Est. 1998 — 27 years of woodworking knowledge
Soffit Construction Question
J. Robison
>I'm building a soffit to enclose some ductwork in the basement. Basically 2 short stud walls on the sides. I'm starting to finish about 2/3 of the basement.....my first major project involving framing.......so I'm not a pro.
In order to preserve every possible inch of headroom in an already short ceiling, can I use 1x4s across the bottom of the ducts as opposed to 2x2s or 2x4s?? Will it be enough structure for drywall?
Re: Soffit Construction Question
Grant Smith(remove 1 for email)
>Depends on the amount of distance they must span. I'd say that given a 16" on center spacing, I'd be comfortable with them spanning about 2.5' of length or so.
If you need a greater span, you might consider drywalling the bottom with high strength drywall in addition.
Further, make sure your local code allows the floor to ceiling headroom that you have before building.
You might also have a look at your ducts to see if they can be raised a bit. Sometimes they are hanging on straps and aren't up against the joists.
FWIW,
Grant in iowa<---built a few soffits himself, but not a pro.
Re: Soffit Construction Question
Bart Goldberg
>I enclosed the duct work in my basement shop with soffits. I used 2" steel framing - very easy to use and worked out great.
Good Luck
Bart
Re: Soffit Construction Question
Barry Irby
>I think Grant asked the pertinent question. How wide is the span?. Remember that trusses are commonly spaced two feet OC and half inch drywall is routinely installed on them. So if your ducts are less than two feet wide, you might be able to install a frame on each side and just run drywall across the bottom without any framing.
Also look at the idea of raising the ducts if an inch or two is critical to you.
When I did this as a builder we usually made "ladders" out of 2 x2's and nailed them to the framing of the ceiling. Then you can add the cross pieces under the duct. I am suggesting you may be able to omit them if the span is not too wide. Carefully support the ladders in the correct position until you fasten the drywall. Use glue and screws to avoid pounding it out of position as you drive nails.
You can make the ladders out of 1 x 2's if you apply a little woodworking skill to making the joints strong.
Be careful not end up driving nails or screws into the ducts. Assuming the ducts are metal, don't crowd them too much and allow them to touch the framing above or the boxing or soffit. It may make them noisy.
Clarification on the original post
J. Robison
>The ducts run perpendicular to the joists with the steel I-beam on one side and a gas line on the other side of the ducts. Total width of the span is about 5'.
They are up tight to the joists.
Re: Clarification on the original post
Barry Irby
>You could still omit the framing across the bttom of the ducts if you can Pad the beam down to the correct height and use a second "Ladder" down the middle to support the drywall. Still might be wise to use fire rated drywall, because it is fiberglass reinforced and stiffer than regular stuff. And leave an air space under the ducts to avoid contact and resonance. If you diceid to build the ladders it might be easier to build three and skip paddign the beam. Attaching to a steel beam can be a problem.
If you don't want to build the laders you might look at Truss Joists or "TJI's". Those are the wooden "I" beam joists. You might luck into some that are jsut the right height for what you want and sue them in place fo the ladders. You might even be able to find soem that are slightly damaged and get them cheap.
Re: Soffit Construction Question
Hal Smith
>I'm posting this just for fun and to be a smart a.. What you're building is a plenum. The bottom surface of the plenum will be its soffit. In architectural terms, a soffit is the bottom surface of any construction feature. Please, no smart a.. replies. Hal