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Get your free estimateTherma-Tru Window Installation: The San Antonio Owner’s Guide
If you need Therma-Tru window installation in San Antonio, we stock Therma-Tru-compatible hardware and sash components on our service trucks, and most single-window mounting or reinstallation jobs run between $275 and $620 per opening, including labor and the specific parts your unit requires. We answer the phone live, and in most cases we can have a technician at your home within one to two business days to match the part and set a firm price in writing. What usually brings owners to this page is a window that no longer seals tight against the San Antonio heat, a sash that binds when you try to open it, or a frame that has started to pull away from the rough opening after years of clay-soil shifting.
Which Therma-Tru Models This Applies To
Our San Antonio installs cover Therma-Tru casement, double-hung, sliding, and picture window lines, including units that were originally paired with Therma-Tru entry doors as part of a manufactured home or light-commercial package. The most common compatibility gotcha we see is with the balance system: Therma-Tru double-hungs use a block-and-tackle balance in older series and a constant-force coil balance in newer builds, and the two do not interchange even when the window sash dimensions are identical. We also carry the matching pivot bars and tilt latches, since a balance replacement without the right pivot bar leaves the sash rattling in the track. If your windows came with the home and the paperwork is long gone, look for two identifiers: an AAMA certification sticker on the sash edge, and a four-digit spacer code etched into the corner of the insulated glass unit. Those two details together tell us the series, the glass pack, and the hardware generation. Lightwell Windows San Antonio is an independent service provider and not affiliated with Therma-Tru, but our technicians work with these units every week and keep the common OEM part numbers organized on the truck.
Styles & brands we work with
Signs Your Therma-Tru Window Installation Is Failing
- Condensation between the glass panes. The spacer seal has failed and the argon or krypton gas has escaped. This happens faster in San Antonio because the thermal cycling between air-conditioned interiors and 100-degree exteriors stresses the seal every afternoon. The fix is a new insulated glass unit, not a caulk bead.
- Visible daylight around the sash edges when the window is closed and locked. This usually means the weatherstripping has compressed permanently or the sash has warped slightly. The thermal break is gone, and your air conditioner is paying for it.
- The upper sash on a double-hung slides down on its own. The balance system has lost tension, or a pivot bar has snapped. This is a hardware issue that gets worse the longer it is ignored because the sash starts wearing an uneven groove in the jamb liner.
- You have to lift or pull the sash sideways to get it to move. The frame has shifted, or the shoe has jumped the track. In San Antonio’s expansive clay soil, this is more common than people expect; the ground moves, and a rigid frame moves with it.
- Drafts in winter, or a room that smells like the outside after it rains. The frame-to-rough-opening seal may have failed behind the trim. This is a reinstallation fix, not a sash fix, and it requires pulling the trim to re-foam and re-seal the perimeter properly.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
For San Antonio homes, here is what we typically see on Therma-Tru window installation and part replacement work:
- Full sash replacement with re-seal and balance adjustment: $275 – $410 per window
- Balance and pivot bar replacement (double-hung): $180 – $260 per window
- Insulated glass unit replacement: $310 – $520 per sash, depending on glass package and Low-E coating
- Full window re-installation, including trim removal, re-foaming, shimming, and re-trimming: $480 – $620 per opening
- Weatherstripping kit, sash realignment, and hardware tune-up: $140 – $210 per window
Every quote is a written line-item price before any work starts. That price covers the parts, the labor, the cleanup, and the 365-Day Done Right Promise that says if the finished work is not right, we make it right. No surcharge at the end because we found something unexpected; if the scope changes during the job, we stop and explain the new number before touching another screw.
DIY or Call Us?
Some things are worth checking yourself. You can inspect the weatherstripping for gaps, note which windows are binding and when, and look at whether the trim has pulled away from the frame. You can also remove a sash on many double-hungs using the tilt tabs and check whether the pivot bar is intact. What you should not do is try to replace a balance system that is still under tension, or attempt to re-mount a heavy sash without the right lifting technique; a double-hung sash on a large Therma-Tru unit can easily weigh 30 to 40 pounds, and the wrong grab sends you to urgent care. Glass unit replacement is also not a weekend project; cutting the old seal cleanly and setting the new IGU without cracking the frame corner is where most DIY jobs go wrong, and you pay twice. If you would rather have it measured, matched, and mounted by someone who does this daily, call Keith Yamada and the crew at (325) 420-4173. We will tell you over the phone whether it sounds like a part we can match same-visit or something we need to order.
FAQs
A properly installed Therma-Tru window should hold up for 15 to 25 years in the San Antonio climate, with the glass seal being the first thing to go, typically around year 12 to 15 when the afternoon sun hits a west-facing wall hard.
Yes, in most cases we can replace the balance, pivot bar, or weatherstripping and keep the original sash and frame. The exception is a failed glass seal, which means the insulated glass unit itself needs replacement rather than repair.
A balance or hardware swap usually takes 45 to 90 minutes per window, while an insulated glass unit replacement runs about two to three hours including sealant cure time. A full re-installation of an existing unit takes half a day on average.
We carry common Therma-Tru balances, pivot bars, tilt latches, and weatherstripping on our service trucks in San Antonio, and we can source specific glass packs or full sash assemblies within a few days if the unit is an unusual size. We also keep parts for PGT, CGI, and CWS window systems when a mixed-brand home needs attention on the same visit.
If your Therma-Tru window is not closing the way it should, or you want a straight answer on whether it is worth fixing or replacing, call us at (325) 420-4173. We will walk you through what we need to know, schedule the visit, and put a written price in your hands before the first tool comes off the truck.
Written by Keith Yamada, Owner, Lightwell Windows San Antonio at Lightwell Windows San Antonio, serving San Antonio and nearby areas.
Six Reasons Homeowners Choose Lightwell Windows San Antonio
Laminated glass and reinforced frames hold up to wind-driven rain, hail and flying debris, so your openings stay sealed when the weather turns.
Low-E insulated impact glass from our manufacturer lines commonly cuts monthly cooling bills 20-30%.
Laminated impact glass shuts out up to 40% of outside noise - traffic, neighbors, weather.
Monitoring services run $30-90 a month. Laminated impact glass resists forced entry around the clock, with no subscription.
Tighter seals and insulated glass even out hot and cold rooms and stop the drafts at the frame.
A full impact package upgrades curb appeal, buyer confidence and appraised value in one project.