Massachusetts Single Room Basement Studio Build

I'm starting a sister thread to the one in the design area to ask more construction related questions and as a build diary. My design thread is here. Here's a 2D everview of the room: Here is some sketchup rendering of the framing: The floor is being done tomorrow. I'll post some before and afters. My next step is to add mass to the existing outer ceiling and South side wall.

Well the flooring guys finally got started today after a couple day delay. Hopefully I'll be able to work in there again tomorrow. Next process is to add the beef to existing ceiling and south side wall. The south side wall was put up when the rec room (the next room over) was finished. At the time I was planning ahead for the studio space but knew nothing about the proper techniques used by folks here. I built that wall on a 2x6 plate with 2x4 studs 24" o.c. on each side staggered. So there's a stud every 12", but they alternate which wall they are flush with (so fas so good). However, at the time I didn't know about caulking the wall and for some reason I can't fathom now I sheetrocked and finished both sides of the wall even though the studio side didn't have any other walls framed yet. To make matters worse the studio side was finished with a layer of homasote first and then 1/2" sheetrock. Oops. My new studio design has an independent wall inside this wall which means that this wall must now be only a single leaf. So, last week I ripped off the sheetrock and homasote on the studio side. This results in kind of backwards seeming before and after pictures! Now I need to beef up the remaining leaf and apply caulk. I have a bunch of leftover homasote and 1/2" sheetrock, so I'm pondering using this for the beef until I run out. I know that no one here would recommend buying this stuff for a studio build, but since I already own it I assume there would be no harm in using it , right? Mass is mass I suppose. Or is the homasote bad for some other reason? If it's just that its mass and cost per square foot are less than sheetrock, then I guess there is no harm in using it up. Could someone comment on this before I go ahead and do something potentially dumb? I'm also trying to understand the caulking requirements especially on the ceiling. I had thought that I might add mass to some, but not all, of the ceiling, as time and budget allowed. But it seems that caulking is described as part of the beefing process and I wonder if the caulking as described makes sense if you are not applying it to the whole ceiling. For example consider the difference between adding one layer of sheetrock to 100% of the ceiling (between the joists) versus adding two layers to 50% of the ceiling. In the first case you would have completely sealed the ceiling with caulk, but in the second case I'm failing to see what the caulk has done for you since you haven't made anything air tight. Am I just being slow here? Is the caulking the beef a waste of time and money if you are not doing 100% coverage? As always, any comments or advice are greatly appreciated!

...and 1/2" sheetrock, so I'm pondering using this for the beef until I run out.

1/2" sheetrock is too thin to be really good at isolating. Yes, it is mass, but the resonant frequency of 1/2 sheetrock is too high, and it is too flexible to be good for low frequency isolation. If that's all you have and cannot afford more, then you could probably use it, but understanding that it won't be optimal. It's better than nothing at all, but not by much! Ideal would be to use 5/8" sheetrock instead.

I had thought that I might add mass to some, but not all, of the ceiling, as time and budget allowed.

Unfortunately, that won't work. That would be like saying that you are going to build an aquarium by adding glass to part of the front, but not all of it... :) Sound is like water: it takes the easiest path. If you beef up 99% of your ceiling but leave a one square foot area where you did NOT beef it up, then that one square foot is where all the sound will exit, totally ignoring the 99 square feet that you spent so much time and effort doing perfectly. In other words, by NOT doing the last 1%, you would have totally wasted the 99%. I saw a very similar issue today, with a door I designed for a church, for one end of the passage that leads to the children's Sunday school room, to reduce sound levels between that room and the main hall. The door itself was installed today, but the rubber seals around it have not yet been put on. It's just a small gap around the edge of the door, maybe 1/4" inch wide... but with that gap, the door makes no difference at all to the sound levels! Open or closed, there is barely a 1dB difference in level, measured a few meters away (yeah, I did measure it, just for fun). When the seals are on, that door should provide something like 15 dB of isolation, but that tiny gap means that the rest of the door right now is just useless! it is accomplishing nothing at all. The doorway hole is way more than 99% filled with the wood, but that tiny little "less than 1%" that hasn't been done yet, is all it takes to mark the difference between success and failure. In other words, if you don't do the entire ceiling, then don't waste your time doing any of it at all. Just doing some of it is useless.

But it seems that caulking is described as part of the beefing process and I wonder if the caulking as described makes sense if you are not applying it to the whole ceiling.

Caulking is your seal, just like in my "unfinished door" example above. Each of your two leaves must be entirely airtight in order for the entire MSM structure to isolate effectively. If you don't caulk every possible place that air might leak, then your ceiling will work out like my unfinished door. It only takes a very tiny gap, crack or hole to destroy the isolation of an otherwise great wall or ceiling!

For example consider the difference between adding one layer of sheetrock to 100% of the ceiling (between the joists) versus adding two layers to 50% of the ceiling.

In the first case you have achieved great isolation, if you caulk carefully. In the second case you have achieved nothing at all, no matter how well you caulk.

Is the caulking the beef a waste of time and money if you are not doing 100% coverage?

The beefing itself is a waste of time if you don't do it 100%, regardless of the caulk! Caulking only makes sense if the beef covers 100%, in which case the caulk must also cover 100% of where it should be. That's one of the unfortunate things about building a studio: it's an "all or nothing" proposition. If you don't do it all right, then it won't work. - Stuart -

Soundman2020 wrote:

The beefing itself is a waste of time if you don't do it 100%, regardless of the caulk! Caulking only makes sense if the beef covers 100%, in which case the caulk must also cover 100% of where it should be. That's one of the unfortunate things about building a studio: it's an "all or nothing" proposition. If you don't do it all right, then it won't work. - Stuart -

OK, I hear what you are saying. But not all of the information here seems to always be in accordance with that. For instance in this thread (which you were a part of) they explicitly showed that they didn't add beef to the ceiling where the cross braces were. Do I understand correctly that you are now asserting that their entire beefing process was a total waste of time because of this? They got no benefit whatsoever?

OK, I hear what you are saying. But not all of the information here seems to always be in accordance with that. For instance in this thread (which you were a part of) they explicitly showed that they didn't add beef to the ceiling where the cross braces were. Do I understand correctly that you are now asserting that their entire beefing process was a total waste of time because of this? They got no benefit whatsoever?

Several comments on that thread. First, the OP was aware of the issue, and prepared to live with it:

We aren't removing the cross bridging, since it seems way harder to remove it then reattach it instead of just working around it and living with the lost isolation... I plan on putting it in the basement, and I realize all the problems and pitfalls associated with that.

Second, it was for lower sound levels than what you are talking about:

To recap, I'm looking to build a functional control room with a small tracking room (for vocals, acoustic guitars, etc, but no drum kit). This is primarily recreational, “in the box” stuff using sampling, and I write and record some commercials for our business.

Also, his problem was more impact noise than just TL, which is why he wanted more mass on the outer leaf:

... so this is to help with bass transmission/footfall)

On the other hand, you say that you have live musicians and children sleeping overhead, one of which is a small baby:

Ideally I would like to support live musicians playing with TV watching possible in the room above, and children sleeping two floors above.

The OP in the other thread has no children, mostly uses samples, and wasn't looking to record live musicians, except for the occasiona acoustic guitar and vocals, which he was going to do in a booth anyway. Basically, you have rather different needs from what the poster in the other thread had, he was aware of the issue and prepared to live with the consequences, and was adding mass for other reasons too.

Ah. Thank you very much for that clarification. Too much info, not enough time to parse all of it. OK, looks like my caulk and sheetrock purchase estimates were low! :cry: BTW, do you know where to get that tool shown in the thread I referenced for inserting the backing rod to the correct depth?

Here's the finished floor: Feels good to be making some progress!

Dolphran wrote:

BTW, do you know where to get that tool shown in the thread I referenced for inserting the backing rod to the correct depth?

He used a screen spline tool, available at big box lumber stores.

A couple of questions on the process of adding beef: I'm adding beef between the studs on an existing wall also. The wall currently just has 1/2" blue-board with plaster on the outside. When adding the beef, is drywall glue recommended? What the correct procedure at the bottom plate where the weight of the sheet is supported? Do I just put caulk down first and set the sheet into it? Where more than one sheet is needed in a single bay, should mud be used where the sheets meet instead of caulk (as is recommended when doing full walls)? Thanks!

Don't use glue! Hold each panel in place with cleats around the edges, and seal with caulk. For joints, do it the same as you would for a wall: backer rod and caulk. - Stuart -

Soundman2020 wrote:

Don't use glue! Hold each panel in place with cleats around the edges, and seal with caulk. For joints, do it the same as you would for a wall: backer rod and caulk.

Stuart, I really appreciate the time you have taken to reply in this thread. I must apologize though because I don't understand your instructions. By cleats do you mean 1x3 stock as in Rod's book? When you say "around" the edges do you mean all the way around (4 sides) or just against the studs/joists? In the wall case, isn't the weight of the sheetrock supported by the bottom edge? How is that caulked (backing rod would be squeezed flat)? And also at the flat edge where two pieces of sheetrock meet in the wall cavity the top piece is supported by the bottom piece, no? You have impressed upon me the importance of getting this process 100% right; can you give me (or point me to) a more explicit step by step how-to procedure? BTW, I was thinking of glue not as the only support for the sheetrock, but just to help hold it for caulking. I had intended to us the 1x3 also as Rod suggests. Thanks!

This might not seem like a lot of help at all, but one of the best threads here about beefing is this one: viewtopic.php?f=10&t=2921&p=20903#p20903 It's a realllllllllly long thread, but flip through it to get to the par where he beefs up the walls, and see how he went about doing it. Very informative. - Stuart -

OK I'm getting drywall delivered tomorrow and I'm just about ready to start beefing. My plan is as follows: The existing (outer) ceiling is using engineered joists, which makes using cleats a problem. So i plan to screw the drywall into the 3/4" OSB above. I'll be using 1-1/4" #6 coarse thread drywall screws through the 5/8ths drywall. I plan on screws every 12" on each side of the drywall strips in the joist "bays". The joists are 16" o.c. For the wall I'll use cleats on the studs to hold up the beef. I'm still not certain what to do where the edges of two drywall sheets meet. If they are butted right up against each other there will not be a gap to put a bead of caulk into. I think I will put a bead on the edge of the existing drywall and then smoosh the new sheet into it where the butt together. If any of this sounds wrong to anyone PLEASE TELL ME NOW. I should start adding beef on Friday. Thanks!

It sounds right. You could use construction glue on the edges where they butt together also. Me, for the small pieces placed into the bays, I wouldn't hesitate gluing those together face to face but cleats are still a requirment to keep them in place. The notion that gluing sheetrock panels together reduces the TL of the full combined panel was tested on full sheets of sheetrock, so it doesn't apply to 16 inch small pieces that do not flex in the same many as something larger and more flexible in size would. My 2 pennies,

All my drywall was just delivered! According to the manifest, 5600 pounds in all! It's in my garage and now I have to schlep it all to the basement :!: :shock: I will shortly be ordering all the framing lumber. I have a some questions related to that: Because it's a concrete floor the base plates of the walls were going to be pressure treated (ACQ) lumber. I realized upon reading a box of drywall screws that they explicitly say they are not for use into ACQ. What have folks here done about this? Is there a source of stainless steel or hot-dipped galvanized drywall screws on the net? All I could find were "deck" screws for ACQ. Are these OK to use with drywall (as long as they are "bugle" head)? I was also considering the use of these "structural gaskets". Anyone have experience with this type of thing? It appears that this stuff would not only seal the air path under the bottom plates, but would also allow me to use non-pressure treated lumber because they isolate from the slab. Thoughts?

Your not going to have to worry about driving screws into the pressure treated plate. Installing a screw about 2-1/2 inchs above the floor, assuming you have minimum 1/4" space between the floor and the bottom of the the sheetrock, will secure the panel. But if you just have to, purchase some exterior deck screws, a little less in price over stainless OR a phosper coated ringed sheetrock nail should be just as effective.

Doh! It never occurred to me that I wouldn't need screws that low. :oops: So what should I put under the ACQ bottom plates? Anything? In case it matters, I plan to attach them with the nail driver that takes a .22 cal. charge.

Many recommendations around here, but a good quality caulk will be real effective to sealing up the potential air flow under the plate, if it exists.

As I'm beefing up the ceiling I realize I haven't considered what if anything to do with the HVAC ductwork going to the room above. I'm not tapping into this HVAC system, but these ducts are running in between my two leaves and I don't know if I need to wrap them in something to reduce sound getting into them even though there is no air connection. Any thoughts?

You can see in the top picture of my previous post that these ducts run in the outer room joist bays which are then filled with insulation. There are four of them branching of the main (insulated square metal) duct running down the center of the ceiling perpendicular to the joists like so: I hadn't planned on doing anything with this ductwork except caulking where the penetrations to the floor registers above are. My inner room ceiling joists are going to be just under this main duct. I should say again I'm not using this HVAC system in the studio at all; I'm simply worried about the sound leakage to the upstairs caused by it being between my two leaves. It's now or never for anything I need to do here. Completely replacing this ductwork will really blow my schedule/budget. I'm hoping that I can live with it as is, but I don't want to come to find out that this made all the other work I'm doing completely worthless. Should I put a layer of sheet rock just over the joist bays where the branches are to make an air tight enclosure? I know this is another leaf, but the duct themselves are another leaf anyway, right? Does the main duct need to be wrapped with some limp mass? How much difference will these kind of measures make? I'm hoping to start framing the inner room as soon as a week from now. I really need to make any decisions concerning these duct immediately. Sorry for the panic; as always thanks for you support.