Home addition / extension cost in New York

Computed from 268 recent building-permit filings in New York, NY — what people actually declared, not survey guesses.

Typical low · P25$46,000
Median$180,000
Typical high · P75$426,500

✓ Verified from 268 recent building-permit filings in New York, NY

Data refreshed July 2026

The short answer: a typical home addition / extension in New York costs around $180,000, with half of all projects landing between $46,000 and $426,500. If a quote falls well outside that range, it isn't automatically wrong — but it deserves an explanation you can understand.

Before you spend on a home addition / extension

💸 What drives the cost

  • Foundations and roof tie-in are the expensive ends; the middle (walls) is comparatively cheap
  • Wet rooms in the new space (kitchen/bathroom) add plumbing runs and cost far more per square metre
  • Planning/zoning constraints can dictate design more than budget does

✂️ How to spend less

  • Build up or convert existing volume (loft, garage) before building out — foundations are the money pit
  • Match, don't fight, the existing roofline to simplify the structural tie-in

🚩 Red flags when hiring

  • A builder happy to start before planning permission/permits are granted
  • No structural engineer involved in a design that touches the existing structure

Home addition / extension in other cities

Other projects in New York

Where this number comes from

Every figure on this page is computed from declared valuations on building permits published by New York's open-data portal. We report the 25th percentile, median and 75th percentile of 268 recent residential filings — never a single-point "average". Declared values are what applicants file, not final invoices, so treat the range as planning guidance rather than a quote. Full methodology →

Questions people ask

How much does a home addition / extension cost in New York?

Based on 268 recent building-permit filings in New York, the median declared cost is $180,000. Half of all projects fall between $46,000 and $426,500.

Are these figures quotes?

No. Permit valuations are what applicants declare when filing, not final invoices. Treat the range as planning guidance and a sanity-check against the quotes you receive.

Why is the range so wide?

Because identical-sounding projects legitimately differ in size, specification and site conditions. That is why we publish the 25th percentile, median and 75th percentile instead of a single misleading "average" — you can see where a quote sits in the real distribution.

Planning something else, or somewhere else? Request a city or project — requests decide what we ingest next.