Therma-Tru Home Additions & ADU Nationwide

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

Therma-Tru entry systems in Santa Clara home additions and ADUs typically run $45,000-$130,000 installed, depending on whether you’re tying into an existing slab or building freestanding. We stock Therma-Tru-compatible sidelite frames, multi-point locking hardware, and composite jamb kits for same-day repair when the original unit starts to fail. Most Santa Clara owners notice the problem first as a draft along the sill or the deadbolt refusing to seat flush after the second rainy season.

Call (669) 259-1843

We are an independent service provider - not affiliated with Therma-Tru - and we source through the same distribution channel that supplies the Central Valley builders, which keeps our written quotes honest and our lead times short.

Which Therma-Tru Models This Applies To

Therma-Tru categorizes their entry systems by door slab type and frame construction, not by a single model year. For additions and ADUs in Santa Clara, we see three product families most often: the Classic-Craft fiberglass line with its compression-molded grain skin, the Smooth-Star primed series popular with painted modern facades, and the Benchmark by Therma-Tru builder-grade units installed in spec homes between 2015 and 2022.

The critical identifier is the hinge-side jamb label, usually a 2″ × 4″ sticker behind the interior casing. It lists the slab model (CCA for Classic-Craft American style, SM for Smooth-Star), the jamb depth (4-9/16″ or 6-9/16″ for 2×4 or 2×6 walls), and the bore location. Multi-point hardware varies by year: pre-2019 units used a two-bolt system with a 45mm backset, while current production runs a three-point with 55mm spacing. The bolt patterns do not interchange without routing the jamb, which is why we verify the label before ordering. OEM hardware from Therma-Tru carries a limited lifetime finish warranty; quality aftermarket equivalents from Hoppe and Baldwin match the function but carry shorter coverage. For Santa Clara’s salt-air exposure near the bay, we typically specify stainless-steel multi-point components regardless of OEM or aftermarket origin.

Signs Your Therma-Tru Home Additions & ADU Is Failing

• Deadbolt misalignment or sticking. The composite jamb has shifted or the hinge screws have backed out, a common issue in Santa Clara additions where the new slab settles differently than the original foundation. The bolt no longer enters the strike plate cleanly, and forcing it will oval the bore.
• Draft at the sill or weatherstrip compression set. The adjustable sill cap has lost its seal or the pile weatherstrip has flattened permanently. In Santa Clara’s dry summers followed by winter rains, vinyl pile hardens faster than in coastal fog zones.
• Condensation between sidelite and door frame. The thermal break in the sidelite frame has failed, or the insulating glass unit seal has breached. This shows up first on north-facing ADU entries where temperature swing is widest.
• Multi-point latch not engaging at all three points. The gearbox has worn internally, or the rods connecting top and bottom bolts have slipped their clips. One-point engagement is not secure; it is a failure mode that precedes frame stress.
• Fiberglass skin delamination or corner cracking. Impact damage or long-term UV exposure has separated the gel coat from the substrate. Classic-Craft doors with darker stain colors show this first in Santa Clara’s south and west exposures.

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Replacement Cost & What’s Included

The full addition or ADU range spans this wide because a freestanding unit needs foundation, MEP rough, and finish work, while a attached addition ties into existing structure. For component-level repair, we itemize parts and labor separately in the written quote - Clause 1 of the Haven Standard requires it. The gearbox we install carries a one-year functional warranty; the full prehung system carries the manufacturer’s limited lifetime plus our 365-Day Done Right Promise. No work proceeds on any change until the change order is signed, which is how we’ve kept 4,000-plus projects within a few percent of the agreed number since 2007.

DIY or Call Us?

An owner can safely inspect the jamb label, check for loose hinge screws, and photograph the sill cap adjustment screws for reference. What we do not recommend: routing a jamb for new multi-point hardware, removing a fixed sidelite from its frame, or attempting to reglaze an insulating glass unit. The multi-point gearbox is under spring tension; improper handling can release the rods with force. The sidelite frame is structural to the entry system; prying it loose without supporting the header risks frame racking.

Measure twice, document once, and never assume the last contractor left things square. Grant Rowan learned that lesson early, watching older homes in Beverly Hills get carved up and rebuilt badly. If you’re seeing any of the five symptoms above, call (669) 259-1843 and we’ll schedule a free estimate with a written price before any work starts.

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