super door construction

I used Rod's book extensively during the contruction of my studio. Everything turned out great with the exception of the doors. I constructed one without getting great results. I have another one to finish, but wanted to get some advice before continuing. Here are my 2 issues/questions. 1) I'm having a little trouble with the seals. I built the doors exactly to spec with all the materials spec'd in the book. The 2 rubber seals are in place, but we had some difficultly getting things to seal as tightly as I would have liked. Sound was leaking out of the room (double wall, double 5/8" contruction) through the door pretty freely even when someone pushed on the door to close it tightly and compress the seals. I have not yet put the 3rd, magnetic seal on the doors. I'm concerned that I'll go to the extra effort and cost and still have issues so I thought I'd check in first before proceeding. Does that 3rd seal really make a significant difference or might I have issues elsewhere that need to be addressed first? ANy recommendations on the type of magnetic seal to use and any ideas where I could source it? 2) I have another door to build. Is it possible to substitue Auralex sheet block for the sheet lead? They report that it works as well (or better) than sheet lead. I appreciate any feedback you can provide. If you want to check out the studio you can see some construction pictures at http://www.myspace.com/madsamrecording Jeff

The door is the weak spot in the isolation. It will be the point of most sound getting through. what are you hearing? High mid frequencies or low frequencies?

I have another door to build. Is it possible to substitue Auralex sheet block for the sheet lead? They report that it works as well (or better) than sheet lead.

1/8" sheet lead (the same thickness as Sheetblock) is 8 lb/ft^2. It is 15 db better than sheetblock, using the mass law. Ask Auralex for the lab test results of Sheetblock and lead of the same thickness. Andre

What I'm hearing is more high mid stuff. Low frequencies are really not a problem. To clarify, I've only got one seal on the door right now. I took the 2nd seal off since the door wasn't closing as tightly with the 2nd seal. My intent was to reset the 2nd seal, but before I went back down that path I was trying to figure out whether the 3rd, magnetic seal was going to make a significant difference to justify the cost/effort and the shrinking door width. Jeff

What you are describing, and that all we have to work with, is a seal problem. Rod detailed a three part seal system for the door. You are looking for results with out the entire system in place. Andre

The trick to getting this right is patience........... Tke off all of the deals and trims. Begin with the door completely closed - and gently place the first seal agains the door - starting at the top on one side - and using a stapler to lock the trim in place. Work both sides of the door and then the top. The rubber should just gently press against the door - too much pressure at any one point will push the door out of position. Once you have a nice even seal - apply the wood trim that locks the bubber inplace. Again - so not press too hard against the door - just a steady even GENLT pressure is all that's required. NOW - work a light outside of the door and not any spots where the light penetrates........ at those spots a small amount of silicone caulk can be used to back the rubber and press it smoothly to the door surface. Allow 24 hours for any caulk to set up. The re-do the entire operation for the 2nd seal.......... the only difference is that this time you will inspect the seat against the door with a light on the inside. Do the same thing with the caulk for a spot backing is you need it. LAstly - install the magnetic seal......... install a steel received on the inside face of the door surface - you can get 1/8" x 1/2 steel strips at Lowes or Home Despot - drill and countersink the surface so the screw heads will be flush. The install the mag strip by allowing it to set against the metal strip and slightly spring it back to allow for just a little pressure. Now that this is all done - you install your door closure - you want a very slow acting latching speed on this so you don't loose people fingers over time. A final door latch (on the inside) of a throw bolt (even better a top and bottom pair) that is installed so you have to slightly pull on the door to latch will make for a perfrect seal. See - easy as pie - but critical that you don't force anything (which is obviously what yu have done.). Rod

Rod, Thanks so much for chiming in here. I appreciate the detailed instructions. I knew that we didn't quite get this right the first time around and that's why we pulled the seals off to try again. I wanted to make sure I was doing things right before we tried this a 2nd time. Do you know if Home Depot/Lowes sells a magnetic seal that's sufficient for the door or do you have a recommended place where I could source those seals? I assume something like you'd find on an external door with a magnetic weather stripping seal would be sufficient. I'll pick up the steel strips you outlined. Andre, thanks for your input as well. I'll give this a shot and let you guys know how it turns out. Rod - I can't thank you enough for writing the book. I've read a lot of acoustics and studio construction books over the years, but this one was the most useful resource I had during the design and construction of my place. Well done! Jeff http://www.myspace.com/madsamrecording