I have room that is 11 feet wide. It has a ceiling but there is no insulation and no way to access the ceiling for insulation. I intend to screw a 2x4 ledger to one side of the wall and use Simpson Strong-Tie Joist Hangers and 2x4 to span the 11' feet with 2x4 at 16" width. Then add R-15 insulation and 1/2 drywall that is 1" under the existing ceiling.

Is this okay and safe, or do I need to upgrade to 2x6?

  • 1
    Why not just take the ceiling that is there now down and place the insulation?
    – crip659
    Jan 4, 2023 at 20:08
  • 2
    Noise can be coupled through wooden members. There are ceiling systems explicitly designed for sound isolation, which use both mass and elasticity/springs to decouple the surface; more expensive but s better bet.
    – keshlam
    Jan 4, 2023 at 20:44
  • 2
    Don't say what type of sound you have or if you own the upstairs. Sometimes just carpet on hard type floors will do wonders.
    – crip659
    Jan 4, 2023 at 22:26
  • amazing thank you all. The old ceiling is 100 years old shiplap its almost structural so I dont want to remove it. I also want to add some LED can lights as well as the insulation for Temp and sound. I will look into local regs but was hoping 2x6 would be a good back up is 2x4 was to weak. Thank you all
    – Clay S
    Jan 6, 2023 at 5:26

2 Answers 2


You can do that, though it sounds like overkill for an internal ceiling (i.e., that much insulation is normally to keep hot in/cold out or vice versa, not for sound).

You might do almost as well with a drop ceiling - thin metal frame and ceiling tiles. The air gap will not be as effective for thermal insulation but may help for sound.

Whatever you do, if there are any lights (or other electrical stuff, but most common in ceilings is light fixtures) that they need to be moved and/or remain accessible. You can't cover a junction box and route a wire from it to a box in the new ceiling because now the old box will be inaccessible.

  • 1
    No, you can't do that. 2x4 will not span 11 feet loaded with drywall and stay flat to modern standards. Good secondary advice, though.
    – isherwood
    Jan 5, 2023 at 14:58

2x4s will not span 11 feet and stay flat under the weight of drywall. You need to either size up (and 2x6 may still not be enough--consult load tables or your inspection office), or suspend at a midpoint. Chances are there's an easy way to do that. Just be sure that your existing ceiling is up to the task of carrying itself and a new ceiling.

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