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Situation: Aged Commercial Roof Required Replacement

 A roof is one of the key components of a building envelope that provides its inhabitants a barrier from the elements. The roof of a building keeps the people, equipment, and merchandise under it clean, cool, and dry.  This crucial building element plays a significant role in the building’s energy consumption, aesthetics, occupant safety, and resale value.  Like any other building component, a roof needs regular maintenance to meet its functional requirements.  Even with regular maintenance though, there comes a time when a roof will meet its expected useful life and need refurbished or replaced.


Murdoch’s, a ranch and home supply retail store in Greeley Colorado had such a roof.  The Murdoch’s store building was built in 1971.  By 2013, the roof had met the end of its functional life and was in need of refurbishment or replacement.

After 42 years of service the roof had basically deteriorated to the point of functional failure.  The original roof was designed with minimal slope allowing water and debris to pool. Stagnant water allowed deterioration and corrosion over time until the roof developed leaks.

Murdoch’s retained REDI Engineering to evaluate the situation and research replacement options.

Over the course of the investigation, REDI determined the overall roof structure was still sufficient to carry the required loads as well as meet local and state design codes.

Action taken to retrofit a replacement roof

Given the deterioration of the roof covering, sound structural integrity, and lack of slope, REDI Engineering concluded that a retrofit roof replacement would be the best approach to refurbishing Murdoch’s roof.  A retrofit roof simply constructs a secondary roof structure directly on top of an existing roof.  This retrofit design will allow the designer to add sufficient slope to the roof to enable water shedding. In addition to the water shedding capability, a retrofit roof can improve thermal performance and increase aesthetic appeal.  Other benefits of this type of system include reduced maintenance, less energy consumption and more robust design against the elements.  A retrofit replacement roof costs less than replacing a flat roof with in-kind materials. Retrofitting also allows the building to remain in-service while the roof repairs are made.

REDI Engineering designed the retrofit roof supporting structure and provided the designs to a Nebraska based manufacturing company to build them.  Roofing materials were shipped directly to the Murdoch facility and a local contracting company performed the installation.

Retrofit roof structure installation at Murdoch’s retail store in Greely, Co.

 Retrofit Roof results at Murdoch’s

The retrofit roof at Murdoch’s Ranch and Home retail store in Greely Colorado was successfully installed and completed in December of 2016.  The great folks Murdoch’s will enjoy clean, cool comfort for years to come with minimal upkeep and maintenance.

“The reroof project for Murdoch’s Home and Ranch Supply in Greeley was a very challenging and rewarding project. The engineering piece of the project had to be just as tough. The design was straight forward and easy to translate in the field. We were very happy with how well everything went together and when we did have any questions, John made himself readily available. Highly recommend REDI”—Jim Clark, Clark Enterprizes Const Co.

Forensic Engineer/Building Envelope Specialist

John Thomazin, MSME, P.E.


John Thomazin, P.E. is the owner of REDI Engineering, Inc. and has been a consulting engineer since 2006. He is a licensed engineer in two states and holds a certificate from the Construction Specifications Institute. A member of the National Academy of Building Inspection Engineers, he assesses buildings, evaluates structures, investigates roofing and waterproofing systems, and provides expert testimony for construction claims. He enjoys solving complex problems and uses his teaching experience to explain construction principles in an easily understandable manner. He has a Bachelor of Science degree in Mathematics, a Master of Science in Mechanical Engineering, and has been providing expert testimony in building-and-construction-related claims since 2007.