Long Island's Basement Experts Since 2011
Basement Finishing Long Island
Long Island's most experienced basement contractor. 580+ basements completed across Nassau and Suffolk Counties since 2011. We've seen every quirk this soil has.
Mon–Sat, 7am–5pm · Free Estimate · No Obligation
Free Estimate — No Obligation
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Responds within a few hours · Mon–Sat 7am–5pm
Everything Your Basement Needs
Our Basement Services
From raw concrete to fully finished living space — we handle every phase in-house with our 14-person crew.
Basement Finishing
Transform your raw basement into livable space. LVP flooring, drywall, recessed lighting, drop ceilings and more.
Basement Remodeling
Full gut-and-rebuild for older basements. New framing, plumbing rough-ins, electrical, and premium finishes.
Basement Waterproofing
Interior drainage systems, exterior membranes, and sump pump installation for Long Island's high water table.
Water Damage Response
Emergency flood response — pump-out, drying, mold prevention, and full remediation. Fast response times.
Sump Pump Installation
Single and dual sump pump systems with battery backup. BSI-certified installation and maintenance.
Egress Windows
Code-compliant egress window installation for bedroom conversions. Includes excavation and window well.
Basement Renovation
Partial or full renovations of existing finished basements — flooring replacement, ceiling updates, and more.
About LI Basement Pro
Built by a Long Islander, for Long Islanders
Dan Farrelly grew up in Hicksville and spent a decade as a finish carpenter before launching LI Basement Pro in 2011. He saw how many contractors were cutting corners on Long Island — skipping egress requirements, ignoring moisture issues, and leaving homeowners with code violations and water problems a year later.
We've done 580 basements on Long Island. We've seen every quirk this soil has. That means we catch the drainage problems before we frame. We spec the right LVP flooring for Long Island's temperature swings. We pull every permit so your finished basement adds real value when you sell.
Our team includes Karen Farrelly (office manager and permit coordinator), Mike Costello (BSI-certified waterproofing tech), and Tony Guerrero (15-year finish carpenter). We're not a referral network — everyone on your job works for us.
Dan Farrelly
Owner · Hicksville native · 15 years
Verified Local Work
Recent Basement Jobs Across Long Island
Real jobs completed by our crew across Nassau and Suffolk Counties.
650 sq ft basement with LVP flooring, recessed lighting, and egress window
Interior drainage system + dual sump pump installation on cape-style home
800 sq ft basement with home office, bathroom rough-in, and drop ceiling
Two egress windows with full excavation and waterproofed window wells
Battery backup sump pump system after basement flooding
550 sq ft playroom/guest suite conversion with full drywall and LVP
Exterior waterproofing membrane + interior french drain system
Emergency basement flood response — drying, mold prevention, full remediation
Project Gallery
Before & After Basement Work
Real projects from Nassau and Suffolk County homeowners who trusted us with their basement.
Hicksville — 650 sq ft Finishing
Garden City — Luxury Finish
Levittown — Waterproofing
Commack — 800 sq ft
Egress Windows
Sump Pump System
Water Damage Response
Serving All of Long Island
What Long Islanders Say
4.9 Stars · 187 Google Reviews
“Dan and his crew transformed our Hicksville basement into a beautiful living space. Professional, on time, and the quality is outstanding.”
Michael T.
Hicksville · Basement Finishing
“We had chronic water issues in our Levittown basement for years. Mike Costello installed a full drainage system and it's been bone dry through two major storms.”
Jennifer L.
Levittown · Waterproofing
“Got three quotes for our Commack basement. LI Basement Pro was the only contractor who measured properly and explained the egress code requirements.”
Robert M.
Commack · Basement Finishing
“Karen in the office was incredibly helpful coordinating Nassau County permits. The whole process was smooth and our finished basement looks incredible.”
Sarah K.
Garden City · Basement Finishing
“Emergency flooding in our Hauppauge basement. They were there within hours. Pump-out, drying, and remediation handled professionally. No mold issues.”
David R.
Hauppauge · Water Damage
Where We Work
Serving Nassau & Suffolk Counties
Got Questions?
Basement Finishing FAQs — Long Island
Basement finishing on Long Island typically runs $50–$85 per square foot installed. For a typical 600 sq ft Long Island basement, expect $30,000–$51,000 fully finished. The range depends on materials (LVP vs carpet, drop ceiling vs drywall), bathroom rough-ins, egress windows, and permit costs for Nassau or Suffolk County.
Get Started Today
Ready to Transform Your Long Island Basement?
Join 580+ Long Island homeowners who chose LI Basement Pro. Free estimates, no pressure, no obligation.
Mon–Sat, 7am–5pm · Free Estimates · No Obligation · Licensed & Insured