Therma-Tru Home Additions & ADU Nationwide

Therma-Tru Home Additions & ADU: The Los Angeles Owner's Guide

If you're planning a home addition or ADU in Los Angeles and want Therma-Tru entry doors or patio doors as part of the build, we install Therma-Tru-compatible door systems as part of our remodeling and addition work. A full home addition in Los Angeles typically runs $53,100 – $153,400, while an ADU runs $106,200 – $259,600 depending on size, foundation work, and finish level. The Therma-Tru doors themselves are a smaller line item inside that scope, but they matter more than most people expect: they're the part of the addition that gets used twenty times a day, seals against Santa Ana wind dust, and takes direct afternoon sun on west-facing Valley exposures.

Call (936) 259-2607

Most homeowners don't call us because a Therma-Tru door "failed" in the dramatic sense. They call because the addition was framed, the drywall went up, and then someone realized the rough opening was set for a generic slab door, not a Therma-Tru frame with its specific jamb depth and sill profile. Or the original door from a 2003 remodel has a worn sill cap, the sweep is dragging, and the whole unit needs to be re-squared before the new flooring goes in. By the time we get the call, the part is usually identified. What they need is a straight answer on whether it gets replaced, rebuilt, or reframed.

Key takeaways:

• We install and replace Therma-Tru door units inside larger addition and ADU scopes in Los Angeles.
• Installed door replacement inside an addition job typically falls between $1,500 and $4,500 depending on the door series, sidelite count, and whether the rough opening needs correction.
• We are an independent remodeling contractor, not a Therma-Tru dealer or affiliate.
• Every job gets a written price before work starts, and a written 365-day promise after it's done.

Which Therma-Tru Models This Applies To

Therma-Tru makes several door lines, and the compatibility question comes down to the frame system more than the slab itself. The most common lines we see in Los Angeles additions are the Classic-Craft, Fiber-Classic, and Smooth-Star series. Classic-Craft doors are thicker, typically 2-1/4" on the slab with a deeper jamb, and they carry a heavier feel which matters when you're pairing them with a new ADU that has a 6" exterior wall assembly. Smooth-Star and Fiber-Classic run closer to 1-3/4" and fit standard 4-9/16" jambs more easily. If you're matching an existing older Therma-Tru door in the main house to a new one in the addition, don't assume the slab profile is the same just because the brand matches. Therma-Tru changed frame and sill designs more than once over the years, and a 1998-era door will not always accept a 2024-era sill kit without modifying the opening.

The fastest way to identify what you have is to open the door and look at the hinge-side edge of the slab, about eight inches up from the bottom. Therma-Tru stamps a manufacturing code there that includes the series and build date. If the door has been painted over multiple times you may need to hold a flashlight at a low angle to read it. When owners can't find the code, we measure the slab thickness and the jamb pocket depth on site and match from there. If you're going aftermarket on the weatherstripping or threshold, there are good third-party options, but for the slab itself we always recommend OEM Therma-Tru for the simple reason that the corner seals and sill interlocks are proprietary. A generic slab that's "close enough" is how you end up with a door that binds in August and lets air in during the January rain.

Signs Your Therma-Tru Home Additions & ADU Door Is Failing

• Daylight visible under the sweep or at the corners. This means the sill cap has worn down or the panel has settled out of square. In Los Angeles, the freeze-thaw cycle is not the culprit here; it's repeated sun exposure drying out seals plus the natural settling of a new addition in the first two years.
• The door binds at the top corner in the afternoon. West-facing additions in the Valley get hammered by heat, and a door that was square at 8 a.m. can hang up at 3 p.m. when the frame moves. This is a frame-squareness issue, not the slab, and it won't fix itself.
• Condensation or fog between the glass panes on a Therma-Tru door with a glass insert. The insulated glass seal has failed. Therma-Tru glass units are replaceable on most series without replacing the entire slab, but the sash profiles vary by series and era.
• You can hear street noise through the door as clearly as through an open window. That means the weatherstripping has compressed past the point of sealing, or the door was never shimmed correctly when the addition was originally trimmed out. ADUs built close to the property line are especially sensitive to this.
• The threshold or corner pads show cracks when you poke them with a screwdriver. Therma-Tru uses a fiberglass composite sill on many models, and while it lasts longer than wood, a 20-year-old sill in direct sun will eventually get brittle.

Replacement Cost & What's Included

For a Therma-Tru door replacement inside a Los Angeles home addition or ADU scope, you're typically looking at $1,500 to $4,500 installed, assuming the rough opening is in good shape and the door is a standard 3-0 x 6-8 or 3-0 x 8-0 size. A full door replacement with sidelites, or a custom-height door on a newer ADU, can push to $6,000 or beyond. The big drivers are the slab series, whether a new frame is needed, the sill condition, and whether the rough opening needs to be re-shimmed or re-flashed before the new unit goes in. Glass inserts and decorative caming add cost, as does a custom color finish.

Every door we install inside an addition or ADU job is priced as a line item in the written quote, so you see the door cost, the labor, and the disposal separate from the framing and drywall work. The written price is the price: if the rough opening turns out to be out of square by an inch and a half, we re-shim it and the number doesn't move. The 365-day Done Right Promise applies to the door installation exactly the way it applies to the rest of the job: if it fails inside a year, we come back and fix it at no charge. When we use Therma-Tru products, their own warranty sits alongside ours.

DIY or Call Us?

Replacing weatherstripping, adjusting the sweep, or tightening hinge screws on a Therma-Tru door are all reasonable homeowner tasks, and if that's the only problem you have, you may not need us. What you should not attempt is pulling an entire door unit out of a rough opening on a new addition or ADU. The frame is tied to the wall assembly, the exterior flashing laps under the siding or stucco, and if you cut the flashing wrong you've created a water path into the wall cavity. Older Therma-Tru frames in Los Angeles homes are often set with lead flashing or built-up caulk joints over years of patch jobs. A wrong pull-and-reset that looks fine for two months leaks for two years. If the slab is dragging, the frame is out of square, or the glass is fogged, that's a call to (936) 259-2607. Give me the whole picture first, then we pick up the tools.

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