Therma-Tru Windows & Doors Nationwide

Therma-Tru Windows & Doors: The Cupertino Owner’s Guide

We stock and install Therma-Tru-compatible windows and doors across Cupertino, with typical installed replacement costs running $4,500-$15,000 for full window sets and entry door systems depending on series and sizing. Most Therma-Tru parts we carry same-day: hinges, multipoint locking hardware, sill caps, compression seals, and insulated glass units for the Classic-Craft, Fiber-Classic, and Smooth-Star lines. Homeowners usually discover a failure when the multipoint lock won’t engage evenly, they feel a draft along the jamb in January despite the latch appearing closed, or condensation appears between the glass panes of a door installed during the 2015-2019 building boom in Cupertino’s Monta Vista and Rancho Rinconada neighborhoods.

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Which Therma-Tru Models This Applies To

Therma-Tru organizes its entry systems by door material and construction, and the part you need depends on which series is hung in your frame. Classic-Craft uses a high-density polyurethane core with oak or mahogany grain; Fiber-Classic is fiberglass-skinned with a composite stile-and-rail; Smooth-Star is the paint-ready fiberglass door with a smoother surface. The multipoint hardware differs across all three: Classic-Craft typically ships with a 45/92mm backset and a 16mm faceplate, while Smooth-Star often uses a narrower 20mm faceplate that looks identical until you measure.

To identify your part, check the hinge edge of the door slab for a stamped manufacturing date and series code, or open the multipoint lock chassis and look for the Truth Hardware or Fuhr model number molded into the mechanism. We source OEM Therma-Tru hardware and also stock quality aftermarket equivalents from Truth and Hoppe that match the spec without the markup. The aftermarket route saves roughly 15-25% on hardware-only jobs, though we recommend OEM for Classic-Craft mahogany-grain doors where the strike-plate finish must match exactly.

Signs Your Therma-Tru Windows & Doors Is Failing

• The multipoint lock handle lifts but the bolts don’t extend fully. This usually means the gearbox inside the mechanism has stripped teeth from repeated operation against a misaligned keep. In Cupertino, we see this most on west-facing doors where thermal expansion from afternoon sun shifts the jamb slightly seasonally.
• Condensation or fog between the glass panes of a door lite. The insulated glass unit (IGU) seal has failed, releasing the argon fill and allowing moisture migration. Once the desiccant saturates, the fog becomes permanent; the IGU must be replaced, not the entire door.
• Draft at the sill or jamb despite the door appearing latched. Compression seals harden over 7-10 years in California’s UV exposure, losing their memory. The door may “feel” closed while leaking air at 15-25 cubic feet per minute, which shows up on PG&E bills before it shows up as discomfort.
• The door sticks or rubs at the top corner seasonally. This indicates jamb movement from foundation settlement or inadequate shimming during original installation. In Cupertino’s clay-heavy soils, particularly in the foothill zones, we see this pattern repeat every dry summer after a wet winter.
• Water staining at the bottom of the frame or subfloor. The sill pan or flashing tape has failed, or the weep holes in a vinyl sill are clogged with debris. Left unaddressed, this rots the subfloor and the bottom rail of the door, turning a $400 sill repair into a $4,000+ door-and-frame replacement.

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Replacement Cost & What’s Included

Full Therma-Tru window replacement in Cupertino typically runs $4,500-$15,000 depending on unit count, series, and whether we’re working within existing openings or reframing. Entry door systems range $3,000-$8,500 installed for standard 3/0 x 6/8 openings with sidelites running higher. Hardware-only repairs: multipoint lock mechanism replacement $280-$520; IGU replacement in a door lite $340-$680; sill cap or compression seal replacement $180-$350.

Every quote we write in Cupertino includes the part, labor, disposal of the old component, and a test-fit verification before we leave. Under Clause 1 of the Haven Standard, that number is written before anyone picks up a tool. Our 365-Day Done Right Promise covers the installation and the part; if the lock doesn’t seat cleanly or the seal doesn’t test tight, we return and make it right. We also document every visit with a photo record, included as standard, so you have evidence of the condition we found and the condition we left.

DIY or Call Us?

There’s a clear line between what an owner can verify and what requires the door to come off the hinges. You can safely check: whether the keeps are loose in the frame (tighten with a driver), whether weep holes are clogged (a pipe cleaner works), and whether the threshold screws have backed out. What goes wrong in DIY: homeowners who remove a multipoint lock mechanism without supporting the door slab first, which drops the weight onto the remaining hinges and bends the pivot pins; or those who try to reglaze an IGU with caulk from the hardware store, trapping moisture and voiding any remaining warranty.

We’re not affiliated with Therma-Tru, but we’ve installed and serviced their products in Cupertino since 2007. If you’re unsure whether you have a Classic-Craft or a Fiber-Classic, or whether that fog between the glass is a seal failure or surface condensation, call us at (669) 202-9618 and we’ll sort it out. Estimates are free, and we bring the right parts to the first visit more often than not.

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