Therma-Tru Door Installation Nationwide | Sightline Windows & Doors Lantana

Therma-Tru Door Installation: The Lantana Owner’s Guide

Therma-Tru door installation in Lantana typically runs $1,800 to $4,200 for a complete fiberglass entry door system, depending on whether you’re replacing a standard 6’8″ slab or upgrading to an impact-rated 8’0″ unit with sidelights. We stock Therma-Tru-compatible frames, sills, and hardware kits on our Lantana trucks, and most installs finish in a single day once the measured survey is complete. Most owners realize something’s wrong when the door sticks in summer humidity, daylight shows under the sweep, or the fiberglass skin delaminates near the bottom rail after years of salt air exposure along the Lantana beachfront corridor.

Call (561) 461-2062

Which Therma-Tru Models This Applies To

Therma-Tru’s product lines span three categories we install regularly in Lantana: the Classic-Craft premium fiberglass series, the Smooth-Star paint-ready line, and the Benchmark by Therma-Tru builder-grade units found in many 2015-2020 homes west of I-95. The critical compatibility check is the hinge stile width, Classic-Craft uses a 4-9/16″ jamb depth while Smooth-Star often ships with 6-9/16″ for 2×6 framing common in newer Lantana construction. We verify this with the AAMA label inside the hinge edge, not by eyeballing the slab.

OEM sills from Therma-Tru carry the part number stamped on the aluminum cap, aftermarket equivalents from Endura and Pemko match the geometry but differ in the sweep profile density. We specify OEM on Classic-Craft units because the adjustable cap design is proprietary, on Benchmark doors we often use an aftermarket equivalent with a composite base that outlasts the original in South Florida’s wet season. The wrong sill shoe will leave a 3/16″ gap that the sweep never seals.

Multi-point locking hardware varies by year: pre-2019 units used a Schlage-compatible 45mm backset, post-2019 shifted to a 55mm backset with a different face plate screw pattern. We stock both on the truck because guessing wrong means a second trip.

Signs Your Therma-Tru Door Installation Is Failing

• The door binds at the top corner in August but swings free in January. This is jamb spread from humidity cycling in unconditioned Lantana garages, not hinge failure. The rough opening was likely framed at 82″ and the jamb has absorbed moisture, compressing the head jamb against the slab corner.
• Water pools on the interior tile after a hard rain, starting at the lock stile. The weatherstrip bulb has lost compression set or the sill end caps have cracked where they meet the jamb legs. On Therma-Tru units, the sill end cap is a separate plastic piece that UV-degrades faster than the aluminum cap itself.
• The fiberglass skin bubbles or whitens within 6 inches of the bottom rail. This is osmotic blistering from water wicking through the composite bottom rail. Therma-Tru’s fiberglass is impermeable, the rail is not, once moisture reaches the rail the damage is structural, not cosmetic.
• The multi-point lock throws but the deadbolt doesn’t extend fully. The mechanism is out of alignment with the strike plate, often because the door has sagged on hinges that were never properly set with a long screw into the framing. The Schlage mechanism will tolerate 1/8″ misalignment, no more.
• Daylight visible at the header even when the door is latched. The compression weatherstrip has taken a permanent set or the door has dropped on its hinges. In Lantana’s salt air, the magnetic seal on higher-end Therma-Tru units loses its grip after 7-10 years, faster than inland ratings suggest.

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Replacement Cost & What’s Included

What moves the number: the condition of the rough opening once we remove the old unit, whether the Lantana home requires a wind-load rating above 140 mph for its zone, and if the interior trim needs replacement after decades of paint buildup. Every quote we write in Lantana includes the measured survey you keep, the written scope, and the photo record of the completed install under our 365-Day Done Right Promise. The price on the page is the price on the invoice, Haven Clause 1.

DIY or Call Us?

There’s one thing a homeowner can safely verify: open the door 90 degrees, set a level on the threshold, and check if the sill cap slopes toward the exterior. If it doesn’t, or if the cap is cracked at the corners, water is entering the subfloor. That’s useful information to tell us when you call.

What goes wrong with DIY on a Therma-Tru install: the multi-point lock requires a specific mortise depth and strike alignment that varies by jamb width, a 1/16″ error and the deadbolt drags or fails to engage. The sill must be bedded in sealant with the end caps lapped correctly over the jamb legs, reversed and water runs inside. And fiberglass slabs are heavier than they look, a two-person lift with proper support brackets, not a shoulder and a prayer. We pull the permit, we pass the inspection, and we document the install with photos you receive. Call (561) 461-2062 to schedule your free measured survey.

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