Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Stevenson Ranch
A room addition or ADU in Stevenson Ranch typically costs between $45,000 and $130,000 for the addition itself, and $90,000 to $220,000 for a full detached ADU. Those are real numbers pulled from the jobs we’ve bid and built across 91381. What’s behind them is equally real: nearly every project in this community has to clear LA County’s Very High Fire Hazard Severity Zone review, HOA architectural approval, and often a soils check on an aging cut-and-fill pad before framing ever starts. Our Home Additions & ADU team has walked plenty of Stevenson Ranch homeowners through exactly that sequence, and we won’t pretend it’s simpler than it is. Call (877) 610-1318 and we’ll talk through your property’s specifics before you spend a dollar on plan fees.
Why Barrett & Sons Construction Is Stevenson Ranch’s Preferred Home Additions & ADU Company
We’re a family-owned outfit founded in 1998, owned and run by Tom Barrett. His sons run the crews, and they’re on-site most days, not calling in from another state. You will see the same faces at the hardware store on Saturday that you saw on your job site Thursday. That matters to the folks we’ve built for up and down Pico Canyon Road, around Hemingway Avenue, and through the neighborhoods off Stevenson Ranch Parkway.
Every job we take in Stevenson Ranch carries our written 90-Day Done Right Promise. If something isn’t right after we finish, Tom comes back and makes it right. One call. It’s printed on the contract, not whispered during the sales pitch.
We also work the way Stevenson Ranch actually requires: permits pulled, inspections signed, and every scope or allowance change delivered as a written change order before it touches your project. The permit inspector works for you, not for me. That’s a good thing, because on a hillside lot in a fire zone, the inspector is the one who makes sure the ember-resistant vent spec actually got installed, not just billed.
Our Home Additions & ADU Services in Stevenson Ranch
ADU Design & Permitting
We handle the full design and permitting path for ADUs in Stevenson Ranch, including the LA County VHFHSZ plan review that flatland contractors overlook. We prepare the Chapter 7A materials list, the architectural review package for your HOA, and the soils documentation if your site sits on a tiered retaining wall. You get a scope in writing before we pull the first permit, so there are no surprise invoices when the county fire marshal’s comments come back.
Garage Conversion ADU
Garage conversions in Stevenson Ranch generally run $30,000 to $80,000, and they’re one of the smartest ways to add rentable square footage without fighting the hillside. On Hemingway Avenue, we framed a garage-conversion ADU where the original Pardee-built home’s builder-grade sliding door had warped and the HOA required a site-specific ember-resistant vent spec before inspection sign-off. Our crew replaced the rough-in with fire-rated glazing and brought the project through the final draw schedule without a single change order.
New Detached ADU
A new detached ADU in Stevenson Ranch runs $90,000 to $220,000, and the range swings on site conditions more than finish level. If your lot is graded into the hillside and the ADU sits near an older block retaining wall, budget for a soils engineer review sooner rather than later. We’ll tell you that before you pay for plans, because finding wall movement during excavation turns a straightforward build into a structural remediation contract, and you deserve to know that risk exists on your specific lot.
Junior ADU & Interior Conversion
Junior ADUs are the quiet workhorse of Stevenson Ranch, converting existing interior space into a permitted, rentable unit without adding a roofline. That path often avoids the full Chapter 7A exterior upgrade triggers, though fire-rated separation between the main house and the JADU still applies. We’ve helped homeowners off Shakespeare Drive and Constitution Avenue turn unused bonus rooms into compliant JADUs with their own entrance and kitchenette.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Stevenson Ranch
When we install or tie into systems on a Stevenson Ranch addition, we use materials you can look up: Schluter for waterproofing and tile substrates, Sterling and Grohe for bath fixtures, GAF for roofing transitions where the addition meets the existing Class A roof. We don’t install mystery brands off a van, and we don’t spec something our own crew wouldn’t put on their own homes. That brand discipline matters on Chapter 7A work especially, because the county checks the assembly, not just the appearance.
Common Home Additions & ADU Problems We See in Stevenson Ranch Homes
- Chapter 7A materials missing from the first bid. Contractors who quote flatland Santa Clarita prices don’t include ember-resistant venting, fire-rated glazing, or Class A edge details. The first inspector visit forces a mid-project re-scope, and the homeowner eats the difference.
- HOA architectural review skipped. Stevenson Ranch HOAs review additions and ADUs before the county will even look at your permit application. If the HOA rejects your setback or roofline after you’ve paid for plans, that money is gone.
- Retaining wall surprises on cut-and-fill pads. Many lots are engineered hillside pads with tiered concrete or block walls now 20 to 30 years old. An ADU sited near one can uncover wall movement or drainage failure during excavation, turning your $120,000 ADU into a $180,000 structural job.
- Builder-grade envelope failures. Homes built by Pardee and William Lyon between 1991 and 2005 are hitting the age where original windows, sliding doors, and stucco start failing together. An addition is the right moment to fix the adjacent envelope instead of patching around it.
Pricing for Home Additions & ADU in Stevenson Ranch, CA
Here’s what we tell Stevenson Ranch homeowners when they ask for straight numbers:
| Project | Stevenson Ranch Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
The spread is real and it reflects site conditions, not finish upgrades. A flat interior lot with simple access and no retaining-wall triggers lands at the low end. A hillside pad requiring Chapter 7A exterior details, a soils report, and HOA landscape mitigation lands at the high end. We give you a written line-item quote before you sign anything, with no trip charge inside the county, and a free second opinion on any written estimate you’ve already received. Call (877) 610-1318 to schedule it.
We Also Serve Cities Near Stevenson Ranch
Our crews work throughout the Santa Clarita Valley, so if you’re just over the hill in Valencia or Santa Clarita, or out toward Castaic and Chatsworth, we can help there too. The fire-code and hillside issues change block by block, and we know which rules apply where. Stevenson Ranch is home base for this page, but the same crews and the same promise cover the neighbors.
Serving Stevenson Ranch, CA - Our Local Coverage Area
We’re based in the Stevenson Ranch area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Home Additions & ADU in Stevenson Ranch
Yes, and it has to come first. Stevenson Ranch HOAs review exterior changes, including ADUs, room additions, and garage conversions, before LA County will accept your permit application. If the HOA rejects your roofline, setback, or exterior finish after you’ve paid for architectural plans, those plan fees are gone. We typically recommend getting the HOA package approved before we spend anything on county plan sets. Call (877) 610-1318 if you want help sequencing that correctly, because most people do it backwards and it costs them thousands.
Chapter 7A is the California Building Code section that governs construction in Very High Fire Hazard Severity Zones, and Stevenson Ranch sits inside one. Any new addition or ADU exterior must use ignition-resistant materials: ember-resistant attic and soffit vents, Class A roofing at every transition, fire-rated siding assemblies, and specific glazing in windows facing wildland exposure. LA County Fire reviews these details during plan check and again at inspection. A flatland contractor who skips them gets the project red-tagged and re-scoped mid-build. That’s exactly why our quotes include Chapter 7A materials from day one. Call (877) 610-1318 for a line-item quote that accounts for the fire zone from the start.
Because flatland Santa Clarita sits outside the VHFHSZ, so its projects don’t carry Chapter 7A material requirements, and its lots don’t have the same cut-and-fill retaining wall density. In Stevenson Ranch, contractors who bid flatland numbers discover the fire-marshal comments or a failing retaining wall after the permit is already open, and that becomes a change order. We issue change orders too, but ours come before work starts and only with your written sign-off. An allowance that isn’t on paper is a surprise waiting for a date. Call (877) 610-1318 to get a quote built for your actual lot, not a generic hill-town template.
You can enclose a patio, but whether it counts as an ADU depends on whether it has a separate entrance, its own kitchen or kitchenette, and a bathroom. A simple enclosed sunroom is a room addition, not an ADU, and it carries different permit requirements. In Stevenson Ranch, any exterior enclosure also triggers the Chapter 7A fire-rated assembly rules and HOA architectural review. We’ve done both over the years, and we’ll tell you honestly which path fits your patio and your budget before you pay for plans. Call (877) 610-1318 for a site visit.
Plan for $30,000 to $80,000 for the conversion itself, plus a contingency line for the unknowns that Stevenson Ranch specifically produces. If your garage shares a wall with an original builder-grade sliding door that has warped, if the HOA requires a site-specific ember-resistant vent spec, or if the slab needs cutting for a new sewer line, those items should be identified during a pre-conversion inspection, not discovered at demolition. We write contingency into the scope in writing, so the draw schedule matches reality. Call (877) 610-1318 and we’ll walk your garage with you before you commit to anything.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Stevenson Ranch since 1998.