Not satisfied with Door isolation, please help

Hello, I've recently completed construction of my studio. I haven't been completely satisfied with the isolation of the door from my live room into my vestibule/iso booth. The vestibule acts as a damper between the control room and live room, which is highly effective. It also doubles as a iso booth. I've got Zero Internation seals on both doors. I'm considering modifying the live room door, which is a 1 3/4" solid core. My idea is to laminate/glue and screw 2 of the same doors together (2-1 3/4" doors), and reposition the zero gasket... Would the extra isolation/mass be worth the trouble? FYI, hanging 2 seperate doors is not and option. thank you! andrew

one of the nice things about adding mass to a door is making a bank vault type seal, the added mass being slightly smaller than the door with a second set of seals. so two doors might not be as good a sound door as adding a sheet of mdf or two to the existing door. sheetrock can also be used or a thin sheet of lead inbetween layers. (the lead idea is from rods book, never tried it) make sure your frame can hold the extra weight, four four screw hinges are also good ideas

Thank you for your response. I'm still not sure if the work would be worth the trouble. Would I actually notice an improvement in the isolation by adding the mass? What I'm trying to achieve is the ability to use the vestibule as an iso booth. I might want to record and acoutic guitar and vocal while drums are being used in the live room. Currently, the drums would bleed into the guitar and vocal mic. thanks you, andrew

You might want to check all of the other points around the door and make sure they are sealed as good as can be. For example, the joint between the drywall and the wood that makes up the door frame. The area around your frame should be calked on both sides and airtight. I know from my studio build that I had extrememly well sealed doors all the way around including a double sealed "bank vault" construction (except the bottom of the door) and while the sound was reduced with the door closed it really wasn't very sound proof. Just the small gap at the bottom of the door was letting all the sound out. Once I sealed that with a Pemko drop down seal, the situation improved dramatically. I'm not sure if you're ever going to get the sound of drums in the next room out completely but if you've got even little gaps between the wall and the door frame, it's going to be much worse. len

Hello, Thank you for your response:) As far as I can tell, the door is sealed very well. I used drywall mud and insulation to seal the gap between the door frame and the drywall. I have a zero international fully mortised drop down jam at the bottom of the door. I would say the door is as good as it can be in it's current state. The seal is definitely effective. It's just not as good as I would hope. Just to add more info, the wall is a typical 2x6 wooden stud wall. Each side of the the wall has 2 layers of 5/8" gyps. The walls are filled with mineral wool. Obviously, because the vestibule isn't floated, or have it's own walls or even staggered studs, there will always be some transmission. Additionally, the door has no holes in it for door knobs... thank you! andrew

You mention the Zero Int'l seal on the bottom of the door but not the seals around the rest of the door. Also, I don't think joint compound at the drywall/door frame joint is going to cut it, especially after the first time you close the door. It's very brittle once it dries. Have you tried calking all the way around the door frame on both sides with an acoustic calk? Do you have any idea (in numbers) how much isolation you ARE getting? len

Hello, In terms of how much isolation I'm achieving, I don't know. What's the easiest way to test that? What kinds of numbers should I expect? As for the drywall mud, you're right about it being brittle. I guess I need to pull the trim off and use acoustic sealant. Maybe I should test the door first, before I tear the trim off. As for the seal kit around the door, I'm using the Zero international seal kit... thank you:) andrew

You might be able to use a RadioShack SPL meter (about $50) or something similar. You'd set up a speaker in the tracking room, make a measurement, then close the door and measure the level from the other side. The difference between the two readings (in dB) is the isolation the door (and walls) are providing you. The only problem with this method is that the RS meter will only go down to 50 dB so if you door is doing much of anything, it's going to be less than that (and therefore a useless measurement). If you could boost the signal in the room to around 100 dBSPL inside, you could measure at least a 50 dB isolation which would be VERY good. Expect about 40 for a well made door system. len

Hello, thank you for you the info. I plan on testing the door this weekend. In the meantime, if we pretend the door is performing like it should, will modifying the door as I mentioned earlier make a worthwhile difference. Or could it make things worse? is it worth the trouble? thank you, andrew

aschatzb wrote:

if we pretend the door is performing like it should, will modifying the door as I mentioned earlier make a worthwhile difference. Or could it make things worse? is it worth the trouble?

Probably not. If you've already got a solid core door, that's most of the isolation you're going to get. If you can determine where the sound is leaking from (like is it THROUGH the door or around the door), others might have some better suggestions. It's going to take a lot of work to add layers to the door because the jams have to change, the seals will have to be moved, probably the hinges too. I think your biggest problem is that you are trying to use a single door to isolation one of the noisiest items (drums) from one of the quietest (vocal). len

Hello...I'm new here, so bear with me. I'm putting the finishing touches on my home studio and am ready to seal the door between the tracking room and control room. I've noticed reference to Zero International and Pemco door seals. Can't find Pemco at all, and Zero's site doesn't offer ordering information. Any help on these or other sources would be greatly appreciated. Thanks,

diviolin, Welcome to the forum! I'll answer your question but PLEASE update your profile so we have some idea of where you are in the world. Thanks! I'm not sure about ordering from Zero International but I can help with the other one. Your first problem is that it's Pemko. It through me too for a long time (and I had been to their site before). pemko.com will get you started. I found that you cannot get order from them though and have to go through a local rep to get pricing and place your order. I bought 5 of their drop down door seals (4301 model I think), and they custom cut each one for you. You can cut them up to two inches yourself but I'd recomend letting them do it for you. There is no charge and it doesn't take them any longer. My local rep did not stock these locally so they had to come from the factory in Tn, but total time from order to arrival was about 10 days. I got 4 that were 36" or less and one that was 48" or less and they cut them down to the right size. It is very important to note that if you are going to semi-mortise this model, you measure EXACTLY the width of the door. If you are going to surface mount them (like I did) you have to specify them 1/8" LESS than the distance between the door stops. FWIW, my 36" inchers were $57/each and the 48" was $75 all of which included the custom cutting. As I recall, Zero International was about 5 times this much. len

Hello Len, Thanks for the info. I contacted Pemko, their local rep and local sales outlet and I'm not getting the whole picture. If I use the surface mount door bottom 4301_RL and the surface mount perimeter stop 350_SR, I'm not sure how it all comes together. If the door bottom goes from door frame to door frame, then the stop would have to come down just to the top of the door bottom, correct? If so, how does one effect a seal at the intersection? The only idea I had was to cut short pieces of stop to seal around the door bottom. Does this make sense???? If the perimeter stop goes all the way to the floor, then the door bottom would not run the whole width of the door, but rather width minus twice the width of the stop... correct???? Even still, there's the problem of seal at the intersection. Nobody seemed to understand my question, which leads me to wonder if I don't understand....which is highly likely :roll: Any help/photos would be greatly appreciated. Thanks,

OR.....if the door bottom is mortised into the door, it would seem to solve the problem, or at least get a lot closer. What think ye? If y'all don't know what I'm talking about, check this link: http://citysoundproofing.com/doorbottoms.html