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Therma-Tru Home Additions & ADU: The Austin Owner’s Guide
Therma-Tru home additions and ADU construction in Austin typically run $45,000 – $130,000 installed, depending on square footage, foundation work, and how much of the existing home has to be tied into. At Penhallow Remodeling Austin, we handle the full build, not just the door package, so if your Therma-Tru entry system is part of a larger addition or detached ADU, the price is written down before we open a single wall. Most owners discover this scope of work isn’t a “part” issue at all: the door jamb is fine, but the house around it has shifted, the subfloor under it is spongy, or the rough opening was never framed correctly to begin with. That’s what we’re actually fixing.
Trevor Nash has been walking Austin job sites long enough to know that a Therma-Tru door rarely fails in isolation. The problem is usually water, heat, or framing, and Travis County’s clay soil pulls more door frames out of square than most people realize.
Which Therma-Tru Models This Applies To
Any Therma-Tru Classic-Craft, Fiber-Classic, or Smooth-Star entry system that’s being incorporated into a new addition or ADU falls under this work. The compatibility point that matters isn’t the door slab, it’s the rough opening and the sill pan. Therma-Tru frames are built to a published rough opening spec, and when an Austin addition settles even a quarter inch, the door binds at the latch or lets air through at the bottom. We measure the rough opening first, then match the door package to what the framing actually is, not what the original plans said.
OEM Therma-Tru parts are worth paying for on the exterior envelope: sills, weatherstripping, and the composite jambs hold up better in Texas humidity than most aftermarket options. But for interior trim, casing, and threshold extensions that get painted anyway, quality aftermarket millwork saves real money without touching the warranty on the door itself. Penhallow Remodeling Austin is an independent contractor, not affiliated with Therma-Tru, and we stock the common factory components while pulling the rest from our local supply house in Cedar Park.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Door binds against the jamb on hot afternoons. Austin heat expands the slab slightly, and if the rough opening was framed too tight, the door sticks. This is a framing tolerance issue, not a door defect, and it only gets worse in August.
- Water stains on the interior floor near the threshold. The sill pan under the door wasn’t flashed properly when the addition was built. In a town that gets flash floods off Highway 290, a missing sill pan means water inside every time it storms.
- The door no longer latches without lifting the handle. Foundation movement below the ADU slab has dropped one corner of the rough opening. Austin’s expansive clay soil moves more than most homeowners expect, and it shows up at the door first.
- Visible gap at the top corner opposite the hinges. The header above the rough opening has settled or the trimmer stud wasn’t seated. This is structural, not cosmetic, and it’s the kind of thing a painter’s caulk won’t hide for long.
- You can see daylight through the weatherstripping. The weatherseal has compressed after five or six Austin summers. Therma-Tru’s bulb seals lose their memory in extreme heat, and a door that won’t seal is costing you money on the AC bill.
See the difference
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After
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AfterReplacement Cost & What’s Included
For Austin work, a full Therma-Tru-compatible home addition runs $45,000 – $130,000, and a detached ADU lands at $90,000 – $220,000. What drives that number: the foundation type (slab-on-grade versus pier-and-beam), how far we have to run plumbing and electrical, the door package you select, and whether the existing roofline ties in cleanly or requires a cricket and re-flashing. When the door itself needs replacing inside that larger project, the door and hardware usually add $1,500 – $4,000 depending on glass package and finish.
Every estimate from Penhallow Remodeling Austin is a written number, not a range. It includes materials, labor, permits, and the 365-Day Done Right Promise in writing. We source Therma-Tru frames and slabs, and the trade brands behind the rest of the job, KraftMaid, Cambria, and Silestone among them, carry the same standard we put in our contract: if it fails inside a year, we fix it at no charge.
DIY or Call Us?
You can check the obvious things yourself: look at the gap between the door slab and the frame at all four corners, run a dollar bill along the weatherstripping to find dead spots, and watch for water pooling at the threshold after rain. None of that requires a tool. But when the rough opening is out of square or the foundation has moved, pulling the door and shimming it back into place without addressing the structure underneath is a waste of a weekend.
Framing, sill pan replacement, and any work that involves cutting into a load-bearing wall is where we say plainly: call us. More than one Austin homeowner has found out the hard way that a door that won’t latch is a sign of a problem that starts three feet below grade. Tell me what you need, I’ll tell you what it costs, and we’ll go from there. Call (325) 225-5429 for a free estimate, and we’ll put the number in writing before any work starts.
FAQs
A properly installed Therma-Tru entry system on a well-flashed rough opening should last 20 to 30 years in Austin. What shortens that lifespan is water at the sill and sattle movement from clay soil, both of which come from the framing and flashing work, not the door itself.
Often yes, if the slab is still sound and the failure is in the weatherstripping, thresholds, or alignment shims. If the jamb has rot or the rough opening has shifted more than a quarter inch, we’ll recommend replacing the frame and addressing the foundation issue rather than patching a door that will fail again. Call (325) 225-5429 and we’ll tell you which one you’re looking at.
The door portion of a larger addition or ADU typically takes two to three working days once the framing inspection passes. The full addition project depends on scope, but the door never holds up the schedule when we’re running the job.
We keep common Therma-Tru weatherseals, sweeps, and composite threshold components on the truck, and our supply house in Cedar Park stocks the full frame and slab line. If you have a specific model, photo the sticker on the hinge edge before you call, it tells us everything we need.
Written by Trevor Nash, Owner, Penhallow Remodeling Austin at Penhallow Remodeling Austin, serving Austin and nearby areas.
