How Much Does a Sunroom Addition Cost on Long Island? (2026)

Adding a sunroom to your Long Island home is one of the most popular renovation projects in Nassau and Suffolk County — and for good reason. It adds livable square footage, brings in natural light, and connects your indoor space to the outdoors without the maintenance headaches of a traditional deck. But before you start, you need a realistic number.

Here's what Long Island homeowners are actually paying in 2026.

Sunroom Cost Ranges on Long Island

Sunroom costs vary widely based on size, type, and materials. Here's a realistic breakdown for Long Island in 2026:

Three-season sunroom: $15,000–$35,000. These are uninsulated enclosures — great from spring through fall but not year-round. Lower framing and HVAC costs keep the price down. Popular in communities like Huntington and Smithtown where families want a porch upgrade without going full addition.

Four-season sunroom: $30,000–$75,000. These are fully insulated, climate-controlled rooms that function like any other room in your house. You'll need proper wall insulation, a real foundation or insulated slab, and HVAC tie-in. Most Nassau County homeowners adding family rooms or offices opt for four-season builds.

Sunroom conversion (existing porch or deck): $10,000–$25,000. If you already have a covered structure, enclosing it with windows and screens is far cheaper than building from scratch.

What Drives the Price on Long Island

Size: Most sunrooms run 100–300 square feet. Budget roughly $150–$250 per square foot for a mid-range four-season build in Nassau or Suffolk County, factoring in Long Island's labor rates and permit fees.

Foundation type: A frost-depth concrete foundation adds $3,000–$8,000 but is required for four-season builds in our climate. Frost here typically reaches 36 inches — shallow footings that might work in warmer states will fail here within a few winters.

Glazing: Low-E triple-pane glass costs more upfront but dramatically cuts heating and cooling costs. On Long Island's coast, UV-resistant coatings are worth every penny to protect furniture from salt-air fading.

Permits: Nassau County permit fees for additions typically run $800–$2,500 depending on square footage. Suffolk County is comparable. Budget for this — unpermitted sunrooms create serious problems when you sell.

Labor: Long Island contractor rates are higher than upstate or out-of-state — expect $75–$110/hour for experienced crews. This is reflected in the per-square-foot ranges above.