John Mavis

Results-driven executive with extensive experience in strategic leadership and operational excellence. Proven track record in fostering team collaboration, driving organizational growth, and adapting to evolving business needs. Skilled in strategic planning, financial management, and stakeholder engagement. Known for strong decision-making abilities and unwavering focus on achieving measurable outcomes.

• Florida State Certified Plumbing Contractor
• Texas Master Plumber
• Maryland Master Plumber/Gasfitter - Maryland Master HVAC
• Baltimore City Oil to Gas Conversion
• Maryland 2 PSI Gas fitter
• Anne Arundel County Master Mechanics License
• Universal Refrigeration Certification
• Medical Gas Piping Certification
• Certified all position pipe welding
• Underground fuel tank and piping EPA certification.

• I started as an apprentice plumber and HVAC mechanic, acquiring my Journeyman’s licenses in 1980, and then Masters Licenses in 1983. I worked in the office and the field, which eventually became his company superintendent and estimator.
• I was hired by Harkins Builders as a project manager who had revenue of over 200 million dollars a year and 500 employees. I was assigned at 27 years old to the largest project in the company’s history which had a value of Eighty Million dollars working along with another project manager and construction manager. The first phase of this project was based on a GMP with a 4.5% fee, negotiated 50/50 split of subcontract and vendor savings, and a standard overhead and profit basis for change orders.
• Started Mavis Mechanical Services, Inc. performing commercial Mechanical Contracting in 1988. Over the years the company grew to over five million in revenue, and 80 to 100 employees. I achieved this success while only having myself in the office and one or two secretaries to do data input on our computers, filing, vendor solicitation, and other miscellaneous duties. I was able to sustain by myself all the project management, accounting, legal, estimating, and other required duties due to my implementation of automation processes in each area, while other similar companies on average had 5 to 20 office and project management personnel.
• After 16 years in business, I shut down my company’s construction operations and moved my focus to consulting operations for small and startup mechanical companies to help them grow their operations.
• Finally, after getting divorced, I decided to leave the area and move to the Florida Keys to start a new life. I settled in the Key Largo area and worked for a local plumbing company for a year as a breather. Then began operation shortly after as Mavis Plumbing, Inc and acquired my Certified Plumbing Contractor License, focusing just on the plumbing side of Mechanical Contracting opening my business in 2006. I did not have an interest anymore in having employees and worked mainly alone from the start doing service, residential home construction and light commercial work until I injured my back around 2017 and had to basically stop most “in the field” work.

• Accounting systems including Peachtree, Peachtree 2000 for large companies with over 5 million in revenue, QuickBooks pro, BPI Software systems.
• Estimating, including computerized using Means system.
• Computer programming and networking.
• Legal preparation and all aspects required for litigation in collection of monies, contract and subcontract preparations.
• Office operations streamlining for daily activity, automation, effectiveness, and efficiency.
• Billing and collections of accounts receivable.
• Job Costing and coding implementation.
• Automatic Temperature Controls expert.
• HVAC and Plumbing systems design.
• Ductwork installer and design.
• Building Heat load and loss calculations.
• Piping & Steam Fitter
• Direct Digital Control Systems expert.
• Refrigeration and A/ Service technician.
• Commercial Boiler assembly, installer, and technician.
• Commercial Chiller installer and technician.
• All types of commercial mechanical equipment installer and technician including pumps, AHU’s
• Steam and water pressure reducing stations, etc.
• Rigging expert for equipment and crane installation.
• Pneumatic controls systems.
• Certified Pipe Welder in 6G all positions.
• Underground Tanks with double wall fuel oil piping systems.