Therma-Tru Home Additions & ADU Nationwide

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

Therma-Tru entry systems in Santa Clarita home additions and ADUs typically run $45,000-$130,000 installed, depending on whether you’re integrating a single door into a new addition or building a full detached ADU with multiple entry points. We stock Therma-Tru Classic-Craft, Smooth-Star, and Fiber-Classic series doors in common Santa Clarita jamb widths, and we can match most existing Therma-Tru profiles without ordering from the factory. Most Santa Clarita homeowners discover their Therma-Tru entry system needs attention when the door won’t seal against the jamb after the first hot Santa Clarita summer, or when they notice daylight around the perimeter of a door that used to sit tight.

Call (747) 294-3985

Which Therma-Tru Models This Applies To

Therma-Tru organizes its residential entry doors into series that differ in skin material, edge construction, and warranty length. The three we spec most often in Santa Clarita additions and ADUs are:

• Classic-Craft - fiberglass with mahogany or oak grain, 4-9/16″ or 6-9/16″ jamb depths, often paired with Satin Etch or Decorative glass. The mahogany grain holds stain well in Santa Clarita’s dry heat; the oak grain is more forgiving if you’re painting.
• Smooth-Star - paint-ready fiberglass with a smooth face, popular in modern ADUs where clean lines matter. Available in 2’0″ to 3’0″ widths, with a 20-minute fire-rated option that meets California’s ADU egress requirements.
• Fiber-Classic - the original fiberglass door, still specified for budget-conscious additions. The 4-9/16″ jamb is standard; the 6-9/16″ is what you’ll need for 2×6 framing or exterior insulation.

To identify your existing door, check the hinge edge for a stamped date code and series mark, or measure the slab thickness (1-3/4″ for entry doors, 1-3/8″ for interior). The jamb width must match your wall assembly exactly; a 4-9/16″ jamb in a 2×6 wall leaves a 1″ gap that every Santa Clarita inspector will flag. We carry both jamb depths on our trucks for Santa Clarita jobs, along with matching brickmould and sill extensions.

Rowan Construction Group Santa Clarita is an independent contractor and not affiliated with Therma-Tru. We source through authorized distributors and can order factory-direct when a custom size or glass pattern is specified.

Signs Your Therma-Tru Home Additions & ADU Is Failing

• Visible daylight around the door perimeter - The compression seal has hardened or the door has settled on its hinges. In Santa Clarita’s heat cycles, the bulb seal on older Therma-Tru units loses resilience after 7-10 years. You’ll feel the draft before you see it, usually in January when the Santa Ana winds pick up.
• Door sticks or drags at the top corner - The frame has racked or the hinge screws have stripped out of the jamb. This is common in additions built on fill soil in Valencia or Saugus, where seasonal settlement is measurable. The door isn’t warped; the opening is.
• Water staining at the sill or base of the jamb - The sill pan or subsill flashing has failed, or the door was installed without a sill pan at all. Therma-Tru’s adjustable Inswing Sill is robust, but if the subsill wasn’t bedded in sealant during original construction, water finds the path of least resistance.
• Glass fogging between panes - The insulated glass unit (IGU) seal has failed. Therma-Tru uses a dual-seal system, but the desert edge of Santa Clarita Valley sees enough thermal cycling that 15-20 years is a realistic lifespan for the IGU, not the 30 years the door itself may last.
• Finish chalking or fiberglass fibers visible - The gel coat has degraded past recoating. This happens on south- and west-facing doors in Santa Clarita without adequate overhang; the UV index here is higher than coastal LA by a significant margin.

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Replacement Cost & What’s Included

The range depends on three factors: whether we’re working in an existing opening or cutting new structure, whether the door is standard size or custom, and whether the Santa Clarita permit requires fire-rated or impact-resistant specification. Under Clause 1 of The Haven Standard, you receive a written flat price before any work starts, with every line item specified. No change proceeds without a signed change order. Our 365-Day Done Right Promise covers the installation; the Therma-Tru factory warranty covers the door itself.

DIY or Call Us?

There’s a short list of checks any Santa Clarita homeowner can make safely: verify the door is actually contacting the weatherstrip by closing it on a strip of paper (resistance means seal, easy pull means gap), and confirm the hinges are tight to the jamb with a screwdriver. Beyond that, entry door replacement involves structural, weatherproofing, and safety considerations that escalate quickly.

A prehung Therma-Tru door weighs 80-120 pounds. The jamb must be shimmed plumb in three planes, the sill pan integrated with the water-resistive barrier, and the lockset bored to exact backset. Get the rough opening 1/2″ too large and the insulation cavity becomes a thermal bridge; too small and the jamb bows. In Santa Clarita’s climate, a door installed out of plane will telegraph every season. We carry laser levels, specific Therma-Tru sill pan kits, and the fastening schedule that satisfies Santa Clarita’s inspection checklist. Call (747) 294-3985 to schedule your free estimate; we’ll measure the opening, confirm the series match, and give you a written price you can screenshot and compare.

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