Caulk substitute idea...

Hey guys, I've learned alot from this forum, but this is my first time posting. I'm planning a home studio build on the lower level of my house. I had an idea, but I'm not sure if it would be effective or not. When using 2 layers of sheetrock, you're supposed to caulk all the seems on each layer, so that it's "airtight". Would it work to use duct tape on the first layer? Since it will be covered up by the second layer, it's ugliness wouldn't matter... Is there some reason why that wouldn't work?

no it wouldnt work the same. you need to use acoustic caulk as it never fully cures so moves with the building but keeps it air tight and is more dense. you should also use backer rod to stop cracking. joey

joey is right on with his reply. the adhesive on the tape does not remain as "gummy" as it is initially over time. If you've ever seen someone try to cover a broken window with ductape, you'll see that it can become brittle quickly over time. grab some GE Silicone II from your local hardware store. pour some in a spoon or shotglass and let it cure. then pull it out and bounce it off the ground. it's just like a superball. it remains elastic and will wrap around the edges of the backer rod and drywall. It fully wraps the seam with an airtight seal that will last over time. the fibers of a peice of tape will wither quickly with the seasonal changes.

Obviously caulking the seems of the first layer won't hurt. But you may also just mud the seems like you would do for the last layer without being too picky with the visual result. Also mud would fill the tapered edges of sheetrock where caulk won't creating an air gap between the two sheets and to top it all mud do cost less than caulk. You may do both... and please forget about tapes :wink: My2 cents

I think you want to caulk the perimeter of the sheetrocked wall(s). Joints still get mud and tape. But I like your thinking out of the box. Usually when I do that someone tries to stuff me back in it:) Looking forward to it,

orangenumerik wrote:

Obviously caulking the seems of the first layer won't hurt. But you may also just mud the seems like you would do for the last layer without being too picky with the visual result. Also mud would fill the tapered edges of sheetrock where caulk won't creating an air gap between the two sheets and to top it all mud do cost less than caulk. You may do both... and please forget about tapes :wink: My2 cents

Orange, You should tape and caulk all perimiter seams - even the one you tape and see. My recommendation for the joints in the field would be a single coat of tape on all tapered seams in the body of the wall - and a caulk joint at the non-tapered edges - all this with the exception of the finish layer - which has all seams finished to the level required for the final room finish (The room corners still to received tape and caulk prior to finishing with tape and compound). Although the tape might make a corner apppear sealed - it isn't even close - the tape itself ends up being your real seal - and not all that good of one at that. The joint compound your tape is setting against dries hard as a rock - allows no movement, it cracks and shrinks considerably when it cures during drying, and continues to crack over time. It is a great system for finishing drywall - but a lousy system for sealing air movement. This is one of the reasons that you will see products like the USG acoustic sealant that has been tested and certified to verify it is acceptable to apply a finish coat of tape and compound over it. And - if you check the USG construction manuals - you will also have verification that simply caulking the corners or base of walls - or the junctions of ceilings/walls - is one of the reasons for failing to attain the STC ratings in sound wall assemblies. Understand that the majority of sound walls tested in the field are as much as 20+ STC less than the walls were designed and tested for in the labs- and they were NOT tested (in the labs) with tape and compound seams to begin with - the seams are always caulked and taped to allow for quicker turn-around on testing. Another - seperate issue here - has to do with what you are attempting to do with these walls that steps outside of maintaining the standards of wall construction for STC purposes - and that is an increase in the LF TL values for these assemblies in the areas where they are the weakest by virtue of the facts of construction. The bottom line here is that there are very good reasons for caulking each joint at the wall perimiter - each layer - and I outline those reasons in my book. If you (strictly on a personal level) choose to save money - then by all means save it - but please don't present that substituting materials like joint compound and tape in leiu of backer rod and caulk as being acceptable alternatives which will result in the same end product - because it just isn't true. Sincerely, Rod

Wow, didn't expect to get this much action... Thanks for all the replies... Rod I got your book a couple weeks ago, it's been a huge source of education for me... Ok so obviously duct tape is out. Just to make sure I read you correctly: First layer - Caulk and tape Second layer - Caulk, mud, and tape. Is that correct?