Tamko Home Additions & ADU Nationwide

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

We stock and install Tamko-compatible roofing, waterproofing, and structural components for home additions and ADUs in Sherman Oaks, with typical installed pricing from $45,000 to $130,000 for full additions and $90,000 to $220,000 for detached ADUs. Most Sherman Oaks homeowners discover their Tamko materials need attention during the dry-season inspection cycle, when cracked Heritage-series shingles or compromised underlayment show up as interior stains after the first hard rain. Measure twice, write it down, then build it.

Call (213) 221-0788

Which Tamko Models This Applies To

Tamko’s product lines for our market break into three categories relevant to additions and ADUs. The Heritage series architectural shingles, common on Sherman Oaks additions built between 2010 and 2020, carry a 30-year limited warranty and measure 39 3/8 inches by 13 3/4 inches per shingle, with a 5 5/8-inch exposure. The Titan XT line, a newer impact-resistant shingle we see on ADUs permitted after 2019, uses a modified asphalt core rated to Class 4 impact resistance, which matters for insurance discounts in LA County. The MetalWorks steel shingles, less common but specified on some modernist ADU designs near the Galleria corridor, interlock with a four-way locking system that fails if the clip geometry is off by even 1/8 inch.

Identifying your Tamko product starts with the package label, usually visible in any leftover bundles stored in the garage or shed. The date code and lot number matter for color matching, Tamko has discontinued certain Heritage color blends including Antique Slate and Rustic Black in the California market, so we verify current availability before quoting. For underlayment, Tamko’s TW Metal and Tile Underlayment, a self-adhering membrane used on low-slope ADU roof sections, carries a printed “TW” logo on the release film; generic equivalents exist but vary in thickness from 30 to 40 mils, and the 30-mil product we pulled off a failed ADU roof in the hills north of Ventura Boulevard had cracked at the seams within seven years. We source OEM Tamko or certified equivalents from our vetted supplier list, fifty-plus brands deep, so the written quote reflects actual material cost rather than a padded contingency.

Signs Your Tamko Home Additions & ADU Is Failing

• Granule loss exposing the asphalt core. Tamko Heritage shingles shed granules faster on south-facing ADU roofs in Sherman Oaks, where summer surface temperatures exceed 160°F. Once the core is visible, UV degradation accelerates and water intrusion follows within one to two rainy seasons.
• Curling or clawing at shingle edges. This indicates the fiberglass mat has separated from the asphalt, often from inadequate attic ventilation in additions where the original home’s airflow pattern wasn’t extended. The shingle is no longer anchored and will lift in Santa Ana wind events.
• Interior staining on addition ceilings after rain. On ADUs with Tamko TW underlayment, this typically traces to failed seam tape or fastener penetrations that weren’t sealed with compatible mastic. The water travels laterally along the deck before dripping, so the stain location rarely matches the leak origin.
• Metal shingle panels that rattle or shift in wind. Tamko MetalWorks uses a hidden clip system; if the installer used generic clips or overdrove the fasteners, the interlock geometry degrades and panels can lift. We found this on a 2018 ADU near Dickens Street where the original crew had substituted standard roofing nails for the specified screws.
• Sagging or soft spots in low-slope roof areas. On ADUs with Tamko’s modified bitumen or TPO systems, ponding water breaks down the membrane at seams and penetrations. Sherman Oaks building code requires 1/4 inch per foot minimum slope on new flat roofs; older additions often sit at 1/8 inch or less, and the material pays the price.

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Replacement Cost & What’s Included

Full Tamko roof replacement on a Sherman Oaks home addition runs $8,000 to $20,000, with ADU re-roofs at the lower end due to smaller footprint and simpler access. The range reflects three variables: whether we’re removing one layer or two (LA County allows two layers maximum, and some 1970s additions have hit that limit), the pitch and height of the roof (steeper means more labor hours and safety rigging), and whether the original deck needs partial replacement, which we find in about 30 percent of addition projects where the original contractor used 3/8-inch plywood instead of the current 1/2-inch minimum.

Every quote from Rowan Construction Group is a flat written price with line-item breakdown: material (Tamko or equivalent, specified by series and color), labor, deck repair if indicated, permit fees, and haul-away. Under Clause 1 of the Haven Standard, that price is delivered before anyone picks up a tool. The 365-Day Done Right Promise covers the workmanship, and Tamko’s own limited warranty transfers to the new owner if you sell. We also stock KraftMaid and Wellborn cabinets, Cambria and Caesarstone countertops, and other brands for the interior finish, so the addition quote can include the whole scope without subcontractor markup.

DIY or Call Us?

A homeowner can safely inspect from the ground with binoculars or from a secured ladder at the eaves, looking for the symptoms above. What you should not do: walk a pitched roof without fall protection, attempt to remove and replace shingles in the summer heat when the asphalt is too pliable to seal properly, or try to heat-weld TPO membrane seams with a hardware-store heat gun. The seam welding requires 600°F controlled application and a 1 1/2-inch roller pass, and a partial weld fails catastrophically. We’ve been called to three Sherman Oaks ADUs in the past two years where the owner’s DIY membrane repair held for one season, then peeled in a January storm and tripled the water damage. For the inspection and the work, call (213) 221-0788 and we’ll schedule a free estimate with a written price before any work starts.

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