Home Additions in Rockville
An addition is the one project where zoning can stop you before design starts. We are a licensed contractor in Maryland (MHIC #111971) — we pull the permits through the Montgomery County Department of Permitting Services, coordinate the licensed trades, and hand you a written line-item scope before demolition starts.
Start your Rockville home additions with a written scope
Tell us the two things we need to call you back — a project manager rings you to book the free walkthrough. We work North Bethesda, Potomac, Derwood and every Rockville ZIP: 20850, 20851, 20852, 20853.
- A written, line-item scope for your Rockville project before anyone swings a hammer
- Permits pulled through the Montgomery County Department of Permitting Services under MHIC #111971
- One project manager from demolition to final walkthrough
Two fields and one question. A specialist calls you back to confirm a time.
The paperwork is the part most contractors gloss over.
An addition starts with zoning, not construction: setbacks, lot coverage and height limits get reviewed before a building permit is issued, and in some neighborhoods there is a stormwater or historic review on top. Then come the footing and foundation inspections, which have to pass before backfill. This is the longest-lead permit of any project we do, and it is why we start the paperwork while the design is still being drawn.
Your Rockville permit goes through the Montgomery County Department of Permitting Services. We pull it under our license and we hold the inspection schedule — you do not chase inspectors and you do not sign the application.
Rockville is its own permitting jurisdiction. If your property sits inside the City of Rockville limits, the permit goes through the city — not Montgomery County DPS — and the two have separate submissions and separate inspectors. Getting that wrong at the start costs weeks, so we confirm which side of the line you are on before anything is filed.
The house decides half the scope.
Rockville's stock runs from 1950s ramblers and split-levels in the older neighborhoods to newer townhome and infill construction. On the mid-century houses, expect to find undersized electrical service and cast-iron or galvanized supply lines once walls are open — both of which we price up front rather than as a surprise change order.
What's included- ✓Zoning, setback and lot-coverage review before design is finalized
- ✓Footings placed below the regional frost line
- ✓Footing and foundation inspections passed before backfill
- ✓Roofline, siding and HVAC tied into the existing house so it does not read as an add-on
A planning range, not a quote. Your written line-item price comes after a free on-site walkthrough. HVAC, electrical and plumbing are performed by licensed trade partners.
Financing is available — most homeowners spread a project this size over monthly payments rather than paying cash up front.
Free Rockville walkthrough
A written, line-item scope for your home additions project. No design fee, no obligation.
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One contractor for the rest of the house
Our Rockville crews cover North Bethesda, Potomac, Derwood, Gaithersburg and every ZIP in the area — 20850, 20851, 20852, 20853.
Straight answers
Do you handle home additions in Rockville, MD?
Yes. United Developers is a licensed contractor in Maryland (MHIC #111971) and works throughout Rockville and Montgomery County, including 20850, 20851, 20852, 20853 and nearby North Bethesda, Potomac, Derwood.
Who pulls the permit for a Rockville home additions project?
We do, under our license, through the Montgomery County Department of Permitting Services. An addition starts with zoning, not construction: setbacks, lot coverage and height limits get reviewed before a building permit is issued, and in some neighborhoods there is a stormwater or historic review on top. Then come the footing and foundation inspections, which have to pass before backfill. This is the longest-lead permit of any project we do, and it is why we start the paperwork while the design is still being drawn.
What should I expect in a Rockville home?
Rockville's stock runs from 1950s ramblers and split-levels in the older neighborhoods to newer townhome and infill construction. On the mid-century houses, expect to find undersized electrical service and cast-iron or galvanized supply lines once walls are open — both of which we price up front rather than as a surprise change order.
What does home additions cost in Rockville?
Most Rockville projects land in the $180 – $340 / sq ft range. That is a planning range for Montgomery County, not a quote — your written price comes after a free on-site walkthrough.
Is the Rockville walkthrough and estimate free?
Yes. The walkthrough and the written scope are free and yours to keep whether or not you hire us. There is no design fee and no consultation invoice.
How long does an addition actually take?
The build is rarely the long part — permitting and zoning review are. Expect the approval phase to run in parallel with final design, and expect us to give you a schedule that names the permit milestone rather than hiding it. We will tell you at the walkthrough if your lot has a setback or coverage problem, because that changes the whole conversation.