WorkTheWood Posted January 19, 2012 Report Share Posted January 19, 2012 I am trying to figure out how to best soundproof the ceiling of my basement shop. Here is an idea I am considering (it's probably not an original idea - I imagine somebody else has done this). I'll try to explain this as good as I can. In each floor cavity, I am thinking about layering 1/2" drywall (sheetrock). On either side of the cavity, I would install some supports to hold the drywall. Think of these supports almost like they are shelf supports. Think of the drywall like it is the shelf. I have attached a very crude drawing. In each cavity I would:Leave a 1 inch air gap at the topInstall a "layer" of 1/2" drywallCaulk/tape all edges to prevent airflowLeave another 1 inch gapInstall a "layer" of 1/2" drywallCaulk/tape all edges to prevent airflow [*]Leave another 1 inch gap [*]Install a "layer" of 1/2" drywall [*]Caulk/tape all edges to prevent airflow And finally, I am going to install a drop ceiling below all of this. I am hoping the sealed air pockets, combined with 1.5 inches of total drywall, and then a drop ceiling will really help to reduce the noise. What are your thoughts on this idea? Overkill? I am open to any and all ideas! Quote Link to comment Share on other sites More sharing options...
Gary Posted January 19, 2012 Report Share Posted January 19, 2012 Hello! You may want to rethink this approach as these air gaps in the cavities could actually turn into resonators. It may make low frequency sound transmission even worse! Personally, I would put fiberglass bats in the joist cavities to stop the sound from bouncing around, then cover the ceiling with two layers of drywall to add mass. Offset the drywall seams and seal the first layer seams with caulk. You can even add a special adhesive between the layers, called Green Glue to further reduce sound transmission. You may want to check out AVS Forum for some soundproofing ideas. http://www.greengluecompany.com/ http://www.avsforum.com Auralex is an acoustic treatment manufacturer that also has some great ideas for reducing sound transmission on their website. http://www.acoustics101.com/ceilings.asp I've done some research in this area already as the wife has agreed to a dedicated theater room... after the master bathroom is finished, and the house has new siding, and I upgrade the electrical, and repaint the upstairs, and put an addition on the kitchen... and... I think my wife tricked me. Have fun! 1 Quote Link to comment Share on other sites More sharing options...
Onboard Posted January 19, 2012 Report Share Posted January 19, 2012 I have seen Roxul used in basement ceilings. Sometimes two layers. Quote Link to comment Share on other sites More sharing options...
Beechwood Chip Posted January 19, 2012 Report Share Posted January 19, 2012 You might get significant sound traveling through the joists themselves. You might want to decouple the drop ceiling from the joists somehow. 1 Quote Link to comment Share on other sites More sharing options...
WorkTheWood Posted January 19, 2012 Author Report Share Posted January 19, 2012 I have seen Roxul used in basement ceilings. Sometimes two layers. Just called local big box store - Roxul is a special order item. It costs $36.95 per bag for 16" width. Each bag contains 59.7 square feet. I would need 8-9 bags. Total cost would be in the 300-350 range. Might be a good option! Quote Link to comment Share on other sites More sharing options...
Onboard Posted January 19, 2012 Report Share Posted January 19, 2012 I don’t know how effective Roxul is for attenuating the noise from woodworking machines. It’s sold mostly for residential use to keep floor to floor noise down. Maybe someone can comment on Roxul from personal experience. I also don’t know if Roxul would attenuate the shop sounds as much as you want. It may even require two layers which would double the cost. Here’s a WTO link that Chet started on soundproofing his shop wall. I don’t know how much was discussed on ceiling sound proofing, but the principles are the same. I posted a few links on soundproofing that are good to read for learning about sound “proofing” walls. A lot of good comments were made, however Chet went a very different route than all of the recommendation which I think you’ll find interesting. Quote Link to comment Share on other sites More sharing options...
Jim DaddyO Posted January 20, 2012 Report Share Posted January 20, 2012 Do not leave an air gap between the layers of drywall. Green glue is too expensive. You need what is called a MSM system (Mass/spring/mass). Any wall/ceiling/floor acts as a drumhead and will transmit sound. The point of MSM is to make the natural harmonic frequency too low to hear (under 20 Hz). You are correct in adding the drywall to the underside of the floor, you now need a spring (hollow cavity filled with cellulose insulation works well) and then another mass, similar to what the floor is. The 2 masses cannot come into contact with each other in any way, or sound will travel through it. Try a bit of studying on this site: http://johnlsayers.com/Recmanual/index.htm Just click the test to the right for each subject. Quote Link to comment Share on other sites More sharing options...
Ted White Posted January 20, 2012 Report Share Posted January 20, 2012 Expense is in the wallet of the beholder. #1 I'd focus your efforts on the ceiling, not (under) the floor area. The goal is to prevent as much vibration as possible from entering the original framing. #2 Use the cheapest R19 fiberglass you can find. Data clearly shows it working as well as anything exotic. Insulation helps, but just a bit, so don't get carried away on insulation. We don't ever want to compact it. #3 Consider decoupling the ceiling drywall from the joists with competant resilient clips and channel. #4 Use double 5/8" drywall. The cheap $8 a sheet stuff. A field application of damping compound will add several STC points to this assembly #5 If you can, drop the ceiling height so that the ceiling drywall contacts the foundation. Seal it to the foundation. This puts a complete lid on the area and you can avoid treating the walls. I would avoid costly items that intuitively seem to add value but simply add cost. Pre-damped drywall, cotton insulation, Mass Loaded Vinyl. are classic examples. Quote Link to comment Share on other sites More sharing options...
areynoldsre Posted January 21, 2012 Report Share Posted January 21, 2012 I read this blog the other with lots of stuff on sound proofing a shop: The Art of Wood Shop Design Might be something in there for you. I've not done any of that as I opt to just annoy my neighbors and my wife with the table saw. Quote Link to comment Share on other sites More sharing options...
billt928 Posted March 9, 2012 Report Share Posted March 9, 2012 I have seen Roxul used in basement ceilings. Sometimes two layers. +1 for Roxul Safe & Sound line. I have used it and it works well.. I also used a product sold by Homedepot called db3 and SoundBreak drywall. I used all three together and I'm very happy with the results, my wife is even happier Quote Link to comment Share on other sites More sharing options...
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