Dennis Sizemore

Cement Mason Superintendent

Dennis is the go-to guy on anything and everything concrete. At age 15, he poured and finished driveways, patios, and shop slabs. When he started at GLY at 18, he was the youngest journeyman in his union. Today, he's a concrete master who oversees projects up to one million square feet. His favorite aspect of the job is the constant change of scenery since he's not on one single project for an extensive amount of time. While concrete is a big part of Dennis’s life, he makes plenty of room for his kids, fishing, hiking, and visiting Kauai, his happy place.

Cassie Withrow

Executive Administrator+Administrative Services Manager

Excellent customer service comes naturally to Cassie, who approaches every task with a can-do attitude. As Executive Administrator, she enjoys working with people that encourage her and test her limits but allow her to have fun along the way. She manages her time—and many others’—with extraordinary ease and keeps things running like a well-oiled machine. Outside the office, you’ll find Cassie hiking, exploring the city, and when the sun comes out, boating on Lake Washington—all with her husband and pups by her side.

Isaias Villa Galvan

Safety Director

GSP, CHST

Bryce Engen

MEP+CX Manager

LEED AP BD+C, BCXA CCP

Bryce is a mechanical systems and commissioning expert and a self-described Swiss army knife. He gets involved during preconstruction assisting with MEP scopes of work. During construction, he becomes hyper focused on QA/QC processes and procedures. On the back end of the job he develops closeout and inspection schedules and plans for startup and commissioning. He is a passionate alumnus of Washington State University, where he studied Construction Management, and minored in Business. His wife, two kids, two dogs, and Macaw parrot keep life busy but fun. Their latest achievement? Building a house together!

Danielle Sessler

Senior Project Manager

Associate DBIA™

Construction was always part of the plan for Northwest native Danielle, having grown up in a family that owned a contracting business. She took a few detours first, earning a BFA in Metalsmithing and Art History from Central Washington University and working as a Senior Estimator focused on honing her preconstruction services skills. When she landed at GLY in 2013, we quickly recognized her background would be perfect for Design-Build projects. Outside of work, Danielle enjoys hiking, bouldering, climbing—and collecting “odd things that most people scratch their heads over.”

Tyler Tonkin

Principal+Executive Vice President

Tyler’s collaborative approach to problem solving and strong technical abilities have helped him successfully lead some of GLY’s most complex and challenging projects. From redeveloping a waterfront building into a life science research facility with vibration isolation technology to delivering fully integrated hospital expansions in occupied campus settings, Tyler is driven to chart a course for the team to meet the challenges inherent to the built environment. As both a Principal and member of GLY’s Executive Team, Tyler has built a reputation as a committed client advocate and enthusiastic leader who brings out the best in our teams.

Mike Martel

Senior Project Manager

Associate DBIA™, LEED AP BD+C

Mike joined GLY in 2013 as a Project Engineer and has steadily increased his responsibilities, becoming a Project Manager in 2020. He holds a BS in Construction Management from the University of Washington, where he later returned to earn a Commercial Real Estate Certificate. That’s just one example of Mike’s passion for continuous learning—and sharing with his teammates. He’s especially versed in the latest developments in 3D modeling and navigating the complex processes of advanced BIM visualization. After a long week at work, Mike burns off steam by running, cycling, and skiing.

Laura Soma

Sustainability Manager

LEED AP BD+C

It’s no wonder that Laura’s passion is helping people find their potential. She’s worked hard to creatively forge her own career path and achieve her goals. She is active in a number of industry groups and peer networks focused on green building and leads GLY’s internal sustainability efforts. Her background as a Project Manager allows her to connect with clients and project teams to drive sustainability project goals while keeping budget and schedule at the forefront. Laura brings her love of responsible practices [and infectious good spirits] to every project.

Bryce Taylor