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Unit pricing

Long Island home addition pricing per square foot

Home Addition cost per square foot in Long Island, New York in 2026.

Low

$58,500

Average

$110,500

High

$182,000

Long Island crews quote about $195 – $585 per square foot.

Multiply local unit rates by your real measurements.

What drives home addition prices in Long Island

Local labor, permitting and climate move Long Island prices away from the national average.

Labor market

Nassau and Suffolk crews are busy year round with premium suburban pricing.

Permits

Town-level permits vary widely and can be slow.

Climate

Coastal wind zones and nor easters affect roofing and siding.

Long Island unit pricing by material

Garage conversion$105 – $260
Sunroom$130 – $325
Bump-out$195 – $455
Single-room addition$195 – $520
Second story$260 – $650
In-law suite / ADU$235 – $585

Ways to lower your Long Island price

  • Build up or bump out rather than adding a new foundation footprint.
  • Keep plumbing on the existing wet wall — moving water and waste lines is the costliest change.
  • Convert existing space (garage, attic, basement) at half the per-square-foot cost.
  • Keep the roofline simple; complex tie-ins add framing labor and leak risk.
  • Lock the design before demolition — change orders during construction carry the biggest premiums.

Long Island questions

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