IKO Home Additions & ADU Nationwide

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

IKO-compatible roofing components for home additions and ADU projects in Campbell typically run $45,000-$130,000 for a complete addition, with IKO shingle systems installed as part of the roof assembly. We stock IKO Cambridge, Dynasty, and Marathon Plus series shingles for same-week installation on Campbell additions where the main roof needs matching or the ADU requires a new assembly. Most Campbell owners discover their IKO roof is failing when the addition’s ceiling shows water staining after the first heavy rain of November, or when city inspectors flag lifted tabs during ADU final inspection.

Call (831) 704-1211

Which IKO Models This Applies To

IKO prints the series name on the back of every shingle, visible from the attic or crawl space if you lift the insulation. The Cambridge line, IKO’s architectural laminate, runs 40 7/8 inches long and 13 3/4 inches wide at the exposure; Dynasty, their performance laminate, is slightly thicker at 3/8 inch and carries a Class 4 impact rating that matters in Campbell where oak and eucalyptus drops are common. Marathon Plus is the three-tab workhorse, still found on 1980s Campbell additions near the Pruneyard corridor.

We match to existing IKO roofs by pulling a sample from the eave, not by eyeballing from the ground. The dye lot shifts enough year to year that a close guess reads as a patch job. For ADUs with new roofs, we quote both IKO OEM and CertainTeed Landmark as a quality aftermarket equivalent - the price difference is usually $800-$1,400 on a 1,200-square-foot ADU roof, and the warranty terms are comparable. Rowan Construction Group Campbell is an independent contractor, not affiliated with IKO.

Signs Your IKO Home Additions & ADU Is Failing

• Curling or clawing at the tab edges. Campbell’s combination of summer UV and winter moisture cycling causes the asphalt mat to shrink at different rates than the fiberglass core. On south-facing addition roofs, we’ve seen this start as early as year 12 on Cambridge shingles rated for 30 years.
• Granule loss visible in gutters or downspout elbows. The ceramic granules protect the asphalt from UV; once they’re gone, the shingle degrades exponentially. In Campbell’s hard water environment, granules often cement in gutter corners, so we check the downspout outlet first.
• Lifted tabs after wind events. IKO’s sealant strip activates with sun and pressure, but shaded ADU roofs under mature oak canopy - common in the Campbell Avenue corridor - never get enough heat to set properly. The tabs lift at 45 mph instead of the rated 70.
• Interior staining at addition-to-house junction. This is almost always step flashing failure, not shingle failure, but the IKO shingles above the flashing must come off to fix it properly. We document the substrate condition with photos before we quote.
• Sagging between trusses on the ADU roof. The OSB or plywood deck has delaminated, usually from a single-point leak that saturated the panel. IKO shingles can look intact while the structure beneath rots; we probe with an awl during inspection.

Before

After

Replacement Cost & What’s Included

The range on a full addition reflects foundation type, whether we’re tying into existing HVAC, and how much of the original structure needs structural upgrade to meet Campbell’s current code. Every quote is flat and written before work starts - Clause 1 of the Haven Standard. The IKO materials carry the manufacturer’s warranty; our labor carries the 365-Day Done Right Promise. Permits, inspections, and the documented photo record are included, not itemized as extras.

DIY or Call Us?

An owner can safely check the attic for staining, note the shingle series from any loose packaging in the garage, and photograph the gutter granule buildup. What goes wrong fast is walking a pitched addition roof to “just lift a few tabs” - the slope on most Campbell ADUs runs 4:12 to 6:12, steep enough that a wet morning or loose granule surface turns a simple look into a fall. The real risk, though, is the structural unknown: we’ve opened ADU roofs in Campbell where three layers of shingles hid rotted skip sheathing from a 1970s build, and the homeowner’s foot went through before they knew it.

We don’t recommend DIY removal on any roof with more than one layer, any structure over 15 years old, or any pitch over 4:12. Call (831) 704-1211 and we’ll scope it with a written price before you commit.

FAQs