An Engineered Open-Web Floor System for Modern Construction
TrimJoist® is an engineered open-web floor joist system designed to meet the structural, mechanical, and construction demands of modern residential and light-commercial buildings. Unlike traditional dimensional lumber or solid I-joists, TrimJoist is purpose-built to deliver long spans, design flexibility, and jobsite efficiency—without sacrificing strength or reliability.
What is TrimJoist?
At its core, TrimJoist is a pre-engineered floor system made up of solid wood top and bottom chords connected by steel or wood web members. This open-web configuration creates a rigid structural frame while leaving clear pathways between the chords. The result is a floor system that performs like a truss but installs with the simplicity builders expect from conventional joists.
TrimJoist is manufactured to precise specifications, ensuring consistent quality, predictable performance, and compatibility with today’s evolving building designs—from vaulted ceilings and wide-open floor plans to heavier loads and complex layouts.
How TrimJoist Works
TrimJoist carries floor loads through its top and bottom chords, while the internal web system distributes forces efficiently along the span. Because the joist is engineered as a system rather than a solid mass of material, it can achieve longer spans with less material and reduced deflection.
The open-web design also allows mechanical, electrical, and plumbing trades to run ductwork, piping, and wiring directly through the joist cavity. This eliminates excessive drilling, notching, and soffits, helping projects move faster and remain structurally sound.
Key Features
Open-web design that accommodates HVAC, plumbing, electrical, and fire-suppression systems
Long-span capability ideal for open floor plans and fewer load-bearing walls
Trimmable ends that allow flexibility in the field without compromising performance
Engineered consistency for predictable strength and reduced callbacks
Lightweight components that are easier to handle and install
Made in the USA, supporting domestic manufacturing and supply-chain reliability
Benefits for the Jobsite and Beyond
For builders and framers, TrimJoist simplifies installation and reduces labor time by minimizing workarounds for mechanical routing. For architects and designers, it enables cleaner ceiling lines, greater freedom in layout, and fewer design constraints. For engineers, it offers dependable performance data and clarity during the design and review process.
Ultimately, TrimJoist helps projects move from design to completion more efficiently—delivering floors that are strong, adaptable, and ready for the realities of modern construction. It’s a system designed not just to hold buildings up, but to make the entire building process work better.
The Design Process
The design process behind TrimJoist is rooted in a balance of structural engineering, constructability, and real-world jobsite feedback. From the outset, the system was developed to solve a common challenge in modern construction: how to deliver long spans, reliable performance, and mechanical flexibility without adding complexity or inefficiency to the build.
Engineering the System
Every TrimJoist begins as an engineered assembly rather than a commodity framing component. Designers start by evaluating anticipated loads, span requirements, and spacing scenarios common in residential and light-commercial construction. The top and bottom chords are sized and specified to carry vertical and lateral loads efficiently, while the internal web configuration is engineered to distribute forces evenly across the span.
This approach allows the joist to perform predictably under real-world conditions—reducing deflection, improving floor stiffness, and supporting today’s open layouts and heavier design loads.
Designing for Flexibility
One of the defining goals in the design phase is adaptability. TrimJoist was engineered with trimmable ends to allow field adjustments without compromising structural integrity—an intentional departure from systems that require exact factory lengths or redesigns when dimensions change. This feature reflects a design philosophy centered on how buildings are actually constructed, not just how they are drawn.
The open-web layout is also deliberate. By leaving space between web members, the system is designed to accommodate HVAC, plumbing, electrical, and fire-protection systems without drilling or notching. This coordination reduces conflicts between trades and preserves the structural intent established during engineering.
Manufacturing with Precision
Once engineered, TrimJoist components are manufactured under controlled conditions to ensure consistency and quality. Each joist is produced to tight tolerances so that what is specified during design is what arrives on the jobsite. This precision supports faster installation, predictable performance, and fewer field corrections.
Quality control is embedded throughout the process, from material selection to final assembly. Because the system is manufactured in the United States, oversight and responsiveness remain closely tied to both engineering standards and market needs.
A Design Process Shaped by the Jobsite
What ultimately distinguishes TrimJoist’s design process is its feedback loop. Lessons learned from builders, framers, engineers, and designers inform ongoing refinements—whether that’s improving installation efficiency, enhancing compatibility with mechanical systems, or simplifying coordination during early design phases.
The result is a floor system that isn’t just engineered to meet code, but designed to work seamlessly from concept through construction—supporting better floors, smoother builds, and more flexible design outcomes.
Sustainability
The TrimJoist Analyzer™ helps demonstrate TrimJoist’s BIM-ready approach by supporting informed structural decisions early in the design process. By allowing designers to evaluate spans, loads, and spacing before a full model is developed, the Analyzer establishes the structural framework that BIM coordination depends on.
This early validation supports smoother multi-trade coordination—particularly for mechanical systems—reducing redesign, minimizing clashes, and creating more predictable BIM workflows. Rather than replacing BIM software, TrimJoist Analyzer brings BIM thinking upstream, helping teams move into coordinated modeling with greater confidence and efficiency.
Notes
TrimJoist is proudly 100% Built in America, reflecting a commitment to domestic engineering, manufacturing, and quality control. Designed and engineered by U.S.-based teams, the system aligns with North American building codes, construction practices, and real-world jobsite demands.
All TrimJoist components are manufactured in American facilities, allowing for tighter oversight, consistent quality, and reliable lead times. This domestic production model supports American jobs while reducing exposure to global supply-chain disruptions.
Built in America isn’t just a label—it’s a practical advantage. It ensures TrimJoist is designed, produced, and refined specifically for the needs of American construction, delivering dependable performance and peace of mind from specification through installation.
Rooted in three generations of joist manufacturing, Trimjoist carries forward a family legacy of innovation in the building materials industry.
What began with one generation’s pioneering work in truss manufacturing evolved when the next generation invented the TrimJoist® system, an open-web, field-trimmable floor joist that redefined construction flexibility. Today, the third generation continues that legacy, expanding Trimjoist’s operations westward while upholding its commitment to USA-based manufacturing. With production facilities in Mississippi and Idaho, Trimjoist manufactures every joist in the United States using domestically sourced lumber and components.
