Boral Home Additions & ADU Nationwide

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

We stock and install Boral-compatible materials for home additions and ADU projects in Sherman Oaks, with typical installed pricing from $45,000 to $130,000 for additions and $90,000 to $220,000 for detached ADUs. Most Boral siding, trim, and veneer orders arrive within 3-5 business days, and we coordinate delivery to avoid weather delays that can warp fiber-cement products. You’ll know your Boral installation needs attention when you see cracked or delaminated boards, gaps at trim joints that weren’t there last season, or moisture staining behind the siding near foundation lines.

Call (213) 221-0788

Which Boral Models This Applies To

Boral’s U.S. residential line centers on TruExterior poly-ash trim and siding, a product we specify regularly for Sherman Oaks additions where the combination of summer heat and winter moisture cycles punishes lesser materials. TruExterior carries a Class A fire rating and won’t absorb water, which matters in the Valley where afternoon sun can push wall surface temperatures past 140°F.

To identify your Boral product, look for the stamped manufacturing date and lot number on the board back. TruExterior trim comes in nominal 5/8″ and 1″ thicknesses with actual dimensions slightly under; siding runs 7-1/4″ exposure with a 12′ standard length. The critical compatibility point: TruExterior requires stainless steel or hot-dipped galvanized fasteners - standard deck screws will corrode and stain the face within two seasons. We source Boral through authorized distributors in the San Fernando Valley; aftermarket equivalents exist in fiber-cement from James Hardie and LP SmartSide, but only TruExterior hits the same thermal expansion coefficient, which is why we spec it when the addition ties into existing stucco that can’t tolerate differential movement.

Signs Your Boral Home Additions & ADU Is Failing

• Board edges swelling or softening. This indicates water intrusion at cut ends that weren’t field-sealed with a compatible primer. Boral’s poly-ash core resists rot, but the factory coating is only skin-deep; we see this most often on DIY installations where the homeowner skipped end-sealing.
• Gaps opening at butt joints or corner boards. TruExterior expands and contracts less than wood or PVC, but it still moves; if the installer left inadequate clearance or used rigid polyurethane caulk instead of a backer rod and sealant system, the joint will telegraph through within 18 months.
• Fastener pops or rust streaks. The wrong fastener material reacts with Boral’s mineral content. In Sherman Oaks, where Santa Ana winds drive rain hard against south-facing walls, a single rusting fastener can bleed 8 inches down the board face.
• Delamination or surface chalking. UV degradation of the factory finish accelerates on west-facing walls. Boral recommends repainting every 7-10 years in high-exposure zones; we inspect the Galleria corridor and hillside homes off Mulholland where reflection off pool decks doubles the dose.
• Moisture inside the addition at base plates. This traces to missing or improperly lapped flashing at the Boral-to-foundation transition. The siding itself isn’t the leak; the detail is. We pull a piece, photograph the condition, and show the homeowner exactly where the water path starts.

Before

After

Replacement Cost & What’s Included

The range reflects wall area, scaffolding needs on two-story additions, and whether we’re tying into existing stucco or starting fresh. Every quote from Rowan Construction Group Sherman Oaks is a flat written price with line-item breakdown: materials, labor, permit fees, and waste hauling. Under Clause 1 of The Haven Standard, that price is locked before any work starts; no change proceeds without a signed change order. We warranty our installation for 365 days under the Done Right Promise, and Boral backs the product itself with a 25-year limited warranty when installed to their spec.

DIY or Call Us?

An owner can safely walk the perimeter and note which boards show damage, but Boral installation is not a weekend project. The boards cut with standard carbide blades, but the dust requires respirator protection; more critically, the flashing details at windows, doors, and foundations determine whether the wall assembly lasts 30 years or leaks in the first rain. We’ve been called to Sherman Oaks additions where the homeowner saved $3,000 on labor and spent $14,000 six months later remediating mold in the wall cavity.

What you can check: fastener type (magnet test - stainless steel is non-magnetic), end-seal condition at any visible cuts, and whether caulk joints have torn or separated. What you should not attempt: removing courses to inspect behind, cutting new pieces without dust control, or re-flashing penetrations. The structural connection between your existing home and the addition is governed by L.A. City code; pull a permit, or verify one exists, before any significant repair. Call (213) 221-0788 and we’ll schedule a free inspection with photo documentation - no charge, no pressure, written findings in hand before you decide.

FAQs