Home Addition Cost in Westchester County (2026 Guide)

Serving Yonkers and all of Westchester County

Adding square footage is one of the biggest investments a homeowner can make, and the cost varies a lot depending on the type of addition. Here’s how the numbers break down.

Home Addition Cost by Type

Why Additions Cost More Per Square Foot Than Remodeling

Unlike an interior remodel that works within existing walls, an addition requires a new foundation, framing, roofing, siding, and a full extension of electrical, plumbing, and HVAC systems. That’s why an addition typically runs $300 to $600 per square foot, well above the $100 to $200 per square foot range for a mid-range interior remodel covered in our renovation cost per square foot guide.

Types of Home Additions

Bump-Out Addition

A bump-out extends an existing room by a few feet, often used to enlarge a kitchen or add a breakfast nook, without adding a full new room. It’s the most affordable way to gain meaningful space since it typically doesn’t require a new foundation footprint as large as a full addition.

Single-Story Addition

A single-story addition adds an entirely new room, such as a family room, primary suite, or home office, on a new foundation. This is the most common type of addition and offers the most flexibility in design.

Second-Story Addition

Building up rather than out is often the right choice on a smaller lot where there’s no room to expand the footprint. It costs more due to structural reinforcement of the existing first floor, but it doesn’t reduce yard space.

Permits and Zoning in Westchester County

Additions almost always require a building permit, and depending on the town, may also require zoning approval if the addition affects setbacks, lot coverage, or height restrictions. Westchester’s towns each have their own zoning rules, so it’s worth checking with your local building department early in the planning process rather than after a design is finalized.

How Long a Home Addition Takes

A bump-out addition typically takes 6 to 10 weeks. A single-story addition usually takes 3 to 5 months. A second-story addition can take 4 to 7 months, largely due to the structural work involved in reinforcing the existing first floor before building up.

Ways to Control Cost

• Keep the addition’s footprint simple, complex rooflines and angles add cost
• Match existing systems where possible instead of upgrading unrelated areas
• Confirm zoning requirements before finalizing a design to avoid costly revisions
• Consider a bump-out if you need modest space rather than a full new room
• Get a detailed, itemized quote covering foundation, framing, and systems separately

Getting an Accurate Quote

The real cost of your addition depends on your lot, existing structure, and local zoning requirements. A detailed, itemized estimate is the only way to know your actual number rather than a rough range.

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• Open Floor Plan & Wall Removal Cost