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  • another way to drop/level a ceiling?

    please refer to the drawing
    Trying to level a ceiling whose supporting wall have sagged 3 inches at one end. (actually it is 26 feed wide apartment with a center hall way that has sagged.) Architect wants to put resilient strips and 2 layers of 1/2inch type X drywall for fire and sound. Any objections to suspending 2x3 or 2x4 under each existing joist by 3 plywood panels? one at each end and one in the center. Most spans are 11 feet. Some may be 14 feet.
    The joists are on 24 inch centers.

    I previously posted a question to try to use standard metal drop ceilings but no company will vouch for their sound performance. The only thing that Canada NBC has is standard wood joists with resilient channels plus drywall layers. So trying to stay as close to that as possible by using 2x4s I could sister them but would need 2x6 and also remove all the existing furring strip, meaning insulation may fall too..

    thanks.
    Attached Files
    Last edited by EFZauner; 10-26-2020, 04:19 PM.
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  • #2

    Re: another way to drop/level a ceiling?

    Hope things work out for you.
    Noel

    "Being so impressed with the beauty of nature, I never cease to be amazed at how the
    'touch of the human hand' can transform it into another kind of beauty that is so uniquely human.
    "

    John Snow, Outdoorsman and Retired Teacher

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    • #3

      Re: another way to drop/level a ceiling?

      If you have the headroom to do so, you would be better off to hang the new ceiling joist, by supporting them at each end on the wall. The plywood between the floor joist and the new ceiling transfers sound between the two. If your inspector is okay with what you are proposing then fine, it will work and be a huge improvement over the existing system.

      If the inspector has concerns, I would suggest one or more of the following. 1) Hang the ceiling on metal connectors, they will be less likely to transfer sound. 2) Use two layers of 5/8 fireguard. The added weight helps with sound transference. 3) Fill the cavity created, including the space between the floor joists and the ceiling, with Roxul insulation.

      Should be doable one way or the other.

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      • #4

        Re: another way to drop/level a ceiling?

        Using Greenglue between the layers of drywall will make a noticeable improvement as well. I agree with Ron, don't hang the new ceiling structure from the old joists.

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        • #5

          Re: another way to drop/level a ceiling?

          Originally posted by Inspector Ron View Post
          If you have the headroom to do so, you would be better off to hang the new ceiling joist, by supporting them at each end on the wall. The plywood between the floor joist and the new ceiling transfers sound between the two. If your inspector is okay with what you are proposing then fine, it will work and be a huge improvement over the existing system.

          If the inspector has concerns, I would suggest one or more of the following. 1) Hang the ceiling on metal connectors, they will be less likely to transfer sound. 2) Use two layers of 5/8 fireguard. The added weight helps with sound transference. 3) Fill the cavity created, including the space between the floor joists and the ceiling, with Roxul insulation.

          Should be doable one way or the other.
          Thanks but supporting them on the wall (at least at one end) is not possible. The wall studs are not secured well and I do not plan on taking them down. I will consider this however. Metal connectors, well now you are moving away from a standard wood joist ceiling. There was a metal grid ceiling before and I wanted to replace it with the same but not possible to sound rate this as there is no such structure in the canada building code. As for 1/2 vs 5/8, the building code STC rating is not much different. I agree with your ideas and I am able to come up with them also but the key is if it is an approved NBC structure..

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          • #6

            Re: another way to drop/level a ceiling?

            Just thinking, with 3" of sag, aren't there more serious structural issues at play that should be addressed?
            stotto likes this.

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            • #7

              Re: another way to drop/level a ceiling?

              Originally posted by drzaius View Post
              Just thinking, with 3" of sag, aren't there more serious structural issues at play that should be addressed?
              yep they have been.

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              • #8

                Re: another way to drop/level a ceiling?

                I would not attempt to attach anything to the existing floor joists.
                I think your best bet is to frame a new ceiling attached to the side walls of the hallway.

                How wide is the hallway?

                Nathan

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                • #9

                  Re: another way to drop/level a ceiling?

                  Originally posted by nnieman View Post
                  I would not attempt to attach anything to the existing floor joists.
                  I think your best bet is to frame a new ceiling attached to the side walls of the hallway.

                  How wide is the hallway?

                  Nathan
                  sound good but it wont pass code. There is no structure in the approved list of canada NBC for this that meets 50db STC. That is the big issue.
                  not just hallway 1400sqft of ceiling

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                  • #10

                    Re: another way to drop/level a ceiling?

                    The building undoubtably does not, and will not, comply with the current building code. It may have when it was constructed but codes change. A good inspector will recognize that you are making the fire and sound separation significantly better than what was existing.
                    There are options to calculate the fire resistance of the floor, in addition to the systems listed in the building code. The individual materials can be assigned a value and added together to achieve the 1 hour rating. The fire resistance rating (the most important issue) is not hard to determine. The sound rating is more difficult.
                    However, if it was proposed to me that you were going to hang a separate ceiling (attached to the joists or hung on the walls) I would consider it to be at least as good as using resilient channel for two reasons. The channel is also attached to the joists so there is a connection and the channel is likely only 1/2 inch deep, while the suspended 2x4 ceiling provides greater separation.
                    A side issue is that perception of sound can be somewhat subjective. Even with a system that provides the 50 STC may not be enough to stop noise complaints between occupants.
                    You need to have a conversation with the inspector and present the alternatives. --Ron
                    nnieman likes this.

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                    • #11

                      Re: another way to drop/level a ceiling?

                      Another option might be to add the resilient strips and 2 layers of 1/2inch type X drywall to the joists.
                      Then add a drop ceiling for cosmetics.

                      Nathan

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                      • #12

                        Re: another way to drop/level a ceiling?

                        You can buy a ceiling track for hanging drywall. It looks like the track for suspended ceiling but heavier built. Have used it in doing basement ceilings. I suggest finding a business that caters to the commercial market. I deal with FBM in London. Their main business is commercial and suspended drywall.

                        Brian
                        If your dreams don't scare you, you are not dreaming big enough

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                        • #13

                          Re: another way to drop/level a ceiling?

                          Originally posted by Brian @ Muir View Post
                          You can buy a ceiling track for hanging drywall. It looks like the track for suspended ceiling but heavier built. Have used it in doing basement ceilings. I suggest finding a business that caters to the commercial market. I deal with FBM in London. Their main business is commercial and suspended drywall.

                          Brian
                          Thanks.. I know about these. But they are not included in the NBC of ceilings that meet 50db STC rating.


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                          • #14

                            Re: another way to drop/level a ceiling?

                            Can you cut off some section of drywall off the walls, hook wood to the studs horizontal across level and under the joists, and do all your sound proofing with an air gap between the insulation above. You might even want to put something up like fabric or vapour barrier to hold the insulation in there good. Hope you find some answers! You might want to investigate why there is a big sag and ensure you don't end up sagging further to damage your work....
                            Good luck!

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                            • #15

                              Re: another way to drop/level a ceiling?

                              Originally posted by EFZauner View Post
                              I previously posted a question to try to use standard metal drop ceilings but no company will vouch for their sound performance.
                              On the contrary all companies publish STC ratings for assemblies using their products. For example the attached brochure is published by CGC and it shows the tested STC ratings of various assemblies using CGC products (page 24 for ceilings). In my working days I used to have a nice little field handbook with the various fire and sound ratings for CGC products. Owens Corning, Georgia pacific etc all publish similar information.

                              Personally I would use drywall grid. It's fast, light, brain dead easy to install, stays tight to the ceiling, dead flat and you get a better STC rating in less space than wood framing. https://www.armstrongceilings.com/co...m=drywall+grid
                              Attached Files

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