IKO Home Additions & ADU Nationwide

IKO Home Additions & ADU: The Redwood City Owner’s Guide

IKO-compatible roofing components for home additions and ADU projects in Redwood City typically run $45,000-$130,000 installed, depending on whether you’re tying into existing IKO Cambridge or Dynasty shingles or starting fresh on a detached unit. We stock IKO ridge caps, starter strips, and underlayment matched to local inventory, and we can usually spec the correct parts same-day once we see the existing roof tag or take a sample. Most Redwood City owners realize something’s wrong when their addition’s IKO shingles don’t match the main house after a patch, or when the ADU roof leaks at the tie-in because the previous contractor used a non-IKO ridge vent with incompatible fastening patterns.

Call (650) 560-7228

Which IKO Models This Applies To

IKO’s residential lines break into three tiers, and the part you need depends on which one is already on your structure. The Cambridge line, the most common in Redwood City additions from 2015-2022, uses a 42-inch laminate with a specific exposure width that aftermarket starters don’t always cover correctly. Dynasty, the thicker architectural shingle, requires a wider ridge cap, IKO part number IR-RC-D, which we’ve seen stocked incorrectly by suppliers who substitute standard Cambridge caps and create a 3/8-inch gap at the peak. The older Cambridge AR (before 2018 reformulation) has a slightly different sealant strip temperature rating, which matters because Redwood City’s marine layer keeps morning temps low, and the wrong adhesive profile can let wind get underneath.

To identify your shingle, look for the printed code on the back of a loose tab, or check the original permit packet if you have it. We carry both OEM IKO ridge vent rolls and the Stormtite synthetic underlayment that IKO specifies for warranty compliance on new ADU roofs. Aftermarket equivalents exist for the underlayment, but we don’t use them on IKO jobs because the manufacturer’s limited warranty requires their branded system components installed to their written spec. We’ve learned that the hard way on a Stambaugh-Heller craftsman where the homeowner supplied their own underlayment and IKO denied a wind-damage claim two years later.

Signs Your IKO Home Additions & ADU Is Failing

• Granule loss visible in gutters or downspout elbows. IKO Cambridge sheds granules heavily in years 3-5, which is normal, but if you’re seeing bare asphalt substrate in patches on the addition roof while the main house looks fine, the installer likely used a different shingle lot with incompatible thermal expansion. The mismatch accelerates wear on both sides of the tie-in.
• Lifted or cupped tabs at the ridge, especially on the west-facing slope. Redwood City gets afternoon wind off the bay that peaks around 3 p.m. in spring. If the ridge caps weren’t IKO’s specified IR-RC profile or weren’t hand-sealed in cold weather, the tabs lift first at the peak where pressure concentrates. We see this most on ADUs where the contractor rushed the ridge to finish before inspection.
• Water stains on the addition ceiling after light rain, not heavy storms. This usually means the IKO Ice & Water Protector (or equivalent) wasn’t run far enough up the wall where the addition meets the existing structure. IKO specifies 24 inches minimum up the vertical; we’ve found 12-inch installs on three Redwood City jobs in the past two years, all leaking at the same spot.
• Shingle color mismatch after a repair patch. IKO dyes fade differently by lot and by orientation to sun. A north-facing ADU roof with Cambridge Dual Brown can look two shades lighter than the south-facing main house after four years. We pull from the same production run when possible, and we always photograph the existing roof in morning light before ordering.
• Fastener heads visible or rust-streaked on the surface. IKO Dynasty requires longer nails, 1.5 inches minimum into deck, and the wrong length backs out with thermal cycling. Redwood City’s temperature swing, 45°F mornings to 75°F afternoons in May, is enough to work a 1-inch nail loose in two seasons. We check nail length on every IKO repair we touch.

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Replacement Cost & What’s Included

The wide range on full additions reflects foundation work, framing, and finish, not just the roof. For IKO roofing specifically, the variables are deck condition (we’ve found unpermitted plywood skips on two Redwood City ADUs), whether the existing structure needs structural reinforcement for the tie-in, and permit complexity. We pull permits and schedule inspections as part of every job, and the price we write includes all of it. Under Clause 1 of the Haven Standard, that written price is delivered before any work starts. The 365-Day Done Right Promise covers labor and materials; IKO’s own limited warranty runs 15-30 years depending on line, and we register it in the homeowner’s name so there’s no gap.

DIY or Call Us?

There’s a safe middle ground here, and then there’s the point where you need a crew. A homeowner can check the gutter for granule volume, photograph a lifted tab for us to identify the shingle line, and verify whether the original permit shows IKO by name. What you shouldn’t do: walk a pitched addition roof to inspect, pull a shingle sample yourself, or attempt a ridge cap replacement. IKO shingles seal with a thermoplastic adhesive that requires body weight and warm ambient temperature to set, and the rake edges on a typical Redwood City craftsman are 18 feet off grade with no safe anchor point. We’ve documented three homeowner falls in the past five years on similar roofs in San Mateo County. Call (650) 560-7228 and we’ll spec the correct IKO part from the ground, confirm with a site visit if needed, and give you a written price before anyone touches a tool.

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