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PGT Home Additions & ADU: The Los Angeles Owner’s Guide
A PGT home addition or ADU in Los Angeles typically runs $53,100 to $153,400 installed, depending on square footage, site conditions, foundation work, and whether you’re building attached or detached. Mason Remodeling stocks the structural components, sheathing, framing hardware, and finishes needed for PGT-compatible additions, and we can usually start your project within a few weeks of permit approval. Most Los Angeles homeowners call us because their existing patio cover or pre-fabricated addition has a failing roof membrane, dry-rotted beam ends, or rusted-out connectors at the wall ledger, and they want to know whether to repair the existing structure or pull the whole thing and start fresh. If you’re seeing water stains on interior ceilings near the addition, sagging ridge lines, or daylight through the roof-to-wall connection, keep reading, because the answer changes what this job will cost.
Which PGT Models This Applies To
PGT’s vinyl and aluminum framing systems show up across Los Angeles in sunrooms, patio enclosures, lanai additions, and small attached ADUs, typically on homes built between the mid-1990s and the mid-2010s. The parts that fail most often are the extruded aluminum wall connectors, the roll-formed roof rafters at the eaves, and the base track where the wall meets the slab. One compatibility gotcha we see regularly: PGT changed the profile depth on its wall extrusions around 2007, so if your addition was built before then, you cannot always interchange new PGT trim or mullion covers with old ones. We handle this by taking field measurements of the extrusion profile, not just the glass size, before quoting any replacement glazing or structural repair. For the decision between OEM PGT parts and quality aftermarket equivalents, the honest answer is that for load-bearing framing components, we recommend OEM or a fabricator that matches the original alloy and profile exactly. For aesthetic trim, flashing, and sealant systems, a high-quality aftermarket equivalent often outperforms the original in Los Angeles UV and marine-layer exposure, and we’re happy to show you the difference in writing.
You may also need related components from the brands we regularly work with on these projects, including KraftMaid cabinetry, Cambria or Silestone countertops, and matching trim packages. Mason Remodeling is an independent general contractor, not affiliated with PGT, which means we’re free to tell you when a non-PGT part is genuinely the better call for your dollar.
Styles & brands we work with
Signs Your PGT Home Additions & ADU Is Failing
- Water staining at the wall-to-roof junction. The original foam gasket and butyl tape PGT used at the eave connection dries out and loses adhesion under Los Angeles’s repeated wet-dry cycles. By the time you see a ceiling stain, the leak has usually been active for a season or two.
- Soft or crumbling base track at the slab. Sprinkler overspray, dog urine, and poor original drainage wick moisture up into the aluminum base channel and corrode it from the channel side, where you can’t see it until the wall starts to shift.
- Fogged or failing insulated glass units. Los Angeles’s temperature swings cause the sealant at the glass-to-frame interface to flex and crack. A fogged unit isn’t just cosmetic: it means the desiccant is saturated and the unit will eventually fail structurally at the edge seal.
- Door that binds or won’t latch. If the addition’s settling or the slab has moved, the door frame is usually the first thing to tell you. The cause is often decomposed compacted fill beneath the original slab, not the door itself.
- Sagging ridge beam or visible rafter deflection. PGT’s roll-formed aluminum rafters are strong for their weight, but they are not over-engineered for decades of California sun and wind load. If you see a dip in the roofline, the internal steel reinforcement has usually lost strength and needs replacement, not a patch.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a full PGT-compatible home addition in Los Angeles, budget $53,100 to $102,500 for a basic attached room with simple roof tie-in, and $102,500 to $153,400 for a larger or more complex addition with structural upgrades, seismic anchoring, and higher-end finishes. A full detached ADU runs $106,200 to $259,600 depending on size, kitchen and bath package, and whether you’re trenching new utilities from the street or tapping existing lines. A garage conversion to an ADU falls between $35,400 and $94,400 at Los Angeles market rates.
What drives the range: whether the existing slab passes a soils and reinforcement check (many Los Angeles additions built before the 2010 code cycle don’t, and that’s a five-figure line item), the condition of the existing roof-to-wall connection, seismic anchoring requirements, and your finish level. Every quote we provide includes a written, line-item price before work begins, with a stated allowance for materials and a guarantee: $0 change orders unless you ask us to change scope. We also pull the permit, schedule inspections, and stand behind the work for 365 days from completion, in writing.
DIY or Call Us?
For a failing PGT addition, this is not a hand-tool job. The dangerous part of any addition repair is the roof-to-wall connection: a partially failed rafter or a stripped wall ledger can let go without warning, and you’re working at height on a damaged structure. That’s a trained professional’s job, full stop. What you can safely check yourself: look for visible gaps at the eave line, test doors for binding, and mark any water stains with painter’s tape so you know if they’re growing. Beyond that, the cost of getting it wrong is a collapsed roof section or a leak that rots the whole wall. If you’re in Los Angeles and want an honest assessment, call (803) 680-2547 and we’ll walk the job with you, take measurements, and put a written price in your hand before you commit to anything.
FAQs
With proper flashing maintenance and periodic resealing at the roof-to-wall joints, a PGT-framed addition typically lasts 25 to 35 years in Los Angeles before the aluminum roof members or the base track require major repair or replacement. The original exterior sealants and gaskets will need attention roughly every 7 to 10 years, more often if you’re within a few miles of the coast where salt air accelerates extrusion corrosion. Call (803) 680-2547 to schedule a free estimate and we’ll tell you exactly what shape your addition is in.
Yes, in most cases the structure can be repaired if the base track, wall extrusions, and roof rafters are still sound and only the sealants, flashing, or individual glass units have failed. Once the structural aluminum is corroded through or the slab has settled beyond tolerance, a repair becomes more expensive than a controlled teardown and rebuild, and we’ll tell you so in writing rather than sell you a patch. For a straight answer on what your specific addition needs, call (803) 680-2547 and we’ll come look.
A simple sealant and flashing repair on a PGT addition takes 1 to 2 days once materials are on site, while a structural repair involving rafter or base-track replacement typically takes 5 to 10 working days, and a full rebuild or new ADU in Los Angeles runs 8 to 16 weeks depending on permitting and foundation work. We give you a written schedule at the same time we give you the written price. Call (803) 680-2547 to get your project on the calendar.
We stock the most common PGT-compatible structural connectors, base track profiles, flashing, sealants, and glazing tape on our trucks in the Los Angeles area, which means most repairs start the day we arrive. Custom extrusion profiles or insulated glass units are ordered to spec and typically arrive within 2 to 3 weeks. We’ll tell you during the walkthrough whether your job is truck-stock or special order.
Written by Isaac Pruett, Owner, Mason Remodeling at Mason Remodeling, serving Los Angeles and nearby areas.
