IKO Home Additions & ADU Nationwide

IKO Home Additions & ADU: The Sunnyvale Owner’s Guide

IKO-compatible roofing components for home additions and ADU projects in Sunnyvale typically run $45,000-$130,000 installed, depending on whether you’re tying into existing structure or building freestanding. We stock IKO Cambridge, Dynasty, and Nordic series shingles plus matching ridge caps, underlayment, and ventilation components for same-day starts on most Sunnyvale permits. Most owners discover their IKO roof system is failing when the addition’s ceiling shows water staining after the first hard rain, or when the city inspector flags mismatched materials during the final - a problem we see regularly in Lakewood Village, where additions from the 1990s used IKO Marathon shingles that are now discontinued and incompatible with current IKO fastening patterns.

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Which IKO Models This Applies To

IKO has produced four distinct residential shingle lines relevant to Sunnyvale additions and ADUs built since 1987. The Cambridge line, still in production, uses a 15-pound felt exposure and requires IKO’s own FastLock sealant strip for warranty coverage - substituting a generic three-tab voids the 15-year ironclad protection. Dynasty, the laminated architectural shingle, runs heavier at 310 pounds per square and needs a minimum 4/12 pitch; we’ve seen DIY additions in Sunnyvale’s Birdland neighborhood fail inspection because the 3/12 shed roof couldn’t support Dynasty’s weight and water-shedding profile. Nordic, the impact-resistant line, carries a UL 2218 Class 4 rating required in some Santa Clara County wildland-urban interface zones.

To identify your existing IKO product, check the back of a loose shingle for the printed date code and series name - usually in the upper corner, stamped in black ink. If you’re matching an existing roof on a home addition, measure the exposure (the visible portion after installation): Cambridge exposes 5 5/8 inches, Dynasty 5 3/4 inches. A 1/8-inch mismatch sounds trivial until you’re staring at a wavy rake line from the street. Rowan Construction Group Sunnyvale is an independent contractor, not affiliated with IKO, though we source their products through authorized distribution and can spec equivalent GAF or Owens Corning systems when IKO’s lead times stretch past permit expiration.

Signs Your IKO Home Additions & ADU Is Failing

• Granule loss exposing the fiberglass mat. IKO’s asphalt coating relies on ceramic granules for UV protection; once the mat shows through, typically after 18-22 years in Sunnyvale’s 260+ annual days of sun, the shingle becomes brittle and cracks at the fastening point. We see this accelerated on south-facing addition slopes above reflective patio surfaces.
• Curling or clawing at the tab edges. This indicates the sealant strip has failed, often from thermal cycling in Sunnyvale’s 40-degree swing between summer highs and winter lows. The shingle lifts in wind, admits driven rain, and the lifted tab snaps off entirely.
• Interior staining concentrated at the addition-to-house junction. The step flashing where the new roof meets the existing wall is the most common leak point in IKO additions - not because the shingles failed, but because the original installer used generic step flashing rather than IKO’s recommended 10-inch wide galvanized or pre-painted steel.
• Sagging ridge line on the ADU roof. IKO requires a continuous ridge vent for their warranty; blocking it with solid ridge cap or improper venting traps moisture in the attic space, rotting the OSB decking from beneath while the shingles look fine from the street.
• City permit hold on resale or refinance. In Sunnyvale, unpermitted additions with non-compliant roofing trigger a full compliance review. We’ve handled three in the past two years where the owner discovered their IKO roof was installed over two layers of old material, exceeding the 240 pounds-per-square structural limit for the addition’s engineered trusses.

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Replacement Cost & What’s Included

For a typical Sunnyvale home addition or ADU roof using IKO materials, expect $45,000-$130,000 total project cost, with the roofing portion usually representing 8-15% of that range. A standalone 500-square-foot ADU roof in IKO Cambridge runs roughly $12,000-$18,000 for tear-off, deck inspection, synthetic underlayment, new flashings, and installation; tying into existing IKO roofing on a second-story addition adds $3,000-$7,000 for matching, weaving, and extended warranty coordination.

What drives the spread: deck condition (we replace punky OSB at $85 per sheet, documented with photos), access difficulty (steep pitches or tight Sunnyvale side yards require scaffolding), and whether the existing IKO product is discontinued. Marathon, SuperGlass, and ArmourGlass shingles from the 1990s and 2000s are obsolete; matching their color profile requires a full-face replacement or accepting a visible transition line, which we diagram in the written scope before you sign. Every Rowan quote lists material costs, labor hours, and subcontractor scope separately - Clause 1 of the Haven Standard. The 365-Day Done Right Promise covers workmanship; IKO’s limited warranty covers manufacturing defect, prorated from installation date with proper documentation we file for you.

DIY or Call Us?

An owner can safely check for granule loss by examining the gutters and downspout outlets - heavy accumulation means the shingles are shedding protection. You can also photograph the roof from a secure ladder at the eave, never from the roof surface itself. What you cannot safely do: walk a pitched roof, remove shingles to inspect deck condition, or handle the 80-pound bundles on a slope. Falls from residential roofs account for one-third of construction fatalities annually, and Sunnyvale’s clay-heavy soil makes ladder footing unpredictable after rain.

The real DIY risk isn’t injury - it’s permit compliance. Santa Clara County requires a roofing permit for any work exceeding 100 square feet or involving structural decking; IKO’s warranty demands installation by a contractor who can document nail pattern, exposure, and ventilation per their spec sheet. We pull the permit, pass the inspection, and deliver your photo record and signed completion documentation. Call (650) 405-3637 to schedule your free estimate - we’ll bring shingle samples, measure your addition, and return a written price before any work starts.

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