Builders want strength, stability, and flexibility on the jobsite. Boiled down, you need a floor system that’s dependable, and frankly, there are a number of myths out there about whether you get those benefits and more from I-joists like BCI® and AJS® joists. 

To cut through the noise, sit down and hear directly from the pros. Dan Cheney, Director of Engineering, digs into how big holes can be in the web, where to cut the holes, and more. Watch the video or read the Q&A to learn more.

Q&A Session — How to cut holes in I-Joists:

Greg Wells, Wood Products Director of Marketing: Dan, thanks for spending time with us. I know your team gets a lot of questions on I-Joists and cutting holes. Can you talk a little bit about that? What makes it so special If you’re running ductwork? 

Dan Cheney, Wood Products Director of Engineering: Great question, Greg. With I-joists in particular, you have the ability to cut holes up to 22″ in length, out towards the middle of the member because of the OSB web that is friction fit in between the two high strength LVL flanges that allows for HVAC, ductwork and electrical to be run, perpendicular to the framing. 

GW: So along those lines, what does that really mean for the builder? I mean, a 22″ hole, that’s pretty big. Can you tell us what a typical HVAC size is?  

DC: Usually, the larger trunk sizes that are used in residential construction are up to 18″ wide. And so that 22-inch length allows for that maximum trunk size of 18″ to be run straight through the product itself. 

GW: So, if I can summarize, a larger hole makes it easy and gives builders more flexibility in the process. Switching gears, when you’re talking about I-Joists, what do builders actually gain from the ability to cut these holes? 

DC: Yeah, there are three main thing builders gain, Greg. Design flexibility is probably the largest perk. With some pre-planning you can run your duct work in, essentially, a straight line. This gives the advantage of fewer fittings and higher efficiency of the system. 

The second perk is labor efficiency. You have less rerouting around the structural members in the floor system, which is huge. And then lastly, builders just get a tighter floor profile. This means no drop ceilings or bulkheads to hide that ductwork. Everything is within the floor cavity itself. 

GW: What about cutting holes after the home has been framed?  

DC: Each joist comes with allowable zones for where holes can be cut more efficiently. Basically, towards the middle, lower shear zones, you can cut larger holes. Then, as you get to the edges or the ends of the joist, the holes need to be smaller. 

GW: Most of the time, is it fairly standard? Meaning, it’s pretty easy for the framers to cut holes in the correct location once they get used to it and understand what they can do and what they can’t do?  

DC: That’s exactly correct. We also have easy-to-reference hole charts that we send along with the product. These are perfect for those cases when HVAC, plumbing, or electrical trades have questions. They can use the easy lookup tables right there on site and make sure that they’re installing those holes in the right locations. 

GW: Oh that’s fantastic. So, what happens if they cut a hole in the wrong location?  

DC: If they do, we have a team of engineers located across the U.S. that can help. Specifically, they are very good at instances where builders and trades find themselves outside the normal design parameters developed for the product.  

GW: Are there any items that builders or framers need to make sure they don’t do? 

DC: There are. There are three big items. First, don’t cut the flanges. Those are carrying most of the bending capacity for the product. Secondly, avoid cutting too close to the ends because those are higher shear zones, and web material is carrying more of the loading. And then third, always refer to our proprietary software and or literature, for that information. 

GW: Dan, thanks a lot. Your insight was very helpful. We have additional resources on our website: https://www.bc.com/resources/.