Plant Prefab Garage Conversion ADU: The San Francisco Owner’s Guide
We stock and install Plant Prefab-compatible garage conversion parts across San Francisco, with most swaps priced between $220 and $1,450 depending on the component. Your garage conversion ADU (that’s accessory dwelling unit, meaning a second living space built on your existing lot) runs on a specific set of hardware: weather sealing, ventilation dampers, threshold plates, and panel connectors that were factory-specified for Plant Prefab’s modular assembly. Most San Francisco owners notice a failure the same way: a draft that wasn’t there last winter, a door that suddenly binds after a wet week, or a humming exhaust fan in a garage that used to be quiet.
For most Plant Prefab garage conversion parts, we can diagnose the issue, confirm the right spec on site, and complete the swap the same visit. Call (707) 760-0502 and someone answers, day or night.
Which Plant Prefab Models This Applies To
Plant Prefab’s garage conversion kits fall under their LivingHome and ADU series, with most Bay Area units built between 2016 and 2024 using the panelized system. The parts that fail most often aren’t the structural modules themselves. It’s the interface hardware: the bottom track seals where wall panels meet the existing garage slab, the exterior caulk joints at the transition line, the louvered dryer vents, and the mini-split line-set covers that run along the old garage wall.
Identifying the right part comes down to measurement, not model number. Plant Prefab changed weather seal profiles in 2021, so a 2020 unit and a 2022 unit on the same block in the Sunset District take different bottom sweeps, even if the door looks identical. Measure the channel width where the old seal sat: 5/16-inch and 7/16-inch channels are both common, and the wrong width either falls out or jams. The same applies to threshold plates: San Francisco’s fog-driven moisture means premature corrosion on bare aluminum thresholds, and we typically recommend anodized or powder-coated replacements in the Richmond and Sunset where salt air pushes through the gate.
We install both OEM Plant Prefab parts and quality equivalents from manufacturers like Pemko and National Guard Products when the OEM part is discontinued or back-ordered. For a seal or threshold, the aftermarket option is often better material at a lower price. For panel connectors or anything structural, OEM only, no exceptions.
Lodgewick ADU San Francisco is an independent service provider. We’re not affiliated with Plant Prefab, but we know their hardware well enough to tell you which parts interchange and which don’t.
Signs Your Plant Prefab Garage Conversion ADU Is Failing
- Visible daylight under the entry door or at the wall base. The bottom seal has compressed or torn. In an Ocean Beach or Outer Sunset conversion, this is usually accelerated by sand and salt air wearing the rubber down faster than the manufacturer’s 5 to 8 year life span.
- A persistent musty smell near the floor line after rain. The transition flashing between the original garage slab and the Plant Prefab wall panels has failed. This is the most common failure we repair in the Mission and Noe Valley, where older garage slabs slope unpredictably and water pools at the seam.
- The entry door sticks only in the morning or after fog. Your threshold has shifted or corroded. San Francisco’s moisture cycle does this to anodized aluminum faster than any other climate in California.
- Increased energy bills with no other change. Failed weather stripping at the wall-to-roof transition lets conditioned air escape. Garage conversions are already the tightest part of most homes, so a small gap can move your bill noticeably.
- Rattling or grinding from the ventilation fan. The damper bearing has worn. This is normal at the 4 to 6 year mark for most Plant Prefab garage conversions, especially those running ventilation continuously in a converted bedroom.
Replacement Cost & What’s Included
Every project starts with a written quote, not a ballpark guess. Here’s what San Francisco homeowners pay us for the most common Plant Prefab garage conversion repairs:
- Weather seal replacement (door bottom, wall base): $220 to $480 installed, including the part
- Threshold replacement (corroded or shifted): $380 to $720 installed
- Transition joint re-flashing and sealing: $450 to $980 depending on the length of the seam
- Ventilation damper or fan replacement: $290 to $610 installed
- Full weatherization pass (seals, thresholds, caulk joints, vents): $1,100 to $1,450 installed
That price includes the part, labor, cleanup, and the written guarantee. We name the price before any work starts, and that price doesn’t change at the door. Every job carries the 365-Day Done Right Promise from the Kingswell family: if it fails within a year, we come back and fix it free.
DIY or Call Us?
Seals and thresholds on a Plant Prefab garage conversion aren’t dangerous to work on. If you’re handy, you can peel out a split bottom seal and slide a new one in. The risk isn’t injury, it’s the wrong part. We regularly see homeowners buy a 7/16-inch seal online for a 5/16-inch Plant Prefab channel and pack the gap with caulk, which only makes the next repair worse.
Anything involving panel connectors, gas lines, or electrical connections in a Plant Prefab unit, leave to a trained professional. A wrong connector torqued incorrectly can compromise the structural connection between modules, and no homeowner should be inside a garage wall cavity with electrical wiring without knowing exactly what they’re looking at. Russ Delmar has walked San Francisco garages for the better part of a decade, including conversions within a few blocks of Dolores Park where Victorian lot lines make every opening a different size than the last one. Tell us what the space needs to do, and we’ll figure out how to build it right.
Call (707) 760-0502. We’ll come look, write you a number, and leave the site cleaner than we found it.
FAQs
In San Francisco’s fog belt, most weather seals on Plant Prefab garage conversions last 5 to 8 years before they need replacement. Units in the Sunset and Richmond wear faster due to salt air and sand abrasion. If your conversion is within a mile of the ocean, expect the lower end of that range.
No, and we won’t try. Seals and thresholds are wear items. Patching a split rubber seal with adhesive buys you a few weeks at most. The honest and cheaper long-term option is a new seal, properly sized, installed clean. Call (707) 760-0502 to schedule a free estimate.
Most weather seal or threshold replacements on a Plant Prefab garage conversion take 60 to 90 minutes. A full weatherization pass, including transition joint work and vent service, usually runs half a day. We give you a defined arrival window and show up inside it.
Yes. Our San Francisco crews carry common Plant Prefab seal profiles in both 5/16-inch and 7/16-inch channel widths, along with replacement thresholds and ventilation dampers. If your part is outside standard stock, we order it and get it in hand before we start, not after we’ve already opened up your wall. Call (707) 760-0502 for an exact quote, estimates are free.
Written by Russ Delmar, Owner, Lodgewick ADU San Francisco at Lodgewick ADU San Francisco, serving San Francisco and nearby areas.
