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Therma-Tru Home Additions & ADU: The San Antonio Owner’s Guide
If you’re planning a home addition or ADU in San Antonio and want Therma-Tru doors, windows, or trim integrated into the build, a complete addition typically runs $45,000 – $130,000, with standalone ADU construction landing between $90,000 and $220,000 depending on square footage, foundation work, and finish level. Mason Remodeling Co San Antonio installs Therma-Tru-compatible entry systems, patio doors, and exterior trim as part of larger addition and ADU projects across Bexar County. Most homeowners reach out after realizing their existing exterior doors won’t survive the structural work, or after a builder quoted them cheap hollow-core doors that don’t hold up to Texas sun and humidity.
We’re an independent service provider, not affiliated with Therma-Tru. That independence means we tell you the truth about what holds up in San Antonio heat and what doesn’t, without a sales rep’s talking points in the room.
Which Therma-Tru Models This Applies To
Therma-Tru builds entry doors, patio doors, and sidelite systems across several lines: the Classic-Craft, Fiber-Classic, Smooth-Star, and Pulse series, plus the Benchmark line for patio configurations. For home additions and ADUs in San Antonio, the practical choice usually comes down to Fiber-Classic or Smooth-Star for budget-conscious builds, and Classic-Craft when the addition faces the street and needs real curb weight. The compatibility gotcha most people miss: Therma-Tru pre-hung units are sized for specific rough openings, and an addition’s framing needs to be set to the door’s published RO dimension, not the door slab size. A 36-inch door needs a rough opening larger than 36 inches, and getting that wrong during framing costs real money to fix later.
When matching a Therma-Tru unit to an addition, check the label on the hinge edge of any existing door you’re matching. It lists the series, size, and swing. For new construction, we spec the unit from the start so the framer knows exactly what rough opening to build. OEM Therma-Tru units carry the full manufacturer warranty and consistent color matching between slab, frame, and sidelites. Quality aftermarket equivalents exist for trim and weatherstripping, but for the door slab itself, OEM is usually worth the premium on an addition, because re-ordering a mismatched color months later is a headache nobody in San Antonio wants in August.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Door won’t latch without lifting or pulling. San Antonio’s clay-heavy soil shifts with drought and rain cycles, and a new addition settles in the first 12 to 24 months. A Therma-Tru door that latched fine in March and won’t catch by July usually means the frame moved, not that the hardware failed.
- Visible daylight around the door edges. Gaps at the top or latch side mean the weatherstripping is compressed beyond recovery or the rough opening was oversized. In a San Antonio summer, that gap is where air-conditioned air leaves and 100-degree air enters.
- Swelling or splitting at the bottom rail. The lower portion of any exterior door takes the most abuse from rain splash and humidity. Therma-Tru’s fiberglass slabs resist this better than wood, but the bottom sweep and threshold seal wear out and let moisture work the frame.
- Sidelite fogging or condensation between glass panes. Therma-Tru sidelites are insulated glass units, and once the seal fails, the fog never clears. This is common on west-facing additions around San Antonio where afternoon sun bakes the glass for years.
- Storm door or patio door dragging on the track. Benchmark patio doors collect grit from San Antonio’s limestone-heavy soil. Worn rollers and a dirty track make the door fight you, and forcing it bends the frame over time.
Replacement Cost & What’s Included
For an addition or ADU project in San Antonio where Therma-Tru doors and windows are part of the scope, the full build ranges from $45,000 to $130,000 for the addition and $90,000 to $220,000 for a complete ADU. If you’re replacing just the Therma-Tru entry system on an existing addition, expect $2,500 to $7,000 installed for a pre-hung fiberglass unit with sidelites, depending on size, glass options, and whether the rough opening needs adjustment. The price drivers are rough opening corrections, sill pan replacement, rot repair at the threshold, and hardware grade.
Every Mason Remodeling project includes a written price before any work starts. Not a verbal range. A written number with labor, materials, and what’s covered spelled out. Our 365-Day Done Right Promise means if the door doesn’t operate correctly within a year of completion, we come back and make it right at no cost to you. Isaac Pruett has been working San Antonio jobs for years, and he knows that a door that won’t latch is the kind of problem that erodes trust fast. So we don’t leave until it’s right.
See the difference
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AfterDIY or Call Us?
There are things you can check yourself. Confirm the hinges are tight. Look for loose screws at the strike plate. Clean the weatherstripping and check the sweep along the bottom. Those are homeowner-level tasks. What you should not do is pull the frame, resize a rough opening, or try to install a pre-hung Therma-Tru unit solo. A fiberglass entry door with sidelites can weigh over 200 pounds, and dropping it means broken glass, damaged slab, or a crushed foot. The frame also has to be shimmed, squared, and sealed correctly or the door will never operate smoothly. This is not a weekend project for most people, and we’d rather tell you that straight than watch you fight a door on the hottest Saturday of the year. Call (254) 269-5071 and we’ll take a look.
Key Takeaways
- Home additions in San Antonio run $45,000 – $130,000; ADUs run $90,000 – $220,000.
- Therma-Tru door replacements on existing additions typically cost $2,500 – $7,000 installed.
- San Antonio soil movement and summer heat are the two biggest threats to door performance on new additions.
- Written price before work starts, every project, no exceptions.
- 365-Day Done Right Promise covers the completed work for a full year.
FAQs
A properly installed Therma-Tru fiberglass door should last 20 to 30 years in San Antonio’s climate, but the weatherstripping, bottom sweep, and threshold usually need replacement every 5 to 8 years. The slab itself holds up well to heat and humidity. What fails first is the seal around it. Call (254) 269-5071 for an exact assessment of your door.
Yes, in many cases. Loose hinges, worn sweeps, failed weatherstripping, and misaligned strike plates are repairable without replacing the unit. If the frame is rotted or the slab is cracked, replacement is the honest answer. We’ll tell you which one you need, not which one makes us more money.
On an existing addition, a standard pre-hung Therma-Tru entry system replacement takes one day, including removing the old unit, correcting minor rough opening issues, installing the new door, and hauling the debris. If the rough opening needs structural work, add a second day. We’ll give you a written timeframe with the written price.
We stock common weatherstripping, thresholds, sweeps, and hardware on the truck for Therma-Tru-compatible units, along with materials we regularly use across KraftMaid, Cambria, and Silestone projects. Full door slabs and pre-hung units are ordered per project to match your addition’s exact specs. If we can fix it same-day with what’s on the truck, we will.
Written by Isaac Pruett, Owner, Mason Remodeling Co San Antonio at Mason Remodeling Co San Antonio, serving San Antonio and nearby areas.
Know who’s coming, know what it costs, know it’s covered – that’s the whole job before the job starts. Call (254) 269-5071 to schedule your free estimate.
