In residential construction in North America, wood has long been a material of choice: abundant, readily available, flexible, and easily repairable, it is less expensive than steel and concrete, and is naturally an overwhelmingly popular material.
For some 40 years now, engineers and builders have had the choice between using traditional lumber or engineered wood for their construction. Now, in new residential buildings, more often than not, a combination of both is being used.
When it comes to floor systems, conventional wood has enjoyed a long tradition of use, created by a universal familiarity with the product as well as the amount of experienced, highly qualified workers using it.
Engineered wood floor systems
Nowadays however, engineered wood floor systems are undergoing rapid market growth due to their many advantages over traditional wood. Engineered wood is more sustainable, using less trees and costs less to use per square foot. It weighs less and is easier to handle, saving time and money on construction sites. It is also stronger and more rigid in its support. Also, depending on the product being used, it can be easily adjusted on site, whether because of a deviation from the original plan or an adjustment to a non-conformity.
Types of joists
Basically two kinds of joists that are currently used in floor systems:
- The I-Joists, has OSB paneling as its central structure, framed by top and bottom chords
- Open web trusses have wood webbing held together by metal plates.
I-joists have major advantages in high-volume construction with standard layouts. This is because they are less expensive. Also, their length is adjusted onsite, without an engineer’s approval. However, they can’t attain the spans of open web trusses. They are somewhat complex to run Mechanical, Engineering, and Plumbing through. This is due to the properties of the OSB paneling. There are some pre-defined hole locations but they are very small, and any additional holes to be made must follow strict guidelines so as not to compromise support.
Open web trusses
Open web trusses, on the other hand, have the advantage in more complex and more rugged construction. Their spans can be much longer than I-Joists. Open web design can accommodate almost any kind of HVAC, Electrical, and Plumbing configuration while allowing greater flexibility during installation. This is a time and money-saving characteristic.
They have specific lengths. You can’t trim them. This is their main disadvantage when on site. To adjust the open-web trusses’ length requires an engineer’s approval. Otherwise, it needs to be replaced. Either way, it requires and engineer’s seal. In both cases, this causes project delays. This is added to the open web truss’s already higher cost.
One more thing: the Metal connector plates used in this type of engineered wood joist are sharp. They can damage electrical wiring during installed. Pull the plate hard enough and some of its teeth can come out of the wood. This could compromise structural integrity. Also, trusses exposed to rain prior to the closing of the structure can rust. Sealants are available to coat the plates and make them waterproof. They require on site application.
A hybrid type
So, there are advantages and disadvantages to open-web trusses and I-joists but there is also a 3rd hybrid type of joist that is gaining in popularity, which effectively combines the advantages of both.
Open Joist Triforce® joists have an open web design, but without using metal plates as connectors for the webbing. It uses waterproof heat rated glue instead. You can also adjust these posts on site. They don’t require an engineer’s approval when trimmed, like the I-joist. You can install the Open Joist Triforce® the other way around if needed. Even though the Open joist Triforce® cannot attain the length of the open web truss, typically they can outspan I-Joists. They do this while retaining impeccable rigidity: up to 30 feet with up to 16’’ depth. This makes it quite suitable in almost any residential, multi-family, hotel/motel, light commercial and even light industrial construction.
Open joist Triforce® a compelling engineered wood floor alternative
Triforce® costs less than open web trusses yet is as strong and as rigid. It has the added benefit of being adjustable onsite. The open-joist Triforce® is a compelling alternative in engineered wood floor systems, well worth investigating.