IKO Home Additions & ADU Nationwide

IKO Home Additions & ADU: The Sherman Oaks Owner’s Guide

IKO-compatible roofing components for home additions and ADU projects in Sherman Oaks typically run $45,000-$130,000 for a complete addition, with IKO Cambridge and Dynasty shingle systems among the most specified brands we install. Most Sherman Oaks homeowners discover their IKO roof on the addition or ADU needs attention when they spot granule loss in the gutters after Santa Ana wind events, or when a home inspection for a refinance flags the secondary structure’s roof age. We stock IKO starter strips, ridge caps, and underlayment matched to existing systems, and we carry the full Cambridge, Dynasty, and Marathon Plus lines on our Sherman Oaks warehouse shelves.

Call (213) 221-0788

Which IKO Models This Applies To

IKO’s residential shingle lines break into three tiers, and the part you need depends on which was originally installed. Cambridge Architectural shingles, the mid-grade workhorse, measure 13-1/4 inches wide by 39-3/8 inches long with a 1-1/4 inch exposure; Dynasty, the premium laminated line, runs slightly larger at 13-3/4 by 39-3/8 with a 1-3/4 inch exposure and a heavier fiberglass mat. Marathon Plus, the three-tab economy line, is 12 by 36 inches with a 5-inch exposure. The compatibility gotcha in Sherman Oaks: many 1980s-2000s additions were roofed with Marathon or Marathon Ultra, which IKO discontinued in 2018. You cannot match new Marathon to old; the color blends won’t line up, and the exposure difference creates a visible ridge. For these, we spec Cambridge as the replacement and run a full re-roof on the addition rather than attempt a repair patch that reads like a scar.

To identify your line, check the shingle bundle wrapper if any were left in the garage, or look at the back of a lifted shingle for the stamped IKO logo and series name. The fiberglass mat weight, printed on the underside, reads 2.6 lbs/sq for Cambridge, 3.0 for Dynasty. If the shingles are brittle and the stamp is faded, measure exposure and tab count: three-tab equals Marathon family, architectural tabs with shadow bands equals Cambridge or Dynasty.

Signs Your IKO Home Additions & ADU Is Failing

• Granule accumulation in downspouts after rain. IKO’s ceramic granule coating protects the asphalt core from UV; once 30-40% of granules have shed, the shingle ages exponentially. In Sherman Oaks, the south- and west-facing slopes of an addition roof see this first due to sun load, often within 18-22 years on Cambridge, 22-28 on Dynasty.
• Lifted or cupped shingle tabs along the rake edges. Santa Ana winds, which funnel through the Sepulveda Pass and hit Sherman Oaks at 40-60 mph during fall events, get under shingle tabs and break the self-seal adhesive. IKO’s FastLock sealant strip reactivates with solar heat, but once wind cycles exceed the adhesive’s shear strength, the tab stays lifted and drives moisture under the course below.
• Cracking in the field of the shingle, not just at stress points. Thermal cycling causes this: Sherman Oaks sees 50°F+ swings between July highs and January lows. IKO shingles with oxidized asphalt (older stock) become brittle faster than polymer-modified asphalt; the crack pattern looks like alligatoring and typically starts at the 15-year mark on south exposures.
• Soft spots or staining on the addition ceiling drywall. This indicates the underlayment has failed, not just the shingle. IKO’s GoldShield or ArmourGard underlayment should outlast the shingles by a decade, but improper valley installation or missing ice-and-water shield at the addition-to-house junction lets water migrate laterally.
• Flashing gaps where the addition roof meets the existing wall. IKO systems rely on proper step flashing and counterflashing; on Sherman Oaks hillside homes, differential settling between the original foundation and the addition’s footing opens these joints. The gap is often 1/8 to 3/16 inch, enough for wind-driven rain.

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Replacement Cost & What’s Included

IKO roofing on a home addition or ADU in Sherman Oaks falls within our $45,000-$130,000 home addition range when the roof is part of a larger structure; a standalone IKO re-roof on an existing addition typically runs $8,000-$20,000 depending on square footage and pitch. What drives the spread: access (steep hillside lots in Sherman Oaks require scaffolding, not ladders), whether the original IKO was nailed over wood shake that must now be stripped to decking, and if the addition’s inadequate ventilation (common on 1990s ADUs) needs correction with ridge vent and soffit intakes.

Our written quote itemizes IKO shingles by line, synthetic underlayment, drip edge, valley metal, and ventilation components separately. Under Clause 1 of the Haven Standard, that price is fixed before work starts; no change proceeds without a signed change order. The 365-Day Done Right Promise covers installation defects, and IKO’s limited lifetime warranty on Cambridge and Dynasty transfers to the next owner if you sell. We pull permits through the City of Los Angeles Department of Building and Safety, Van Nuys office, and schedule inspections so you don’t chase the inspector.

DIY or Call Us?

What you can safely check: from the ground, use binoculars to scan for missing tabs or lifted edges; from inside the addition attic, look for daylight through the roof deck or water stains on the rafters. Mark the location with tape and note the date.

Where DIY goes wrong: IKO shingles require a minimum 4/12 pitch for standard installation; below that, the warranty voids and you need a modified bitumen or standing-seam system instead. More critically, any work above 10 feet on a pitched surface in Sherman Oaks requires fall protection under Cal/OSHA Title 8, Section 1670. The rake edges of addition roofs are often tighter to property lines than the main house, meaning less room to stage a ladder safely. We’ve replaced homeowner DIY attempts where the nail pattern was wrong (IKO specifies six nails per shingle in wind zones, not four) and the entire course had to come back off. Measure twice, write it down, then build it - and if you’re not set up to do all three on a roof, call us at (213) 221-0788.

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