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Blue Island Homes

Headquartered on Long Island, Blue Island Homes is one of the region’s premier Residential Brokerages and Real Estate Developers. Our team of award-winning agents represent both buyers and sellers, and truly understand the intricacies of every local market. From starter homes to large estates, we are ready for the assignment. Blue Island Homes is a full-service custom home builder. With more than thirty years of experience building high-end luxury custom homes. We have earned an enviable reputation for quality. We take great pride in this status and continue to earn recognition by paying particular attention to the details, utilizing the highest quality materials, and bringing together subcontractors of superior craftsmanship. We have planned, developed, and built dozens of homes throughout the north and south shores of Long Island, from starter to multimillion-dollar luxury homes.

Come visit us today in our state-of-the-art offices.

Blue Island Homes Office



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Mark Stempel

CEO/Founding Partner

Mark Stempel is a Licensed Real Estate Broker and seasoned professional with a deep-rooted background in the construction industry. As a proud native of Long Island, Mark has dedicated over three decades to refining his expertise and knowledge within this field. His educational journey culminated in a Master's degree in Architecture, igniting his passion for design and the development of residential homes.

Throughout his career, Mark Stempel has consistently remained at the forefront of real estate brokerage and emerging design trends in residential construction. This unwavering commitment to innovation ensures that his company, Blue Island Homes, consistently delivers the highest quality in every project. With a notable track record of crafting custom speculative homes across the Hamptons and various Long Island communities, Mark is dedicated to creating extraordinary living spaces.

One hallmark of Mark's approach is his steadfast dedication to client satisfaction. At Blue Island Homes, Mark and his team consider their clients an integral part of their extended family. They tirelessly go the extra mile to understand and exceed their clients' needs and expectations.

Mark Stempel is deeply committed to his community and the broader Long Island region. He actively supports charitable organizations and local community groups while prioritizing his cherished relationships with family and friends.

In summary, Mark Stempel's extensive experience, educational background, unwavering dedication to quality, and profound commitment to the Long Island community have solidified his reputation as a respected figure in the real estate and construction industry.

Mark Stempel: "I grew up here, I live here, and I love Long Island."
Mark Stempel
Jennie Katz

Jennie Katz

President, Founding Partner

Jennie Katz is a Licensed Real Estate Sales Agent, who has established an illustrious career characterized by an impeccable reputation and a devoted following. During her impressive career, Jen has not only clinched numerous prestigious awards but has also garnered an extraordinary grasp of the Long Island real estate landscape, along with her ability to forge meaningful connections with people. With more than 35 years on Long Island, she has truly made this vibrant community her home.

Jen's unwavering passion lies in people and nurturing relationships. Her keen design sensibility is finely tuned, and she possesses an intricate understanding of the residential market. Jen's mission is two-fold: to secure the highest value for her clients' homes and to seamlessly match her clients with their ideal new homes. Trust Jennie Katz to guide you on your journey through Long Island's real estate landscape.

What Our

Clients Say

“I have had the privilege to work with Jennie Katz on two different occasions and both times she has been top notch. She is kind, patient, attentive, and at the height of professionalism in the real estate market. Her passion for detail and never ending work ethics are Exemplary! If you have any real estate needs, look no further then Jennie. She is Long Island's Best!”

- Mark B. – S. Bellmore, New York

“I’ve worked with Jenny in various capacities, both personally and in business and can tell you she gets the job done, she’s got a great eye for detail, great taste, and if you saw the house she built for her own family, it would be enough said. Jenny is filled with ideas and great advice, she simply knows what you want. If I’m building my dream home, I’m definitely making sure Jenny’s in my corner.”

- Jehonathan B. – New York, New York

“I wanted to take a brief moment to extend my sincere appreciation to you for working with me on my most recent real estate transaction. You made what most often could be a stressful experience into one of an incredibly positive experience. I have purchased several luxury homes in the past, I have a real estate investment company of my own, and have worked with endless amounts of brokers/agents over the past 30 years and in my opinion you are the best of the best. You have a stellar work ethic, honesty and integrity, your knowledge within the marketplace is second to none. You are an incredibly rare person that goes above and beyond without having to be asked. I will enjoy with complete confidence referring you to anyone in the market for your services. I wish you much deserved continued success in all your future dealings. All my best, ”

- Gerard T. – Bellmore, New York

“Upon meeting Jennie Katz at an open house, we were immediately put at ease by her vast knowledge of real estate and housing markets, particularly, our local high-end market. However, her reputation had actually preceded her. We already knew Jennie Katz to be a powerhouse in the industry via social and standard media marketing, as well as the sheer number of listings and quick, successful closings all around us. We experienced, first-hand, Jennie's savvy marketing prowess, her keen eye, attention to detail and extensive knowledge of home decor and design she used to guide us and prepare our home for sale. Not only did we purchase the house we met Jennie at, but she sold our home over asking price within days of being listed. Her knowledge, guidance, communication and advice through every step of the process was priceless. Tireless work ethic, extensive experience, depth of knowledge of both real estate and home design and true commitment to and caring for her clients makes Jennie Katz THE ONE you want to work with.”

- Kristen W. – Merrick

“Easiest, most pleasurable and efficient home purchase I have ever made. This builder is professional, competent, conscientious and buyer friendly, from the top to bottom of the staff. Superior construction and finish work. My sincerest compliments and congratulations, you are an awesome team!”

- Charlotte T. – Westhampton Beach, New York

“Nearly every time I wander around our house and property, I can’t help but have a feeling of gratitude in my heart for you and your commitment to fine workmanship, organization and a good attitude. [We] really love our home and we are so thankful that you were at the helm of our remodeling project.”

- John & Sara W. – Westhampton Beach, New York

“How do we begin to express our thanks and gratitude to Mark Stempel? Thank you so much… to you, your crew, and subs for building our dream house! The quality of your work, your attention to detail, your (seemingly) effortless management of the project ensuring every single day progress was being made, did not go unnoticed. Additionally, your creative resolution to situations that would arise and “can do” attitude were icing on the cake. Would we build again? YES, but only if we could use you. You are extremely talented, hardworking, honest, communicative, and approached each day with the utmost integrity. ”

- Dennis R. – Locust Valley & Westhampton Beach, NY