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Therma-Tru Home Additions & ADU: The West Covina Owner’s Guide
If you’re planning a home addition or ADU in West Covina and you’ve specified a Therma-Tru entry door system for the project, you’re likely wondering two things: what it costs to get it installed correctly, and whether the door package will actually perform once it’s in the wall. A full home addition in West Covina runs $45,000 to $130,000 depending on foundation scope, roofline tie-ins, and finish level, and a detached ADU typically lands between $90,000 and $220,000 when built to current California energy and fire codes. The Therma-Tru component, which most owners don’t think about until a door binds, leaks, or won’t latch, is usually a fraction of that total, but it’s the part you touch every single day. Here’s what we’ve learned replacing, adjusting, and retrofitting Therma-Tru doors on additions and ADUs across West Covina: the hardware and weatherstripping fail long before the slab ever does.
Which Therma-Tru Models This Applies To
Therma-Tru builds its entry systems around fiberglass door slabs matched to specific frame kits, sill options, and weatherstripping profiles. The lines we see most often on West Covina additions and ADUs are the Classic-Craft, Fiber-Classic, and Pulse series, plus the Benchmark line for builders working to tighter budgets. Here’s the compatibility gotcha most homeowners don’t discover until it’s too late: Therma-Tru hinges and strike plates are not universal across series. A Classic-Craft door slab won’t hang cleanly on a Benchmark frame without shimming, and the bottom sweep on a Pulse door is a different profile than the one on a Fiber-Classic, which means ordering the “same part” you see on a parts website often yields a part that’s off by an eighth of an inch, which is all it takes for a door to whistle in a Santa Ana wind.
Identify what you have before you spend a dollar. The model name is stamped on the hinge edge of the slab, usually about 18 inches up from the bottom, and the frame sticker, if it’s still there, will list the series and the original distributor. If the sticker is gone, measure the slab thickness and the sweep channel. Therma-Tru slabs run 1-3/4 inches thick, and the sweep channel widths vary by series. We stock OEM sweeps, hinges, and strike plates for the three series listed above, and we’ll tell you honestly when a quality aftermarket equivalent will do the job. For weatherstripping and hinges, it usually will, and it saves money. For the door slab itself, we always go OEM, because the fiberglass layup and the millwork tolerances are what you’re paying for.
Styles & brands we work with
Signs Your Therma-Tru Home Addition or ADU Door Needs Attention
- Daylight at the bottom corner, or a draft you can feel standing two feet away. Almost always a compressed or torn bottom sweep. In West Covina’s dry summer heat, rubber sweeps get brittle fast and crack at the corners first. Water follows the same path, which is how you get swollen jambs and ruined flooring on an ADU slab.
- The door binds at the top of the latch side and gets harder to close as the afternoon warms up. This is the frame moving, not the door warping. Fiberglass slabs are dimensionally stable; the wall framing behind a new addition settles in the first two years, and the door reveals shift with it. A hinge adjustment or a re-shim usually fixes it.
- The deadbolt won’t throw without lifting the handle or pressing the door with your knee. This means the strike plate and the latch are no longer aligned. On new ADUs, it’s often because the slab settled a quarter inch before the concrete cured. It’s a 20-minute fix with the right strike plate, and it’s also the most common reason a door won’t lock properly, which matters on a rental unit.
- You hear a rattle where the weatherstripping meets the frame on windy days. The magnetic weatherstripping Therma-Tru uses in its higher-end series loses its grip over time, especially on west-facing doors in West Covina that get direct afternoon sun. The magnetic strip separates from the kerf and the door sounds loose even when it’s fully latched.
- Condensation or a musty smell in the corner of the door opening, especially on a south-facing ADU wall. The sill pan flashing under the door is failing or was never installed correctly at rough-in. This is a water intrusion issue, not a door issue, and it’s the one that turns into a $4,000 rot repair if you ignore it.
See the difference
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After
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AfterReplacement Cost & What’s Included
For Therma-Tru door work on a West Covina addition or ADU, here’s what you should expect to pay. A complete weatherstripping and sweep replacement, including the magnetic kerf inserts, runs $180 to $450 installed depending on the series and how many sides of the frame are involved. Hinge and strike plate alignment, including any shimming and hardware replacement, runs $250 to $600 on most jobs. A full slab replacement on a Classic-Craft or Pulse door, including re-hanging in the existing frame, new hardware, and weatherstripping, typically runs $1,800 to $4,200 installed. If the frame itself is compromised, which happens more often on additions where the framing was rushed, a full frame-and-slab replacement runs $3,500 to $6,500.
Every quote we write lists the part cost and the labor separately. You’ll know exactly what the door slab costs and exactly what we’re charging to put it in. We deliver that written price before any work starts, and the price doesn’t change once we’re in the wall. Our work on Therma-Tru door replacements and adjustments is covered for 365 days from the completion date. If a hinge works loose or a sweep tears within that year, we come back and make it right at no charge.
DIY or Call Us?
A bottom sweep on a Therma-Tru door is a reasonable Saturday job if you have the right part and a decent screwdriver. The sweep slides out of a channel, and honestly, it’s the one repair we tell homeowners they can handle. Beyond that, things get trickier. Hinges require patience and an understanding of reveal gaps, and the risk isn’t injury, it’s a door that never closes right again. The genuinely dangerous territory is anything involving the door’s structural frame on a load-bearing wall. An entry door on an addition or ADU sits in a wall holding up roof load, and if the header or king studs were compromised during construction, pulling that frame out without temporary support is how you damage ceilings and, in the worst case, lose structural integrity. If the frame is moving or water is getting in at the sill, call us at (707) 760-7579. Some jobs take experience, not tools.
FAQs
The fiberglass slab itself will outlast most of the house components around it, 30 to 40 years is realistic with basic care. What won’t last that long is everything else: the weatherstripping, hinges, and sweeps are 8 to 12 year components in Southern California, less if the door gets direct afternoon sun. Call (707) 760-7579 if your door is older than a decade and you’re fighting drafts or latching problems.
In most cases, yes. Hinges, sweeps, weatherstripping, strike plates, and threshold caps are all replaceable, and we stock common Therma-Tru parts on the truck. The decision point is the slab itself: if the fiberglass is cracked through, split at the hinge mortise, or waterlogged from a sill leak, patching is a temporary fix and you’ll be back in the same spot in two years. We’ll show you the damage before we recommend a replacement, and we’ll give you a written price either way.
A slab swap in an existing frame takes about three to four hours on site, assuming the frame is sound. A full frame replacement is a one-day job, sometimes two if water damage extends into the subfloor or the rough opening needs re-framing. We schedule the work so you know exactly which day we’re coming, and the technician who arrives will match the name and photo we send you before the visit.
We keep the most common replacement parts on the truck, sweeps, weatherstripping profiles, hinges, and strike plates for Classic-Craft, Fiber-Classic, and Pulse doors. Slabs are ordered per job, which usually takes a week to ten days from our supplier. If you need something outside the standard catalog, we’ll tell you the lead time before you commit to anything.
At Mason Remodeling Co West Covina, we handle Therma-Tru door work as part of larger addition and ADU projects, and as standalone repairs. We’re an independent service provider, not affiliated with Therma-Tru, but we’ve worked with their products on projects near Eastland Center and throughout West Covina for years, and we know how their specifications hold up in this climate. We also work with KraftMaid cabinetry, Cambria and Silestone surfaces, and other specification-grade materials on the larger projects where the door is just one piece of the scope. Isaac Pruett and our crew built our reputation on honest schedules and scopes that don’t change once the work begins. You should know what you’re getting before we ever pick up a tool. Call (707) 760-7579 for a free estimate on your Therma-Tru door repair or your West Covina home addition and ADU project, and a live person will answer.
Written by Isaac Pruett, Owner, Mason Remodeling Co West Covina at Mason Remodeling Co West Covina, serving West Covina and nearby areas.
