Home Additions in South Jersey
The region's specialist in large-scale home additions — in-law suites, second stories, rear and side extensions, bump-outs, garage conversions, and primary suites. Architect-led, fully permitted, and built to match the home they extend.
Get a Free EstimateSouth Jersey's specialist in large-scale home additions
When a South Jersey home is in the right place but no longer has the right space, the answer is rarely to move — it's to add on. MAG Development designs and builds substantial home additions across South Jersey and the Pennsylvania Main Line: in-law suites, second stories, rear and side extensions, bump-outs, garage conversions, and primary suites, all engineered, permitted, and finished to match the home they extend.
We focus exclusively on large-scale, $40K+ residential projects — no small repairs, no flips, no low-budget work. That focus is what lets us bring real structural rigor, an architect-led design process, and a white-glove client experience to every addition we take on, from the first site visit to a closed permit.
The home additions we specialize in
Every addition is its own kind of project. Start with the one closest to what you have in mind — each links to a dedicated page — or tell us the problem and we'll recommend the right approach.
In-Law Suites & ADUs
Private, self-contained suites for multi-generational living — attached, detached, or over the garage. See in-law suites & ADUs.
Second Story Additions
A full or partial new floor that doubles your living space without giving up your lot. See second story additions.
Rear & Side Extensions
Expanding the footprint to open up a kitchen, add a family room, or extend a primary suite. See home additions.
Bump-Outs
The targeted few feet that fix the one room that doesn't work, often without a new foundation. See bump-out additions.
Garage Conversions
Turning an attached or detached garage into finished living space inside square footage you already own. See garage conversions.
Primary Suite Additions
A new primary suite — first floor, over the garage, or as part of a second story. See primary suite additions.
An architect-led, design-build process from concept to closed permit
The difference between an addition that looks original to the house and one that looks bolted on is decided at the design stage — which is why we bring an architect and engineer in early on every project. You get one team responsible for design, structure, permitting, and construction, instead of a designer who hands off to a builder who blames the drawings.
Every project runs on a line-itemed contract with a payment schedule tied to completed, inspected milestones — not a front-loaded deposit against a hole in the ground. We pull and close every permit, carry full registration and insurance, and collect lien waivers from every subcontractor. The result is an addition that's on the township record as legal square footage and built to hold its value.
If you're still in the research stage and worried about choosing the right contractor at all, our red-flag guides walk through exactly what to watch for before you sign with anyone.
How a home addition runs with MAG
Site visit & design
We walk the property, talk through what you need, and bring an architect in early so the design is right before structural and budget decisions lock in.
Permits & engineering
Stamped drawings and permit submission to your township, with zoning, setbacks, and structural scope confirmed before the contract is signed.
Construction
Built in sequence — structure, mechanicals, insulation, drywall, finishes — with township inspections at each phase on a written milestone schedule.
Inspection & closeout
Final inspections, permits closed out, new square footage on the township record, lien waivers from every subcontractor in hand.
Building home additions across South Jersey and the Main Line
We design and build additions throughout South Jersey and the Pennsylvania Main Line. Each town handles permitting, zoning, setbacks, and inspections through its own construction office — and we manage that process end to end, in every town we serve, so the new square footage ends up legal and recorded.
Choose your town for local detail, or reach out and we'll tell you exactly how the process works for your address:
South Jersey home additions FAQ
How much does a home addition cost in South Jersey?
It depends entirely on the type and size of addition — a bump-out, an in-law suite, a second story, and a rear extension are very different projects. All of our additions start at the $40K+ level and most full additions run well into six figures. The only honest number for your project comes from a line-itemed estimate after we walk your property; per-square-foot figures online don't reflect your home's structure, your township, or your finishes.
What types of home additions do you build?
We build the full range of large-scale residential additions across South Jersey: in-law suites and ADUs, full and partial second story additions, rear and side extensions, bump-outs, garage conversions, and primary suite additions. We focus exclusively on substantial $40K+ projects rather than small repairs or flips.
Do I need an architect for a home addition?
For any structural addition, yes — and we bring an architect and engineer in early as part of our design-build process, so the design is buildable, code-compliant, and in keeping with your home before the contract is signed. You don't need to hire your own separately; it's built into how we work.
Which South Jersey towns do you serve?
We work throughout South Jersey — including Haddonfield, Moorestown, Voorhees, Collingswood, Haddon Township, and Haddon Heights — and across the Pennsylvania Main Line in Ardmore, Bryn Mawr, Wayne, Villanova, and Swarthmore. Each town's addition is permitted and inspected through its own construction office, which we handle end to end.
How long does a home addition take?
Plan on a project measured in months, with design and permitting taking a meaningful share of that time before any on-site work begins. A bump-out is faster than a second story addition; a detached ADU sits somewhere in between. We give you a realistic written timeline up front rather than an optimistic one.
How do you handle financing for a home addition?
Many of our clients fund additions through home equity — a HELOC or a cash-out refinance — given the equity South Jersey and Main Line homes have built. We're not lenders and don't give financial advice, but we're happy to talk through how the project phases line up with a financing timeline so you can plan with your own lender.