View Full Version : Soffit for basement ductwork

02-11-2013, 08:10 PM
I've read about ductwork framing but couldn't find answer for the question - is it possible to use i-joist as part of frame instead of making the frame from scratch from lumber? it would save me a lot time and work.

02-12-2013, 03:46 PM
Anyone? Is it such a bad idea to use 2 1/2" x 11 7/8" instead of hand made frame?

02-13-2013, 06:41 AM
Personally, I would make it out of metal studs. They cut and screw together a lot faster and easier than wood. But the "I-joist" would work.

02-13-2013, 07:58 AM
I built my soffits very similar to the way those I-beams are constructed - two 2x2s screwed into a strip of OSB. So they should work. Are all your soffit heights shallow enough that the I-beams will work? My soffits ranged in height, from 7" to almost a foot or so, depending on what I was covering.

I also found that the bottom of my floor joists weren't exactly level going across. So I cut the OSB an inch or so long, screwed the top 2x2 onto the OSB, temporarily screwed it to the bottom of the floor joists, then snapped a level line across the bottom of the OSB at the finished height. Then I pulled it down, cut on the chalk line, screwed the bottom 2x2 on, and did the final install. I'm not sure how much leeway you'll have with the I-beams for adjusting to level unless you shim some of the floor joists when you attach the beam.

02-14-2013, 07:11 AM
You CANNOT "adjust an I-beam" for level, because it does not "bend". You fasten it at one location and then level it from there, using shims if necessary. With metal studs you can fasten them to the ductwork and be flush with the bottom of the duct which would give more space in the room.

02-14-2013, 07:26 AM
Thank you for your inputs. As novice I thought that maybe this idea is too crazy:D but for me I-beam is time and space saver (where every cm counts), and I know that I'll need shims, but it will be for example 2d and 5th beam, not all row going to one direction.