James Hardie Garage Conversion Contractor in San Francisco: What to Know First
James Hardie garage conversions in San Francisco typically run between $140,000 and $260,000 depending on whether you’re converting an attached garage, building out a detached structure, or adding a full ADU with plumbing and electrical. As an independent James Hardie service provider, Lodgewick ADU San Francisco handles the full conversion: structural work, insulation, drywall, permits, and finishes, usually completing a garage-to-living-space project in 12 to 20 weeks. We give you a written price before any work starts, and if it’s not done right within 365 days, we come back and fix it free. Call (707) 760-0502 to talk through what you’re working with.
This page is for homeowners who own a James Hardie-sided home or garage in San Francisco and want to convert that space into something livable. Whether you’re turning an attached garage into a bedroom, building a detached garage ADU, or converting a garage into a full apartment, the Hardie siding on the structure matters more than most people realize. Here’s what to know before you cut a single stud.
How James Hardie Products Fail in Garage Conversions – and How We Fix Them
James Hardie siding is tough stuff, but garage conversions stress it in ways new construction doesn’t. We walk into these jobs all over San Francisco and see the same handful of issues. Here’s what we find, why it happens, and what we do about it.
- HardiePlank lap siding with hidden moisture damage behind the bottom course. In San Francisco garages built before 1990, the bottom row of HardiePlank lap siding often sits too close to grade. Fog, rain, and decades of splashback soak the OSB sheathing behind it. On a conversion, you don’t know until you pull the siding. We replace the rotted sheathing, flash the bottom edge properly, and reinstall with the correct 6-inch clearance above grade. It’s the difference between a room that lasts and one that smells like a wet basement in November.
- HardiePanel vertical siding punctured by old garage door track bolts. When we remove a roll-up garage door on a San Francisco attached garage, we usually find half a dozen bolt holes through the HardiePanel above the opening. Homeowners are surprised because the holes were hidden behind the track. We cut out the damaged panel, install matching HardiePanel with the correct reveal, and caulk with Hardie’s recommended sealant. If the panel is on a front elevation, we’ll match the texture so you can’t see the repair from the street.
- HardieTrim boards separating at corners. San Francisco’s temperature swings aren’t dramatic, but the wet-dry cycle is. HardieTrim at outside corners pulls away over time when it wasn’t back-primed before installation. During a garage conversion, we remove and reflash those corners, back-prime every cut edge, and repaint. It’s not a cosmetic fix; exposed edges are how water gets behind the siding.
- Cracking at nail heads on HardiePlank installed with incorrect fasteners. James Hardie requires specific fasteners: corrosion-resistant, minimum penetration, correct spacing. Older San Francisco installs often used standard roofing nails. Over 15 or 20 years, the fiber cement swells and contracts, the nails don’t give, and the plank cracks. We see this most often on the south- and west-facing walls of detached garages. During conversion, we inspect every course, replace cracked planks, and use the right fasteners on reinstall.
- HardieBacker board used as wall sheathing where a conversion needs structural shear. Some San Francisco homeowners are surprised to learn their garage interior is lined with HardieBacker, not drywall. It’s a cement board rated for tile, not structural load. When we frame a garage conversion, we strip the HardieBacker, add plywood shear panels where the engineer requires, then insulate and drywall. Keeping HardieBacker in place just hides the problem and adds weight without strength.
Our James Hardie Garage Conversion Contractor Process
Every garage conversion we build follows the same pattern. No surprises, no change orders at the door, no unreturned calls.
- 1
Walk the site. Russ Delmar walks every San Francisco job before quoting. He checks the Hardie siding condition, the slab, the roofline, the electrical panel, and the lot lines. You can’t price a conversion from photos.
- 2
Written scope and price. We give you a line-item written price covering structural work, siding repair or replacement, insulation, drywall, electrical, plumbing, and finishes. That price doesn’t change once we start, unless you change the scope.
- 3
Permits and planning. We pull permits with San Francisco’s Department of Building Inspection. If the conversion is a full ADU, we handle the planning process too. You’ll know the permit status at every step.
- 4
Structural conversion. We remove the garage door, frame the opening, repair or replace Hardie siding and trim, and run the mechanical rough-in. We protect the existing Hardie where we can; where we can’t, we match it.
- 5
Finishes and inspection. Insulation, drywall, paint, flooring, fixtures. Then we walk the job with you before final inspection.
- 6
The Kingswell Guarantee in writing. Before we leave, you get a written guarantee: if anything we built fails within 365 days, we come back and fix it. No invoice, no argument.
What James Hardie Garage Conversion Contractor Costs in San Francisco
Real numbers, because you shouldn’t have to call just to get a ballpark. Here’s what we typically see in San Francisco:
- Attached garage conversion to bedroom or office: $140,000 – $190,000 depending on bathroom, kitchenette, and structural work.
- Detached garage conversion to living space: $160,000 – $230,000, higher when the slab needs leveling or the existing Hardie siding needs full replacement.
- Garage ADU with full kitchen and bath: $210,000 – $280,000, including all new utility runs, sound insulation, and Hardie exterior work required by San Francisco code.
- Hardie siding repair or replacement during a conversion: $8,000 – $25,000 depending on square footage, plank replacement count, and whether we’re matching texture on the front elevation.
What moves the price: the condition of your slab, whether the garage shares a wall with the house, the age of your electrical panel, and how much Hardie siding has to come off. Call (707) 760-0502 and we’ll give you a written estimate for your specific job. Free, and it doesn’t commit you to anything.
Why San Francisco Homeowners Call Lodgewick ADU San Francisco for James Hardie Work
Homeowners who’ve been burned before don’t want promises. They want paper. That’s why every Lodgewick job runs on The Kingswell Way: say the price before the work, show up in the window we gave you, leave the site cleaner than we found it, and put the guarantee in writing. The 365-Day Done Right Promise means what it says: if it’s not right, we make it right, and we come back within a year if anything fails. Our techs are background-checked and uniformed, and when you call, a live person answers. Not a voicemail loop, not a chatbot. Someone picks up, 24 hours a day.
We work with James Hardie products every week, and we know how to repair and match them. We also work with Abodu, Cover, and Dvele if you’re weighing a prefab ADU against a stick-built garage conversion. Russ and the crew will tell you which route makes sense for your lot, your timeline, and your budget. Tell us what the space needs to do, and we’ll figure out how to build it right.
FAQs
No. James Hardie’s product warranty covers manufacturing defects in the siding material itself, not the structure behind it. Converting the interior doesn’t void the siding warranty, but improper installation or repair of Hardie siding during the conversion can. We follow Hardie’s installation specs to the letter on every job: fastener type, spacing, clearance, flashing, and caulk. Your siding warranty stays intact because we don’t cut corners on the exterior work while we’re building the interior.
Yes. HardiePlank lap siding, HardiePanel vertical siding, and HardieTrim are all available in current production, and we can match the reveal, texture, and paint color with a close visual match. On older San Francisco homes where a particular color was discontinued, we’ll color-match with a spectrophotometer and repaint the affected elevation so the repair disappears. Exact match is possible in most cases. Call (707) 760-0502 and tell us what you’re seeing.
Most attached garage conversions run 12 to 16 weeks. Detached garage ADUs with new utility runs run 16 to 20 weeks. Permitting with the San Francisco Department of Building Inspection adds 4 to 10 weeks depending on whether you’re converting existing space or building a full ADU with its own address. We’ll give you a real timeline in your written estimate, and we hit it because we plan the material deliveries and inspections before we start.
If your Hardie siding needs replacement as part of the work, add $8,000 to $25,000 to the conversion total, depending on how much area is affected and whether the damage is on one wall or the whole structure. The good news: we catch the damage during the walkthrough before we quote, so the number you get in writing already includes it. No surprise invoice after the walls come off. Call (707) 760-0502 for an exact quote on your property.
Yes. We handle every permit with the San Francisco Department of Building Inspection, including structural, electrical, mechanical, and plumbing permits as required. If you’re converting a garage to an ADU, we also handle the planning review through the ADU unit. You’ll get permit numbers and inspection dates in writing. Nothing gets built without paperwork, because a garage conversion without permits is a liability when you sell the home.
Converting an existing garage means you’re working with the slab, walls, and roof already there. Building a new detached ADU means demoing the old structure, pouring a new foundation, and framing from scratch. New ADUs cost more, but you get a bigger envelope, better insulation, and a floor plan that doesn’t inherit awkward garage dimensions. On San Francisco lots, the existing detached garage is often better suited for conversion because the setback requirements make new construction tight. We’ll walk you through both numbers before you commit.
Get Your James Hardie Garage Conversion Quote
If you’re ready to see a real number for your garage conversion in San Francisco, call (707) 760-0502. Russ or a member of the crew will answer. We’ll schedule a walkthrough, give you a written quote, and you can decide from there. No pressure, no obligation, no call after call. Just a straight answer and a price that holds.
Written by Russ Delmar, Owner, Lodgewick ADU San Francisco at Lodgewick ADU San Francisco, serving San Francisco and nearby areas.
