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Therma-Tru Home Additions & ADU: The Los Angeles Owner’s Guide
Therma-Tru home additions and ADU construction in Los Angeles typically runs $53100 to $153400, depending on square footage, foundation scope, and whether you’re building up or out. We install Therma-Tru exterior doors as part of the addition or ADU package, and we stock the weatherstripping, thresholds, door sweeps, and hinge hardware that match Therma-Tru’s specific jamb profiles. Most homeowners call us when they’ve already pulled a permit and realized the door package matters more than they thought, or when an existing Therma-Tru door on an older addition has started binding, leaking air, or showing daylight at the threshold.
If your Therma-Tru door is sticking, letting water in at the sill, or the sweep has worn flat across the bottom, you’re in the right place. We’ll cover compatibility, honest pricing, and what a proper replacement actually involves.
Which Therma-Tru Models This Applies To
Therma-Tru builds a wide line of fiberglass and steel entry doors, and the part compatibility depends on which series you have. The Classic-Craft, Fiber-Classic, and Smooth-Star lines are the most common in Los Angeles homes, and each uses different sill and sweep hardware. Classic-Craft doors, for example, have a thicker door slab profile than Smooth-Star, which means the bottom sweep and threshold cap are not interchangeable between the two, even if the door looks the same from the outside.
Here’s the gotcha we see constantly: homeowners measure the visible door width and assume a standard replacement sweep will fit. Therma-Tru uses a proprietary kerf slot on many of their slabs, and a generic big-box sweep will either fall out or sit too proud against the threshold. The fix is matching the part to the series name printed on the hinge-edge label or the sticker on the top of the slab. If the label is gone, we measure the kerf slot depth and the overall door thickness to identify the right OEM or spec-matched aftermarket part.
For OEM versus aftermarket: Therma-Tru OEM sweeps and thresholds are manufactured to exact factory tolerances, and they carry the manufacturer’s own warranty. Quality aftermarket equivalents from companies like Endura and PortaSeal work well and cost 20 to 40 percent less, but you need to confirm the kerf dimension and threshold profile before committing. We stock both on our trucks for Los Angeles service calls and use OEM when the door is under warranty, aftermarket when it is not and the homeowner wants to keep costs down.
Bradford Remodeling is an independent contractor, not affiliated with Therma-Tru. We work with their product line because the specs are documented and the doors hold up well in Southern California’s dry heat and coastal salt air, provided the seals are maintained.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Daylight visible under the door. This almost always means the sweep has worn down or the threshold cap has dropped. Warm air pours out in the summer, and dust from the Santa Anas blows straight in. The fix is a matched sweep and threshold replacement, not shimming the hinges.
- Water pooling at the interior sill after rain. Los Angeles gets the occasional heavy storm, and when it does, a failed sill pan or a compressed threshold gasket shows itself fast. We see this most often on ADU doors that face west and take the brunt of winter rain off the Pacific.
- The door binds or rubs at the top corner. This is usually a hinge or jamb issue rather than the slab itself. Over time, the top hinge screws strip out of the jamb, especially in stucco-clad additions where the rough opening moves with seasonal soil shifts.
- Drafts around the perimeter, not just the bottom. Weatherstripping on Therma-Tru jambs sits in a milled groove. When it tears or loses its memory, air moves around all four sides. Replacing it properly means pulling the old strip without chewing up the groove, then pressing in the correct profile.
- Visible rust or corrosion on the hinge screws or threshold screws. Coastal air in neighborhoods like Playa del Rey and San Pedro is hard on exposed fasteners. Once those screws rust, the door loses alignment and the threshold can lift.
See the difference
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After
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AfterReplacement Cost & What’s Included
Here’s what a full Therma-Tru home addition or ADU project costs in Los Angeles, all in:
- Home addition (standard build): $53100 to $153400
- ADU construction: $106200 to $259600
- Garage conversion to living space: $35400 to $94400
For the Therma-Tru door components specifically, a new OEM sweep runs $18 to $45, a threshold cap $60 to $140, and full perimeter weatherstripping $45 to $110. Installed labor typically adds $120 to $280 depending on whether the existing hardware is salvageable. If we’re pulling and re-hanging the slab to correct a binding issue, expect another $200 to $400.
Every price includes the part, labor, disposal of the old hardware, and a written line-item breakdown before we start. No numbers move at the door. That’s The Garrison Standard: every price and every guarantee in writing before a single tool comes out.
DIY or Call Us?
Replacing a bottom sweep on a Therma-Tru door is genuinely DIY-friendly if you have the right part number and a clean kerf slot to work with. Most homeowners can handle a sweep swap in under an hour with a utility knife and a rubber mallet. Thresholds are trickier: you’re dealing with screw extraction from concrete or wood subfloor, shimming, and sealing, and a poorly seated threshold will leak from day one.
What you should not do is try to re-hang a binding Therma-Tru door by planing the slab or forcing the hinges. Fiberglass slabs have a specific edge profile, and once you cut into it, you can void the manufacturer warranty and ruin the door. If the door is dragging, the problem is usually the rough opening or the hinges, not the slab itself. That’s a job for someone who does it weekly.
Call (903) 568-7222 and we’ll tell you over the phone whether it’s a truck-stock fix or a re-hang. If it’s simple, we’ll say so. If it’s not, we’ll give you a written price before we touch anything.
FAQs
Expect 3 to 7 years in Los Angeles depending on sun exposure, door usage, and proximity to the coast. Doors on south- and west-facing walls in neighborhoods like Sherman Oaks or Woodland Hills bake in direct sun about 300 days a year, and the rubber compounds lose flexibility faster there than on shaded north-facing entries. If you’re replacing seals every couple of years, the real problem is usually direct sun exposure, which means a higher-grade aftermarket sweep with UV stabilizers is the better move. Call us at (903) 568-7222 and we’ll match the part to your actual exposure, not just your door width.
Most thresholds can be repaired if the damage is limited to the rubber gasket or the adjustable cap. Full threshold replacement is only necessary when the metal or composite base has cracked, the screw anchors have stripped out of the subfloor, or the sill pan underneath has failed. Los Angeles homes built before about 1990 often have wooden sill pans that rot over time, especially on additions where the flashing was never properly lapped. We’ll tell you which route makes sense once we pull the threshold and look at what’s underneath. Estimates are free.
A sweep, weatherstripping, or threshold gasket replacement is typically a 60 to 90 minute job. Re-hanging a binding door or replacing a full threshold assembly runs 2 to 3 hours depending on what we find underneath. If you’re in the middle of a planned ADU build or home addition, we sequence door work around framing and drywall so the schedule stays consistent. Call (903) 568-7222 to get on the calendar with a real person.
We carry the most common Therma-Tru sweeps, thresholds, and weatherstripping profiles on our trucks for Los Angeles service calls, along with matched aftermarket equivalents for the Classic-Craft, Fiber-Classic, and Smooth-Star lines. If your door is an unusual size or an older production model, we may need a day or two to source the correct OEM part. We’ll tell you before we quote the job, and the written price already accounts for parts acquisition, so there’s no surprise line item later. Working with name-brand materials like KraftMaid, Cambria, and Silestone alongside Therma-Tru means the specifications are traceable and the quality is not left to guesswork.
Written by Curtis Lane, Owner, Bradford Remodeling at Bradford Remodeling, serving Los Angeles and nearby areas.
