Owens Corning Home Additions & ADU Nationwide

Owens Corning Home Additions & ADU: The Pomona Owner’s Guide

Rowan Construction Group Pomona installs Owens Corning-compatible roofing, insulation, and weather barrier systems for home additions and ADUs, with typical installed pricing from $45,000 to $130,000 for full additions and $90,000 to $220,000 for detached ADUs. Most Owens Corning material failures in our Pomona projects trace back to one of three issues: thermal bridging at the addition-to-existing junction, moisture infiltration where the new roof ties into the old, or insulation compression that drops the effective R-value below Title 24 compliance. We stock Owens Corning Duration, Oakridge, and ProEdge components, plus R-30 to R-49 fiberglass batts and FOAMULAR rigid board for the thermal breaks Pomona’s 100-plus summer days demand.

Call (626) 606-1081

Most Pomona homeowners spot trouble during the first heat wave after their addition or ADU is finished. The new room runs 8 to 12 degrees hotter than the original house, or they notice water staining where the old fascia meets the new gable. Sometimes it’s a draft that won’t quit, traced to a gap in the housewrap tape at the shear-wall transition. These symptoms don’t announce themselves dramatically. They accumulate.

Which Owens Corning Models This Applies To

We work with Owens Corning systems across four product families, and identifying what you have matters for matching.

Roofing: Duration Series (TruDefinition and standard), Oakridge, Supreme, and Berkshire. The label is printed on the shingle back, visible from the attic or during removal. Duration carries a 130-mph wind warranty when installed with six nails; Oakridge tops out at 110 mph. For Pomona’s Santa Ana exposure, that distinction is worth the upgrade.

Insulation: EcoTouch PINK Fiberglas (R-13 through R-49), FOAMULAR NGX (extruded polystyrene, R-5 per inch), and PROPINK blown-in loosefill. The batts have a printed code date and R-value every 24 inches. FOAMULAR comes color-coded by compressive strength: pink for standard, blue for high-load applications like under slab.

Weather barriers: HydroGap drainable housewrap and PinkWrap. HydroGap has a 1.5-mm spacer fabric bonded to the face; if your wrap feels textured, that’s what you have.

OEM Owens Corning parts ensure warranty continuity, particularly on Duration shingles where the TruProtection non-prorated period requires OC-certified installation. Quality aftermarket equivalents exist for insulation and housewrap (Johns Manville, Typar), but for roofing we specify OEM to keep the 50-year limited warranty intact. Measure twice, then we can talk.

Rowan Construction Group Pomona is an independent contractor, not affiliated with Owens Corning Corporation.

Signs Your Owens Corning Home Additions & ADU Is Failing

• Temperature stratification between old and new spaces. The addition runs hot while the original house cools normally. This usually means compressed or displaced EcoTouch batts at the rim joist, or a thermal bridge where FOAMULAR was omitted at the foundation stem wall. Compressed fiberglass loses up to 50 percent of its rated R-value.
• Water staining at the addition tie-in, especially after wind-driven rain. The step flashing or cricket was likely omitted or undersized where the new roof meets the existing wall. Owens Corning roofing systems depend on proper flashing integration; the shingles themselves don’t fail, but the water gets around them.
• Visible daylight through the attic at the shear-wall junction. The housewrap tape failed at the transition between old and new framing, or the HydroGap was not lapped correctly. In Pomona’s dry climate this reads as a draft; during rare heavy rains it becomes a leak path.
• Shingle cupping or curling on the addition roof within the first five years. This points to inadequate attic ventilation, a common error when adding square footage without proportionally increasing exhaust venting. Owens Corning specifies 1 square foot of net free vent area per 150 square feet of attic floor; additions often get shortchanged.
• Blown-in PROPINK settling below the top plate in cathedral ceilings. The loosefill was installed at insufficient density (below 0.5 pounds per cubic foot) or the baffles collapsed. You see this as a cold band at the ceiling edge, exactly where Pomona’s summer sun hits hardest.

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Replacement Cost & What’s Included

Full Owens Corning system replacement for a home addition or ADU in Pomona runs $45,000 to $130,000 for attached additions and $90,000 to $220,000 for detached ADUs. The spread reflects square footage, foundation type (slab-on-grade vs. raised perimeter), and whether we’re matching an existing roof plane or building entirely new.

Here’s how that breaks down on a typical project:

• Roofing system: $8,000-$20,000 for Owens Corning Duration with synthetic underlayment, ice-and-water shield at valleys, and proper intake/exhaust ventilation
• Wall insulation package: $3,500-$8,500 for R-21 batts plus FOAMULAR sheathing in a 2×6 wall
• Foundation/slab insulation: $2,500-$6,000 for FOAMULAR NGX under slab or perimeter
• Weather barrier and flashing: $2,000-$5,500 for HydroGap, integrated tape, and compatible flashing at all penetrations
• Labor and project management: 40-45% of total, including documented photo record, permit coordination with Pomona Building & Safety, and inspections

Every quote is a flat written price with line-item scope, delivered before any work starts. Under Clause 1 of the Haven Standard, that number doesn’t change unless you sign a change order. Our 365-Day Done Right Promise covers workmanship; Owens Corning’s material warranties transfer with the property.

DIY or Call Us?

There’s a safe middle ground here, and a hard stop.

What you can check: attic insulation depth with a ruler (should match the labeled R-value thickness, uncompressed), visible housewrap lapping at the addition junction (upper courses over lower, like shingles), and whether your soffit vents are blocked by insulation. These are look-and-measure tasks, no tools beyond a flashlight.

Where DIY goes wrong: roofing removal and replacement involves fall hazards, proper nail placement (six per shingle for 130-mph rating), and integration with existing flashing that may be embedded in stucco or siding. Insulation installation looks simple but fails silently when batts are compressed, cavities are missed, or vapor retarder placement violates Title 24. The result is a room that doesn’t perform, discovered too late.

We’re not going to tell you a homeowner can’t swing a hammer. We will tell you that the callbacks we run in Pomona’s Lincoln Park and Phillips Ranch neighborhoods are usually on work that looked fine from the street. Call (626) 606-1081 and we’ll give you a written price to do it once, with the photo record to prove what got installed where.

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