This is part 2 of a post about why you should use open web joists in your construction projects. See part 1 called Open web design is open to the future.
Previously on this subject, I talked about how open web joists like TRIFORCE® eliminate the need to drill holes to pass ducts and plumbing. Without a doubt, this is a big time waster on construction projects. It can lead to damaged joists and repairs. An open design means Plumbers, electricians and HVAC techs have more freedom and will install faster.
If you look to the future, there are more compelling reasons to switch to an open web design. Have a look at this graph.
Residential code pushing for better energy efficiency
In the graph from the Building Codes assistant project website, you can see how the IRC has systematically reduced energy use standards since the 1970s. Don’t let the graph fool you either. This downward trend will continue. newly built homes will have to be even more energy efficient. This means they will need to be tighter too.
Increasingly sophisticated ventilation systems
With tighter homes come increased concerns about Internal Air Quality (IAQ).
Past exhaust or supply ventilation systems had simple configurations that pushed air into the house or pulled it out. Many, many homes have been built with supply systems that include return air ducting. The return air ducting system is often not equivalent to the supply system as some loss is accounted for through natural leaks in the house. Of course, such systems are inadequate today. So, just as housing is moving towards lower energy consumption, the ventilation industry is moving towards balanced-air systems to provide safe, breathable air for occupants inside these tighter homes.
Open web joists ideal for balanced air and energy recovery ventilation systems
Balanced air systems require a lot of ducting. this is needed to keep the air pressure equivalent to outside air pressure while providing optimal levels of fresh air to each room. For example, here is where ducting starts out from
Imagine the number of holes needed in an I-joist floor system to accommodate this. It represents a considerable waste of time, knowing you can work with an open web joist.
The movement towards tighter houses and more sophisticated ventilation systems is just as sure as customers’ increasing demand for more energy efficient, healthier homes.
And what if demand for solar panels continues to develop? You don’t want to be caught in situations like this
Finally, will you stick with a joist technology that hinders your ability to answer these demands, or will you open up to the new possibilities?
If you have easy access to an adjustable joist with an open design, you should be using it.
I used the TriForce open-web floor joists and can attest to their simple installation and the ease of running services within the triangular webs. Saves huge amount of time. My one caveat would be the orientation that the truss is installed into the structure. The Barrette calculations will typically show the trim web being installed to the ‘outside’. In other words, the trimable portion would be placed against the exterior walls. However, I found (too late) that this is not the most desirable orientation. I would recommend placing the fixed side of the truss against the most consistent bearing point plane for that entire elevation of the dwelling. For many homes this would represent the exterior walls. This will ensure that the bays of the truss line up from one end of the elevation to the next. If the trimmed side of the truss is placed at the exterior wall, then the bays between differently trimmed trusses (to reach different distances to bearing walls on the interior of the home) will not line up and make running services a lot more difficult.
Hi Sean,
Thanks very much for your comment. You are absolutely right in saying that you have to choose the most consistent bearing point plane. We talk about it in a recent article called when you deviate from the drawings and the joist placement plan. We always recommend setting the block end on the straightest run so you can get the most out of the open web design. Thank you for reading us!
Eric