What drives the cost of an addition up or down?

The big movers are foundation type (crawl space vs. full basement vs. slab), how much roofline has to be rebuilt to tie in, whether bathrooms or a kitchen are included (plumbing-heavy rooms cost more per square foot), site access, and finish tier. Electrical, plumbing, and HVAC scopes are performed by licensed trade partners and priced per scope.

How long does a home addition take?

Plan on 2–4 months of design and permitting, then roughly 3–6 months of construction depending on size — a single-room bump-out is at the short end, a second-story pop or in-law suite at the long end. We sequence the build so your home stays weather-tight and livable throughout.

United Developers · Home Additions

Add the space. Keep the address.

Family rooms, primary suites, second-story pops, and in-law suites/ADUs — designed, permitted, and built by one licensed contractor from foundation to finish.

Free consultation anywhere in Maryland and Northern Virginia. You get feasibility on your actual lot, a per-square-foot number in writing, and a straight answer if an addition isn't the right move.

Book My Free Consultation →Price It in the Project Builder →

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FREE ADDITION CONSULTATION

Feasibility, setbacks, and a per-square-foot number — before you commit to anything

✅ Lot & zoning feasibility check for your county
✅ Good/Better/Best pricing at $180 / $250 / $340 per finished sq ft
✅ Design-to-final-inspection timeline, in writing
✅ A straight verdict — if the lot won't support it, we say so

All prices on this page are typical ranges, not quotes — your exact number is confirmed in the free consultation, with $0-down financing quoted alongside.

★★★★★ 130+ reviews · A+ BBB · MHIC #111971 · VA Class A #2705183185

Free addition consultation

30 seconds. A real person confirms within one business hour (8am–7pm).

Good / Better / Best

Simple per-square-foot framing — typical ranges

Addition pricing that hides behind "it depends" wastes your time. We frame it per finished square foot, then refine against your actual lot and plans. All figures are typical ranges confirmed in your free consultation.

Good — $180 / finished sq ft

400 sq ft ≈ $72,000

Solid, code-built space with quality standard finishes.

Standard foundation & conventional framing
Builder-grade windows, LVP flooring, standard trim
Tie-in to existing HVAC where capacity allows — by licensed trade partners

Better — $250 / finished sq ft

400 sq ft ≈ $100,000

Upgraded envelope and finishes; the most popular tier.

Upgraded windows, hardwood or tile, custom trim
Bathroom-ready plumbing scope — by licensed trade partners
Rooflines and siding blended so it never reads as "the addition"

Best — $340 / finished sq ft

400 sq ft ≈ $136,000

Architect-driven design with premium everything.

Vaulted ceilings, oversized glazing, premium exterior materials
Full bath/kitchenette scopes — by licensed trade partners
Dedicated HVAC zone by licensed trade partners

Typical ranges, not quotes — foundation, roofline, and plumbing-heavy rooms move the per-foot number. Confirmed in your free consultation. Try your square footage in the Project Builder →

Typical Projects

The four additions we build most

Family room bump-out

200–500 sq ft off the kitchen or rear elevation — the fastest way to get the living space your main floor is missing, usually on a crawl space or slab foundation.

Primary-suite addition

Bedroom, walk-in closet, and full bath — typically 300–600 sq ft. Plumbing-heavy, so it prices at the upper end per foot, and it's the addition that moves resale the most.

Second-story pop

Build up instead of out when the lot is tight: a new level over all or part of the existing footprint. The most engineering-intensive option — and the biggest square-footage gain without losing yard.

In-law suite / ADU

Independent living space — bedroom, bath, kitchenette, often a separate entrance — for parents, adult kids, or rental potential where county rules allow. We handle the zoning questions up front.

How It Works

Design to final inspection, one contract

Design & architect

Feasibility on your lot — setbacks, zoning, lot coverage — then architectural drawings and structural engineering. You approve the plans and a written Good/Better/Best budget before anything is filed.

4–10 weeks

Permits

Stamped drawings submitted to your county; we manage plan review comments and revisions. Trade permits for electrical, plumbing, and HVAC — performed by licensed trade partners — are filed under the same project.

County-dependent

Foundation

Excavation, footings, and foundation walls — or structural reinforcement for a second-story pop — inspected before anything is built on top.

Inspected first

Shell

Framing, sheathing, roof, windows, siding — the addition gets weather-tight fast, and rooflines and exterior materials are blended into the existing house so it reads as original construction.

Weather-tight fast

Finishes & final inspection

Rough-ins by licensed trade partners, then insulation, drywall, flooring, tile, trim, and paint — through county final inspection, a full walkthrough, and your 2-year workmanship warranty in writing.

In writing

What Drives Cost

Why one addition is $180/ft and another is $340

Foundation type

Slab is the value play, crawl space is the standard, and a full basement under the addition costs more up front but adds finishable space later.

Roofline complexity

A simple shed tie-in is cheap; matching gables, valleys, and existing rooflines — or rebuilding the roof for a second story — is where framing dollars go.

Wet rooms

Bathrooms and kitchenettes carry plumbing, venting, tile, and fixtures — performed by licensed trade partners — so plumbing-heavy layouts price above the per-foot average.

Finish tier & access

Window packages, flooring, ceiling height, and how easily crews and material can reach the work area all move the final number.

Financing: $0-down plans from 12 to 180 months on approved credit, quoted alongside your consultation number — the monthly payment next to the project price, not after it.

Common Questions

Straight answers

What does a home addition cost in Maryland or Virginia?

Typical framing: about $180 per finished square foot at the Good tier, $250 at Better, and $340 at Best — so a 400 sq ft family room typically lands between $72,000 and $136,000 depending on tier. These are typical ranges, not quotes; your exact figure is confirmed in a free consultation.

What drives the cost up or down?

Foundation type, roofline complexity, wet rooms (bathrooms and kitchenettes are plumbing-heavy and performed by licensed trade partners), site access, and finish tier. The consultation prices your specific combination in writing.

How long does an addition take?

Plan on 2–4 months of design and permitting, then roughly 3–6 months of construction depending on size — a single-room bump-out at the short end, a second-story pop or in-law suite at the long end. Your home stays weather-tight and livable throughout.

Do I need an architect and permits?

Yes — additions require stamped drawings, zoning review, and building permits in both states, plus trade inspections along the way. We manage the architect, engineering, and permit process end to end; it's built into the timeline and the price.

Is an addition worth it versus moving?

Often, yes — when you like your lot, your schools, and your mortgage rate, adding the missing space usually beats transaction costs and a new loan. The free consultation gives you a written number to compare against the real cost of moving, and $0-down financing is available on approved credit.

Your lot. Your plans. A real per-foot number.

Free consultation anywhere in Maryland and Northern Virginia — feasibility, timeline, and Good/Better/Best pricing in writing.

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Where we work

Home additions by town — Maryland & Virginia

Permit routing and what is behind the walls both change town to town. Pick yours for the local detail — who issues your permit, and what we typically find in homes of that vintage.

See every town we build in →