ADU Contractor Long Island
We build high-quality ADUs and accessory apartments, and work within Long Island’s Plus One ADU programs where available.
Understanding ADUs
An Accessory Dwelling Unit (ADU) is a secondary residential unit on the same lot as a single-family home. Also known as accessory apartments, in-law suites, or backyard cottages, ADUs provide legal, safe, year-round housing for:
Common Long Island ADU Types:
ADU Options
Convert existing space within your home—basements, attics, or unused rooms—into a fully legal accessory apartment with separate entrance and utilities.
Transform your attached or detached garage into a comfortable living space, or build an apartment above an existing or new garage structure.
Extend your home with a purpose-built addition that creates a legal accessory unit—perfect for expanding your footprint while adding value.
Where zoning permits, build a standalone cottage in your backyard—offering complete privacy and flexibility for family or tenants.
Funding Opportunities
New York State’s Plus One ADU initiative supports Long Island homeowners with grants and funding to create legal accessory dwelling units. Program availability varies by municipality.
Grants up to $125,000 in many participating towns
Gap-funding loan options may be available when grant funding does not cover the full project cost
Program Requirements
Are you a homeowner looking for a contractor to do your bathroom remodeling? Look no further than the experts at Cascella and Sons Construction. We have years of experience designing and executing bathroom renovations of all sizes, from small powder rooms to large master bathrooms. We will work with you to create a custom bathroom design. Click below to fill out the form to schedule an estimate with us.
How It Works
From initial feasibility to final inspections, we guide you through every phase of your ADU project with expertise and transparency.
Long Island Real Talk
Long Island has some of the highest housing costs in the nation. ADUs provide affordable housing options for families and communities.
Keep aging parents close while maintaining independence, or provide a launching pad for adult children starting their careers.
Provide comfortable, private accommodations for live-in caregivers while keeping your loved ones close to home.
Generate substantial long-term rental income to offset mortgage costs, property taxes, or fund retirement.
Long Island has some of the highest housing costs in the nation. ADUs provide affordable housing options for families and communities.
Long Island has some of the highest housing costs in the nation. ADUs provide affordable housing options for families and communities.
Long Island has some of the highest housing costs in the nation. ADUs provide affordable housing options for families and communities.
Long Island has some of the highest housing costs in the nation. ADUs provide affordable housing options for families and communities.
Long Island has some of the highest housing costs in the nation. ADUs provide affordable housing options for families and communities.
ADU Contractor Long Island
ADU costs vary significantly based on type, size, and finishes. Interior conversions typically range from $75,000-$150,000, while detached cottages can range from $150,000-$400,000+. Garage conversions fall somewhere in between. We provide detailed estimates during our feasibility review.
Permitting timelines vary by municipality but typically range from 3-6 months. Complex projects or areas with strict zoning may take longer. Design and engineering work happens concurrently, so we maximize efficiency in the pre-construction phase.
Typically no. Plus One ADU programs and most local regulations focus on creating long-term, year-round housing. Short-term and vacation rentals are generally not permitted for ADUs receiving grant funding or built under accessory apartment provisions.
ADU Inspiration
Clean modern exteriors • Indoor/outdoor layouts • Compact efficient kitchens • Bright studio interiors • Warm modern finishes
Start Your ADU Project
Whether you’re looking to house family, generate income, or add value to your property, we’re here to guide you through every step of the ADU process.
Serving Suffolk & Nassau County, Long Island
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