Therma-Tru Home Additions & ADU Nationwide

Therma-Tru Home Additions & ADU: The Carlsbad Owner’s Guide

Therma-Tru entry systems are commonly specified for Carlsbad home additions and ADUs where the main house already runs Therma-Tru, and matching the sightlines matters to the HOA or the owner’s resale plan. A typical Therma-Tru-compatible entry installation for an addition or ADU in Carlsbad runs $3,200-$7,800 depending on sidelite configuration, jamb depth, and whether the wall is new construction or a retrofit into existing framing. We stock the Classic-Craft, Smooth-Star, and Fiber-Classic series jambs and sills on our trucks, and we can usually pull a replacement from our Bressi Ranch warehouse same day if the original spec is known.

Call (858) 815-9080

Most Carlsbad owners discover a problem when the ADU tenant mentions drafts, or when the deadbolt starts binding after the first winter rains. The fiber-reinforced door slab itself rarely fails; it’s the composite jamb leg, the adjustable sill cap, or the weatherstrip kerf that takes the load of seasonal expansion in coastal Southern California.

Which Therma-Tru Models This Applies To

Therma-Tru uses a three-tier naming system, and the part you need depends on which tier was originally specified. Classic-Craft uses a 4-9/16″ or 6-9/16″ engineered jamb with a composite stop and a PVC-wrapped exterior; Smooth-Star uses a similar jamb but with a different corner-seal detail and a paintable smooth skin on the slab; Fiber-Classic, the oldest line still in production, has a thicker jamb leg and a different weatherstrip groove width, 1/4″ versus 5/16″ on the newer series.

To identify yours, open the door and check the hinge jamb for a foil label with a 12-digit serial number. The first three digits indicate the series: CCA for Classic-Craft, SMA for Smooth-Star, FCA for Fiber-Classic. If the label is gone, measure the weatherstrip kerf width with a tape measure; 1/4″ points to Fiber-Classic, 5/16″ to the newer lines. We carry OEM jambs and sills for all three, plus an aftermarket composite jamb from Endura that meets Therma-Tru’s spec and carries the same 10-year warranty. The OEM part costs 15-20% more; we quote both and let the owner decide. Rowan Construction Group Carlsbad is an independent service provider, not affiliated with Therma-Tru.

Signs Your Therma-Tru Home Additions & ADU Is Failing

• Deadbolt binds or won’t throw. The jamb leg has swollen or the strike plate has shifted as the composite material cycles through Carlsbad’s morning marine layer and afternoon sun. We see this most in west-facing ADU entries in La Costa and Calavera Hills where the door gets six hours of direct exposure.
• Visible gap at the sill or light under the door. The adjustable sill cap has compressed or the composite sill substrate has delaminated from standing water. Therma-Tru’s composite sill is rated for splash, not ponding; if the concrete stoop was poured without slope, the cap fails in 3-5 years.
• Draft despite closed door. The kerf-mounted weatherstrip has lost compression set, usually from UV exposure. Carlsbad’s 260-plus annual days of sun harden the bulb faster than the manufacturer spec assumes for a national average.
• Door slab rubs the head jamb seasonally. The header has settled or the jamb was shimmed without proper load transfer to the framing. In Carlsbad’s coastal climate, wood framing moves less than inland, but ADU headers are often undersized for the span and sag over time.
• Water stain on interior flooring near the threshold. The sill pan flashing was omitted or the Endura sill pan was not lapped correctly over the weather-resistive barrier. We find this in about 30% of ADU retrofits where the original contractor used a pan but did not seal the corners.

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Replacement Cost & What’s Included

For a Therma-Tru entry system in a Carlsbad home addition or ADU, installed pricing breaks down as follows:

The range depends on three things: whether the wall is open framing or finished drywall, whether the original was flashed correctly (bad flashing means more teardown), and whether the slab itself needs replacement or just the jamb. We deliver a written price before any work starts, every time, under Clause 1 of the Haven Standard. The quote is flat; if we find rot in the subfloor once the sill is out, we stop, photograph it, and write a change order before proceeding. No work moves forward on a change until the change order is signed. Our 365-Day Done Right Promise covers the installation; the OEM or Endura part carries its own manufacturer’s warranty.

DIY or Call Us?

An owner can safely check three things: the hinge screws for tightness, the sweep for debris, and the sill cap adjustment screws for range of travel. Beyond that, the risks stack up. A prehung door in an ADU or addition is structural; the jamb carries the header load, and if the shims are wrong the door binds in weeks, not years. More importantly, most Carlsbad ADUs were permitted under 2019 or 2022 California energy code, which means the door must meet specific U-factor and air-leakage numbers; swapping in a non-compliant unit without updating the Title 24 documentation can trigger a correction notice at resale.

We carry the compatible jambs, sills, and weatherstrip on our trucks. If you have the serial number or a photo of the label, text it to us and we’ll confirm the part before we roll. Call (858) 815-9080 to schedule your free estimate.

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