Open Web Joists
One technology that we’ll need to support the second floor is a “joist.” The job of a joist is to support a load - in my case, most likely a concrete floor.One of the “problems” with joists is that they reduce your ceiling height and can be a barrier for mechanicals (electrical, plumbing, etc.) Here’s a traditional LVL joist:
As you can see, one would need to drill through the joist for PVC pipe and other stuff.
An alternative to the LVL is the “open web” joist. Open web joists allow the passage of mechanicals and are pre-engineered for construction (no trimming on site). However, their light weight and open design are idea, especially if I’m going to run dust collection pipe.
A third option is a hybrid “open joist” design uses wood (not metal) to form the web. They are more attractive and can be trimmed on the job site. One concern about this technology, however, is the thickness of the joist required to support a load. Most joists are nearly 12″ thick. Add to this the thickness of the floor and you eat up a lot of valuable headroom
Here’s an example of this product:
Here’s a chart that demonstrates the relationship between joist height and load. One thing to consider - the smaller the joist, the more are required to carry a load AND the smaller the opening. Here’s a brochure that shows the various joists and spacing between the webs. I’ll need at LEAST a 6″ opening for the dust collection pipe.