Basement finishing is one of the most popular home improvement projects on Long Island — and for good reason. A properly finished basement adds livable space, increases home value, and on Long Island's notoriously tight real estate market, can make a meaningful difference in your home's appeal.
But what does it actually cost to finish a basement on Long Island in 2026? After finishing 580+ basements across Nassau and Suffolk Counties, here's our honest breakdown.
Long Island Basement Finishing Cost Per Square Foot
Basic
$50–$65/sq ft
LVP flooring, drop ceiling, basic recessed lighting, no bathroom
Standard
$65–$75/sq ft
LVP, drywall ceiling, upgraded lighting, half bath rough-in
Premium
$75–$85+/sq ft
Full bathroom, custom ceiling, premium LVP, built-ins
Total Cost for Typical Long Island Basements
| Basement Size | Basic Finish | Standard Finish | Premium Finish |
|---|---|---|---|
| 550 sq ft | $27,500–$35,750 | $35,750–$41,250 | $41,250–$46,750+ |
| 650 sq ft (typical) | $32,500–$42,250 | $42,250–$48,750 | $48,750–$55,250+ |
| 800 sq ft | $40,000–$52,000 | $52,000–$60,000 | $60,000–$68,000+ |
| 1,000 sq ft | $50,000–$65,000 | $65,000–$75,000 | $75,000–$85,000+ |
| 1,200 sq ft | $60,000–$78,000 | $78,000–$90,000 | $90,000–$102,000+ |
* Nassau and Suffolk County permit costs ($500–$1,500) included in estimates above.
What Drives Basement Finishing Costs on Long Island
Several factors can push your basement finishing cost above or below the typical range:
1. Bathroom Addition
Adding a half bathroom to a basement finishing project adds $6,000–$12,000 depending on how far plumbing needs to be run and whether you need an ejector pump. A full bathroom with tub/shower adds $10,000–$18,000. These are significant additions but dramatically increase the basement's functionality and resale value.
2. Egress Windows
Required for basement bedrooms. Each egress window installation costs $3,500–$8,000 including excavation, structural work, and the window well. If you want a legal bedroom in your basement, this is not optional in Nassau or Suffolk County.
3. Waterproofing
If your basement has water intrusion issues — common in Long Island due to the high water table — waterproofing before finishing adds $3,000–$12,000. Never skip this step. Finishing a wet basement without addressing the moisture is one of the most expensive mistakes Long Island homeowners make.
4. Ceiling Height
Many Long Island homes — especially Levitt-era capes — have lower ceiling heights (6'4″–7'0″). This limits your ceiling options and can require creative solutions. We do a lot of beam wrapping and low-profile drop ceiling systems for these projects.
Nassau vs. Suffolk County: Any Price Difference?
Labor costs are consistent across Long Island — there isn't a meaningful price difference between Nassau and Suffolk County for the same scope of work. Permit fees vary slightly (Nassau County permits tend to be $100–$300 more than Suffolk towns for comparable projects), but this is a minor factor in overall cost.
Our basement finishing page walks through how a project runs from framing to final inspection, and if you are in the Town of Hempstead, see our page on basement remodeling in Hempstead.
How to Get an Accurate Estimate
The only way to get an accurate basement finishing cost is an in-home estimate. Any contractor who quotes you over the phone without measuring is guessing. At LI Basement Pro, A senior estimator visits your home, measures precisely, assesses moisture, and discusses your goals — then provides a written itemized quote within 24–48 hours.
Get a Free Estimate for Your Basement
We visit Long Island homes Mon–Sat. Free, no-obligation estimates with written quote within 48 hours.