6 feet (!!!) ceiling therapy

Hi everybody! I am new to this forum and am working really hard to build my own home studio in the basement of my appartment with the landlord's agreement. Oubviously, I don't want to spend thousands of dollars on my project, as I won't be there forever. The width of the room is about 14 feet, the depth is 10 feet, and 12 feet, so the room is in a small "L" shape. The height is just 6 feet high. I began by taking off the drywall from the ceiling that was already there, as it was causing too much early reflexion, espectially on drums, and I wanted to isolate the ceiling as my room is just upstairs (and the lanlord's room up to mine). So, I followed by beefing up the sub-floor above by putting pieces of 1/2 drywall between the joists with drywall screws. I took care to leave about 1/4 inch of space between the drywalls and the joists for the caulking process. My plan is to put another layer of drywall for maximum beef, leave an airgap of about 2 inches, putting a layer of 3 inches Roxul and then add some kind of cloth. This is for every space inbetween joist, to create a "cloud" integrated into the ceiling as I have only 6 feet to deal with... This would be a "ceiling-less" construction... Now, I am wondering what should I do. I was thinking about adding a layer of 5/8 drywall on the 1/2 drywall that is already there as I read that 2 layers of the same density MUST be of different thickness (1/2 and 5/8 drywall). But I read last night in Rod Gervais's book that this would be kind of a myth (Maybe I misread as, as you probably realized, english is not my first language). So, according to my interpretation, I could put 2 layers of 1/2 drywall upthere without problem, as I still have access to a load of 1/2 drywall pieces. Putting layers of drywall between joists is such a LONG process especially in my basement as the space between the joists is varying from 16 inches to 22 inches (!!!), so I need your advices before I call my friends and buy a 12 pack of beer for the hard work. So, my main questions are: 1. Can I put another layer of 1/2 drywall on the 1/2 drywall already there between the joists or I MUST put 5/8 drywall" 2. Is there a good alternative to acoustic caulk as aparently it is such a mess to work with? 3. Is it good to use drywall screws for both layers of drywall or not? I'll try to add pictures of the room later this day. Thank you very much!!! Guillaume

1. Can I put another layer of 1/2 drywall on the 1/2 drywall already there between the joists or I MUST put 5/8 drywall"

it's just about mass. 5/8th is more massive so that's why it's being used. more mass same amount of work. what you do need to think about is the load you are adding. drywall is heavy and you don't want to overload the ceiling. try and find someone who knows about structural engineering.

2. Is there a good alternative to acoustic caulk as aparently it is such a mess to work with?

all caulk is a mess imho. the idea with acoustic caulk is that it maintains the seal. this seal is very important.

3. Is it good to use drywall screws for both layers of drywall or not?

i guess it would be ok so long as there is something on the other side to support the drywall. for me i can't do it because i'll screw into the roof or siding. it takes a while to understand this stuff. it may be a good idea to spend more time studying the concepts and doing the construction later. save money and time.

Hi Guillaume, and welcome!

My plan is to put another layer of drywall for maximum beef, leave an airgap of about 2 inches, putting a layer of 3 inches Roxul and then add some kind of cloth. This is for every space inbetween joist, to create a "cloud" integrated into the ceiling as I have only 6 feet to deal with... This would be a "ceiling-less" construction...

You didn't mention what that floor is made of, but assuming that what you are adding (2 layers of drywall) is going to double the mass of that floor, then all that will get you is roughly 6 dB of extra isolation, additional to what you had before. Is it worth the effort?

1. Can I put another layer of 1/2 drywall on the 1/2 drywall already there between the joists or I MUST put 5/8 drywall"

You can if you want, but like cporro said, more mass will get you more isolation. It would have been better to go with two layers of 5/8, but you already have that layer of 1/2 up there, so the best you can do is to add a layer of 5/8 now. But once again, are you sure that the limited additional isolation is worthwhile? I don't want to sound like a wet blanket, but unless you can put a proper ceiling in there and decouple it in some way, you are stuck with mass law, and mass law isn't very encouraging. Mass law says that each time you double the mass, you get another 6 dB of isolation. You don't say how much isolation you have at present or how much more you need, but 6 dB isn't much. Is 6 dB of additional isolation good enough for your needs? And I'm still assuming that a total of 1 1/8" of drywall is enough to double the mass that was up there already: If not, then it won't even be 6 dB. Also (and once again I'm just echoing and emphasizing what cporro already said): Are you certain that the structure can handle all that extra mass? From your dimensions, that's something like 140 square feet of drywall you are adding up there. As near as I can figure it, 140 sq.ft of 1/2" is about 300 lbs (roughly), plus 140 sq.ft. of 5/8" is roughly 400 lbs. That's a total of 700 lbs of mass that you are adding to your floor, not including the caulk, insulation, cloth, trim, and other stuff. Is the floor capable of safely supporting that? Did you check with a structural engineer? If not, then maybe you should. You might be fine, but you also might not. Only a structural engineer can tell you for sure. - Stuart -

Hello all! After soooo much reading and sooo much work, I almost finished the room! The walls are all filled with 3 inches Roxul Safe'n Sound (except where there is concrete wich is simple fluffy fiberglass) beneath one 5/8 drywall on RC channels on the inside and a simple 1/2 drywall on the exterior. Now, for the ceiling, I filled the joists cavities with 2 layers of 1/2" drywall (with a gap of 1/4 inch so they won't touch the joists) fastened directly on the sub-floor, taped and mudded the seams and sealed the second layer with backer rod and latex caulk. I also put some acoustic caulk between the two layers... just for fun... I inspected carefully the latex caulk as there is some places where it cracked and I filled the cracks with acoustic caulk and filed the air gap between the "doubled joists" As the joists have different depth from one half of the room to the other (see the pictures), I am planning to put as much Roxul as possible: 6 inches in the deepest half, and 3 inches on the other side. Before I finish filling the rest of the cavities with Roxul and cover it up with burlap, is there anything more I can do to maximize isolation (and acoustic treatment), from your experience or from your knowledge? Would taking off the screws form drywall and filling the holes with acoustic caulk (or mud?) help reducing sound transmission? Should I REALLY add a third layer of 1/2 (or 5/8?) drywall? Something is still bothering me: the big trust going across the room right in the middle. Is there something I can do to minimize this flanking path source? Here are the updated pictures: http://img696.imageshack.us/img696/515/dsc07253.th.jpg http://img686.imageshack.us/img686/6586/dsc07255o.th.jpg http://img686.imageshack.us/img686/214/dsc07249.th.jpg http://img14.imageshack.us/img14/1608/dsc07252o.th.jpg http://img532.imageshack.us/img532/4121/woodbeamctfentre.th.jpg http://img704.imageshack.us/img704/6891/woodbeamvuecouch.th.jpg Thanks for ANY advice! Guillaume

I can't see the pic?

Guillaume - this site has facility to post pictures - there's no point posting them on external sites as like Lilith said, we can't see them.

Sorry guys... I know this is a stupid question but how can I attach pictures on this forum? Thanks!

Ok! I got it (I think...) Here are updated general pictures of the room: L-Shape: The door (unfinished) 1 3/4" cedar wood and 1/2" don't-know-what wood More pics of the ceiling to come...

Here is a picture of the subfloor (room's ceiling) taken from outside the room: subfloor and floor are 3/4" thick, spaced by 3/4" This is how the ceiling of the room looks for now: Water pipes...: This is where the two sets of joists are meeting, on the beam (haven't finished seal all the "double joists" as you can see). On this side of the room (separated by the beam), after two layers of 1/2 drywall,the gap of the joists are still between 6" and 6 3/4", depending on the joist (consistency of dimensions was strictly forbidden at the time they built this house :lol: ) On the other side of the room, after two layers of 1/2" drywall, gap is now between 3" and 3 3/4", depending on the joist... Hope this helps! Thanks again! Guillaume

By the way, I don't care about the noise transmitted to the room above the tracking room as it is my bedroom! I care more about the noise transmitted to the room up to my bedroom witch is the landlord's bedroom... So my bedroom would be kind of an "air gap"... :?

niva wrote:

By the way, I don't care about the noise transmitted to the room above the tracking room as it is my bedroom! I care more about the noise transmitted to the room up to my bedroom witch is the landlord's bedroom... So my bedroom would be kind of an "air gap"... :?

Perhaps i might act that way - but I doubt it. The problem is that you have a 1 leaf ceiling - and nothing to decouple your room from the building structure - and this is where you ae going to lose it..... What isolation you have right now is a good as you are ever going to get - the fabric and trims will add virtually nothing. So the question is this - if you go make noise in the room right now - can you hear it in your landlords? You probably want to answer this BEFORE you finish your ceiling........ Rod

http://img704.imageshack.us/i/woodbeamvuecouch.jpg/ I am still not completely convinced this is a beam. With the joists clearly offset from overlapping above this flat board it looks like at one time this was the top plate of a support wall. And since someone has installed a fresh 2X onto the side for additional rigidity (most likely it is sagging) it makes me wonder if a post was there and was removed or what is about this that just does not look safe? Might just be me....

And since someone has installed a fresh 2X onto the side for additional rigidity (most likely it is sagging) it makes me wonder if a post was there and was removed or what is about this that just does not look safe?

You are correct! There was a post standing about 2/3 length of this "beam" (wich is actually not a beam, just supporting the joists where they overlap). That was very annoying. So the landlord, who works in construction, decided to compromise by removing the post and put this 2x6 to restore rigidity achieved by the post. Now, I was having a little question: the back side of the orange wall that you can see below is made of horizontal wood planks and one layer of 5/8 drywall fastened on them. Those planks are very thick and the job was well done (and this was less trouble) so I decided to leave them there. Was this a good idea or should I remove them as they could be a source of flanking paths? Here you can see the inner side (in the room) of the wall (5/8 on RC channels with Roxul) Here you can see the back of the wall (wood planks + 5/8 drywall) before the construction of the inner side: View from the inside the room. You can see the post on the left before it has been removed. The post on the right is actually a lamp! :) : You can also see that I did cut the concrete to gain a couple of inches of height and to even the floor. The actual floor is now 1/2 thick rubber strips of a worn out 2 foot wide concrete compactor strap from a cement plant I got for free. Those strips are layered on compacted ground. It reminds me that I have to seal the seams! Floor: View of the exterior side: Tell me what do you think. Thanks! Guillaume

"So the landlord, who works in construction, decided to compromise by removing the post and put this 2x6 to restore rigidity achieved by the post." I have worked in construction for thirty years and it would have been my profound duty to explain to you why you shouldn't remove a support post and attempt to get the same rigid stable support from installing a horizontal board that clearly cannot do what a post can do in respect to overcoming gravity. I would then go further and explain to you what happens in a live load collapse. Everything is fine. It stays fine. But at a point that cannot be predetermined the stress on the overhead two floors that meet in this area no longer manage to support one another and begin to be overcome by gravity. They sag...you are already seeing this. Then they collapse, more accurately called structural failure. People die my friend...it is not pretty. Put the damn post back...tell your landlord to put the damn post back in or you guys build a wall to support what obviously he has no understanding of and you are hoping he is right so you blindly trust. PUT THE DAMN POST BACK IN!!!!!!!!!!! Jesus...

There was a post standing about 2/3 length of this "beam" (which is actually not a beam, just supporting the joists where they overlap). That was very annoying. So the landlord, who works in construction, decided to compromise by removing the post and put this 2x6 to restore rigidity achieved by the post.

Hate to tell you this - but that IS a wood girder (a Beam is technically steel) it is a structural member that carries transversly loaded floor joist . In the case you describe - with the joists being installed in 2 pieces (joints breaking over the girder) the load is actually 1/2 of the entire floor load being carried by the member - and typically (although i am not there I can picture the construction) there is a wall installed directly above the girder - this is a bearing wall - the joist for the floor above that would typically bear on that wall - (although it is always possible that a post is installed directly above that post to transmit the load above) and the girder is now carrying 1/2 of the upper floor as well PLUS the ceiling load above that (I am assuming that your landlord's apartment is on the top floor). Removal of that member without having this analyzed by a structural engineer is insane - the 2x6 member is not capable of carrying the load of a post - it will fail (eventually) under bending if not under compression - but it will eventually fail. There is a reason builders install posts where they do - it is all determined by math due to load - for your landlord to do what he has done is not only wrong in principle - it is a flagrant code violation - and if there was ever the catastrophe X is referring to - he could face criminal charges if anyone were hurt or killed. Put the column back until you can have this assessed by a real structural engineer - someone who can provide you with a signed and sealed stamped letter certifying that this is structurally acceptable. The cost would only be 2 or 3 hundred dollars for a simple field visit and letter. Rod

Hello. I talked to the landlord about the post and we'll put it back. So, I almost finished the room. We did some sound tests yesterday and the landlord told me that the sound was really good... in his room :? But he told me this with a smile as he agreed with my project and can live very well with the noise, as long as we play on "civilized hours"... There is 6" thick Roxul above the drum area and 3" on the other half between the joists, as planned. I found some nice small trees winter insulation blankets at the garden shop to cover the joists. It looks pretty much like felt, but not as dense. Then, I put some 1"X3" wood strips perpendicular to the joists and on the perimeter to support the Roxul so that it won't tend to fall and create some "balloons" in the ceiling. Here are some updated pictures of the room. Although it is not finished yet, I am quite happy with the result as the room is much less darker now, the ceiling doesn't seem so low as it actually is and I guess the room looks quite neat! Now, I have a couple of questions before I finish the room: 1. Is there too many wood strips on the ceiling, so it could create unwanted reflexions? I don't think so... 2. Can I varnish them? I am asking that question because I heard a story of studio owner's who had to completely remove the varnish on the entire wood floor as it was the source of too much reflexion... 3. Now I am into the acoustic treatment of the room. I want to begin by building bass traps in every corners to have the bass frequencies a little more focused, as I think this is a "must do" for such a small room. These traps are going to be built out of piles of 24" wide Roxul triangles from floor to ceiling, covered with fabric, of course. The question is: Do I have to also treat the "L" corner above as well? If so, Do I have to do the same treatment as the other corners (pile of Roxul triangles) or can I just put a single 4" thick panel, as I guess (I might be wrong) this corner would be less exposed to sound... So I could save a little Roxul for the other corners... That's enough questions for today. Thanks! Guillaume