Home Additions & Extensions in Bethesda and Rockville
Expand Your Living Space
Our home addition services help you create additional living space that seamlessly integrates with your existing home. From light-filled sunroom additions to second story additions and detached ADUs, our expert team will design and execute additions that enhance both function and value. If staying within your footprint is the goal, our basement remodeling services are another way to gain space.
The right addition depends on your home and your lot. The mid-century ramblers and split-levels common in Bethesda and Chevy Chase are ideal candidates for second story additions that double living space without sacrificing yard, or a rear bump-out that finally opens up a cramped kitchen. Owners of the newer colonials and townhomes around Rockville and the Pike District often add a four-season sunroom or a primary-suite extension. On the larger estate lots of Potomac, there's room for a detached ADU or in-law suite. We manage every Montgomery County permit, setback, and inspection so your addition is fully compliant.
Planning finishes for your new space is easier in person. Our iDesign Interior Solutions showroom is in North Bethesda's Pike District, just a 5-minute drive from Rockville Town Center, so homeowners in Bethesda, Rockville, Chevy Chase, and Potomac can compare materials firsthand. Plan a visit to the showroom, or see how an addition fits a larger home remodeling plan.
Popular Addition Projects:
- Master suite additions
- Kitchen extensions
- Sunrooms and enclosed porches
- Second story additions
- Home office spaces
Our Addition Process
- 1
Initial Assessment
We evaluate your property, discuss your needs, and explore feasible options.
- 2
Architectural Design
Our architects create detailed plans that blend with your existing structure.
- 3
Permitting
We handle all necessary permits and approvals to ensure your project is compliant.
- 4
Construction
Our skilled craftsmen build your addition with minimal disruption to your daily life.
- 5
Interior Design
We complete the space with interior design elements that match your style.
Ready to Expand Your Home?
Contact our team today to discuss your home addition project and receive a detailed estimate.
Request a ConsultationFrequently Asked Questions About Home Additions
How much does a home addition cost in Bethesda?
Costs depend on the type and size of the addition. A bump-out runs roughly $20,000 to $60,000, a single room or sunroom addition typically runs $60,000 to $150,000, and a large multi-room or second-story addition can run $150,000 to $400,000 — roughly $200 to $500+ per square foot. Site conditions and finishes drive the final price. We provide a fixed, itemized quote after an on-site assessment so there are no surprises.
Do I need permits and zoning approval for an addition in Montgomery County?
Yes. Additions require building permits and zoning and setback review from the Montgomery County Department of Permitting Services (DPS). We handle all the drawings, permits, and inspections for you so your addition is fully compliant from start to finish.
Is iDesign a licensed and insured addition contractor?
Yes. iDesign Interior Solutions is a licensed and insured Maryland home-improvement contractor, and we've completed thousands of projects across Montgomery County over more than 25 years. We're happy to share our license details and references during your consultation.
How long does a typical home addition take to complete?
Most home additions take about 2 to 5 months to complete, depending on the size of the project and permitting. Smaller bump-outs are on the shorter end, while large multi-room or second-story additions take longer. During your consultation, we'll provide a detailed timeline specific to your project.
Will the addition match my existing home?
Yes. We match rooflines, siding, trim, windows, and interior finishes so your new addition looks like it was always part of the house — not bolted on. Our designers carefully blend the new space with your home's existing architecture inside and out.
Why Bethesda Homeowners Choose iDesign
25+
Years remodeling DMV homes
2,700+
Completed projects in the area
Licensed
& insured Maryland contractor
Permits
& zoning handled for you
We're a local Montgomery County design-build team with a North Bethesda showroom — not a national franchise. From the older homes of Edgemoor, Bradley Hills, and Westmoreland Hills to the estates of Potomac and Avenel and the newer builds in Rockville near King Farm, we know how homes in this area are built, how additions tie into existing structures, and how to clear Montgomery County DPS permits, zoning, and setback review. Every project is handled by our own designers and craftsmen and backed by a written quote and clear timeline.
Cost of Home Additions in the Bethesda & Rockville Area in 2026
| Project Scope | Estimated 2026 Cost* |
|---|---|
| Bump-out additionExtending an existing room a few feet for a larger kitchen, bath, or closet. | $20,000 – $60,000 |
| Single-room / sunroom additionA new room on the existing foundation footprint or a four-season sunroom. | $60,000 – $150,000 |
| Large multi-room or second-story additionAdding significant square footage, new systems, and structural reinforcement. | $150,000 – $400,000 |
| Detached ADU / in-law suiteA standalone accessory dwelling with its own kitchen and bath. | $120,000 – $350,000+ |
*These figures are rough planning estimates only. Your actual quote will depend on in-home measurements and the current cost of materials and labor at the time of your project, as well as the specific finishes and scope you choose. For an accurate price, schedule a free in-home consultation with our team.
Home Addition Services in the DMV Area
We provide professional home addition services throughout Maryland, DC, and Northern Virginia, including:
Bethesda, MD
North Bethesda, MD
Rockville, MD
Potomac, MD
Chevy Chase, MD
Silver Spring, MD
Washington, DC
McLean, VA
Explore Our Other Services
Visit Our Showroom
Visit our showroom to discuss your home addition project with our design team.
iDesign Interior Solutions · North Bethesda, MD
(301) 881-1115 · Mon–Fri 9am–6pm · Sat 9am–6pm · Sun 10am–3pm