Skip to content
open web floor joist
11 min read

How Open-Web Floor Trusses Deliver on Value & Performance

While there's no one way to build a floor, there are some that are better than others.

For those exploring prefabricated building components as an option for their project – be it a home, commercial, or even light industrial building – manufactured trusses provide a range of advantages that make them an attractive solution. 

But among the many truss options available, open-web floor trusses offer a unique blend of value and performance that can't be matched.

Integrated into your project, open-web floor trusses provide a strong & cost-effective option through value engineering.

Breaking Down Open-Web Floor Trusses

A misnomer of sorts, open-web floor trusses are not actually trusses, but rather a type of joist.

While trusses are traditionally what supports a structure's roof, this building component fills the role of a joist as it can support a floor without alteration.

The pre-manufactured truss consists of two or more parallel members connected by a web of small, triangular pieces to create an open framework. The open design allows for better
airflow and easy access to certain areas of the structure (more on this later).

6 Benefits of Open-Web Floor Joists for Your Project

Representing how modern design and engineering can create a superior product that delivers on multiple fronts, open-web floor trusses bring a variety of benefits to a project:

  1. Utility installation
  2. Insulation
  3. Lightweight
  4. Strength
  5. Longer spans
  6. Fire rating

1. Utility Installation

Being open by design, this type of floor truss features easy access to the spaces between its webbing (the triangles between its chords). 

You'll have no problem installing wiring, plumbing, or other utilities through the truss without having to cut through it or make other alterations. This isn't always possible with other styles of floor joists, as installing hidden utility lines usually requires drilling through the structural component's lumber.

With the ability to essentially contain utilities within the joist, you can drywall up to the joist without needing a dropped ceiling to cover mechanicals that would otherwise hang below typical joists made from dimensional lumber.

2. Insulation

The same principle as the last point applies here as well.

With its open design, it's much easier to install insulation and cover the flooring trusses, boosting a structure's energy efficiency and soundproofing.

3. Lightweight

Compared to other types of joists, open-web floor joists are typically lighter in weight.

Requiring fewer materials, this pre-engineered wooden floor truss is designed to have the same level of strength as other types of joists or those made of other materials, such as steel.

For framers and builders, a lightweight floor truss makes a job a lot easier – not only is there literally less heavy lifting, but moving and installation require fewer hands.

4. Strength

Unlike some other types of joists, open-web floor trusses harness the power of physics to create a structural component that can shoulder a heavier load.

Again, it comes down to design. 

With its webbing comprising multiple small, triangular pieces that create an open framework, weight is distributed evenly across the truss.

Ultimately, the truss is able to do the same amount of work as those with more complex designs or joists made from stronger, heavier materials.

5. Longer Spans

Bringing together our last two benefits, open-web floor trusses can handle meeting longer spans than other types of joists.


You guessed it – design.

With an optimal strength-to-weight ratio, the truss is able to carry a heavy load over a longer distance without requiring additional structural support. This makes them ideal for large spaces like auditoriums, gymnasiums, and warehouses, where long spans are often required.

6. Fire Rating

This one isn't so much about the building component as it is about what it does for a building.

In certain aspects, open-web floor joists simplify protecting a building from fire. 

While open-web joists are lightweight and the nature of the open webbing makes it easier to install mechanicals and wiring, one of the drawbacks is that they lack the fire-rating protection offered by dimensional lumber. 

Builders working with open-web joists definitely need to know the building code and how to obtain the proper fire protection. In many cases, code may require the ceiling created by an open-web joist to be drywalled. In a basement for example, this may not be a desired feature, or expense. 

To offer the best of both worlds, North American Truss offers open-web joists by Trifocre Truss. Through their proprietary system, Triforce Truss’ open-web joists meet fire codes without needing to encapsulate the support system, thus eliminating the need to drywall or figure out alternate means to meet safety standards. 

In short, open-web floor joists take some of the hard work out of making sure a building is protected from fire.

In Brief: Open-Web Floor Trusses Vs. I Joists

When considering open-web floor trusses for a project, they're often compared to another popular instructional option – the I joist.

An engineered structural support, I joists consist of a vertical web made from oriented strand board (OSB) or plywood, and top and bottom flanges made from either laminated veneer lumber (LVL) or solid-sawn lumber.

While I joists do offer their own benefits, such as being able to span larger distances than traditional lumber, they also come with some downsides. I joists:

  • Often come at a higher price point than open-web floor trusses due to the additional materials and labor involved in their production and installation. This can be especially true when working with large spans or custom sizes.
  • Tend to be heavier than open-web floor trusses. This can make them more difficult and time-consuming to lift and install, which in turn can increase labor costs further.
  • Require additional support structures like beams or posts in order to carry heavier loads over large distances, which can add even more time and money on top of that many projects aren't prepared for.
  • Make it impossible to install utility lines between them without cutting through or altering the component, which opens doors to compromising the joist's integrity.

Open-Web Floor Trusses for Maximized Value

Open-web floor trusses offer a unique blend of value and performance that can't be matched by other types of joists or building components. 

With everything they bring to the table, open-web floor trusses are an ideal prefab building component that maximizes the value of any project.

Start Your Open-Web Floor Truss Order

Contact us today to discuss your project:

NAT Contact