Trusted Home Addition Contractor Nationwide
A home addition contractor handles the design, permitting, and construction work that expands your existing home’s footprint, whether that means a new ground-floor wing, a second story, or a converted garage brought into the main floor plan. Seedling ADU Builders builds home additions with the same discipline we bring to our ADU projects: a written price before a single tool is picked up, background-checked crews in uniform, and a crew that leaves your home clean at the end of every workday. Led by Ben Ortega, our team has spent years managing additions and accessory dwelling units across the country. Most families reach us by phone at (707) 383-5338 before they’ve chosen between an addition and an ADU, and we help them think through both with guidance from The Complete Home Addition Contractor Guide for Los Angeles Homeowners.
Key Takeaways
- Written pricing first: You receive a full line-item price before any work begins. No surprise change orders.
- 365-Day Done Right Promise: Every addition Seedling builds is covered in writing. If it’s not done right, we make it right.
- Cedarwell Care Promise on every visit: Shoe covers, drop cloths, pet-safe products where there is a choice, and a clean-up photo before the crew leaves.
- One phone number, a live person: Call (707) 383-5338 any time during your project. No voicemail trees.
- Real material choices: Work with quality systems like Dvele and Plant Prefab when you want factory precision, or James Hardie siding for site-built work.
Sunroom Addition
A sunroom addition is a glazed, light-filled room built onto an existing exterior wall, usually on a slab or low deck foundation. It’s the right choice when you want usable daytime living space, a plant room, or a quiet breakfast area without the full cost of a traditionally framed extension. Seedling ADU Builders handles sunroom additions from foundation to finished trim, and we write your price before we start. Depending on size, glazing quality, and roof tie-in, a sunroom addition typically runs between $25,000 and $80,000.
Glass and Comfort Decisions
Most sunrooms live or die by the glass package. We walk you through low-E glazing, regional sun exposure, and thermal breaks so the room stays comfortable in both summer and winter. For a three-season sunroom, we recommend simpler glazing and ceiling fans; for a four-season room, we specify insulated frames and a ducted mini-split.
Foundation and Roof Tie-In
Sunroom foundations don’t need to be as deep as a full addition, but the roof connection to your existing home matters. We pull permits, reinforce the existing fascia and rafters where the new roof lands, and flash the junction properly so the room never leaks.
Room Addition Contractor
A room addition contractor builds new habitable square footage onto your home: a family room, home office, or flex space that ties into the existing roofline and foundation as if it had always been there. Homeowners call us when the house feels cramped but moving isn’t the right answer. Seedling ADU Builders manages the whole process, from structural drawings to paint, and every project starts with a written price. A single room addition typically costs between $45,000 and $110,000 depending on foundation depth, roof complexity, and interior finishes.
Matching What You Already Have
The best room addition contractor makes the new space feel like it grew from the original house. We match roof pitch, window style, and floor transitions so the addition doesn’t read as a bolt-on. This matters for resale and for how the room feels when you walk through it every day.
Living Through the Work
Most families stay in the house during a room addition, which is why our crews protect floors with drop cloths, wear shoe covers at the door, and keep tools quiet near bedrooms during school hours. The Cedarwell Care Promise is a written part of every project.
Second Story Addition Contractor
A second story addition contractor builds new living space above your existing ground floor, which means removing part or all of the roof and strengthening the structure below. Second-story additions are the right call when your lot can’t expand outward but your family has outgrown the footprint. Seedling ADU Builders plans these jobs around your family’s daily life, and you’ll have a written price before demolition starts. A second story addition typically runs between $120,000 and $300,000 depending on the number of rooms, bathrooms, and structural reinforcement required.
Structural Engineering First
Before we touch the roof, an engineer evaluates your existing foundation and first-floor walls. Many single-story homes need additional footing or shear-wall work to carry the second level safely. We include that in the written estimate, so you know the real number up front.
Living Below an Active Build
Because your family lives under the work zone, we sequence the job to keep one floor habitable as long as possible. The crew covers furniture, isolates the work area, and sends you a photo of the clean-up before they leave each day.
Garage Addition Contractors
Garage addition contractors build attached or detached garages, or expand an existing garage into a larger workshop, storage, or vehicle space. You need garage addition contractors when your current garage is too small for your vehicles, your tools, or both, and a home addition is the cleaner alternative to off-site storage. Seedling ADU Builders builds garages from slab to truss, and we’ll give you a written price before the concrete is poured. A standard attached or detached garage addition typically costs between $30,000 and $75,000 depending on size, electrical, and finishing.
Beyond Vehicle Storage
Many families use a garage addition as a workshop, gym, or future ADU shell. We frame and rough-in for these possibilities at the start, which costs less now than retrofitting later. This is one of the most practical home addition projects for resale value.
Slab, Drainage, and Door Openings
Garage slabs need proper slope and drainage, and the door openings need sturdy headers. We handle these details at the framing and pour stage, so your doors open cleanly and water never pools inside.
Bathroom Addition Contractor
A bathroom addition contractor builds a new full or half bath where one didn’t exist, often as part of a larger room addition or by capturing underused closet or hallway space. A bathroom addition makes sense when mornings are a traffic jam and no remodel will fix the lineup. Seedling ADU Builders handles rough plumbing, waterproofing, tile, and finishes, all with a written price before work begins. A new bathroom addition typically costs between $25,000 and $60,000 depending on fixtures, tile choices, and how far the new drain line runs.
Plumbing and Ventilation
The two details that make or break a bathroom addition are drain slope and exhaust air. We run waste lines with proper fall, vent through the roof, and install a quiet exhaust fan that actually moves moisture. These are the things you’ll never see but will always notice if they’re wrong.
Fixture and Finish Choices
Bathrooms age fast when you choose finishes only by look. We help you pick grout, sealants, and fixtures that hold up to daily use, and we talk through options like curbless showers if you’re thinking long-term.
Bedroom Addition Contractor
A bedroom addition contractor builds a new sleeping room that meets code for egress, light, and ventilation, usually alongside a small closet and sometimes a private bath. Families need a bedroom addition when a new child arrives, an aging parent moves in, or a home office quietly became a bedroom. Seedling ADU Builders builds bedroom additions with sound-dampening walls and proper egress windows, and your written price covers the whole room. A bedroom addition typically runs between $35,000 and $90,000 depending on whether you add a bath and how much structural work the existing wall requires.
Egress, Light, and Sleep
A legal bedroom needs a window large enough to exit through in an emergency, and natural light that makes the room feel like a bedroom, not a closet. We size egress windows to code and place them for good morning light when the lot allows it.
Sound and Privacy
Kids sleep during the day, parents sleep after night shifts, and bedrooms need walls that don’t carry every conversation. We use staggered studs and solid-core doors where it matters, small moves that make a real difference in a busy home.
Brands We Service
We work regularly with Dvele for factory-built modules that arrive on-site with most of the interior finishes already complete. Our crews handle the site work, utility connections, and finish trim, and we know Dvele’s connection details well enough to keep the schedule honest.
Plant Prefab gives families a custom-designed, panelized or modular build with high indoor-air-quality materials, which matters to households with kids and pets. We coordinate with Plant Prefab’s engineering team so the factory and field work line up. James Hardie siding is our standard fiber-cement option for site-built additions because it stands up to weather, fire, and time. Whether you bring us a Dvele plan, Plant Prefab drawings, or a request for James Hardie cladding on a site-built addition, we can help.
Signs You Need a Pro Right Now
- Roof leaks where an old addition meets the house. This junction is the most common failure point on poorly built additions. Water that follows that seam can rot framing and drywall silently for years before you see a stain.
- Floors slope or bounce in a room that was “added on” years ago. That movement usually means the foundation or floor framing wasn’t sized for the load. A pro can assess whether it’s cosmetic or structural before someone gets hurt.
- Windows or doors stick only in one part of the house. Localized sticking points to settling or frame movement in one area. If it’s the added section, the foundation may need attention.
- You can hear every conversation through an interior wall. Missing insulation or improper framing means no privacy for a bedroom or office. A contractor can open the wall and correct it without rebuilding the room.
- Your family has outgrown the house and adding on costs less than moving. When the math works, an addition is the better financial move. We’ll help you compare real numbers before you commit.
Our Process, Step by Step
- 1
Call and talk through the idea. You reach a live person at (707) 383-5338. We ask about your lot, your house, and how you actually use the space, then we talk honestly about whether an addition or an ADU is the better fit.
- 2
Walk the site and take measurements. We visit your home, measure the existing structure, check the foundation and roofline, and photograph the junction points. This is where we catch problems that would otherwise show up as change orders later.
- 3
Written price and plan review. You receive a line-item written estimate before any work starts. We review the scope together, answer questions, and adjust if you want to phase the project.
- 4
Permits, prep, and protection. We pull permits, schedule inspections, and set up protection inside your home: shoe covers, drop cloths, and a clear work zone. You’ll meet the crew lead before tools come out.
- 5
Build, clean, inspect, and close out. Work proceeds with daily clean-up and a photo of the space before the crew leaves. Final inspections are passed, and every job is backed by the 365-Day Done Right Promise.
How Much Does Home Addition Contractor Cost?
A home addition costs real money, and the range varies by scope. A modest sunroom addition typically runs $25,000 to $80,000. A single ground-floor room addition lands between $45,000 and $110,000. A second story addition is the largest line: $120,000 to $300,000 depending on bathrooms, roof work, and engineering. Garage additions start around $30,000 and climb to $75,000. Bathroom and bedroom additions sit in the $25,000 to $90,000 range depending on finishes and plumbing. The biggest cost drivers are foundation depth, roof tie-in complexity, the number of new bathrooms, and material choices like tile, siding, and windows.
How you avoid overpaying is simple: get a written price that includes the structural work, not just the pretty finish line. Many contractors price the visible part and then hand you change orders when the foundation or framing surprises them. Seedling includes the reinforcement, drainage, and engineering in the first written number. A free estimate from our Home Addition Contractor in Los Angeles includes a site visit, measurements, and a line-item breakdown. Call (707) 383-5338 to schedule yours.
Where We Work
Seedling ADU Builders serves homeowners and businesses across the United States through local crews who work under the same Cedarwell Care Promise. Wherever your lot is, the process is the same: written pricing, background-checked uniformed technicians, daily clean-up, and a live person on the phone throughout your project.
Frequently Asked Questions About Home Addition Contractor
A home addition contractor is a licensed professional who designs, permits, and builds new square footage attached to an existing home. That includes ground-floor room additions, second story additions, sunrooms, garages, and new bathrooms or bedrooms. Seedling ADU Builders provides a written price before work starts and backs every project with a 365-Day Done Right Promise.
A typical ground-floor room addition takes two to four months from first demo to final inspection. A second story addition usually runs four to eight months because of the structural work and weather exposure. Sunrooms and garage additions often finish in one to two months.
Costs vary by scope: sunrooms run $25,000 to $80,000, room additions $45,000 to $110,000, second story additions $120,000 to $300,000, and garages $30,000 to $75,000. Bathroom and bedroom additions range from $25,000 to $90,000. Call (707) 383-5338 for a written estimate based on your specific home.
Yes. We work with Dvele and Plant Prefab panels and modules, plus James Hardie siding on site-built work. We coordinate with the factory engineering teams so the on-site and off-site work line up without gaps.
We are not an emergency storm or flood service. But if an existing addition fails structurally, leaks at the roofline, or becomes unsafe, call (707) 383-5338 and a live person will help you figure out next steps.
Every home addition Seedling builds is covered by the 365-Day Done Right Promise in writing. If it’s not done right, we make it right. That promise covers workmanship for a full year after completion, and it’s part of every contract.
Start by deciding which rooms your family actually uses most and where the addition would make daily life easier, not just add square footage. Then call (707) 383-5338. We’ll walk the site, take measurements, and give you a written price before any work begins.
Schedule Your Home Addition Contractor Service Today
Ready to talk through your addition? Call (707) 383-5338 and you’ll reach a live person who can answer questions, walk you through pricing, and schedule a free on-site estimate. Our crews are background-checked, uniformed, and held to the Cedarwell Care Promise. Your written price comes before any work starts, and every job is backed by the 365-Day Done Right Promise. No obligation, just clarity.
Written by Ben Ortega, Owner at Seedling ADU Builders, serving homeowners nationwide.