James Hardie Garage Conversion Contractor in Woodland Hills: What to Know First
A James Hardie garage conversion in Woodland Hills typically costs $85,000 – $165,000 depending on whether you’re converting an attached or detached garage, with design and permitting taking 4 – 8 weeks before construction begins. As an independent James Hardie service provider, Seedling ADU Woodland Hills handles the full conversion: structural work, insulation, drywall over your existing Hardie siding, flooring, electrical, plumbing, and all the finish details. Every project receives a written price before any work starts, and every job is backed by our 365-Day Done Right Promise. This page is for Woodland Hills homeowners who already have James Hardie siding or Hardie board on their garage and want to know how the conversion will work, what to watch for, and what it’ll cost. Call (559) 249-3776 for a free estimate.
How James Hardie Products Fail – and How We Fix Them
James Hardie fiber cement is tough stuff, but garage conversions in Woodland Hills put specific stress on it. Here’s what we see most often:
- HardiePlank lap siding water wicking at the bottom edge. In Woodland Hills garages, the slab sits low and sprinkler overspray or heavy winter rain splashes up. HardiePlank is cement-based, so it absorbs water at exposed cut edges. We see the bottom course swell, soften, or delaminate within a few years. Our fix: when we convert the garage, we cut any damaged planks above the splash line and install a proper metal flashing detail before re-siding or adding a stem wall extension.
- HardiePanel vertical siding nail pops and seam separation. HardiePanel is common on 1970s – 1990s Woodland Hills garages. Over decades of valley heat, the panel joints open up and nails back out. It looks cosmetic, but open seams let water behind the panel and into the framing. During conversion, we pull affected panels, inspect the framing, replace any rotted studs, and reinstall with proper gap tolerances and flashing.
- HardieSoffit damage from roof leaks that went unnoticed. Garage soffits are easy to ignore because nobody looks up. By the time we convert, soffit panels on older Woodland Hills homes are often spongy from a long-slow roof leak. We replace those before we insulate, because sealing a wet cavity behind new drywall creates mold problems nobody wants to discover later.
- HardieBacker board used as exterior sheathing on older garage additions. Some Woodland Hills garages were originally built or added onto using HardieBacker as a structural sheathing panel, which was never its intended use. When we open walls for electrical and plumbing, we find cracked or sagging panels. We replace those with proper OSB sheathing and retain the James Hardie exterior look you already have.
- Improper clearance between Hardie siding and grade or hardscape. James Hardie specs call for a minimum 6-inch clearance between siding and soil or paving. On Woodland Hills lots where concrete patios or planter beds were added after the garage was built, that clearance gets buried. We routinely correct grade and trim the bottom course during conversions so your warranty stays intact and water doesn’t sit against the siding.
Our James Hardie Garage Conversion Contractor Process
Here’s what a typical garage conversion looks like with our crew in Woodland Hills, from first call to final walkthrough:
- 1
You call (559) 249-3776 and tell us what you need the space to do. Ben Ortega or one of our project leads listens first, asks about your Hardie siding condition, and schedules a site visit.
- 2
We inspect the garage structure, siding, slab, and roofline. We check for the failure modes above, measure clearances, and test the slab for moisture vapor transmission, because a garage slab that wicks moisture will wreck flooring later.
- 3
You get a written line-item price. We break down the conversion: framing, electrical, plumbing, insulation, drywall, flooring, windows, doors, and any James Hardie repairs. No surprise line items after that, period.
- 4
We pull permits and start structural work. The crew may need to pour footings, add a stem wall, or reinforce the existing framing depending on what the plans call for. We handle the paperwork and the inspections.
- 5
We build out the conversion. Insulation goes in, then mechanical rough-ins, drywall, flooring, and finish work. James Hardie repairs happen during this phase so the exterior looks right when we’re done.
- 6
Final walkthrough and clean-up photo. We walk the space with you, test everything, and hand you the keys. You get a photo of the clean-up before we leave, and the 365-Day Done Right Promise applies for a full year after completion.
What James Hardie Garage Conversion Contractor Costs in Woodland Hills

Here are realistic price ranges for James Hardie garage conversions we’ve done in Woodland Hills:
- Attached garage to bedroom or office conversion: $85,000 – $125,000. Existing walls and roof stay, but you’re adding insulation, drywall, electrical, windows, and a proper foundation connection.
- Detached garage to full ADU with kitchen and bathroom: $130,000 – $180,000. This includes sewer and water line runs, a small kitchen, a bathroom, and upgraded electrical service in most cases.
- Garage apartment conversion above a garage: $150,000 – $200,000. These often need structural floor upgrades, stair access improvements, and fire separation work.
- James Hardie siding repair during conversion: $1,800 – $6,000 depending on how much siding we’re replacing and which Hardie product line you have.
What moves the price: the condition of your existing slab, how far utilities need to run, whether your electrical panel needs an upgrade, and the level of finish you want. Call (559) 249-3776 for an exact quote – estimates are free.
Why Woodland Hills Homeowners Call Seedling ADU Woodland Hills for James Hardie Work
We’re not the cheapest contractor in the San Fernando Valley, and we’re not trying to be. What we offer is certainty. You get a written price before a single tool is picked up. The crew is background-checked and uniformed, and they show up with shoe covers and drop cloths every single time. Our Cedarwell Care Promise means we use pet-safe products where there’s a choice, we keep noise down near bedrooms, and we send you a photo of the clean-up before we leave each day. If we’re converting your garage while your kids are doing online school in the house, we plan hammering and saw cutting around that. Ben Ortega grew up in Los Angeles and has worked on Woodland Hills projects near Warner Center, where he’s seen how a thoughtful ADU quietly changes what a family can do. We also work with Abodu, Cover, and Dvele prefab systems when a panelized approach makes more sense than a conventional build. Tell me what you need the space to do, and we’ll figure out how to build that.
FAQs

Yes, in most cases we convert the garage and keep your existing Hardie siding intact. We only replace damaged sections, repair clearance issues, and re-detail flashing where needed. If your siding is in good shape, it stays.
Your Hardie siding warranty typically remains valid as long as installation and repairs follow James Hardie’s published specs. We maintain proper clearances, use correct fasteners, and flash joints per Hardie’s installation requirements so your warranty isn’t voided by the conversion. We are an independent James Hardie service provider, not an authorized installer, so we recommend confirming coverage details with James Hardie directly.
Most garage conversions in Woodland Hills take 8 – 14 weeks from permit approval to final inspection. Attached garage conversions with minimal structural work trend toward the shorter end; detached garage ADUs with kitchens and bathrooms take longer because of utility trenching and foundation work. We give you a written timeline with the price before work begins.
Yes, we pull all required permits with the City of Los Angeles Department of Building and Safety. Every inspection is scheduled by us, and we’re on site for each one. You don’t manage the paperwork, we do.
If your slab has significant slope or moisture vapor transmission, we’ll address it during the conversion. That might mean grinding, leveling compound, a vapor barrier, or a raised floor system. We test for moisture before we quote so you’re not surprised by a change order later. Call (559) 249-3776 for an exact evaluation – estimates are free.
Written by Ben Ortega, Owner, Seedling ADU Woodland Hills at Seedling ADU Woodland Hills, serving Woodland Hills and nearby areas.


