Hello, I am new to the forum, have done a few searches for "engineered joists", found some excellent topics, but not what I need now.
I am finishing the basement in the 3-year old house I just bought. I would like to attach the duct enclosure, made of a 2”x4” frame and ½” drywall, to the Engineered Floor Joists, which are on 16" centers. I have never had the Engineered Floor Joists (wood I-beams?), have read quite a bit about them, and want to make sure I don't degrade or damage them.
Is it OK to use 3” coarse drywall screws to fasten the enclosure top 2”x4s” to the engineered I-beams? The screws would penetrate the engineered I-beam bottom flange about 1-½”. (I suspect that it may not be OK, but I can’t come up with another easy way, so I thought I would ask.)
In the sketch below, the webs of the engineered joists actually are quite a bit thinner than depicted.
we always screw and nail to the bottom of these floor joists. I can't see that a few screws would downgrade the joists in any way. The inspectors have never said anything about nails or screws into them so I wouldn't worry about it. These floors are usually over engineered in the first place.
I received an email from the EWP Products Enginering Manager at Louisiana-Pacific, and he included eight (.pdf) pages of instructions for hanging methods from the I-Joists. The instructions are intended for hanging sprinkler systems, but it certainly gives the overall idea.
Sure enough, two of the methods consist of driving screws into the lower flange, as you suggested would be OK.