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GAF Home Additions & ADU: The Fort Lauderdale Owner’s Guide
If you’re researching a GAF-related home addition or ADU in Fort Lauderdale, the short answer is this: a full home addition tied to your existing GAF roof system typically runs $45,000 – $130,000 in Broward County, while a detached ADU starts closer to $90,000 – $220,000 depending on square footage, foundation work, and the roof tie-in complexity. We handle the remodel side of that equation: the framing, drywall, plumbing rough-in coordination, cabinetry, tile, and finish work that turns raw space into livable square footage. Where most owners discover trouble is a roof intersection that was never flashed correctly against the original GAF shingle line, which quietly leaks through the first hard South Florida rain.
Penhallow Remodeling Fort Lauderdale is an independent contractor. We’re not affiliated with GAF, but we’ve worked around their roofing systems enough to know exactly where the water goes when a previous crew cuts corners. And in Fort Lauderdale, water always finds a way.
Key Takeaways:
- Home additions tied to existing structures: $45,000 – $130,000 installed in Fort Lauderdale.
- ADU construction: $90,000 – $220,000, driven by foundation, utility runs, and roof system type.
- We write the price before work starts. The number on day one is the number on the invoice, backed by our 365-Day Done Right Promise.
- Call (754) 551-2922 and a real person answers. Not a service, not a callback queue.
Which GAF Models This Applies To
Here’s the part most Fort Lauderdale homeowners don’t hear until it’s too late: the GAF shingles on your main roof don’t care about your addition. But the addition’s roof-to-wall intersections, the valley where the new roofline meets the old, and every nail that passes through the new underlayment absolutely do. GAF Timberline HDZ, Timberline UHDZ, and Royal Sovereign are the three shingle lines we most often see on Broward County homes. Each has a slightly different exposure and nail strip, which means the starter course on your addition’s roof needs to match the existing exposure, not just the color.
The compatibility gotcha is in the flashing detail. When a new addition ties into an existing GAF roof, the roofer has to cut back the old shingles and weave the new underlayment under them at least two courses deep. Skip that, and you’ll get a water intrusion point right at the transition, which shows up as a brown stain on the new drywall six months later. When we quote a home addition in Fort Lauderdale, we specifically flag this transition point, because it’s the most common place for a previous contractor to hide behind a “verbal estimate” that never covered the real fix. Tell me what you need, I’ll tell you what it costs – then we’ll get it done.
For the interior side of a GAF-tied addition or ADU, we also work with KraftMaid and Wellborn cabinetry, plus Cambria and Silestone countertops. Those brand warranties layer on top of our own written guarantee, which is the kind of redundancy you want when you’re writing a check in the five figures.
Styles & brands we work with
Signs Your GAF Home Addition or ADU Is Failing
- Water staining on the ceiling where the new roofline meets the old. This almost always traces back to an underlayment splice or a missing shingle weave at the transition point. In Fort Lauderdale’s rainy season, the stain grows weekly.
- Musty smell in the new closet or storage area. That’s not “new construction smell.” Moisture is getting trapped behind the drywall, usually because the wall-to-roof flashing detail wasn’t sealed on the addition’s wall side.
- Shingle granules collecting at the bottom of downspouts from the new section. If the roofer ordered the right color but the wrong exposure line, the shingles don’t seat correctly, and they shed granules faster than they should.
- Cracks in the stucco or siding at the junction between the old structure and the new. Different materials expand at different rates in South Florida heat and humidity. If there’s no proper expansion joint, the crack is structural, not cosmetic.
- Doors inside the addition that stick in summer but close fine in winter. That’s the frame adjusting to moisture swings, which is common in Fort Lauderdale. What’s not normal is a door that won’t close at all, which suggests the floor system wasn’t leveled before framing.
See the difference
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After
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AfterReplacement Cost & What’s Included
In Fort Lauderdale, a home addition running $45,000 – $130,000 reflects the wild range between a modest 300-square-foot bedroom bump-out and a 1,200-square-foot great room with plumbing, a new kitchen, and structural beam work. An ADU at $90,000 – $220,000 swings on three things: whether you’re pouring a new slab or building over a garage footprint, how far the utility lines have to run from the street, and whether the roof system is a simple GAF shingle match or something more involved like a standing-seam metal tie-in.
What’s included in our written price: framing, drywall, flooring, electrical and plumbing rough-in coordination with our licensed trades, all interior trim, cabinetry, countertops, painting, and the finish details. What’s also included, which most Fort Lauderdale contractors leave out: a line item for the roof-to-wall flashing review at the transition point, with the exact decking or underlayment correction written into the scope. If the number changes before we open the walls, that’s our failure, not your surprise. Every job gets our 365-Day Done Right Promise in writing: if it fails inside the guarantee period, we come back and fix it at no charge.
DIY or Call Us?
You can safely do some things: check your attic after a hard rain with a flashlight, look for dark streaks on the underside of the roof decking at the addition’s tie-in point, and pull a small section of baseboard to see if the drywall behind it is soft or stained. Those are observations, and they help us quote the job accurately.
What you shouldn’t do is cut back shingles, remove underlayment, or attempt any structural modification where the addition meets the main roofline. That’s high tension between your warranty and your insurance company, and one wrong cut with a hook blade turns a $1,200 flashing repair into a $12,000 water damage claim. Fort Lauderdale homeowners have learned that lesson the expensive way. If you suspect the transition point is failing, call (754) 551-2922. We’ll send a background-checked, uniformed technician to look at exactly what’s happening, give you a written number, and never ask you to guess.
FAQs
In our climate, a properly installed GAF architectural shingle roof on a new addition lasts 18 – 22 years before the granules start failing to the point of needing replacement. The weak point is never the shingle itself; it’s the flashing detail at the transition, which can fail inside five years if it wasn’t done correctly. Call (754) 551-2922 and we’ll inspect the tie-in point before you spend money on shingles you don’t need.
Yes, in most cases. If the shingles are intact but the underlayment splice or flashing detail failed, we can cut back the old course, install proper underlayment, re-weave the shingles, and re-flash the wall line. That runs $400 – $1,800 in Fort Lauderdale depending on the linear footage of the problem area. If the decking underneath is rotted, the price goes up, because we replace the decking, not the symptom. Call (754) 551-2922 for a written quote on the exact repair.
A simple roof tie-in repair on a GAF system takes one day. A full interior remodel of an existing addition, like a kitchen expansion with cabinets and countertops, runs 6 – 10 weeks in Fort Lauderdale depending on cabinet line lead times. An entire ADU from ground-breaking to final paint runs 4 – 7 months, driven largely by Broward County permitting turnaround and utility scheduling. We’ll write the timeline into the scope, so you know which weeks you can’t use the driveway.
We don’t stock shingles, but our technicians carry the flashing types, sealants, and underlayment materials that work with GAF Timberline and Royal Sovereign installations. That means we can typically do a transition point repair in one visit. We also stock KraftMaid and Wellborn cabinet samples, Cambria and Silestone countertop samples, and all the finish hardware catalogs, so you can make selections at your own kitchen table instead of driving to a showroom in Miami. Call (754) 551-2922 and we’ll bring the samples to you.
Written by Trevor Nash, Owner, Penhallow Remodeling Fort Lauderdale at Penhallow Remodeling Fort Lauderdale, serving Fort Lauderdale and nearby areas.
