I received a call on Monday from my friend who gave me a hand with the drywall strips last weekend saying that he had Thursday available to help me. I didn't waste a moment of time and filed a request to take the day off. We ended up working from about 8:30AM until 6:30PM yesterday, stopping only for a combined lunch drive-through / supply replenishment trip as I had run out of caulking. I couldn't believe how much caulking is needed to complete this part of the project and I severely underestimated how much caulking was needed. But I guess in retrospect, even if I had a nice, tight 1/8" or less gap I am still filling that 1/8" gap to a 5/8" depth....twice.
Just so everyone knows the process I used, I did no caulking during the installation of the first layer. Instead, I waited until the fit of the second layer was confirmed before caulking the first layer. Then, while the first layer was still wet, I installed the second layer with the Green Glue then caulked this second layer immediately. I did a fairly meticulous job of caulking the first layer, taking a small drywall knife to scrape any excess caulking completely flush with the first layer of drywall. Once the second layer was in I smoothed out the caulking for the second layer with my finger which gives a slightly rounded finish bead at the intersection of the drywall and the side of the joist. As much as I took my time fitting the first layer of drywall, I REALLY took my time fitting the second layer to ensure a really nice and tight fit with a slight gap on all sides to allow for caulking. I also made sure there was significant overlap on the first layer's seams by staggering the seams of the second layer. Anytime I had a butt joint I laid a bead of caulking for when I pushed the two pieces together to really get an ultra-tight seal. If my house flipped upside down I feel completely confident this basement ceiling would hold water.
All-in-all I have to say the job looks really good but I will let you be the judge of that for yourself. I have 39 smaller pieces left until I can say that I am completely done with both layers so hopefully between this evening's work and tomorrow's work I can declare this part of the project complete. But even before the last of the caulking is dry, I am going to immediately be moving on into the wall decoupling brackets. To be perfectly honest, I think it will be a dream to stop working with heavy drywall and caulking above my head and get back to normal wood-based construction!!!
Now, on to the pics:
Back right of the theater
Back left of the theater, all seams fully caulked
Close up of one joist bay
Close up of another joist bay. You can see a light amount of the caulking "squeeze out" between the butt joints.
More progress pics to follow tomorrow, hopefully showing the completed ceiling soundproofing.