Our Firm

Engineering Excellence.

Since our inception in 1981, O’Donnell & Naccarato has transformed from a 3-person structural engineering firm into a national presence with over 120 dedicated professionals operating from seven strategically located offices. This journey reflects our unwavering commitment to our core values of communication, quality, innovation, growth, and collaboration.

O&N is a trusted partner for structural solutions across all sectors of the construction industry. With a diverse portfolio of projects spanning every corner of the United States, we offer local expertise with a national reach.

Our depth of experience and limitless creativity are the cornerstones of our approach. Whether crafting innovative designs for new structures or breathing new life into existing ones through expansion, renovation, or restoration, our aim is singular—to help property owners realize the highest and best use of their assets.

As an employee-owned structural engineering firm, nearly all our staff are members of the ESOP, reflecting our deep ownership mindset. This pride in ownership permeates through every aspect of our work and is evident in the care we dedicate to our projects.

Our Professional Engineers Are Registered in 49 States Across the U.S

1,000

Averaging Over 1,000 Projects Annually in Every Major Construction Sector

Over 2 Billion SF of BIM Structures Produced Since 2006

$6B

Annually Responsible for $6+ Billion in Construction Value

7 Offices Nationwide

Our History

O’Donnell & Naccarato was founded by Bill O’Donnell and Pete Naccarato, whose dedication to building long-lasting client relationships became the cornerstone of our firm’s success. With a passion for delivering quality and creative engineering solutions, they ensured that every project not only met client needs but also strengthened those partnerships. This vision and commitment remain deeply embedded in our firm’s culture and continue to drive our growth and excellence today.

O’Donnell & Naccarato Founded

1981

Provided structural engineering services for the Wyndham Atlantic City, formerly known as Tannen Tower. This 32-story hotel and parking structure was constructed using cast-in-place, post-tension concrete with a precast concrete alternative. This project marked the beginning of our proficiency in high-rise developments.

First Major Highrise Project

1983

Our firm made a significant leap forward by adopting AutoCAD, one of the most advanced computer-aided design tools at the time. This early embrace of cutting-edge technology allowed us to enhance precision, streamline workflows, and produce more efficient, innovative structural documents.

O’Donnell & Naccarato Adopts AutoCAD

1988

Completed our first major healthcare project at St. Christopher’s Hospital for Children in Philadelphia. This 183-bed, 310,000-SF replacement hospital marked the beginning of a long-standing commitment to healthcare design.

First Major Healthcare Project

1989

O&N worked on the major expansion of the King of Prussia Mall which led it to become one of the top 3 largest malls in the United States. We designed the structure for the multilevel retail space as well as the Neiman Marcus anchor store and two 1,000 car parking garages.

First Major Retail Project

1995

Provided structural design for the University of Pennsylvania’s fast-tracked, mixed-use development. The 305,000 SF structure included a campus bookstore, retail shops, and the 259-room Inn at Penn hotel.

Mixed-Use Hotel

1998

Provided structural engineering services for a 9-story, 207,000 SF cancer hospital addition to Robert Wood Johnson University Hospital. The advanced radiation oncology department featured two linear accelerators, an MRI, CT simulation, and stereotactic radiosurgery. This was one of many large projects on this campus.

Oncology Building

1998

Provided structural engineering services for The Inn at Somerset Hills, the very first project to utilize the Girder-Slab structural system. This highly efficient method of construction allowed the structural portion of the 4 story, 69,000 SF building to be erected in just 16 days. This project marked the beginning of a long-standing commitment to innovative construction methods, which remains an integral part of the firm’s portfolio today.

First Girder Slab Project

2000

Led the structural design and project management for Peconic Landing Retirement Community. The project encompassed multiple structures, including detached cottages, an apartment building, and a community/health center. The design integrated various framing systems tailored to each structure’s needs, from single-story wood frames to composite joist-supported apartments.

Major Senior Living Project

2001

Began our transition to an Employee Stock Ownership Plan (ESOP), giving employees a vested interest in the firm’s success and fostering a deep sense of pride and responsibility across the team.

Transitioned to ESOP

2003

Further cemented our commitment to innovation by incorporating REVIT. This adoption of BIM technology allowed for a more comprehensive visualization of structures, improved coordination across disciplines, and reinforced our position as a forward-thinking leader in structural engineering.

Adopted to REVIT

2006

Designed multiple buildings for Episcopal Academy’s new private school campus in Newtown Square, PA. The project included five structures, notably the campus’s 900-seat chapel. Each building, ranging from the lower and upper schools to the athletic center, was steel-framed and designed to support the educational environment.

K-12 Educational Campus

2008

Completed the structural design for Villanova University’s 185,000 SF law school building. Certified LEED Silver, the project included classrooms, offices, a 60,000 SF library, and structured parking for 600 cars.

Higher Education Building

2009

In response to a tragic event in Philadelphia, O’Donnell & Naccarato consulted with City Officials to help establish Philadelphia’s Façade Ordinance and established a Rope Access Team. This initiative not only reinforced O&N’s commitment to public safety but also positioned our firm as a leader in building envelope assessments and repair.

Developed Rope Access Team

2010

Grand Opening of the 905,000 SF Capital Health Medical Center in Hopewell, NJ. Certified LEED Gold, this complex project included a six-story replacement hospital, two medical office buildings and future expansion capabilities for another 140,000 SF patient tower.

Replacement Hospital Campus

2012

Opened an office in Northern New Jersey to serve the growing regional market. This strategic decision enhanced the firm’s ability to respond quickly to client needs and provided a platform for further expansion in the Northeast.

NJ Office Opens

2013

Provided structural design for Holtec International’s 7-story office building, manufacturing facility, and warehouse at the Krishna P. Singh Technology Campus. The project earned three LEED Gold Certifications and was named the 2018 LEED Project of the Year.

Design-Build Corporate Campus

2017

2018 – Expanded into New York City, enabling the firm to operate in the city and capitalize on opportunities in the nation’s largest metropolitan market. This office established a base for the firm’s continued growth and success in New York.

NYC Office Opens

2018

Acquired McComas Engineering in Indiana, expanding our core building design services to include specialty engineering for precast concrete, cold-formed steel, and aquatics structures. This acquisition strengthened the firm’s national presence and diversified its service offerings.

Indiana Office Opens

2019

Expanded into the Florida market by acquiring Douglas Wood Associates and opening an Orlando office. This move supported the firm’s rapidly growing client base in Florida, with notable healthcare projects for Ascension Sacred Heart Health, Baptist Health, and others, along with high-profile cultural and commercial projects like the Biltmore Hotel Miami Coral Gables.

Miami and Orlando Offices Open

2022

Completed the design for the 14-story, 358,340 SF Children’s Pavilion at The King’s Daughters Hospital. The state-of-the-art pediatric psychiatric hospital features inpatient beds, therapy spaces, executive offices, and a rooftop recreation area. O&N also designed the adjacent 7-level parking garage.

Patient Tower & Garage

2022

Opened a new office in Columbus, Ohio, positioning the firm within the Midwest’s booming healthcare market. This strategic expansion allowed O&N to better serve clients in the region and broaden our national reach.

Columbus Office Opens

2023

Served as Engineer of Record for Republic Airways’ $200 million mixed-use corporate headquarters in Indiana. This development includes a training center, hotel expansions, and plans for additional multi-family housing and office space.

Design-Build Corporate Headquarters and Training Center

2023

Completed the structural design for the 5-story, 405,000 SF Honorable Frank J. Guarini Justice Complex, a state-of-the-art replacement for the Hudson County Administration Building constructed in 1957. One of the complex’s standout features is a pair of colossal steel trusses, each spanning 700 feet in length and standing 35 feet tall, designed to protect the upper floors from potential disasters.

Design-Build Justice Complex

2024

O&N underwent a strategic leadership reorganization, positioning our firm for long-term success and growth. The newly formed leadership group is tasked with expanding the firm’s national reach and driving growth in key markets across the country.

Strategic Leadership Reorganization

2024

High atop Miami’s iconic Freedom Tower, we provided structural repairs as part of a $25 million restoration project. The 17-story National Historic Landmark, once a processing center for Cuban immigrants, received extensive enhancements to preserve its historic significance.

Prominent Cultural Restoration Project

2025 (est.)

O’Donnell & Naccarato delivered comprehensive structural engineering design for the Philadelphia College of Osteopathic Medicine’s 55,000-square-foot, steel-framed Activities Center. This dynamic facility serves PCOM students, their spouses, and employees, offering an extensive range of athletic spaces, equipment, and classes. Key features include a professional NBA-regulation basketball court with six stations, racquetball courts, a weight training and cardio area, and a versatile, roof-level multi-sport deck designed for deck hockey, basketball, soccer, and shuffleboard. The center also provides student lounges and recreational areas, fostering a vibrant community atmosphere.

Athletic Center

1999

O&N staff at desk | Structural Engineering Firm | O'Donnell & Naccarato

Trusted partners in our clients’ success stories.

We are committed to deliver exceptional structural engineering solutions, while providing value to our growing family of clients, employees, and communities across the country.

Meet Our Team