Craftsmanship That Multiplies Value

Home Addition Contractor Serving the Austin Metro

Room additions, second-story additions, and in-law suites for homeowners across Austin and the surrounding towns. We scope the work honestly, coordinate the permits, and build it right the first time.

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Adding Square Footage the Right Way

You've outgrown your house and you're deciding whether to add on. That's the actual problem, and it's a bigger decision than picking a finish. Hundredfold Services is a home addition contractor working across Austin and the surrounding towns, and we handle the whole arc: the framing, the roof tie-in, the foundation, the electrical and plumbing rough-ins, and the finish work that makes the new space read like it was always part of the house. We coordinate the plan review and permits a City of Austin addition requires, and we bring in the licensed trades an addition needs, all under one point of contact instead of four crews you have to chase. Before you commit to a full addition, it's worth walking through whether a remodel of your existing footprint gets you there for less. Call (318) 348-4317 and we'll tell you plainly which path fits your house.

Here's the part most contractors won't say out loud on the first call: adding square footage is rarely the cheapest way to get more usable space, and it isn't always the right one. A ground-floor addition means new foundation on Central Texas expansive clay, which moves with the seasons and has to be engineered for it. A second-story addition means proving the existing structure can carry the load before a single stud goes up. We tell you which of those you're actually looking at before any number gets discussed, because a quote written without knowing what's under your slab and inside your walls is a guess. You'll know exactly what your addition involves before we pick up a tool.

What a Home Addition Contractor Actually Builds

Room additions, second-story additions, and in-law suites are three different jobs. Here's how they differ before you scope one.

Room additions

The single-room bump-out: a larger primary suite, a real home office, a family room off the back of the house. A room addition ties new framing and roofline into the existing structure, so the roof-to-wall connection and the foundation transition are where the job is won or lost. Done wrong, that seam is where water finds its way in three winters later.

Second-story additions

Building up instead of out when your lot is tight or you want to keep the yard. A second story lives or dies on the existing foundation and framing: we verify the slab and load path can carry the added weight before committing, and pull in a structural engineer when the span calls for it.

In-law suites

A self-contained suite for aging parents or an adult kid: bedroom, bathroom, often a kitchenette and its own entrance. In-law suites carry their own permit and code questions around egress, separate metering, and occupancy that a standard bedroom addition doesn't.

Conversions vs. new build

Enclosing a covered patio, turning that outdoor space into a year-round sunroom, converting a garage, or finishing an attic is often the fastest path to more living space because the roof and foundation are already there. When that's the smarter move for your house, we'll say so instead of selling you a bigger project.

Room Additions

The Addition That Doesn't Look Added On

home addition framing and construction, professional service in Austin, TX

A room addition contractor's real job is the transition, not the box. Anybody can frame four new walls. The work that separates a good addition from an obvious tack-on is how the new roofline meets the old, how the new slab is tied to the existing foundation, and how the flooring, trim, and paint carry through so the addition doesn't announce itself the moment you walk in. We handle the full sequence on a room addition: foundation work, framing, roof tie-in, exterior finish to match the existing house, electrical and plumbing rough-ins, drywall, and the finish carpentry. For open-concept additions that remove a wall between old and new space, load-bearing wall removal is part of the scope, and it starts with confirming what that wall is actually holding up. We header it properly and transfer the load before anything comes down. That's not the step to rush.

Process

How a Home Addition Goes With Hundredfold Services

01
Assess before we quote
We walk the space, look at your foundation, your existing framing, and where utilities run. This is where we tell you whether a room addition, a second story, or a conversion fits your house and your budget. The answer changes the entire project.
02
Plans, permits, and review
Additions in Austin need plans and a permit, and larger jobs need engineered drawings. We handle the plan submission and the City of Austin review process so you're not standing in a permit line trying to interpret code on your own.
03
Build in the right order
Foundation, then framing, then dry-in, then the trades, then finish. We sequence it so inspections pass the first time and the new space is weather-tight before interior work starts. You know what's happening each week.

Building Up

Second-Story Additions Start With the Structure

second story home addition construction, professional service in Austin, TX

A second-story addition is the most misunderstood job we quote. Building up keeps your yard and your lot footprint, which is a real advantage on the tight lots common in older Austin neighborhoods and in newer subdivisions around Cedar Park and Round Rock. But it's not simply cheaper because you're not pouring foundation. Before anyone frames a second floor, three things get verified: 1. The existing foundation and slab can carry the added dead and live load, confirmed by a structural engineer when the numbers are close 2. The existing wall framing and headers can transfer that load down to the foundation, or get reinforced so they can 3. The stair location works with your current floor plan without gutting the level below

"We've turned down second-story jobs where the honest answer was that reinforcing the existing structure cost more than the addition was worth. Building out was the smarter call for that house, and we said so."

Get that structural picture right and a second story is one of the best ways to add real bedroom-and-bath square footage in the Austin metro. Get it wrong and you're chasing cracks for a decade. Ready to find out which your house is? Call (318) 348-4317.

In-Law Suite Additions, Built to Live In

An in-law suite is more than a spare room. Here's what a suite for aging parents or adult family actually needs.

Bedroom and accessible bath

A private bedroom and full bathroom, sized for comfort and for aging in place: a curbless shower, wider doorways, grab-bar blocking in the walls. This is the core of most in-law suites we build.

Kitchenette and living space

A kitchenette with a sink, counter, and space for a compact range or cooktop turns a suite into something someone can actually live in. It also raises code and permit questions we sort out before framing.

Private entrance and egress

A separate entrance and egress-compliant windows are what make a suite feel independent and keep it legal. Egress is the first thing an inspector checks on any room meant for sleeping.

Utilities and metering

Whether the suite gets its own HVAC zone, water heater, or sub-metering depends on how it'll be used. We walk through those choices with you rather than defaulting to the most expensive option.

When a Home Addition Is the Wrong Call

One honest section on when NOT to add on, before you spend money finding out the hard way.

This is the honest part most addition contractors leave out, because it can cost them the lead. Don't build an addition if a remodel of your existing footprint gets you the space you actually need. Reworking a cramped layout, opening a wall, or converting a garage is often half the cost and a fraction of the timeline of new construction, with no new foundation to engineer. If your problem is a bad layout rather than a genuine shortage of square footage, an addition is the expensive fix. An addition is the right call when you're genuinely short on rooms, when the layout is fine but the house is just too small, or when you need a self-contained space a remodel can't create. If that's you, adding square footage beats trying to repair around a cramped layout forever. Not sure which describes your situation? Tell us what's going on and we'll come back with a straight answer.

What Keeps Home Additions From Going Wrong

01
The seams are everything
The foundation-to-foundation and roof-to-roof transitions are where additions fail. We tie new work into old with the flashing, headers, and slab connections the job actually needs, not the shortcut that photographs fine and leaks later.
02
Engineer for the soil you have
Additions across the Austin metro sit on expansive clay. A foundation designed for that soil movement is the difference between a slab that holds and one that separates from the house. We don't guess at it.
03
Permit it and scope it before day one
A clearly defined scope and a real permit protect you from a job that never ends and an addition that can't be sold or refinanced later. We agree on what's in before we start, and we build to code so it passes inspection.

Ready to Talk Through Your Home Addition?

Call us directly and describe what you're trying to add. We'll tell you honestly whether an addition, a remodel, or a conversion is the right move for your house.

Call (318) 348-4317 Call to Discuss Your Addition

Frequently asked questions

Do I need a permit and plans for a home addition in Austin?

Yes. Home additions in Austin require plans and a building permit, and larger or structural jobs need engineered drawings stamped by a licensed engineer. Hundredfold Services prepares the plan set and manages the City of Austin plan review and permit process for you, then schedules the required inspections at each phase so the work is signed off legally. Building an addition without a permit creates real problems when you go to sell or refinance, so we don't skip it.

How long does a home addition take to build?

Timelines vary widely with scope, but a straightforward single-room addition typically runs several weeks of active construction once permits are in hand, while a second-story addition or a full in-law suite commonly stretches to a few months. The permitting and plan-review phase happens before that and adds time on the front end. We give you a realistic schedule after we've assessed your foundation, framing, and the permit path, not a hopeful number on the first phone call.

Can you remove a load-bearing wall to open up the new addition?

It depends entirely on the wall. Before any load-bearing wall comes out to open up an addition, we confirm what it's carrying, size and install a proper header or beam to transfer that load, and support the structure through the process. Interior non-load-bearing walls are simpler. The mistake we see on other jobs is a wall opened up without transferring the load first, which shows up later as sagging ceilings and sticking doors above it.

Is a home addition worth it, or should I just remodel?

Not always, and that's the honest answer. If your problem is a poor layout rather than a genuine lack of square footage, a remodel of your existing footprint or a garage or patio conversion often costs far less and skips new foundation work entirely. An addition makes sense when you truly need more rooms, when the house is simply too small, or when you need a self-contained suite a remodel can't create. We help you figure out which situation you're in before you spend money on plans.

Do I have to move out during a home addition?

For most additions, no. Because the new space is built alongside the existing house and only connects to it late in the sequence, daily life keeps running through most of the project. You'll want to plan around noise, the tie-in phase when we open the wall between old and new, and any period a utility is briefly interrupted. We stage the work so the addition is weather-tight before we ever open your existing exterior wall.

What areas do you build home additions in?

We build home additions throughout the Austin metro, including Cedar Park, Round Rock, Pflugerville, Leander, Buda, and Georgetown. Because we're a service-area business rather than a storefront, the simplest way to find out if your project is a fit is to call (318) 348-4317 and tell us where the house is and what you're trying to add.