Do Finished Basements Add Real Value on Long Island? (2025 Guide)

Unlocking Hidden Potential: Why Your Basement Might Be Your Home’s Smartest Investment

Dreaming of more living space or a new hangout spot for your family? For Long Island homeowners, a finished basement isn’t just extra square footage. It’s a chance to boost your home’s value, comfort, and appeal. But does it really pay off? Let’s break down the facts, local trends, and the Keenan Custom Homes difference.

Not all finished basements are created equal. For real value, yours should include: - Moisture control & waterproofing (essential on Long Island) - Insulation and climate control - Quality flooring, lighting, and egress windows - Permits and code compliance (for safety and resale) - Polished finishes—think custom trim, built-ins, and beautiful details

In Suffolk County, finished basements can make your home more attractive to buyers, but appraisers often value below-grade space differently than main floors. Still, a well-finished basement adds serious lifestyle appeal—think guest suites, home offices, gyms, or entertainment rooms.

• ROI averages 65–75% of the remodeling cost—higher if the space is dry, code-compliant, and designed for today’s needs.
• On Long Island, finished basements are especially desirable due to limited space and high property values.
• Recent listings show finished basements can boost resale value by $30–$40 per square foot or more, depending on quality. That is at the minimum, we have seen it go much higher in properties that we have worked on.
  

• Waterproof first: Long Island’s climate means moisture is enemy #1.
• Get permits: Unpermitted work can hurt value and delay sales in the future. If you are planning on staying in your home for the long run, there is possibility of not needing permits.
• Match main-level quality: Use custom woodwork, detailed trim, and finishes that reflect your home’s style.
• Flexible spaces: Create rooms that can adapt. Think playrooms, in-law suites, or media centers.
• Add egress windows for bedrooms: Required by code and a big plus for safety as well as resale. A typical egress window will cost you approximately $5,000-$7,000.
  

• Will I recoup my investment? Most homeowners see 65–75% ROI, plus years of added enjoyment and easier resale.
• Is a finished basement right for my home? If you need more space, crave a custom touch, or want to stand out in the Long Island market, absolutely.
• What about flooding? Professional waterproofing and drainage are a must! Keenan Custom Homes specializes in these Long Island essentials and has decades of experience in different methods of which will best suit your needs.