IKO Home Additions & ADU Nationwide

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

IKO home additions and ADU projects in Los Angeles typically run between $53,100 and $153,400 when built as a permitted, inspected structure with a written scope and a fixed price. We install IKO-compatible roofing, underlayment, and waterproofing materials as part of full additions and accessory dwelling units across Los Angeles County, and we carry the fasteners, flashing, and sealants IKO specifies on our trucks, not ordered in after the fact. Most Los Angeles owners discover an IKO-material problem the same way: a water stain on the ceiling at the addition’s tie-in point, a soft spot where the new roof meets the original house, or a failed seal around the ADU’s roof penetration six or seven years after installation.

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Which IKO Models This Applies To

IKO manufactures roofing shingles, underlayments, and ice-and-water barriers under several product lines, and the compatibility question matters more on additions and ADUs than on standalone homes. The Cambridge and Dynasty architectural shingle lines are the two we see most often on Los Angeles additions, and they are not interchangeable with IKO’s Nordic or Marathon performance lines when it comes to matching exposure, color lot, or warranty continuity. The practical gotcha for Los Angeles owners: if your original house was roofed with an IKO Cambridge in a discontinued color, the addition’s roof cannot be patched seamlessly with the current palette. You either reroof the whole structure, accept a visible transition at the tie-in, or we document the mismatch in the written scope before anyone starts. We are an independent service provider, not affiliated with IKO, which means we can quote the aftermarket equivalent honestly alongside the OEM part and tell you which one holds up under Los Angeles sun exposure.

Signs Your IKO Home Additions & ADU Is Failing

• Granule loss concentrated at the south-facing slope. Los Angeles UV exposure wears IKO shingles faster on the addition’s sun-facing roof plane, and the tell is granules collecting in the gutter at the addition’s downspout while the original house’s gutters stay relatively clean.
• Lifting or curling at the roof-to-wall tie-in. Where the addition’s roof meets the existing house wall, thermal expansion and the different settling rates of old and new framing create a stress point. IKO shingles there will lift before they wear out.
• Water staining at the ADU’s interior ceiling, directly under a roof penetration. Exhaust fans, plumbing vents, and mini-split lines all pierce the ADU roof. The failure is almost always the sealant collar or the underlayment lap, not the IKO shingle itself.
• Mold at the kickout flashing below a roof-wall intersection. The kickout directs water into the gutter instead of behind the stucco. When it is installed short or missing, IKO shingles can look fine while water runs behind the wall assembly.
• Shingles that crack when you touch them after year eight. Asphalt shingles in Los Angeles lose flexibility as volatile compounds bake out. If the addition’s IKO shingles snap rather than flex during a routine inspection, the replacement conversation starts.

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Replacement Cost & What’s Included

IKO home additions and ADU work in Los Angeles spans $53,100 to $153,400 depending on whether we are tying a new roof into the structure, framing new square footage, or building a full ADU with its own systems. The lower end of that range covers a modest addition with an IKO roof tie-in, standard framing, and no foundation complications. The upper end covers a complete ADU with kitchenette, bath, separate electrical panel, and a fully permitted IKO roof system. Every quote from Rowan Construction Group is a flat written price with a written scope, including the specific IKO materials by name, the fastening pattern, the underlayment type, and the warranty term. No change proceeds without a signed change order, which under Clause 1 of the Haven Standard is why our projects finish within a few percent of the agreed number.

DIY or Call Us?

An owner in Los Angeles can safely inspect a few things: look for granule accumulation in the addition’s gutters, check for visible shingle lift at the tie-in point, and photograph any interior water staining with a date stamp. What an owner should not do is get on an ADU roof to reseal penetrations, pry up shingles at the tie-in, or attempt flashing work where the addition meets a two-story wall. Falls from one-story roofs injure people every week in Los Angeles County, and the flashing details that fail are the ones that look simple. If you want an honest read on whether the IKO material is the problem or the installation was, call (470) 298-9650 and we will bring the photo record and a written price, not an estimate.

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