Since 1969 our modular inplant offices, guard booths, outdoor equipment enclosures, prefabricated mezzanines, and towers have been used for thousands of unique construction applications across North America and throughout the world. We provide our customers with cost effective, highly functional, easy to assemble alternatives to conventional construction.
Headquartered in Earth City, Missouri, Porta-King manufactures five different types of prefabricated buildings, multiple wall systems, structural steel mezzanines, and towers. With ten regional sales offices in the United States and two production facilities in Montgomery City, Missouri with more than 160,000 total square feet, we have the staff, the space, and the expertise to meet your needs.
A Long-Standing Commitment to Innovative Prefabricated Solutions
We rarely sit still at Porta-King. Over the past 50 years, we’ve changed product lines, expanded facilities, and introduced brand-new patented systems. As the times have changed, construction needs have changed, too. We’ve introduced several product innovations throughout our history, driven by customer demand for more modular and prefabricated solutions to fit an ever-growing list of construction applications. They include:
- Duraluminum, prefabricated buildings
- Pivot-Lock, pre-framed modular wall system
- Versa-King, modular wall systems
- Versa-King HD, modular tall wall system
- Durasteel & Durasteel PC, prefabricated buildings
- Durasteel ES, prefabricated equipment enclosures
- PK Structures mezzanines, observation towers, and video towers.
While the company has grown over the years, our commitment to quality manufacturing and excellent customer service has never wavered.
Modular Designs to Suit Any Application
Our Modular Systems offer the flexibility you need for any application. Fully customizable, our portable buildings and shelters are constantly being modified to accommodate today’s environmental demands. In addition, we manufacture a full line of structural steel mezzanines, catwalks and work platforms, which are all designed in compliance with the latest national code.
Let us Know What We can Build for Your Facility
At Porta-King, we take the work you do seriously, and we build structures your team can rely on. Porta-King structures are durable, versatile, and 100% customizable. Installation is more cost effective and less disruptive than anything you could build using traditional construction methods.
We strive to be the leading manufacturer of modular and portable buildings in the United States, but we can’t do that without you. Please feel free to contact us at any time for more information or with suggestions on how we can make doing business with Porta-King easier for you, our valued customer.
Cordially,
Steve Schulte, President
Request a Free Quote Today
Partner with Porta-King for Sustainable Design



Porta-King Building Systems offers more prefabricated and modular building systems than any other manufacturer. We offer five different types of prefabricated buildings and shelter systems that include high-level ballistic rated construction. We also manufacture eight different types of modular wall systems, structural steel mezzanines, and towers. If you want to incorporate a sustainable design philosophy into your business, Porta-King can help. Here’s what else you can expect when you contact our sales team:
A Wide Range of Construction Options
- In order to address the broadest range of construction applications, we offer a variety of different building systems and structures. These include prefabricated and modular buildings along with mezzanines and towers.
- As a custom fabricator, we have a wide range of design options that can be incorporated into our prefabricated buildings, like custom wall and roof designs to enhance the aesthetics along with construction options that are more functional in nature. Options include factory installed restrooms, custom cabinetry, ballistic-rated materials, and more. Additionally, to construct your guard building, equipment enclosure, or other prefabricated building application, we offer the choice of steel or anodized aluminum construction. Our design team can personalize each structure we make to meet your project requirements.
- We offer more design options for our modular buildings and wall systems than any other manufacturer. They are available in a range of wall thicknesses, panel heights, core compositions and finishes to address an endless array of interior construction applications. These different construction options allow us to address application requirements such as sound control, insulation values, fire ratings and aesthetics.
- Construction options for mezzanines include special flooring, custom paint colors, different load capacities along with virtually unlimited floor plan design options. All of these construction choices enable us to create a range of code compliant structures that support equipment, inventory storage, and fall protection.
- Our towers are designed to support prefabricated buildings for applications like guard, range, and observation towers or as stand alone structures such as sports video towers, rappelling platforms, or observation decks. Construction options include different custom stair designs, guard railings for both private and public access, lifting or swing gates, and more.
Superior Onsite Service
- With knowledgeable representatives across the country and nearly 50 years of experience in the industry, we’re available to make sure your installation goes smoothly. Our representatives have experience in both the public and private sector. In fact, Porta-King has been awarded a GSA Federal Supply Schedule Contract, which provides federal government customers with the fastest acquisition method available. Our regional offices throughout the United States provide product review, design assistance, and installation support on-site. The speed at which we can build and install a custom-designed solution for your business just can’t be beat.
A Commitment to Innovation
- We believe the key to our success has been our ability and willingness to adapt to new industry trends. Since our inception we have responded to our customers by introducing many “industry firsts” to address these developing trends in the modular and prefabricated construction industry. These trends include new products and modification to existing products, along with adaptations to address new building and energy code requirements. Our designs are modified frequently to accommodate changes to codes or other industry requirements and customized to fit seamlessly with any architectural design.
Our Process
Our process begins with communication. We ask each client probing questions to fully understand the project and develop an appropriate solution. Our detailed quote process ensures that you’ll know exactly what to expect. After receipt of your order,our production engineers then present a comprehensive set of approval drawings for your approval. Once approved, our Porta-King engineers will put together a complete system design and material list. This information serves as the instructions that our plant personnel will use to fabricate your structure.
- We use customer information to design structures that meet functional requirements, performance requirements, sound and thermal requirements, and durability and energy-efficiency standards. We will work with your team to address state and local codes and regulations to ensure your installation goes smoothly
- Manufacturing time varies by product but with the outstanding production capacity and our experienced staff you can be assured that the expediting of your order is always our top priority.
If you have questions, our representatives are on-hand to help. We also offer resources on our website. you will find downloadable construction drawings in both Auto CAD and PDF formats, CSI formatted specifications, product literature and other technical and sales related information. On-site follow-up from one of our regional representatives comes standard.