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Therma-Tru Home Additions & ADU: The Austin Owner’s Guide
If you’re planning a home addition or ADU in Austin and want Therma-Tru doors and entry systems integrated into the build, we handle the full construction scope, from framing and foundation work to installing and weather-sealing Therma-Tru entry doors, patio doors, and sidelights. A complete home addition in Austin typically runs $45,000 to $130,000, while a detached ADU runs $90,000 to $220,000. Most homeowners call us after they’ve already bought Therma-Tru products or after a previous contractor installed them incorrectly, and they’re dealing with gaps, sticking, or water intrusion around the door frames.
Therma-Tru makes entry doors, not additions, so this page is for Austin homeowners who want their addition or ADU built correctly around Therma-Tru products. What we see most often: a homeowner orders a Therma-Tru door with a specific rough opening dimension, the framing crew doesn’t build the opening to spec, and the door never hangs right. That’s the failure point we fix and prevent. Isaac Pruett and our crew have framed additions and ADUs throughout Austin, including several projects in Mueller, and we’ve learned which Therma-Tru install mistakes show up a year later when the Texas heat and humidity settle in.
Key Takeaways:
- Home additions in Austin: $45,000 – $130,000 installed, depending on square footage, foundation type, and finish level.
- ADU construction in Austin: $90,000 – $220,000, with City of Austin permitting and site prep included.
- Therma-Tru door installation is part of our framing and finish scope, not an afterthought.
- Written price before any work starts, every time, no exceptions.
- 365-Day Done Right Promise: if it’s not right within a year of completion, we make it right at no cost.
Which Therma-Tru Models This Applies To
Therma-Tru’s residential line covers three main series that show up in Austin additions and ADUs: the Classic-Craft, the Pulse, and the Smooth-Star. Classic-Craft is their fiberglass wood-grain line, built to mimic hardwood but rated for the heat and moisture swings we get here. Pulse is their premium fiberglass with dent resistance and higher R-values, which matters when you’re adding square footage and want to keep cooling costs down. Smooth-Star is the smooth-skin fiberglass entry point, more budget-friendly but still solid.
The compatibility gotcha with Therma-Tru is rough opening size. Their doors are manufactured to fit specific rough opening dimensions, and unlike a wood slab door you can plane down on site, a Therma-Tru unit is a complete pre-hung system. If your framing is off by a half inch, you don’t shave the door, you fix the opening. We verify every rough opening against the Therma-Tru spec sheet before we set the frame, because retrofitting a mis-framed opening costs real money and the door still won’t seal correctly.
We are an independent Austin remodeling contractor. We’re not affiliated with Therma-Tru, but we install and integrate their products into additions and ADUs every year, and we’ve learned exactly where the failures happen.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Door sticks or binds at the top latch side in summer. Austin’s heat and humidity expand framing lumber and the slab shifts. The underlying cause is often a rough opening that was too tight from day one, or a header that’s picking up roof load it wasn’t sized for.
- Visible light or air gaps at the door perimeter. Therma-Tru doors ship with a specific gap tolerance. If you see daylight at the weatherstripping, the frame isn’t square or the threshold wasn’t set level, and your cooling is literally leaking out.
- Water staining at the threshold or bottom corners. A Therma-Tru door that’s installed without proper flashing or with the sill pan done wrong will let water in during heavy Austin thunderstorms. In Mueller, we’ve seen this on additions where the siding crew, not the framing crew, set the doors.
- Cracks in the drywall above or beside the door. This points to a header issue or too much flex in the wall assembly. The door may still operate, but the structure around it is moving, and in an ADU it’s usually the wall that also carries the roof load.
- Door slab aligns fine but the deadbolt fights you. When the strike plate no longer lines up, the frame has racked. On an addition, this usually means settling at the foundation or a missing shear panel transfer. A new deadbolt won’t fix the rack.
See the difference
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AfterReplacement Cost & What’s Included
Home additions and ADUs in Austin are priced by square footage, foundation condition, utility runs, and finish level. A ground-level addition with basic finishes starts around $45,000. A 600 – 800 square foot ADU with a kitchenette, bathroom, and independent electric panel typically lands between $90,000 and $220,000. If Therma-Tru doors are part of the scope, we include them in the written quote as a line item, so you see the door unit cost, flashing, hardware, and installation broken out separately.
What drives the range more than anything is whether we’re building on a slab, over a crawl space, or on piers. In central Austin, many lots have expansive clay soil, which means pier foundations and more structural steel. That’s a real cost difference, not contractor markup. Every project comes with a written price before any work begins, and that’s not a promotion, it’s how we operate.
Our labor and installation work is covered by the 365-Day Done Right Promise. If something we built or installed isn’t right within 365 days of the completion date, we come back and make it right at no cost. If a Therma-Tru product itself fails under warranty, we handle the removal and reinstallation, and we coordinate with the manufacturer on your behalf.
DIY or Call Us?
For a Therma-Tru door that’s sticking or leaking on an existing addition, there are small things you can check yourself: the threshold height adjustment, the weatherstripping condition, and whether the hinge screws have backed out. If adjusting those doesn’t resolve it, stop there. The next steps involve checking the rough opening, fixing framing, and possibly reframing the header, and that’s structural work.
When it comes to the addition or ADU itself, we always recommend a licensed general contractor, and here’s why: Austin’s permit process for additions and ADUs requires sealed drawings, site plans, and in some cases energy calculations. If the foundation or structure is done wrong, the Therma-Tru door you paid $3,000 for will never close right. Tell me what’s wrong with it. We’ll figure out what it actually needs. If it’s a full addition or ADU build, or if the door frame itself is the problem, call (903) 623-1966. The estimate is free.
FAQs
A properly installed Therma-Tru fiberglass door should last 25 to 40 years in Austin’s climate, but the frame, flashing, and weatherstripping need attention every 5 to 7 years because summer heat and occasional freezes harden the seals. The slab itself rarely fails first; the installation around it does. Call (903) 623-1966 and we’ll inspect the installation, not just the door.
Yes, in many cases we can add shims, reface the jamb, or make structural adjustments to correct a rough opening without tearing out the entire wall, but it depends on how far off the opening is and whether there’s a load issue at the header. The fix may cost $800 to $2,500, versus $4,500 to $11,000 for a full frame reconstruction. We’ll always quote the least invasive fix that actually fixes the problem, and call (903) 623-1966 for an exact assessment.
A ground-level addition typically takes 10 to 16 weeks from start to finish in Austin, and an ADU takes 4 to 8 months depending on permitting, utility work, and foundation type. Therma-Tru door installation happens in the finish phase, usually 1 to 2 days including flashing and hardware. Call (903) 623-1966 for a schedule estimate based on your scope.
We don’t stock complete Therma-Tru door units on our trucks because each is built to specific rough opening dimensions and finish options, but we do stock the installation components: flashing, sill pans, shim packs, and weatherseal kits. We also work with KraftMaid, Cambria, and Silestone for other parts of the build, so you’re not juggling multiple suppliers. Call (903) 623-1966 to get your Therma-Tru door ordered to exact spec.
Written by Isaac Pruett, Owner, Mason Remodeling Co Austin at Mason Remodeling Co Austin, serving Austin and nearby areas.
