About Us

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Mark Line Industries Custom Modular Fabrication.

Since 1968, Mark Line Industries has been delivering custom modular buildings to clients across North America and overseas.  From our roots, as a manufacturer of relocatable offices and classrooms, Mark Line grew from a single location, to one of the country’s foremost custom fabricators of modular buildings and permanent modular construction.  We serve clients in need of modular schools, modular classrooms, modular offices, modular medical buildings, modular urban housing, and modular hotels.

Today, we are recognized as one of the industry’s most innovative fabricators, serving both private and public sector clientele across North America as well as delivering mission critical facilities overseas.  We are proud to be a family-owned fabricator, proving that American manufacturing and innovation is alive and well.

See Our Fabrication Process.


Mark Line is a custom modular fabricator meaning we can produce a number of prefabricated unit types, ranging for volumetric modular construction, to containerized structures, to sub-assemblies or prefabricated components.

These are the most typical U.S. modular building offerings which are volumetric six-sided units typically delivered with a high percentage of completion, although as a custom modular fabricator, we work with each client to optimize scope of work.  These units can be for relocatable or permanent and site-specific applications.

Long a concept loved by designers, containerized buildings seek to take advantage of the standardization and ease of transit of ISO (International Standards Organization) ocean freight containers.  Whether modifying existing standard or high cube containers, fabricating custom sized containers, or fabricating a hybrid system using an ISO like tube steel frame, Mark Line can deliver.

Modular buildings and containerized buildings are not always the ideal solution to every building challenge, and as such Mark Line can fabricate smaller components and sub-assemblies to serve the needs of contractors engaged in large scale construction projects.  Headwalls, restroom cores, and MEP racks are common types of prefabricated components / sub-assemblies.


Modular construction is not a new idea.  But the scale and complexity of buildings being delivered with modular fabrication, prefabrication, and other modern methods of construction (MMC) is rapidly changing and much misinformation still remains.  Below, we have created an FAQ / Wiki with common queries about modular construction.

Modular vs. Conventional Construction
This is an area of serious confusion, with many people equating commercialized modular construction with the national HUD code of manufactured housing. Modular fabrication is merely a more efficient delivery method, not a substantially different end product. Your modular building will be fabricated to the building and energy codes of the site where it will be installed.
Where Can ML Build?
Mark Line builds everywhere east of the U.S. Rockies, holds CSA certification for construction in Canada, is one of the few NYC Approved Fabricators who can fabricate permanent modular construction in the City, and as we support the federal government and private sector clients with secure or technology embedded buildings overseas.
Building Systems
As a custom modular fabricator, Mark Line produces buildings with wood framing systems, “true modular” systems with no integral steel frame, steel frame construction, poured concrete slabs, engineered precast, and light-gauge and composite systems based on our clients’ needs and relevant building codes.

Benefits of Modern Methods of Construction (MMC)

Mark Line fabricates modular structures off-site in a climate controlled indoor fabrication facility.  Our company’s sustainability goals are to reduce the amount of materials diverted to landfills and re-use materials wherever feasible.  The controlled shopfloor environment allows us to do this in a manner that conventional construction never could.

Off-fall steel and lumber is recycled or re-used in appropriate places (backers, etc) and the indoor secure fabrication building keeps stored materials out of the elements and eliminates theft and vandalism.  Mark Line generates much less than 2% waste compared to site construction which can exceed 5%.

Modular fabrication can dramatically compress and accelerate construction timelines, delivering reductions of 25-50% depending on the details of the project.  From an overall process standpoint, modular fabrication allows for concurrent construction:  the building is being fabricated offsite as modular units at the same time that site development and foundation construction is happening at the site.

By working indoors, using an assembly line process similar to that of the automated, lean manufacturing employed by the automotive industry, buildings are completed faster and more efficiently, while the indoor nature of the process eliminates weather delays that plague conventional projects.

Modular buildings are a smart solution in today’s economy.  By working offsite in a manufacturing environment, there is a much greater degree of cost certainty.  The overruns that can be commonplace in conventional construction can be removed from one phase of the project by utilizing offsite fabricated modular units.

The modularity of structures also allows for flexibility for the owner as their needs change over time.  Too often a new building is a captive solution and owners must project their needs far out into the future.  Modular buildings can be designed to scale overtime, adding to the overall footprint or height of the building all while minimizing disruption to the current occupants.