Therma-Tru Home Additions & ADU Nationwide

Therma-Tru Home Additions & ADU: The Oakland Owner’s Guide

Therma-Tru entry systems in Oakland home additions and ADUs typically run $45,000-$130,000 for a complete installed project, with door-specific components and integrated sidelite or transom units available for replacement or upgrade. We stock Therma-Tru-compatible frames, thresholds, and weatherseal kits for same-day installation on most Classic-Craft and Fiber-Classic series units. Most Oakland homeowners discover their Therma-Tru door system is failing when they notice water staining at the base of a sidelite or feel a draft they cannot trace to the weatherstrip alone.

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Which Therma-Tru Models This Applies To

The parts and installation protocols we carry apply across Therma-Tru’s three residential entry door lines: Fiber-Classic (the fiberglass skin over engineered frame), Classic-Craft (the premium fiberglass with deeper panel profiles), and Smooth-Star (the paint-ready fiberglass for high-humidity applications like ADU bathrooms and kitchenettes). Each series uses a different threshold geometry. Fiber-Classic and Classic-Craft share the adjustable composite sill with a 4-9/16 inch or 6-9/16 inch jamb depth, while Smooth-Star often ships with a fixed aluminum sill that traps water if the weep holes clog, a problem we see repeatedly in Oakland’s flat-sited ADUs where drainage was never properly graded.

To identify your unit, open the door and check the hinge jamb for a stamped manufacturing date and series code, or measure the slab thickness (most are 1-3/4 inch) and the overall frame width. The OEM part number will start with a series prefix: FC for Fiber-Classic, CC for Classic-Craft, SS for Smooth-Star. We source factory-direct components where the lead time justifies it, but for threshold and weatherseal replacements we typically use quality aftermarket equivalents that match the compression spec and carry the same thermal break rating. The aftermarket decision saves two to three weeks on delivery without sacrificing the R-value performance that matters in Oakland’s marine climate.

Signs Your Therma-Tru Home Additions & ADU Is Failing

• Water staining at the base of the door or adjacent drywall. The composite sill cap has cracked or the end seal dams have separated from the jamb legs, allowing runoff from Oakland’s winter storms to pool behind the threshold. In ADUs with concrete slabs, this moisture wicks upward and shows as efflorescence before the drywall ever darkens.
• Draft at the bottom corner even with the door closed and locked. The adjustable threshold cap has sagged or the compression seal has flattened beyond recovery. Therma-Tru’s adjustable sills use a turnscrew mechanism that strips if overtightened; we find this in roughly one-third of the failed units we inspect in the East Bay.
• Daylight visible between the door bottom and the sill. The door slab has settled on its hinges or the frame has shifted in the rough opening, a common issue in Oakland’s older stock where the original framing was never strapped for seismic movement. The gap is usually uneven, wider at the lock stile than the hinge stile.
• Sidelite glass fogs at the edges or shows condensation between panes. The insulated glass unit seal has failed, which on Therma-Tru sidelites means replacing the entire glass pack rather than attempting a field reglaze. The SDL or GBG grid pattern must match exactly for the unit to read correctly from the exterior.
• Difficulty latching or the deadbolt binding. The multi-point locking system has lost alignment with the keepers in the frame, often because the composite frame has absorbed moisture and swelled, or because the installation shim pack compressed over time. This is a security issue, not merely a convenience one.

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Replacement Cost & What’s Included

The range depends on three factors: whether the existing frame can be preserved or must be re-rough-opened, whether the finish is stain-grade or paint-ready, and whether the unit is a single door or a door-plus-sidelite configuration common in ADU front entries. Every quote we deliver is a flat written price with line-itemized components, material specifications with brand and model noted, and a written scope before any work begins. Under Clause 1 of The Haven Standard, that price does not change unless you sign a change order. Our 365-Day Done Right Promise covers the installation and the hardware function; the Therma-Tru factory warranty on the slab and glass remains with the original owner and transfers with the property.

DIY or Call Us?

An owner can safely inspect the threshold cap for cracks, verify that weep holes are unobstructed with a piece of wire, and check the hinge screws for tightness. These checks cost nothing and often reveal the obvious failure. What goes wrong in DIY is the threshold replacement itself: the composite sill must be cut to length with a fine-tooth blade to prevent delamination, the end caps must be bedded in sealant, and the jamb legs must be co-planar within 1/8 inch or the door will bind and the weatherstrip will not seat. We have rebuilt three Oakland ADU entries this year where the homeowner’s threshold replacement leaked worse than the original because the sill pan flashing was disturbed and never resealed. For multi-point hardware or sidelite glass, the tools and calibration are outside a typical homeowner’s kit. Call (628) 300-4376 and we will schedule a free estimate with a written price before any work starts.

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