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Therma-Tru Home Additions & ADU: The Tampa Owner’s Guide
A Therma-Tru home addition or ADU in Tampa typically runs $45,000 to $130,000 installed, depending on square footage, foundation work, and how much of the existing structure has to be tied in. We install Therma-Tru exterior door systems as part of every addition and ADU we build, because a Florida addition lives and dies by its openings. The most common way homeowners find us is mid-project: they’ve got a door frame that’s racked, a threshold that’s leaking, or an addition shell that never got closed up properly by the previous contractor.
Here’s the reality of building onto a house in Tampa. Heat, humidity, and afternoon thunderstorms mean the building envelope has to be right the first time. A Therma-Tru door hung out of square will bind within six months. A sill pan flashed wrong will rot the subfloor inside two years. We see it in Seminole Heights bungalows and 90s tract houses alike: the addition itself might be framed fine, but the door openings are where the failures start. That’s where the Therma-Tru part of the equation matters most.
Which Therma-Tru Models This Applies To
Therma-Tru makes three broad lines that show up in Tampa additions and ADUs: the Classic-Craft series (fiberglass, wood-grain texture, used on higher-end additions), the Smooth-Star series (smooth fiberglass, common on ADUs and garage conversions), and the Pulse series (premium, used when the addition calls for impact-rated or high-end decorative entry). Each uses the same rough opening standards, but here’s the gotcha: Therma-Tru slab sizes and hinge prep are not interchangeable across series. A Smooth-Star slab will not fit a Classic-Craft frame without modification, and the hinge mortises are cut differently between series.
If you’re replacing a failed door within an existing Therma-Tru frame, the fastest path is to match the series and the swing. Look for the Therma-Tru label on the hinge edge of the slab. It’ll have a series code and sometimes a date stamp. If the label’s gone, measure the slab thickness (1-3/4 inches is standard for most Therma-Tru exterior doors, but some older Classic-Craft units are 2-1/4 inches) and note the hinge spacing. We match OEM when the frame is sound. When the frame itself has rot or racking, a full frame replacement makes more sense than trying to save a slab that’ll never seat right.
Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
- Door binds or scrapes at the top corner. The rough opening shifted or the framing wasn’t squared at install. In Tampa’s clay-heavy soils, slab movement is common within the first two years after an addition is poured.
- Water staining on interior trim or flooring near the threshold. The sill pan was flashed wrong or never installed. This is a failing we fix on additions built by other contractors more than almost any other single issue.
- Visible daylight around the weatherstripping. The door’s out of plane, or the weatherstripping channel is crushed. Air leaks mean humidity gets in, and humidity in a Florida addition means mold inside wall cavities.
- Door won’t latch without lifting the handle. Hinge wear or a sagging frame. The strike plate doesn’t align with the latch anymore, and every forced close makes the misalignment worse.
- Frame rot at the bottom corners. Water’s been sitting against the jamb. In Tampa’s rainy season, a threshold that doesn’t shed water away from the frame will rot a wood jamb in three to five years. Therma-Tru’s composite jambs resist this much better, which is exactly why we spec them on new additions.
See the difference
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AfterReplacement Cost & What’s Included
For the scope this page covers, a Tampa home addition or ADU that includes Therma-Tru door systems runs $45,000 to $130,000. That’s the full project: foundation, framing, roof tie-in, electrical rough-in, drywall, trim, and the Therma-Tru exterior doors hung, flashed, and adjusted. If you’re only replacing a failed Therma-Tru door within an existing addition, you’re in a different range, typically $1,800 to $4,500 fully installed for a fiberglass entry system, depending on series, glass package, and whether the frame needs replacement or just the slab.
What drives the addition price range: square footage is the biggest lever, then foundation type (slab-on-grade is cheaper than a raised wood floor over crawlspace), then kitchen or bath rough-ins if the ADU includes them, then roof complexity. Every line item is written down before we start. No numbers move at the door. The written price covers all labor, materials, permits, and the Therma-Tru doors specified on the plan. The work carries a one-year written guarantee through our 365-Day Done Right Promise: if any part of it fails inside that window, we come back and correct it at no charge.
DIY or Call Us?
What you can safely check yourself: visible water staining around the door, whether the door closes square within the frame, and whether the weatherstripping is crushed or intact. That’s inspection, and it’s useful to know before you call. What you should not do is pull a Therma-Tru slab off a frame and try to re-hang it on an addition that’s shifted. Doors weigh 80 to 120 pounds, hinge screw placement matters more than it looks, and a dropped slab takes out your threshold or your foot. We’ve also seen homeowners shim a binding door aggressively and crack the fiberglass skin, which turns a $200 adjustment into a $2,000 slab replacement.
If you’re seeing binding, rot, water intrusion, or latch failure on a Therma-Tru door in a Tampa addition or ADU, call (941) 655-9297. We’ll send a background-checked, uniformed technician to look at it, tell you what’s actually wrong, and hand you a written price before any work starts.
FAQs
A properly installed Therma-Tru fiberglass door in a Tampa addition should last 20 to 30 years, but the installation details matter more than the door itself. In our climate, the failure point is rarely the slab. It’s the flashing, the sill pan, or the rough opening shifting under the door. We’ve pulled 25-year-old Therma-Tru slabs that were perfectly sound out of frames that had rotted around them. Call (941) 655-9297 if you want an honest read on yours.
Yes, depending on what failed. Hinge adjustment, weatherstripping replacement, and threshold re-leveling are common repairs we handle directly. Slab cracks, severe rot in the jamb, or a frame that’s racked beyond shimming typically warrant replacement. We’ll tell you which one you’re looking at and why, with a written price either way.
A straightforward slab replacement inside a sound frame takes one day. A full frame replacement, including flashing and interior trim, takes one to two days. If the rough opening itself needs re-framing because the addition shifted, plan for two to three days. We’ll give you a timeline in writing before the work starts, and we stick to it.
We don’t warehouse slabs, because the series and size combinations for Tampa additions are too varied to carry meaningfully. We order Therma-Tru doors against the exact specs of your opening, and because we work with a documented supplier network, lead times are predictable. What we do carry on the truck: shims, sill pans, flashing, weatherstripping, and the hardware needed to square and seal a door the same day we diagnose it. We also work with KraftMaid, Cambria, and Silestone on larger addition and ADU projects that include kitchen or bath finishes.
Straight number, clear scope, no surprises at close-out.
Written by Curtis Lane, Owner, Bradford Remodeling Co Tampa at Bradford Remodeling Co Tampa, serving Tampa and nearby areas.
