Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Therma-Tru Home Additions & ADU: The Dallas Owner’s Guide
If you’re planning a home addition or ADU in Dallas and want Therma-Tru doors and trim specified into the build, you’re looking at $45,000 to $130,000 for the addition itself, with Therma-Tru entry systems, sliding doors, and weatherstripping adding roughly $2,500 to $8,000 depending on door count and series. We spec, order, and install Therma-Tru products as part of our addition and ADU builds, and we keep common replacement seals, thresholds, and hinge kits on hand for existing Therma-Tru doors that have started underperforming. Most Dallas homeowners discover a Therma-Tru failure the same way: a door that suddenly sticks in August, a sweep that lets dust blow in from the alley, or an ADU entry that won’t latch cleanly after a foundation shift.
We’re an independent Dallas remodeling contractor, not affiliated with Therma-Tru, but we’ve built enough additions and ADUs with their door systems to know exactly what holds up here and what doesn’t.
Which Therma-Tru Models This Applies To
Therma-Tru’s residential lineup splits into a few families that matter for Dallas additions and ADUs. The Smooth-Star series is fiberglass with a smooth finish, commonly spec’d for ADU entries because it takes paint well and handles direct sun without warping. The Classic-Craft line is their higher-end fiberglass that mimics wood grain, often chosen for main-house additions where the door faces the street. The Pulse series is their premium foam-core door, heavier and quieter, which matters when the addition is a home office or rental unit.
Here’s the compatibility gotcha: Therma-Tru slabs and frames are machined as a system. You can’t always drop a Therma-Tru slab into a generic frame and keep the weather seal intact. The hinge prep, corner pads, and threshold profile are specific. That’s why when an addition goes wrong on a Therma-Tru install, it’s usually because someone mixed a big-box frame with a Therma-Tru slab. We order the slab and frame as matched units. For replacement parts like sweeps, bottom seals, and astragals, we match by the door’s series and the hinge prep code stamped near the hinge mortise.
On OEM vs aftermarket: for weatherstripping and thresholds, quality aftermarket equivalents from brands like Endura and ODL work fine and cost less. For slabs, hinges, and multi-point lock hardware, we recommend OEM Therma-Tru parts. The lock prep geometry on Classic-Craft doors doesn’t forgive substitutions.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Drafts at the threshold or jamb. The door sweep or corner pads have compressed. In Dallas clay soil, even a new addition settles slightly in the first 18 months, and the door that once sealed tight starts letting air through.
- Door rubs or binds in summer. Heat expands the fiberglass slab. Sometimes it’s just the door, but frequently the frame has shifted out of square. Not something to plane down, it’s a realignment job.
- Latch won’t throw cleanly. A strike plate that no longer aligns means the frame has moved. We see this often on ADUs built on pier foundations in East Dallas and Mesquite, where clay expansion cycles are brutal.
- Visible water staining at the sill. The adjustable sill cap or its sealing gasket has failed. A leak here doesn’t stay small in a Dallas downpour season.
- Hinges sagging or screws stripping. A door that’s heavier than the frame expects, or a frame that was set out of plumb from day one. This shortens slab life too.
Replacement Cost & What’s Included
For a Therma-Tru door replacement as part of an addition or ADU build in Dallas, you’re in the $1,800 to $4,200 range per door installed, including the slab, frame, hardware, weatherseal, and labor, depending on series and whether it’s a single entry or a sliding patio unit. If you just need parts – sweeps, corner pads, sill caps, hinge sets – those run $25 to $350 for the parts, plus a service call.
What drives the price up? Multi-point locks, custom sizes, sidelites, and transoms. What drives it down? Standard 36×80 Smooth-Star slab on an existing square frame. We write the price on paper before we start, every time. No verbal estimate that grows later. That’s the whole point of the way we work.
See the difference
Before
After
Before
After
Before
AfterDIY or Call Us?
Replacing a door sweep or adjusting a threshold cap? That’s reasonable weekend work if you have the right series-matched part and a drill. Soldering brickmold, shimming a frame out of plumb, or replacing a multi-point lock on a Classic-Craft? Call (432) 302-8761. The number of Dallas addition doors we’ve seen ruined by an enthusiastic Saturday attempt with a belt sander is not zero. A binding fiberglass slab doesn’t need shaving, it needs the frame corrected.
FAQs
A properly installed Therma-Tru door system lasts 25 to 30 years in Dallas on the slab itself. The wear parts – sweeps, weatherstripping, sill caps – should come out every 5 to 8 years due to our heat and UV. Call (432) 302-8761 for an exact on-site read of your door.
Yes, if the sill deck and cap are intact, we can strip and re-set the assembly with fresh gasketing and a new cap. It runs $185 to $400 in Dallas, done the same visit in most cases.
A clean slab and frame replacement on an existing rough opening takes one full day, sometimes a second morning for trim and paint touch-up. We protect the surrounding drywall and trim as part of the written price.
We keep common Smooth-Star and Classic-Craft sweeps, corner pads, astragals, and hinge kits on the truck. Slabs and multi-point lock sets are ordered to the series and hinge prep, which usually lands in 3 to 5 business days within Dallas. For custom sizes or Pulse-series hardware, expect about a week.
You Should Know Before You Call
We also build and replace work around KraftMaid cabinets, Cambria and Silestone countertops, and a full scope of addition and ADU construction throughout Dallas. You should know who is coming, what it costs, and what happens if something goes wrong – before we ever pick up a tool. Isaac Pruett walks every job himself before the first nail goes in, because a plan on paper and a house in front of you are two different things. Call (432) 302-8761 for a free estimate on your Therma-Tru addition or ADU project.
Written by Isaac Pruett, Owner, Mason Remodeling Co Dallas at Mason Remodeling Co Dallas, serving Dallas and nearby areas.
