A free site visit, a check of what your lot allows and a written, line-item price.
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A home addition contractor plans, prices, and builds new square footage onto an existing house, whether that means a sunroom, a second story, a garage-level build, or a new bedroom and bath. At Sutton ADU Builders, we’ve done this work since 2006, and every project starts the same way: a written price before any tool is lifted, and a named, photo-badged crew you know before they arrive. If you’re adding a room or a whole ADU, call (472) 248-8213 and we’ll walk you through what’s realistic on your lot and your budget, or read our Complete Home Addition Contractor Guide for Los Angeles Homeowners to prepare.
Most homeowners call us with the same three questions: what will this cost, how long will it take, and who exactly is coming onto my property. We answer all three in writing. The Threshold Standard governs every build: a 365-Day Done Right Promise covering workmanship, a free second visit if any element fails, and a crew that’s background-checked, identity-verified, and photo-badged before they set foot on your driveway. No vague estimates, no unfamiliar faces, no surprise change orders. That’s the whole point of hiring Sutton.
Sunroom Addition
A sunroom addition extends your living space with glass, light, and a conditioned room that bridges indoors and outdoors without the full cost of a conventional stick-built extension. Most sunroom additions run $35,000 to $90,000 depending on glazing, foundation work, electrical runs, and whether you’re adding heating and cooling to the space. Sutton ADU Builders handles the design, permitting, framing, glazing, and finish work, and we give you a written price for the entire scope before we start, so you never absorb a surprise line item mid-build.
Foundation and Glazing Choices
Sunrooms sit on one of three foundation types: a poured slab, a crawlspace, or an engineered deck system. The choice affects your price more than any other single factor, and we’ll explain the tradeoffs in plain language before you commit. Glazing packages range from single-pane storm glass to low-E insulated units that actually hold temperature through winter.
When a Sunroom Makes Sense
If your existing living room feels cramped three seasons a year, a sunroom addition often costs less per square foot than a full room addition and gives you usable space nearly year-round. Homeowners who work from home use them as daylight offices. Families use them as breakfast rooms, playrooms, or reading nooks that don’t require enlarging the home’s original footprint dramatically.
Second Story Addition Contractor
A second story addition contractor builds upward instead of outward, adding a full or partial upper level to a single-story home when the lot won’t support a ground-floor expansion. A partial second story (one or two rooms over a wing) typically runs $120,000 to $250,000, while a full second story often lands between $200,000 and $400,000 depending on structural reinforcement, stair placement, and roof rebuild scope. Sutton ADU Builders evaluates your foundation, existing framing, and roofline, then delivers a written price covering engineering, permits, framing, mechanicals, and finish work.
Structural Reality Check
Not every single-story house can carry a second floor without significant reinforcement, and some cannot at all. We assess your slab or crawlspace, existing wall framing, and roof structure before quoting anything. If the foundation needs underpinning or shear wall upgrades, that work is included in your written price, not discovered later as a change order.
Living Through the Build
Adding a second story means your roof comes off, and that’s a real disruption for any family. We schedule the tear-off, framing, and dry-in as a single compressed phase, getting your home weather-tight again as fast as the engineering allows. Our crews are the same vetted, photo-badged team from day one, so you always know who’s on your property.
Garage Addition Contractors
Garage addition contractors build new attached or detached garages, or convert and expand an existing garage into conditioned living space, depending on what the household actually needs. A new attached single-car garage addition typically runs $45,000 to $90,000; a detached two-car garage with a workshop or storage loft can reach $110,000 to $180,000 when electrical, insulation, and finish grades are included. Sutton ADU Builders handles garage additions, garage-to-ADU conversions, and Tuff Shed structure placement, with the same written pricing and vetted crew standard on every job-learn more in our guide to DIY vs Professional Home Addition Contractor: What’s Safe to Do Yourself.
Attached Garage Additions
An attached garage addition ties into your existing roofline and requires matching exterior finishes, a proper fire-rated wall assembly, and often a new driveway apron. We coordinate the site work, foundation, framing, and finish so the new structure looks like it was always there. Utility runs for an EV charger or workshop circuit are priced in writing before we break ground.
Detached Garage and ADU Hybrids
Some homeowners want a detached garage with a small living space above it, which functions as a garage addition today and a rental or guest quarters later. This hybrid approach often qualifies under local ADU rules, and our familiarity with prefab and modular systems, including Boxabl and Plant Prefab units, means we can give you honest guidance on whether a panelized build saves you time and money versus conventional framing.
Bathroom Addition Contractor
A bathroom addition contractor adds a full or half bath where none exists, typically by capturing space from a bedroom, hallway, closet, or unfinished basement area. A standard full bathroom addition runs $25,000 to $55,000 when plumbing lines are nearby; moving drain lines across a house or adding a bathroom to a second story can push that to $60,000 to $90,000. Sutton ADU Builders handles the rough-in, waterproofing, fixture setting, and finish work, with a written price covering the entire scope before demolition begins.
Plumbing and Ventilation Scope
Adding a bathroom is less about square footage and more about getting water in and waste out. We map your existing drain lines, vent stack location, and supply plumbing before quoting, because the distance from the new wet wall to your main stack drives cost more than tile choice does. Proper exhaust ventilation is non-negotiable on our builds, and we size the fan to the room, not the budget.
Adding a Bathroom Without a Full Remodel
You don’t need to gut the whole house to add a bathroom. Many of our jobs capture a walk-in closet, an oversized laundry area, or dead hallway space and turn it into a code-compliant three-piece bath. We’ll tell you if your planned location can support the drain slope you need before you spend money on design drawings.
Bedroom Addition Contractor
A bedroom addition contractor builds a new sleeping room onto the house, with the egress, closet, electrical, and heating requirements that make it a legal bedroom and not just a finished space. A ground-floor bedroom addition typically runs $60,000 to $120,000 depending on foundation type, roofline complexity, and whether a bathroom is part of the same build. Sutton ADU Builders designs and builds bedroom additions that meet code for egress windows or doors, smoke detection, and thermal comfort, with the complete price in writing before framing starts.
What Makes a Bedroom Legal
A legal bedroom needs a second means of egress (typically a window meeting minimum size and sill height), a closet in most markets, a heat source, and a smoke detector tied to the home’s system. We build these requirements into every bedroom addition by default, and we pull permits and pass inspections before we call the job done. No one wants to find out at resale that their “bedroom” was never a bedroom.
Bedroom Plus ADU Potential
Some counties allow a larger bedroom addition with a private entrance and a small bath to be classified as a junior ADU, which changes its rental and resale value significantly. We work with Dvele and Mighty Buildings panelized systems when that route fits the lot and budget, and we’ll tell you honestly when conventional framing costs less. The decision never happens behind your back.
Brands We Service
Our crews have direct, hands-on experience with leading prefab and modular ADU product lines, which matters when a panelized kit arrives and needs a builder who’s seen its particular connection details before. We’ve assembled and finished Dvele units, with their precision-cut wall panels and integrated utility chases, and we know how their tolerances interact with foundation flatness requirements. Our team also works with Mighty Buildings panels, whose composite printed wall system requires different fastener schedules and flashing details than a standard wood-framed wall.
Boxabl’s folding room modules and Plant Prefab’s panelized kits each have their own sequencing quirks, especially around crane access and module alignment, and we’ve managed both on tight urban lots and rural sites. Whether you have a Dvele, a Mighty Buildings, a Boxabl, a Plant Prefab unit, or a standard stick-framed addition, we can help, and our written price covers the work before the first panel comes off the truck.
Signs You Need a Pro Right Now
- Your foundation is settling or cracking. Diagonal cracks wider than 1/8 inch, sticking doors, or visible floor slope can signal soil movement that will compromise any addition you build. A pro needs to evaluate load paths before you spend money on framing.
- Your roof leaks during heavy rain. Adding square footage under a compromised roof means trapping moisture in the new structure. Fixing the existing roof and tying in the addition’s roofline correctly is not a DIY weekend project.
- Your electrical panel is full. A room addition needs new circuits, and if your panel has no open slots, you’re looking at a subpanel or service upgrade. This is work that requires a permit, an inspection, and a licensed electrician, not a handyman.
- You found unpermitted past work. If a previous owner finished a space without permits, your addition may need to bring that work up to code before anything new can be approved. Sutton ADU Builders has untangled these situations before, and we’ll tell you exactly what the inspector will flag.
- You need to know who’s coming onto your property. If the idea of an unvetted crew showing up at your door makes you hesitate, that’s not paranoia, it’s a legitimate security question. Every Sutton technician is background-checked, identity-verified, uniformed, and photo-badged, and their name and photo are sent to you before arrival.
Our Process, Step by Step
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Initial consultation and site walk. We walk the property with you, measure what exists, and listen to what you’re actually trying to solve: more bedrooms, a rental unit, space for aging parents. You’ll get a plain-spoken read on what’s feasible on your lot, not a sales pitch.
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Written scope and price. Before any work begins, you receive a written line-item price covering labor, materials, permits, and the specific finish level you chose. The Threshold Standard means no surprise invoices later, and no scope creep slipped silently onto the bill.
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Permitting and engineering. We prepare the drawings, structural calculations, and permit applications your local building department requires, and we manage the review process until permits are in hand. If an inspector flags something, we handle it without charging you for our own corrections.
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Build and daily communication. You’ll know who is on site every day because the same vetted, photo-badged crew runs the whole build. We keep you updated on progress, weather delays, and inspection results, and we protect the untouched parts of your home from dust and traffic.
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Final walkthrough and 365-Day Done Right Promise. We walk the finished addition with you room by room, verify everything against the written scope, and hand you the 365-Day Done Right Promise in writing. If anything isn’t right within a year, we make it right, including a free second visit if an element fails.
How Much Does a Home Addition Contractor Cost?
A typical sunroom addition runs $35,000 to $90,000, a ground-floor bedroom addition runs $60,000 to $120,000, a bathroom addition runs $25,000 to $55,000 when plumbing is nearby, and a full second story addition lands between $200,000 and $400,000 depending on structural scope. Garage additions run $45,000 to $180,000 depending on attached or detached, size, and finish level. These are national ranges; your specific lot, soil, existing structure, and finish choices will move the number, which is exactly why we put it in writing after a site walk, not over the phone.
What moves the price the most: foundation type (slab vs. crawlspace vs. second-story load transfer), how far new plumbing drains must run, roof tie-in complexity, and the level of interior finish you choose. What doesn’t protect you: a low verbal estimate that “might adjust” once work starts. Our written price includes everything in scope, and if you want to change the scope, we price the change in writing before we do it. A free estimate from Sutton means exactly that: a real number, line by line, with no obligation and no pressure to sign. Call (472) 248-8213 to schedule yours.
Where We Work
Sutton ADU Builders serves homeowners across the United States through local crews operating under Threshold Verified standards, including our Home Addition Contractor in Huntington Park team. Every Sutton location is independently owned and operated, but every crew follows the same rules: written pricing before work starts, the 365-Day Done Right Promise, and background-checked, identity-verified, photo-badged technicians on every visit. Wherever you are, the Threshold Standard applies.
Frequently Asked Questions About Home Addition Contractor
A home addition contractor is a licensed builder who plans, permits, and constructs new square footage attached to or adjacent to an existing home, including sunrooms, second stories, garage additions, bathrooms, and bedrooms. Sutton ADU Builders has done this work since 2006 as your Home Addition Contractor in Los Angeles, and every project is governed by a written price and the 365-Day Done Right Promise. We handle design, engineering, permits, and construction under one roof so you’re not juggling four different companies.
Most ground-floor additions (bedrooms, bathrooms, sunrooms) take 8 to 16 weeks from permit approval to final inspection, depending on foundation work and finish complexity. A second story addition typically takes 4 to 6 months because the roof must come off, the structure must be built upward, and the entire home must be re-dried-in before interior work can proceed. We’ll give you a written schedule with your written price, and we’ll tell you when weather or inspection queues are affecting the timeline.
National ranges run from $25,000 for a simple bathroom addition with nearby plumbing up to $400,000 for a full second story. Sunrooms run $35,000 to $90,000, bedrooms $60,000 to $120,000, and garages $45,000 to $180,000. Your final price depends on foundation type, structural scope, mechanical runs, and finish level, and Sutton puts that number in writing before any work begins. Call (472) 248-8213 for an exact quote, estimates are free.
Yes, our crews have direct assembly and finish experience with Dvele, Mighty Buildings, Boxabl, and Plant Prefab units, plus Tuff Shed conversions and James Hardie exterior systems. We understand the specific connection, flashing, and utility details each brand requires, which prevents costly assembly errors on delivery day. Whether you have one of these brands or a conventional stick-built design, we can build it.
If a structural issue, failed foundation element, or storm damage affects your existing home before or during an addition project, call (472) 248-8213 any hour. A live person answers every call, 24 hours a day, 7 days a week. We’ll assess the issue, advise you on immediate safety steps, and schedule a site visit as soon as a vetted, photo-badged technician can reach you.
The 365-Day Done Right Promise covers defects in workmanship for one full calendar year from project completion. If something we built isn’t right within that year, we make it right, and a second visit to correct a failed element is free, no haggling, no fee. You get the promise in writing, stamped on your project documents, before you sign anything.
Start by listing what you actually need the space to do, not just what it should look like: a quiet home office, a rental unit, a bedroom for an aging parent. Gather any old surveys, prior permit records, or inspection reports you have, because they save us time during the site walk. Then call (472) 248-8213 to schedule a free consultation, and we’ll handle the rest with a written price before any commitment.
Schedule Your Home Addition Contractor Service Today
If you’re ready to add square footage and want a builder who puts the price in writing before work starts and sends you the name and photo of every technician before they arrive, call (472) 248-8213. You’ll get a free, no-obligation estimate, a straight answer about what’s feasible on your lot, and the 365-Day Done Right Promise on everything we build.
Written by Miles Hartwell, Owner at Sutton ADU Builders, serving homeowners nationwide since 2006.
