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Therma-Tru Home Additions & ADU: The San Francisco Owner’s Guide
If you’re planning a home addition or ADU in San Francisco and want Therma-Tru doors and entry systems incorporated into the build, a complete project typically runs $53,100 to $153,400 depending on square footage, foundation work, and finish level. We work with Therma-Tru products as part of larger addition and ADU projects – the doors, frames, and weatherstripping get installed correctly the first time so the entry performs for decades, not just until the next fog season. Most San Francisco owners come to us after walking through a partially-finished addition or a converted garage and noticing the entry door doesn’t sit square, binds at the top corner, or lets a draft through that no amount of caulk seems to fix. The root cause is almost always the same: the rough opening wasn’t framed to Therma-Tru’s tolerances, or the door was hung before the foundation had fully settled, and now the slab has shifted enough to throw everything out of plane.
Key Takeaways
– Full home additions and ADUs in San Francisco: $53,100 – $153,400
– Therma-Tru doors require specific rough-opening tolerances; San Francisco’s clay-heavy soil and micro-climate moisture make proper flashing and sealing non-negotiable
– We write the full project price before any work starts – the number you sign is the number you pay
– The 365-Day Done Right Promise covers every completed project: if it’s not right, we make it right
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Which Therma-Tru Models This Applies To
Therma-Tru’s residential entry lines most commonly spec’d into San Francisco additions and ADUs are the Classic-Craft (fiberglass, with the look of wood grain but without the rot problems that plague fog-belt doors), the Fiber-Classic (smoother fiberglass, often painted), and the Smooth-Star (a more budget-conscious fiberglass line that still carries Therma-Tru’s core warranty). Each line has different slab thicknesses – Classic-Craft slabs run 1-3/4 inches, while some Smooth-Star models come in 1-3/8 inches – and that measurement matters when you’re matching an existing door to a new frame or ordering replacement hinges.
The identification step is simple: open the door and look at the hinge edge of the slab. Therma-Tru stamps a manufacturing code there, usually a series of letters and numbers. That code tells us the exact model, the year it was made, and what replacement parts match. If the label is painted over or worn off, we measure the slab thickness, the hinge spacing (most Therma-Tru residential doors use 4-1/2-inch hinge spacing, but some older models used 4-inch), and the bore locations for the lockset. Then we cross-reference against Therma-Tru’s current production specs. One gotcha we see regularly in San Francisco: homes built before roughly 1995 often have non-standard rough openings that were furred out with scrap lumber, and a modern Therma-Tru pre-hung unit won’t drop in without reframing. We flag that before ordering anything so you’re not paying for a door that doesn’t fit the hole.
As for OEM versus aftermarket: Therma-Tru’s own weatherstripping, sweeps, and hinges are engineered to their slab profiles, and we use OEM parts on any door still under warranty so the warranty stays intact. For out-of-warranty doors, quality aftermarket weatherstripping from brands like M-D Building Products often matches or exceeds OEM performance at a lower cost, and we’ll quote both so you can decide. We also work alongside the other named-brand materials we install – cabinets from KraftMaid, countertops from Cambria and Silestone – so the entry system gets specified in the same plan set as everything else, not as an afterthought. Elmstead Remodeling San Francisco is an independent contractor and not affiliated with Therma-Tru, which means we’re free to recommend what actually works rather than what a rep pushes.
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Styles & brands we work with
Signs Your Therma-Tru Home Additions & ADU Is Failing
– The door binds at the top corner on the latch side. This usually means the foundation or framing has settled and the rough opening is no longer square. In San Francisco’s clay-heavy soils, especially in the Sunset and Richmond districts, minor settlement is common after a new addition goes in. If left alone, the constant rubbing wears down the weatherstripping and eventually the slab edge itself.
– You can see daylight around the weatherstripping even when the door is closed and locked. Compression-set weatherstripping loses its rebound after a few years of fog-season moisture and temperature swings, and once it flattens, the door no longer seals. It’s not just a draft; it’s the door slowly rotting at the sill from water that gets past the failed gasket.
– The threshold or the bottom sweep is worn flat on one side. Uneven wear points to a door that was hung slightly out of plane, or to hinges that have loosened over time. The fix sometimes requires pulling the casing, shimming the jamb, and re-hanging the slab, not just replacing the sweep.
– The door rattles when a bus goes by on Geary or 19th Avenue. That rattle means the weatherstripping isn’t compressing evenly and the door isn’t seating against the stops. The noise itself is just annoying; the real problem is that every gap is a path for air and water to get where they shouldn’t.
– You notice rust staining on the hinges or the threshold screws. San Francisco’s salt air – especially in the Sunset, the Richmond, and anywhere within a few blocks of the bay – accelerates corrosion on steel and plated hardware. Once the hinges start oxidizing, they bind, and the door starts to sag just enough to throw off the latch alignment.
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See the difference
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After
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After
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AfterReplacement Cost & What’s Included
A full home addition in San Francisco runs $53,100 to $153,400, and an ADU (attached or detached accessory dwelling unit) typically lands between $106,200 and $259,600 depending on size, foundation type, and finish levels. Garage conversions fall in the $35,400 to $94,400 range. When the scope includes a Therma-Tru entry system as part of the build, the door, frame, hardware, and installation are line items in that written price – not a change order halfway through. What drives the range: the condition of the existing rough opening, whether we’re reframing the wall or working with what’s there, the specific Therma-Tru line you choose, hardware grade, and whether we need to bring the opening up to current code for egress or accessibility. Every quote includes the door and all components, labor, disposal of the old unit, flashing and sealing, and the written price before any work starts. The 365-Day Done Right Promise covers the completed work.
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DIY or Call Us?
For a Therma-Tru door inside a new addition or ADU, what you can safely check yourself: run your hand along the weatherstripping on a cold morning and feel for drafts, look at the threshold for even wear, and check whether the hinge screws are tight. That tells you the door’s condition. What you shouldn’t do yourself is pull the door or the frame to fix an out-of-square rough opening. Once you start pulling casing and shimming jambs on a fiberglass entry system, you’re working with a 100-pound slab, finished wall surfaces, and flashing details that keep water out of the wall cavity. If the flashing goes back wrong, the first you’ll know about it is a mold smell inside the wall in two years. We’ve re-done enough homeowner attempts around the city that it’s worth saying plainly: this is the kind of job where the mistake costs more than hiring it done right the first time. Tell me what the room needs to do, and we’ll figure out the rest from there. For a free estimate on any home addition or ADU work in San Francisco, call (831) 480-4497.
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FAQs
How long do Therma-Tru doors last in San Francisco?
A properly installed Therma-Tru fiberglass door in San Francisco will last 30 years or more, though the weatherstripping, sweeps, and finish usually need attention every 5 to 7 years because of the fog, salt air, and temperature cycles. The slab itself rarely fails; the seals and hardware around it do. Call (831) 480-4497 and we’ll tell you exactly what’s wearing and what it costs to fix.
Can a failing Therma-Tru door be repaired instead of replaced?
Yes – if the slab is sound, we can re-shim the jamb, replace the weatherstripping and sweep, install new hinges, and re-hang the door so it seats properly. Replacement only makes sense when the door itself is damaged, outdated, or when the rough opening needs reframing anyway as part of an addition or ADU project. For an exact quote on either path, call us at (831) 480-4497.
How long does a Therma-Tru door installation take in San Francisco?
A straightforward door replacement in an existing opening takes one day. If we’re reframing the rough opening, correcting settlement issues, or working as part of a larger addition or ADU, the door work gets sequenced into the project timeline and the schedule is part of the written plan you’ll have before we start. Call (831) 480-4497 and we’ll walk you through timing for your specific project.
Do you stock Therma-Tru parts or do you have to order them?
We keep common Therma-Tru weatherstripping, sweeps, hinges, and thresholds on hand for the models most often installed in San Francisco additions and ADUs. Unusual sizes or specific finishes have a short order lead time, and we tell you that before you commit to anything. Call (831) 480-4497 and we’ll check stock on your exact model code.
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Written by Graham Stein, Owner, Elmstead Remodeling San Francisco at Elmstead Remodeling San Francisco, serving San Francisco and nearby areas.
