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Therma-Tru Home Additions & ADU: The Miami Owner’s Guide
If you’re planning a home addition or ADU in Miami and want Therma-Tru doors, windows, or trim to match what’s already on your house, we can handle the full scope, from rough opening to final casing, including sourcing the correct Therma-Tru units for your specific addition. A full home addition in Miami typically runs $53,100 – $153,400, and an ADU (accessory dwelling unit) is a larger project at $106,200 – $259,600. Most owners discover they need Therma-Tru-specific help when their architect or existing home uses Therma-Tru entry systems and they want the new structure to match, or when a failed flashing or threshold detail on an existing Therma-Tru door has caused water intrusion at the addition’s connection point.
We’re Penhallow Remodeling Miami, an independent general contractor, not affiliated with Therma-Tru. But we’ve installed and integrated their products on additions and ADUs across Miami for years, and Trevor Nash makes sure every job gets a written price before the first tool is picked up.
Which Therma-Tru Models This Applies To
Therma-Tru makes several door and trim lines that show up on Miami additions and ADUs. The most common we see are the Classic-Craft, Fiber-Classic, and Pulse series entry doors, along with Smooth-Star and Benchmark lines for secondary doors. The compatibility gotcha most homeowners miss: Therma-Tru door slabs are designed to work with Therma-Tru frames and sills. You can’t reliably hang a Therma-Tru slab in an off-brand frame and expect the weather seal, hinge alignment, and air infiltration rating to hold up, especially in Miami’s wind-driven rain conditions.
If you need to match an existing Therma-Tru door on a new addition, look for the certification label on the hinge edge of the door slab. It lists the series, the glass package, and the manufacturing date code. That label is how we confirm which exact unit to order for the new opening. For ADUs, we often recommend the Smooth-Star line because it carries a strong energy rating and a fiberglass skin that doesn’t warp in Miami humidity, unlike wood doors that swell in August and bind against the frame.
On OEM versus aftermarket: for door slabs and glass packages, OEM Therma-Tru is the right call. For brickmold, weatherstripping, and sill pans, quality aftermarket equivalents from brands like Endura or Pemko often perform as well or better, and they cost 20-30% less. We’ll tell you which is which before we order anything.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Water staining on the interior casing or floor near the door. This usually points to a failed sill pan or degraded weatherstripping at the threshold. In Miami, afternoon thunderstorms push water sideways, and a small seal gap becomes a leak fast.
- The door drags or binds when you open it. On an addition, settlement or slab movement can shift the rough opening. If the Therma-Tru frame wasn’t shimmed and fastened correctly at the threshold, the door will catch and the seals will tear.
- Visible light or air coming around the door perimeter. That’s weatherstripping that’s been compressed past its service life. On an ADU with a high-efficiency HVAC system, a leaky door frame wastes real money every month.
- Condensation between the glass panes in the door’s window unit. That means the insulated glass seal has failed. Therma-Tru glass packages are replaceable without buying a whole new door, but it’s not a homeowner-level repair.
- The fiberglass skin is delaminating or blistering. This happens on older Therma-Tru doors that were exposed to years of direct Miami sun, especially on west-facing additions without an overhang. Once the skin starts to separate, the door loses structural integrity and needs replacement.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a Therma-Tru entry door installed as part of a Miami home addition or ADU, you’re typically looking at $2,360 – $7,670 for the door unit itself plus installation labor, depending on the series, glass package, and whether we’re also replacing the frame and sill. That range sits inside the larger addition budget, but it’s the line item most owners ask about once they see how much a mismatched door stands out.
What drives the number up: full-frame replacement instead of slab-only, decorative glass, custom finish colors, rotted rough-opening repair, and hurricane-rated hardware. What brings it down: a standard Smooth-Star unit, no glass, a straightforward opening that’s square and dry. Every quote includes the door, all sealing and flashing materials, labor, and haul-away of the old unit, in writing, before we start. No change orders at the door. And every installation carries our 365-Day Done Right Promise: if the door leaks, binds, or fails inside a year, we come back and fix it at no charge.
DIY or Call Us?
There’s a safe middle ground here. You can check whether the door is out of square with a level, check the weatherstripping for visible tears, and look for daylight around the perimeter. That’s useful information to have when you call us. What you shouldn’t do is pull the door slab off its hinges, attempt to reset the frame, or try to replace a sill pan yourself. Therma-Tru pre-hung units rely on precise shimming and sealing at the rough opening, and a small mistake there is how Miami additions end up with water behind the stucco or tile, where you won’t see it until the damage is extensive.
Replacing a door on an addition or ADU isn’t a weekend project for most homeowners, but it is a job we can usually handle within a day or two once the unit arrives. If you want a second set of eyes on whether you need a repair or a full replacement, call (850) 988-7559 and we’ll talk you through what we’re seeing. Give you a number first, then pick up the tools.
FAQs
A properly installed Therma-Tru fiberglass door should last 20 to 30 years in Miami, though the weatherstripping and exterior finish will need attention every 5 to 8 years due to UV exposure and salt air. Water intrusion at the sill is the most common lifespan shortener we see. Call (850) 988-7559 if you’re seeing staining or drafts, and we’ll give you an honest read on repair versus replacement.
It depends on what failed. Weatherstripping, sill pans, brickmold, and glass packages can usually be replaced without changing the door slab. If the fiberglass skin is delaminating or the frame has rotted or shifted, replacement is almost always the better long-term call. We’ll show you the condition of what’s behind the casing before we recommend anything.
A straightforward single-door replacement typically takes one day of on-site work. If we’re also repairing the rough opening, addressing water damage, or installing a custom glass package, plan for two to three days. We’ll give you a defined arrival window and a written schedule before work starts.
We keep common Smooth-Star and Benchmark units accessible through our local supply partners in Miami, and custom Classic-Craft or Pulse units with specific glass packages usually take one to two weeks to arrive. We’ll give you accurate lead times up front so your addition’s schedule doesn’t stall at the door installation stage. Call (850) 988-7559 for a free estimate.
Written by Trevor Nash, Owner, Penhallow Remodeling Miami at Penhallow Remodeling Miami, serving Miami and nearby areas.
