GAF Home Additions & ADU Nationwide

GAF Home Additions & ADU: The Los Angeles Owner’s Guide

If you’re planning a home addition or ADU in Los Angeles and want GAF roofing materials as part of the build, a full addition or accessory dwelling unit typically runs $53,100 to $153,400 depending on square footage, foundation work, and finish level. We stock and install GAF-compatible roofing as part of our additions and ADU projects, and we can typically schedule your materials check within a few business days. Most homeowners reach out after an architect or previous contractor specified GAF shingles, underlayment, or ventilation products, and they want a builder who won’t swap in a cheaper substitute mid-project.

Call (936) 259-2607

We’re an independent remodeling company, not affiliated with GAF. That matters because we’re free to tell you exactly what a GAF product costs and whether it’s the right call for your Los Angeles addition, without pushing a brand line. Trevor Nash has built additions across LA County, and the first question he asks on any project is “Give me the whole picture first, then we pick up the tools.” That means your roofline, your foundation, your permit status, and your material spec are all on the table before a single price is written.

Which GAF Models This Applies To

GAF makes several roofing lines that show up on Los Angeles additions and ADUs, and they are not interchangeable. The Timberline HDZ and Timberline UHDZ architectural shingles are the most common on LA additions, with the UHDZ carrying a thicker profile and higher wind rating. The Camelot II and Grand Sequoia lines are heavier, premium architectural shingles. For flat or low-slope sections on modern ADUs in areas like Silver Lake or Echo Park, GAF’s TPO and Liberty SBS modified bitumen systems are the more likely spec.

The critical compatibility gotcha: GAF’s warranty coverage changes based on whether the entire roofing system, not just the shingles, is GAF. That means deck protection like Deck-Armor or FeltBuster, leak barriers like StormGuard, ridge cap shingles like Seal-A-Ridge, and ventilation all need to be GAF products to qualify for the stronger system warranty. A lot of owners don’t learn this until after a roof is on and the paperwork arrives. If you’re building an ADU in Los Angeles and want the full GAF warranty, we spec the whole system up front and write every component into your contract. We also work with KraftMaid, Cambria, and Silestone on the interior side of additions, so your roofing, cabinetry, and countertops can be coordinated without chasing three suppliers.

Signs Your GAF Home Additions & ADU Roofing Is Failing

• Granule loss in gutters or at downspouts – This is normal in the first year as excess granules wash off, but heavy loss after a Los Angeles summer means the shingle’s protective layer is degrading faster than it should. The asphalt underneath is now exposed to UV.
• Curling or lifting at shingle edges – Los Angeles heat cycles push roof surface temperatures above 140°F, and poor attic ventilation accelerates shingle curl. Once edges lift, wind gets under them and tear-off becomes the likely fix rather than repair.
• Water staining on ceilings or at the wall-roof junction – On additions, the tie-in point between the new roof and the original structure is the most common failure location. Improper step flashing or a skipped leak barrier at that transition lets water in slowly, sometimes for a year before it shows.
• Sagging or soft spots where the new roof meets the old roof – This is often a sheathing or framing issue from the addition, not a shingle failure. If the original roofline transition wasn’t properly framed or the substrate was reused when it should have been replaced, the whole assembly shifts.
• Higher cooling bills after the addition went in – Poorly ventilated Los Angeles ADU roofs trap heat in the attic, and that heat pushes down into the living space. GAF ventilation products like Cobra Ridge Vent or Solar-Powered attic fans are often the missing piece on a low-bid addition.

Replacement Cost & What’s Included

A full Los Angeles home addition with GAF roofing typically lands between $53,100 and $153,400. An ADU construction project runs higher, $106,200 to $259,600, because it includes its own foundation, utilities, and kitchen or bath. Roofing alone on these structures is only one line item, and here’s what drives the roofing portion: roof size, pitch, number of tie-in points to the existing house, whether tear-off of an old surface is needed, and which GAF line gets installed. A small detached ADU with a simple gable roof might need $9,000 to $15,000 in roofing materials and labor, while an addition with multiple valleys, a flat section, and skylights will go higher.

Every written quote from Penhallow Remodeling lists parts and labor separately. You see the per-square cost for shingles, the underlayment, the flashing, the ventilation, and the labor to install it. The number we write before any work starts is the number on the invoice, backed by our 365-Day Done Right Promise. If roofing work we installed fails inside that year, we come back and fix it at no charge. There’s no second-visit fee on a warranty call, ever.

DIY or Call Us?

Roofing is not a DIY job, and GAF’s own warranty language requires installation by a licensed contractor to maintain coverage. The work involves heights, ladders, and material that gets slippery when wet or dusty. We recommend homeowners stay off the roof entirely. What you can do safely: check your gutters for granule buildup, look at shingle edges from the ground with binoculars, and walk the interior rooms below the addition to check for faint ceiling stains. If you see any of those signs, call us at (936) 259-2607 and we’ll send a technician for a roof inspection. The inspection leads to a written report and a written price, not a sales pitch.

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