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IKO Home Additions & ADU: The Los Angeles Owner’s Guide
We install and build IKO-compatible home additions and ADUs throughout Los Angeles, with full project pricing typically landing between $53,100 and $153,400 depending on scope, finishes, and site prep. Most homeowners reach out after realizing their existing space has hit a wall: a converted garage that’s peeling apart at the seams, a sunroom that bakes in summer and leaks in winter, or an accessory dwelling unit that never quite met code.
What you’re really dealing with is a structure problem, not a single failed part. IKO roofing and underlayment components on older LA additions and ADUs degrade from UV exposure and thermal cycling. When the roof membrane fails, everything below it suffers: framing, drywall, insulation, electrical. That’s the point where a patch job stops making sense and a proper rebuild starts.
Here’s what we cover on this page: which IKO-era additions and ADUs we work on, the failure signs we see most often in Los Angeles, what a full replacement costs, and the honest split between what you can check yourself and what needs a licensed contractor. Sawyer Remodeling is an independent general contractor. We are not affiliated with IKO, but we work with their roofing and underlayment products regularly and source compatible materials for every rebuild.
Key Takeaways
- Full IKO home addition or ADU reconstruction in Los Angeles runs $53,100 to $153,400 installed.
- The failure is almost never cosmetic: roof membrane breakdown, unpermitted framing, and moisture intrusion are the big three.
- We handle design, permits, demo, framing, roofing, and finish work under one written price.
- Every project carries the 365-Day Done Right Promise and the Relay Visibility Guarantee.
Which IKO Models This Applies To
IKO produces a broad line of asphalt shingles, underlayments, and waterproofing membranes rather than complete pre-built ADU kits. So when we say “IKO home addition” in Los Angeles, we’re typically talking about a structure built between roughly 1995 and 2015 that used IKO shingles (Cambridge, Dynasty, or Marathon lines) over IKO underlayment on a stick-framed addition or converted garage. The compatibility gotcha matters here: IKO Cambridge shingles from the early 2000s have a different sealant strip pattern than current production, which means partial roof repairs often fail at the seam where old meets new.
The right move is almost always a full tear-off and re-roof when the underlying structure is sound, or a full rebuild when it isn’t. For the structure itself, we’re not matching parts to a model number: we’re evaluating joist spacing, shear wall placement, foundation depth, and whether the original work was ever permitted. In Los Angeles, unpermitted additions from that era are common. About a third of the ADU and addition projects we quote in neighborhoods like Van Nuys, Reseda, and West Adams have at least one permit problem that has to be resolved before construction starts.
If you want to check what you have before calling, look in two places. First, check the roof edge for a nail line or any visible shingle markings, and check the building permit history through the LA Department of Building and Safety’s online portal. Second, measure the ceiling height and wall thickness. Pre-2005 additions in LA were frequently framed with 2×4 exterior walls and no shear paneling, which fails current seismic code and drives a portion of that rebuild cost.
Styles & brands we work with
Signs Your IKO Home Additions & ADU Is Failing
- Granule loss in the roof valley or at rakes. IKO shingles shed granules as the asphalt oxidizes under LA sun. You’ll see bare spots or a sandy wash of granules at downspout outlets. This means the shingle has maybe two to three years of useful life left, and the underlayment is next.
- Soft spots or sagging at the ridge or around skylights. Water has gotten past the roof membrane and into the OSB or plywood decking. By the time you feel a soft spot from the inside, the decking is compromised and the fix is not a repair: it’s a tear-off and deck replacement.
- Musty smell inside the ADU that gets worse after rain. This is trapped moisture in wall cavities or under flooring, usually from a roof leak that traveled down a rafter. Mold remediation plus structural drying adds real cost, so this is not one to wait on.
- Cracks at wall-to-ceiling joints or doors that stick seasonally. LA’s freeze-thaw cycle is mild, but our wet-dry cycle is not. Clay soil expands and contracts, and a poorly anchored addition or ADU will move with it. Sticking doors in January and gaps in July point to a foundation or framing issue, not humidity.
- Visible daylight through roof sheathing or at the eaves. We see this on older garage conversions where the original roof was never properly tied into the main structure. If you can see light, water and pests have an open invitation, and the cost to fix climbs the longer it goes.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a full home addition rebuild or ADU reconstruction in Los Angeles, plan on $53,100 to $153,400. The spread is wide because two factors dominate: whether the existing foundation and framing can be saved, and what finish level you choose. A basic 400-square-foot ADU rebuild with builder-grade finishes on an existing slab lands near the bottom. A 700-square-foot addition with seismic upgrades, a full kitchen or bath, and mid-tier brand materials (KraftMaid cabinetry, Cambria or Silestone countertops, Kohler fixtures) climbs toward the top.
Here’s what a typical project includes, line by line:
- Demolition and debris removal: $3,000 – $8,000 depending on access and dumpster runs.
- Permits and plan check: $2,000 – $6,000 depending on LA Department of Building and Safety requirements.
- Foundation repair or new footings: $6,000 – $18,000 if soil movement or missing footings are found.
- Framing and shear wall upgrades: $8,000 – $22,000 for code-compliant seismic work.
- Roof tear-off and IKO-compatible re-roof: $9,440 – $23,600.
- Rough and finish electrical, plumbing, HVAC: $7,000 – $20,000.
- Drywall, insulation, paint, trim: $5,000 – $14,000.
- Finishes (flooring, cabinetry, counters, fixtures): $12,000 – $42,000 depending on brand selections.
Every quote we write is a fixed number before work starts. No change orders unless you add scope. The 365-Day Done Right Promise covers the workmanship for a full year after we finish: if it’s not done right, we make it right, in writing, on every project.
DIY or Call Us?
You can safely check the obvious things: granule buildup in gutters, visible daylight at the eaves, water stains on interior ceilings, and whether the permit history for the structure exists online. Those checks cost you an hour and give us useful information before we come out.
What you should not DIY is anything structural. Cutting into a roof deck, removing shear wall, relocating a bearing wall, or rewiring an old garage conversion are jobs where a mistake means injury or a failed inspection. Los Angeles code enforcement on unpermitted ADU work has gotten stricter in the last few years, and a homeowner permit on structural work means you own the liability. Luca Romano has been swinging tools in LA for over two decades, and the jobs we get called to fix most often are DIY structural attempts that passed a visual check and failed the first real rain or tremblor. Good work doesn’t need a sales pitch, it just needs to be done right.
If you’re anywhere in Los Angeles and your addition or ADU is showing any of the signs above, call (254) 272-5876 and we’ll schedule a walkthrough. The estimate is free, the price you get is the price you’ll pay, and you’ll know exactly who’s showing up before they arrive.
FAQs
A properly permitted, code-compliant addition or ADU built with current materials lasts 50-plus years for the structure, with the roof being the first major replacement at roughly 20 to 25 years depending on sun exposure. IKO-compatible architectural shingles in Los Angeles typically give 20 to 28 years with proper attic ventilation, though south-facing roofs in the Valley trend toward the shorter end. Call (254) 272-5876 for an exact assessment of your structure.
If the foundation and framing are sound, we can often do a roof tear-off, deck replacement, and interior remediation without a full rebuild, which lands lower in the cost range. If water has been moving through the walls for more than one wet season, or the original framing was never permitted or sheared, repair stops being cost-effective. We’ll tell you which path applies after the walkthrough, and the quote will make the numbers clear either way.
A full ADU rebuild usually runs 10 to 16 weeks from demo to final inspection. Permits through LA Department of Building and Safety add 4 to 8 weeks on the front end depending on plan check volume, which is why we file as soon as the contract is signed. You’ll get photo updates before and after every major phase, and a live arrival time for every day our crew is on site.
We source everything: IKO-compatible shingles and underlayment, framing lumber, fasteners, insulation, and all finish materials from our network of suppliers. You don’t need to buy or store anything. Our material partnerships include KraftMaid, Cambria, Silestone, Kohler, and GAF, and we’ll spec the right IKO-compatible roofing system for your specific structure and exposure. Call (254) 272-5876 to get your free estimate scheduled.
If you’re looking at a failing addition or ADU in Los Angeles and want a straight answer on cost and scope, call (254) 272-5876. We’ll walk the property, write the real number down, and you’ll know exactly what happens next, who shows up, and what it costs. That’s how every Sawyer Remodeling project runs, no exceptions.
Written by Luca Romano, Owner, Sawyer Remodeling at Sawyer Remodeling, serving Los Angeles and nearby areas.
