I'm finishing my basement and need to build a soffit around the HVAC trunks, pipes, and a wood beam. I'm planning to build a ladder on one side of the ducts and another between the ducts and the beam.

I'm hoping that I can just screw the drywall into the beam to make one large soffit.

  • Why do you think that is an issue? Of greater concern is what other support structures you will attach the drywall to, especially as it goes around pipes and ducts.
    – bib
    Jul 13 '15 at 16:57
  • You don't know what you don't know, I guess. There will be 2x4 soffit style ladders on each side of the ducts. Jul 13 '15 at 17:01
  • I did not appreciate your reference to ladders. Sounds like the right approach.
    – bib
    Jul 13 '15 at 17:14

In general, there is no problem in screwing drywall (or most other materials or light weight fixtures) into any framing members. This includes 2X studs, beams, steel studs or other variants on these.

There are restrictions on notching and drilling large holes. Dimensional lumber is most forgiving of these modifications, but manufactured beams have especially strict rules about what size and shape holes can be punched through them, and also restrict where they can be put.

Screws, especially thin drywall screws, present no such compromise. If there is some reason why you don't want to screw into the beam, you could use construction glue, but this is much harder to remove if there is some need to change or repair the area.

  • 2
    Expanding just a tiny bit on what you alluded to with dimensional lumber vs prefab joists and trusses; if you cut into the top or bottom plate of a prefab joist/beam/truss (an I beam) at all, you have compromised the integrity of the part. You generally have a lot of flexibility for cutting holes in the centers of prefab beams/joists, so long as you don't exceed the specifications from the manufacturer. In any beam, almost all of the load is carried in the top and bottom of the beam, with virtually no load in the dead center. That's why an I beam can be so strong with so little material. Jul 13 '15 at 19:59
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    @Craig And some laminated beams have strict requirements that there can be no significant holes drilled except in the middle third of the beam, both laterally and horizontally, and even then there are specific size limits and positionings on the holes.
    – bib
    Jul 13 '15 at 20:29

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