A great business is made up of great people.

Darren Diack

Managing Director

Darren has over 30 years’ experience in leadership and management. He spent the first 20 years of his working life at Carter Holt Harvey, and joined Gemco as the Managing Director in 2003. Darren has led Gemco through a period of sustained growth, to become the large successful business it is today. He pins much of the business’s success on three key principles: people, attitude and quality.

Karl Johnson

Executive Director, Trades General Manager, Coatings and Masonry Division Manager

Karl manages the teams of highly skilled in-house trades specialists. “I have a real passion for all the trades available within Gemco. We support and compliment the activities of Gemco Construction by having the same work ethic and desire to deliver a quality product with service to match”. Karl is a past President of HB Master Painters, and has a NZ Diploma in Business.

John Sarten

Executive Director and Quantity Surveyor

John is hugely experienced in all aspects of commercial construction and has comprehensive industry know-how. His key role is managing the delivery of a high-quality, fully integrated life-care village construction project in Wellington. John is a certified Builder, registered Quantity Surveyor, founding shareholder and Director of Gemco.

Mike Smith

Executive Director and Financial Controller

Mike heads the accounting and administration functions of the business. He delivers timely and accurate financial reporting to the board and management. Bringing the same rigour and attention to detail to Gemco’s financial affairs as the construction professionals bring to their specialist areas. Mike is a highly experienced, qualified Chartered Accountant of NZ (CAANZ).

Edwin Brown

Non-Executive Director and Board Chairman

Edwin brings specialist senior management, marketing, strategic planning, and governance skills to the Gemco board. Drawing from his significant commercial and management expertise built up over a lengthy career. He has worked across a variety of sectors including retailing, manufacturing, building, forestry, horticulture, exporting, land development, accommodation and tourism. Today he is a professional Director and company advisor.

Brent McAsey

Operations Manager

Proven strengths in meeting project time frames and client expectations are key strengths for Operations Manager, Brent. He oversees all of our carpenters, supporting them, mentoring them and planning which project they will be working on. Part of the Gemco team since day one, Brent is an integral part of the continued success of Gemco.

Steve Meek

Commercial Manager

Steve has a genuine love of building and the construction industry as a whole. With over two decades of experience, he knows the industry inside out. He started off as a carpenter, before qualifying as a QS, but still enjoys getting his boots dirty, as much as the high level strategic planning required, to realise the full potential of a build project.

Chris Olsen

Project Manager

As Gemco's Project Manager, Chris takes extreme pride in completing all projects on time and to very exacting standards. His strong belief in honesty and communication being the keys to success are evident in any dealings you have with him. Here from the beginning, Chris knows the ins and outs of Gemco and has formed excellent relationships with clients and subcontractors. With over 28+ years of experience in large complicated commercial builds, multi story builds and historical renovations, Chris is a handy man to have around.

Sam McCarthy

Office Manager

A key player in the Gemco team, Office Manager, Sam runs a tight ship and leads the smooth and efficient running of Gemco HQ. She wears many different hats, managing HR, IT, payroll, marketing, admin and social functions. Sam worked her way up through the business, initially starting with Gemco as the Office Receptionist in 2005. Her hands-on experience and extensive knowledge of the business is invaluable.

Brooke Walker-Allen

Health and Safety Manager

Brooke is responsible for implementing and improving Health and Safety systems at Gemco. She is passionate about creating an open, honest, and respectful Health and Safety culture within the business operation for employees, contractors, and subcontractors. Her experience gained in the Australian Mining Industry, working alongside Senior Health and Safety Advisors, inspired her to pursue further training in the area of Health and Safety. Looking for continuous improvement and innovation, Brooke is always open to suggestions and ideas that help Gemco to lead the way in Health and Safety.

Graeme Johnson

Construction Manager

With a wealth of knowledge, and experience across a range of different builds and construction methods, Graeme is an extremely versatile member of the Gemco family. Graeme heads many of our large scale, complex projects, and provides great mentoring to those in his team.

Eddie Holmes

Construction Manager

One of Gemco's most experienced Construction Managers, Eddie brings a wealth of knowledge, skill and experience to Gemco and his project team.  Not one to shy away from getting out on the tools, Eddie still has a real passion for getting out there and getting hands on in his projects.

Benn Ratana

Construction Manager

As Gemco's main man in Wellington, Ben heads the delivery of a large scale, multi story life care village complex. Ben, as a qualified carpenter, brings a diverse range of skills and practical experience to the Construction Manager role, whilst also providing mentoring and guidance to those in his team. With an eye for detail and high standards, you can be assured a quality build outcome.

Gary Stratmore

Project Manager

One of the longest serving members of the construction industry at Gemco, Gary has nearly four decades of experience under his belt. Building is in his blood. He brings his extensive hands-on knowledge, skill, and expertise to Gemco, these days, to work in a project management role. It is Gary’s outstanding people skills that are the secret weapon for the critical path of successful projects completed on time, to a very high standard.

Derek Lawson

Quantity Surveyor / Project Manager

Derek has extensive QS and Project Management expertise gained from over 30 years in the industry. With a keen eye for detail, he is very well versed with all budgeting, contract administration, programming, and management needs on construction projects. His technical skills are complemented by excellent people and communication skills. Derek has established invaluable long term Client and Subcontractor relationships over the years for Gemco.

Andrew Moran

Quantity Surveyor / Project Manager

Andrew quickly established himself in the local construction market, as a Project Manager who is rarely flustered, for whom there’s no problem too big to overcome. His “down to earth” and “nothing can’t be fixed” approach is backed up with almost two decades of practical building experience. This killer combination ensures many of the successful project outcomes at Gemco.

Hayden Earl

Quantity Surveyor / Project Manager

Southern man Hayden is a qualified Carpenter and Quantity Surveyor with over 14 years experience in the construction industry. Since joining Gemco in 2011, his skills and experience have enhanced the success of many of our large scale commercial and industrial building projects.

Karl Johnson

Executive Director, Trades General Manager, Coatings and Masonry Division Manager

Karl manages the teams of highly skilled in-house trades specialists. “I have a real passion for all the trades available within Gemco. We support and compliment the activities of Gemco Construction by having the same work ethic and desire to deliver a quality product with service to match”. Karl is a past President of HB Master Painters, and has a NZ Diploma in Business.

Mike Lee

Plumbing Division Manager

A highly skilled plumbing professional, Mike has undertaken a wide variety of roles including pricing and management of contracts. Mike is responsible for managing the Gemco Plumbing team’s work across all projects, from residential to commercial. He is a Certified Plumber and Drainlayer with over 28 years of experience in the industry. Qualified with a NZ Diploma of Business and NZIM Diploma of Business.

Phillip Panapa

Plasterboard Division Manager

Phillip manages the team of Plastering tradespeople, executing a huge variety of activities across all types of projects including the construction of suspended ceiling systems, and plasterboard fixing and stopping. Phillip gained extensive experience in the construction industry in NZ and Australia, working as a qualified carpenter, plasterboard stopper and fixer.

Craig Russell

Joinery Division Manager

Craig leads Gemco Joinery’s team of tradesmen and apprentices from our Joinery factory in Havelock North. With great attention to detail, creating perfect interior and exterior joinery for all projects. Qualified with a trade certificate in Joinery and a background in the shop-fitting industry, Craig was equipped with wide-ranging technical expertise, as well as management and pricing experience.

Amelia Longley


Gemco’s bright and bubbly Receptionist, Amelia, is the first point of contact both at Gemco HQ, and by phone. With great efficiency, her excellent time management and organisational skills keep her on top of the continual comings and goings in our very busy office.