Originally Posted by Colton Walker
Quick note: the basement is weirdly shaped. Pic attatched with all dimensions and a drawing. Entrance is on the bottom (currently no door, will have to be fixed of course).
Concrete block walls in the basement I believe, yes. The floor is concrete as well. We may leave the carpet, due to the acoustical benefits it provides. The basement, with a 7ft ceiling, is directly below the living room ... The neighbors unit, once you get out of the basement, is separated only by drywall as far as I can tell (I haven't taken the wall apart, but when I look in behind the electrical boxes I can see brown paper backing of drywall board on all levels except the basement).
I'm concerned mainly with the sound bothering my neighbors. The basement has shared centers (cinder, I believe), but above that is shared studs as far as I can tell. Noise travelling inside my place isn't as big an issue as keeping it away from the neighbors, but I figure once the noise leaves the basement, it's going to carry straight through my structure into their living space/bedrooms. I seem to get from feedback here that the ceiling is core. The issue is that there's a LOT of ducting in the ceiling. About 80-90 sq ft of drywall just covering ducting. The room is 18' x 12', 7'1" with a 6' x 7' mechanical room. Taking out the mechanical room, the drywall needed for the ceiling works out to about 230sqft with a lot of cuts and corners.
I'm willing to tear out all of the drywall if need be, but my budget for the whole room is going to be around $600 CAD MAXIMUM. Lower is better, but I'll be doing all the work myself.
Side note: the mechanical room doesn't even have drywall or insulation inside of it. I'm assuming I should insulate and add drywall at a minimum - but is there anything else I can do for relatively little spend to keep the furnace noise down?
Double drywall layers on the walls of the mechanical room. Thoughtful positioning of door to the mechanical room. That's on the cheap end of the scale.
What are your thoughts on the portion of the room you envision as your HT area? Could you outline that space on your diagram and describe it?
What is the minimum ceiling height in the basement allowed by code? What is the minimum height acceptable to you?
I'm concerned your biggest issue is likely to be flanking noise from the corners where the walls and ceiling meet. Somewhere up there behind the walls will be a transition from concrete block to shared studs, with regards to your home and your neighbors'.
1a. The drywall on the walls.... my painter .... he suggested screwing resilient channel directly into the existing gypsum on the walls (I assume into the studs, but perhaps using wall plugs?), and then hang new Type X gypsum on top. The stuff here is about 3.2lb/sqft. He suggested Styrofoam to fill the gap between the two, but I assume that may do more harm then good. Not sure. Is this an acceptable option?
Normally, no. However, in your case I think you could reasonably do that. Since you have a concrete block wall anyway, attaching drywall to it directly is a bit unorthodox, but it can be done and there have been a (very) tests that looked at that as an option. The key is you should mud the wall first, as it were another layer of drywall. Seal all the crevices and layer a think coat of mud over the concrete blocks, then apply the drywall and secure it. The point of the mud is that without it, you will have tiny air gaps all over the place between the drywall sheet and the concrete.
A better method would be to apply Green Glue on the back of those drywall sheets, and then slap them onto the concrete block. That would do 2 things for you: 1) you don't need to worry about the uneven surface of the concrete blocks, provided their raw surface dimples are shallower than the Green Glue layer (which ought to be the case); and 2) the properties of Green Glue will provide you additional improvement in reducing the resonance of the wall.
It's a bit unorthodox of an approach for purists, but every build is different and IMHO sometimes you have to be creative in adapting to the budget and circumstances of the homeowner, so there you have one suggestion for how to deal with the walls.
Now... GG is expensive. It's going to run you around $10/tube or more. You will need a minimum of 1 tube per 4x8 drywall sheet. Minimum. And in this type of scenario, I would use at least 2 because of the texture of the concrete blocks. OR you could possibly try the mudding idea (smooth out the concrete surface), then layer GG + drywall sheet on top. More work. Possibly cheaper.
If you mud the walls first, take care to make them as uniform as possible before you allow it to dry and apply the drywall, using whichever method. Your goal is to add mass to the existing wall, such that you are not creating an air gap during the process of adding mass.
Simply add another layer of drywall directly onto the existing walls, using Green Glue in between. Which option would offer better attenuation?
1c. Build a false wall around the whole perimeter. I'd need to take up the floor to do this I assume? That's a much bigger job, but I assume the best option.
Correct. 1c would be the best approach. You would need to remove any floor finishing (i.e. carpet or hardwood, etc.). You must get to the bare concrete. You would also need to consider how the interior wall would be secured. It would be ideal to place the interior wall on a system of padded flooring, such as plywood/rubber mat/plywood, but I doubt that is realistic from the perspectives of room height and cost.
Combine option of choice for 1 with:
2a. The ceiling. I can rent a drywall lift to hold it in place for me. I already have a clearance issue in the one spot of the room, the bottom in the diagram just to the right of the entrance. 6'. That goes up to 6'4" by the other end, but anyway. What should I do with this...? Take it down, insulate, add resonance control to the duct (if anyone is familiar with automotive sound deadening, I'd use CLD Tiles (one of the best viscoelastic stick-on materials around)), and then mount new drywall using (MAYBE) clips, or resilient channel? I have no idea how to handle all of the ductwork with this. Clips are likely way out of my budget. Resilient channel is cheap, and if instructed how to install it I'm sure I can do it properly.
2b/c. Mirroring 1a and 1b - either use resilient channel and add a layer, or green glue and add a layer of drywall.
2c. Lower the entire ceiling to about 6'4", in line with that ductwork. Add insulation. I could try to force some of that low ductwork higher up by modifying the ceiling. I mean, it's probably doable...? And may give the best result? But that could really mess up acoustics and make the room feel way too small. I don't know.
From the perspective of uniformity, that may be a good option. Moving the ductwork would depend on a number of factors. You might have to resize portions of it, and that could present building code issues or create other problems. All depends on its purpose and other factors. I hate to be so vague, but you just won't know unless you rip out the ceiling around it and examine the situation. Then you can determine your options.
Lowering the ceiling height won't mess up the acoustics, as you said, but psychologically if the room is disproportionately long, it may feel like you're in a tunnel. Height is one of those things that has a different effect for different people. It's also relative to your height (and your guests), of course. That said, you will be sitting down most of the time.
Another factor related to height is if you plan to use a projector, you need to consider where it would be mounted relative to pedestrian pathways and seating location. This is where creative placement of seats, door, etc. comes into play.
2d. Tear the entire ceiling out for the heck of it, then decide what to do.
Sometimes, it's not a bad idea. It forces you to figure out a solution and you are able to see what is and isn't possible. Worst case scenario is you have to replace the ceiling in the exact same position/design.
I'm thinking before you go any further, you need to figure out where your screen is going to be, your seating plan, type and placement of speakers.