IKO Home Additions & ADU Nationwide

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

IKO-compatible home additions and ADU construction in Cupertino typically runs $45,000-$130,000 for additions and $90,000-$220,000 for detached ADUs, with written quotes delivered before any work begins. We stock and install IKO roofing systems, insulation, and waterproofing components as specified phases of addition and ADU projects throughout Cupertino, including the Monta Vista neighborhood. Most homeowners discover their IKO system needs attention when a permitted addition project uncovers existing roof deck saturation, or when an ADU foundation inspection reveals the primary dwelling’s IKO ice-and-water shield has degraded past the 15-year mark in our Santa Clara Valley sun exposure.

Call (669) 202-9618

Which IKO Models This Applies To

IKO residential systems found in Cupertino additions and ADU tie-ins fall into three product families: the Cambridge architectural shingle line (laminated, 240 lb. per square), the Dynasty series with ArmourZone reinforcement (common on spec-built homes from 2010-2019), and the IKO GoldShield synthetic underlayment used beneath tile conversions. The identifying mark is a stamped manufacturing date and lot code on the shingle back, visible when a corner is lifted, or a printed roll tag on underlayment left in attic spaces during original construction.

The OEM-versus-aftermarket decision for IKO is straightforward in our experience. IKO’s Cambridge and Dynasty shingles carry a limited lifetime warranty when installed as a complete system with IKO EdgeMetal drip edge and IKO StormShield ice-and-water barrier. Substituting a generic drip edge voids the wind-resistance portion of that warranty, which matters in Cupertino because the city adopts California Building Code wind exposure Category C for hillside lots above 500 feet elevation. We source IKO OEM components through authorized distribution and stock GoldShield underlayment on our trucks for same-phase installation. For older IKO 3-tab shingles (discontinued Marathon Ultra from pre-2015 stock), we match with Cambridge as the functional replacement; the exposure dimension differs by 5/8 inch, which we account for in the tie-in layout.

Signs Your IKO Home Additions & ADU Is Failing

• Granule accumulation in gutters with exposed fiberglass mat visible on shingle surfaces. The asphalt binder oxidizes faster in Cupertino’s inland valley heat than in coastal zones; once granules shed, the mat absorbs moisture and the shingle loses structural integrity. We see this pattern on south-facing slopes after 12-14 years.
• Lifted or curled shingle corners along the addition tie-in line, even without wind events. IKO Cambridge uses a fiberglass mat that stiffens with thermal cycling; the contraction stress concentrates at the bond line where old roof meets new framing. This is the first place we inspect on any addition project.
• Water staining on the existing home’s ceiling drywall directly below the IKO underlayment overlap zone. The IKO StormShield self-adhered membrane bonds to clean OSB or plywood; if the original installer left dust or if the substrate has swollen from prior leaks, the lap seal fails. We remove and replace the affected section rather than overlay.
• ADU foundation moisture with no plumbing leak identified. IKO AquaBarrier below-grade waterproofing on older Cupertino homes (pre-2012 construction) used a 40-mil thickness since superseded by 60-mil product. The thinner membrane pinholes at stress points where the foundation step-down meets grade.
• Interior humidity spikes in the new addition space despite mechanical ventilation. IKO Ener-Air insulation, when compressed during a hasty addition framing sequence, loses its R-value and creates a thermal bridge. We verify thickness with a probe at the insulation inspection; 5.5 inches is spec for 2×6 walls, not 4.5.

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After

Replacement Cost & What’s Included

The range driver is substrate condition, not shingle color. We open the roof at the tie-in and photograph the decking before quoting; if the OSB is saturated past 19% moisture content per our pin meter, we replace it and the price moves to the upper portion of the range. Under Clause 1 of the Haven Standard, that written price does not change unless you sign a change order. We’ve kept projects within 3% of the agreed number across 4,000-plus jobs since 2007 by following that discipline.

DIY or Call Us?

There’s a safe middle ground for IKO roof inspection, and a hard stop. A homeowner can check the gutter downspout discharge for granule load, photograph any visible shingle damage from a secured ladder at gutter height, and verify attic ventilation is unobstructed. What you cannot safely do is walk a pitched roof to lift shingle corners for the date stamp, remove shingles to inspect underlayment bond, or handle compressed insulation in a wall cavity where electrical and plumbing penetrations create unseen hazards.

IKO’s Cambridge and Dynasty shingles carry a Class A fire rating and a 130 mph wind warranty, but both depend on installation according to the IKO Pro4 system specification, which specifies nail placement, quantity, and exposure. A nail gun set to the wrong depth, or nails placed above the manufacturer’s nail line, voids the warranty and creates a liability exposure. We carry the IKO installation certification and pull the permit; Cupertino requires a roofing permit for any work exceeding 100 square feet or involving structural tie-in. Call (669) 202-9618 and we’ll schedule a free written estimate with the photo documentation included as standard.

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