually on-site within a few days of your first call to walk the property and talk numbers. Most homeowners discover their existing space no longer works when a family member moves in, a home office becomes permanent, or the garage stops functioning as storage. The part that fails first isn’t always visible: it’s often the integration point where old roof meets new, where the existing slab meets the addition’s foundation, or where the original electrical panel runs out of capacity.

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Which GAF Models This Applies To

GAF manufactures roofing systems, not home additions, so there’s no GAF “addition model” to match. What matters is which GAF roofing product line your existing home carries, because the new addition’s roof has to tie into it correctly. GAF’s Timberline shingle lines (HDZ, UHDZ, and Natural Shadow) cover most Fort Lauderdale homes built after 1990, while older homes in neighborhoods like Victoria Park or Poinsettia Heights often carry GAF’s discontinued Marquis or Sentinel lines that require color-matching to current production. If you don’t know what you have, check the roof decking edge for a leftover bundle label, or look at the shingle width: Timberline HDZ runs 13-1/4 inches wide with a 5-5/8 inch exposure, while older GAF lines measure differently. We handle the OEM-to-aftermarket decision case by case: for roof tie-ins where the GAF warranty matters, we spec GAF product and GAF-certified accessories. For underlayment, flashing, and ventilation, we use GAF’s Deck-Armor and Cobra Ridge Vent systems because they’re sized to work with GAF shingle profiles and hold up in South Florida humidity without trapping moisture.

Signs Your GAF Home Additions & ADU Is Failing

• Water staining at the seam where the addition meets the original roofline. This is the most common failure point on Fort Lauderdale additions. The original builder either skipped the step flashing or used caulk instead of metal, and our afternoon downpours find that gap every time.
• Doors inside the addition that stick or won’t latch in summer. This usually means the addition’s foundation has settled differently than the main slab. In Fort Lauderdale’s sandy, high-water-table soil, that differential movement is predictable if the builder didn’t compact the base properly.
• A musty smell that returns even after cleaning. This points to moisture trapped under the addition’s flooring, often because the vapor barrier was installed incorrectly or the crawl space (if there is one) has no cross-ventilation. In our humidity, a damp slab never dries on its own.
• Visible cracks running diagonally from the corners of windows or doors in the addition. Not all cracks are structural, but diagonal ones usually are. They indicate shear stress the original framing wasn’t designed to carry, often from a roofline that wasn’t tied to the existing structure properly.
• The addition never cools below 80 degrees on hot days, even with the AC running. This is an undersized HVAC or a poorly sealed envelope. We see it constantly in garage conversions around Fort Lauderdale, where the original walls and slab were never insulated to living-space standards.

Replacement Cost & What’s Included

In Fort Lauderdale, a standard home addition runs $45,000 to $130,000, while a detached ADU with its own kitchen and bath runs $90,000 to $220,000. A garage conversion into living space lands at $30,000 to $80,000. What drives the range: whether you’re building on a slab (cheaper) or elevated on pilings or stem walls (more expensive), the condition of your existing electrical panel (a 200-amp upgrade adds $3,000 to $5,000), the roof tie-in complexity, and finish level. Every Mason Remodeling Co Fort Lauderdale quote comes as a written price before any work starts: line items for demolition, foundation, framing, roofing, rough-in plumbing and electrical, drywall, finishes, and the GAF roofing materials themselves. No verbal estimate that grows. No change orders unless you ask for something new. The labor and materials are covered by our 365-Day Done Right Promise, which means if work from a completed addition fails within a year of the completion date, we come back and fix it at no charge, including a free second visit on any repair that doesn’t hold.

DIY or Call Us?

There are things you can safely check yourself: walk the seam where the addition’s roof meets the original house and look for lifted shingles or visible gaps in the flashing. Check the breaker panel to see whether it’s at capacity. Look for cracks in the slab around the addition’s perimeter. But building or repairing a home addition is not a DIY job. You’re dealing with structural loads, roof tie-ins, plumbing and electrical work, and GAF warranty requirements that only hold if the installation follows GAF’s published details. The dangerous part isn’t hypothetical: a bad roof tie-in during a hurricane is how a roof comes off a house. If you suspect your existing addition or ADU has a structural or roofing problem, call us at (754) 354-3720. Isaac Pruett will walk the site with you, tell you what we found, and put the fix in writing before we touch a thing.