Montgomery County · MD

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.

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Permits & inspections in Montgomery County

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.

Local to Rockville

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.

What we find in Rockville homes

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
Planning range — Montgomery County
$180 – $340 / sq ft

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.

20850208512085220853North BethesdaPotomacDerwoodGaithersburg

Free Rockville walkthrough

A written, line-item scope for your home additions project. No design fee, no obligation.

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Also in Rockville

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.

Rockville home additions questions

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.

Is there anything specific to Rockville I should know?

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.

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.

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