Room Additions, In-Law Suites, Sunrooms & Primary Suites. Designed and Built by a Local Crew You Can Trust.
You love your house. You love your neighborhood, your neighbors, your kids’ school, and the fact that you’ve finally got the yard the way you want it. The only problem? You need more room.
That’s the moment most Quad Cities homeowners start looking for a home addition contractor. Moving doesn’t make sense, but staying as-is doesn’t either.
Northstar Construction designs and builds home additions for homeowners across Moline, Rock Island, Davenport, Bettendorf, and East Moline. We handle everything from the first sketch to the final coat of paint, so you end up with an addition that looks like it was always part of the house, not a box bolted onto the side of it.
Get a free addition estimate. Call (309) 519-4677.
Most homeowners we work with land on an addition for one of these reasons:
If any of those sound familiar, an addition is probably on the table. The next question is what kind.
“Home addition” covers a lot of ground. Here’s what we actually build for Quad Cities homeowners, and what each option works best for.
Room Additions
The classic add-on: a single room expanding off your existing floor plan. Family rooms, primary bedrooms, home offices, playrooms. Whatever the room you wish you had. Room additions are usually the most cost-effective option when you have the lot space for it, because we’re tying into existing utilities and structure rather than rebuilding them.
In-Law Suites and Accessory Dwellings
With multi-generational living becoming more common across the Quad Cities, in-law suites are one of our fastest-growing project types. We design these as self-contained spaces (bedroom, bathroom, sitting area, often a small kitchenette) that integrate with your main home but give everyone their own space. Done right, an in-law suite also boosts long-term resale value and gives you optional rental income down the road.
Sunrooms and Four-Season Rooms
There’s a meaningful difference between a three-season sunroom and a true four-season room, and most contractors quote the cheaper option without explaining the trade-offs. We build both, and we’ll walk you through what each one will actually feel like in February so you don’t end up with a beautiful room you can’t use five months a year. Properly built four-season additions in the Quad Cities need real insulation, sized HVAC, and the right window specs for our climate.
Kitchen and Family Room Expansions
Sometimes the right move isn’t a new room. It’s making the rooms you have bigger. Bumping out a kitchen by 6 to 10 feet, removing a load-bearing wall and extending the back of the house, or combining the kitchen and family room into one open space. These projects tend to deliver the biggest day-to-day quality-of-life upgrade.
Primary Suite Additions
Adding a primary bedroom and en-suite bath, usually on the back or side of the house, is one of the highest-return additions you can build. It also lets you redesign your existing bedroom into something useful (office, guest room, expanded kid’s space).
Mudroom and Entry Additions
Small footprint, big quality-of-life win. A proper mudroom with built-ins, bench seating, and a dedicated entrance changes how your house functions every single day. Especially in our climate, where you’re tracking snow, slush, and yard mud half the year.
Bump-Outs
Smaller-scale additions, typically 2 to 6 feet, that extend a single room without requiring new foundation work or roof tie-ins on the same scale as a full addition. Great for expanding cramped kitchens, bathrooms, or living rooms when budget is the main constraint.
Need to add significant square footage without expanding your lot footprint? A second-story addition might be a better fit.
Additions are more complicated than most homeowners expect. Not because the construction itself is hard, but because of everything that has to happen before construction starts. Tying into an existing structure means working around what’s already there: existing framing, foundation, electrical, plumbing, HVAC capacity, roof lines, exterior materials, and city setback requirements. Skipping any of those upfront leads to expensive surprises later.
Here’s how we keep additions on track:
We walk your property, look at where the addition could realistically go, and talk through what you're trying to accomplish.
We check setbacks, lot coverage, easements, and any HOA constraints. Then we develop a design that fits your home architecturally, not a generic shape that screams "addition."
We assess whether your existing HVAC, electrical panel, and plumbing can support the new space, or whether they need to be upgraded as part of the project. This is where most contractors guess and homeowners pay later. We don't.
Line-by-line pricing, realistic timeline, clear allowances for selections, and a written scope of work. You see everything before you commit to anything.
We pull all required permits in Moline, Rock Island, Davenport, Bettendorf, or East Moline, and coordinate with city inspectors.
Foundation, framing, mechanical rough-ins, exterior tie-in (siding, roofing, gutters), interior finish work. Our crew runs the project. We don't disappear and let a sub run the show.
We walk every inch of the new space with you, handle the punch list, and don't ghost you after the final invoice.
This is the number-one question we get, and any contractor who gives you a precise answer over the phone is lying. Real pricing depends on size, finishes, foundation type, whether you’re tying into existing systems or upgrading them, and the condition of your existing structure.
That said, here’s a realistic ballpark for the Quad Cities market based on the projects we actually do:
Bump-outs (small additions, no new foundation)
Typically $25,000 to $60,000 depending on scope and finishes.
Room additions (200 to 500 sq ft, single story)
Typically $80,000 to $200,000.
In-law suites with bath
Typically $150,000 to $300,000+.
Large additions or primary suite additions
Typically $175,000 to $350,000+ depending on size, finishes, and whether mechanicals need upgrading.
Four-season sunrooms
Typically $60,000 to $150,000 depending on size and glazing specs.
These ranges aren’t quotes. They’re orientation. Once we walk your property and understand what you want, we give you real numbers in writing.
Plan on 4 to 9 months total: roughly 4 to 8 weeks for design and permits, then 3 to 6 months of active construction depending on size and complexity. Larger projects with custom finishes can run longer. We’ll give you a specific timeline before you sign anything.
We handle design in-house for most addition projects. For larger or more complex builds, especially anything involving significant structural changes or non-standard architectural elements, we’ll bring in a licensed architect or structural engineer and coordinate with them directly. You don’t have to manage a separate design team.
Almost always, yes. Most additions are built off the side or back of the house, so we can keep your existing space functional and only break through the exterior wall toward the end of the project. We’ll talk you through what to expect, including any short periods when specific rooms or utilities will be impacted.
Yes. We pull every required permit (building, electrical, plumbing, mechanical) in whichever Quad Cities municipality your home is in, and we coordinate all inspections.
Likely yes. Adding square footage typically increases your home’s assessed value, which can affect your property taxes. The amount varies by municipality and assessor. We can give you a rough sense of the impact, but for specifics, your county assessor’s office is the right call.
In most cases, yes. If your existing materials are discontinued, we’ll either find a close match or recommend a thoughtful design choice (like updating an accent area) so the addition reads as intentional rather than mismatched. Either way, we walk you through options before any material is ordered.
Older Quad Cities homes often have surprises lurking: knob-and-tube wiring, cast-iron drain lines past their lifespan, foundations that need reinforcement. We assess the existing structure as part of the design phase so issues are identified before they become emergency line items. If your home needs work to support the addition, you’ll know about it upfront.
Call (309) 519-4677 or fill out our contact form. We’ll schedule a free on-site consultation, walk through your goals, and get you a written estimate within a few business days.
If you’re serious about adding to your home in the Quad Cities, the best next step is a conversation. We’ll come out, look at your property, listen to what you’re trying to accomplish, and give you a straight answer on what’s possible and what it’ll cost.
Call (309) 519-4677 today or request your free addition estimate online.
