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Therma-Tru Home Additions & ADU: The San Jose Owner’s Guide
If you’re planning a home addition or ADU in San Jose and want Therma-Tru doors as part of the build, a full addition typically runs $53,100 – $153,400 and an ADU runs $106,200 – $259,600, with Therma-Tru exterior doors adding roughly $800 – $4,500 per opening depending on the series and glass package. We frame, finish, and install Therma-Tru entry systems as part of our remodel scope, and we carry the common hinge, threshold, and weatherstrip components on the truck so a door that shifts or leaks after the addition settles doesn’t leave you waiting on a parts order. Most San Jose owners first notice a problem when the door starts dragging on the threshold, a corner of the frame pulls away from the new wall, or the weatherstrip no longer seals against the California dry-season dust that works its way into every gap.
We’re an independent San Jose contractor, not a Therma-Tru dealer or affiliate, which means we match the right Therma-Tru product to your addition without a brand pitch attached. Trevor Nash has been running remodel and addition projects across the South Bay for the better part of two decades, including a stretch of kitchen and bath work in Willow Glen he still considers some of his cleanest finish work. Give me the real problem and I’ll give you the real number.
Which Therma-Tru Models This Applies To
Therma-Tru builds entry systems, patio doors, and sidelight configurations across several series lines, and the model matters when you’re planning the rough opening for an addition or ADU. The Classic-Craft and Fiber-Classic lines are common in San Jose additions because they take paint well and hold up to the dry heat we get from July through October. The Smooth-Star line is the budget-conscious option that still carries a solid warranty, while the Pulse line adds that contemporary look a lot of Willow Glen and Campbell ADU owners want.
The compatibility gotcha most homeowners miss: Therma-Tru door slabs are interchangeable within a series, but the hinge prep and strike locations are not universal across series lines. A Classic-Craft slab won’t drop cleanly into a Smooth-Star frame without re-mortising the hinges. If you’re adding on and want to reuse an existing door, we check the series label on the hinge edge (it’s a small white tag with a code like CC, FC, or SS) before we size the rough opening. For new work, we spec the door before framing so the rough opening lands exactly where Therma-Tru’s installation guide says it should, which is a gap of 1/8 inch on each jamb side and 3/16 inch at the header.
One thing specific to our climate: San Jose’s dry summers cause fiberglass door frames to move less than wood, but the direct afternoon sun on a west-facing entry will fade a factory finish faster than the warranty assumes. We generally recommend a solid-body paint color with UV-stable pigments for any Therma-Tru door that faces the afternoon sun in neighborhoods like Almaden Valley or Evergreen.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- The door drags on the threshold. This usually means the addition’s slab has settled a fraction of an inch, which throws the reveal off. Therma-Tru frames are stiff, so the door can’t flex to compensate the way a wood door would.
- You can see daylight around the weatherstrip. After a dry San Jose summer the weatherstrip can compress and stay compressed. When the rainy season hits, the first storm finds that gap and you’ll see water staining at the sill.
- The door won’t latch without lifting the handle. This means the frame has racked slightly out of square, common in the first year after an addition as the new foundation settles independently of the original house.
- The bottom sweep is torn or brittle. Therma-Tru sweeps are replaceable, but a damaged one lets dust and cold air in. In San Jose it’s more dust than cold, but the dust is relentless from May through October.
- The frame shows a hairline crack at a corner joint. Fiberglass frames don’t crack on their own, which means the rough opening was undersized or the header is deflecting under load. That’s a structural flag worth a look.
Replacement Cost & What’s Included
In San Jose, a new Therma-Tru entry door installed as part of a home addition or ADU project runs $800 – $4,500 per opening, with the spread driven primarily by the series line, the glass package (a half-lite with decorative glass easily doubles the slab cost), and whether the frame itself needs re-shimming or full replacement. A straight slab swap on an existing frame with reusable hinges lands at the low end; a full-frame replacement with new brickmold, sill pan, and exterior trim work climbs toward the top.
Every quote we write includes the door, the hardware, the weatherstrip, the sealants, the labor, and the haul-away of the old unit. The written price you get before work starts is the price on the invoice. No change orders because we found something after demo, no re-trip fee if the door needs adjustment after the addition settles. That’s the Kingswell Way: say the price before the work, show up in the window we gave, leave the place cleaner than we found it.
Our 365-Day Done Right Promise covers the installation in writing. If the door binds, leaks, or fails to latch properly inside a year, we come back and fix it at no charge. No service call fee, no re-inspection fee. And because we install Therma-Tru products, the door itself carries the manufacturer’s warranty on top of our workmanship guarantee.
See the difference
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AfterDIY or Call Us?
There’s a fair amount an owner can check before calling anyone: look at the reveal gaps around the door, check whether the hinges are tight, and see if the threshold screws have backed out. Those are safe to inspect, and sometimes a dragging door is just a threshold that’s adjusted too high for how the addition settled.
Whats not safe or practical for most owners is re-setting a Therma-Tru frame in a rough opening. These frames are heavy, they need to be shimmed in a specific sequence, and the sill pan under the threshold has to be flashed correctly or you’re creating a slow water leak into your new addition. We’ve also seen DIY slab swaps where the hinge mortises didn’t line up and the owner wound up buying a second door. If the frame is out of square or the door binds, call (669) 274-2362 and we’ll square up what’s happening before you spend money on parts that won’t fix it.
FAQs
A properly installed Therma-Tru fiberglass door in San Jose lasts 25 to 30 years on average, though the weatherstrip and bottom sweep usually need replacing every 5 to 7 years because our dry summers bake the rubber. Call (669) 274-2362 for a quote on a sweep or weatherstrip swap, estimates are free.
Yes, we regularly repair hinges, thresholds, weatherstrip, and latch alignment on Therma-Tru doors without replacing the slab, typically for $200 – $600 in San Jose depending on the specific part and the extent of the frame adjustment. Call (669) 274-2362 and we’ll tell you honestly whether the door is worth saving.
A slab swap takes about half a day including hardware transfer and weatherstrip; a full-frame replacement with trim work takes a full day, sometimes two if we’re matching stucco texture or exterior paint on a San Jose addition. Call (669) 274-2362 for a written price and a real arrival window.
We keep common Therma-Tru-compatible hinges, thresholds, sweeps, and weatherstrip on the truck for most series lines, so a weather-related or settlement callout in San Jose usually gets handled in one visit. For full door slabs and sidelight glass, we order per job and turnaround is typically 1 to 2 weeks depending on the series and glass package.
Get Your Therma-Tru Addition or ADU Door Priced in Writing
If you’re planning a home addition or ADU in San Jose and want Therma-Tru doors done right, call (669) 274-2362 for a free estimate. We’ll put the price in writing before any work starts, cover the installation with our 365-Day Done Right Promise, and send a background-checked, uniformed technician who knows the difference between a Classic-Craft and a Smooth-Star rough opening. No pressure, no change orders, just a real number you can hold us to. We also work with KraftMaid cabinetry, Cambria and Silestone countertops when your addition or ADU needs the full remodel scope.
Written by Trevor Nash, Owner, Penhallow Remodeling San Jose at Penhallow Remodeling San Jose, serving San Jose and nearby areas.
