A few months ago we looked at various aspects of the physical construction of a home studio including how to build a floating floor and walls / ceilings. There are a couple of weak links in any studio construction. Windows, Doors and Ventilation are the key problems. This month we will look briefly at Window and door construction for the home recording studio.
Doors - Hard to have Room Without them!
Recording rooms would be so much more sound proof if we didn't need a way to get people into them! Maybe there is a way we could build the room around the artist and then feed them through tubes in the wall.... Short of that, recording rooms need doors and these seemingly small details tend to ruin an otherwise quiet room.
The one main problem is that you cannot completely seal off doors from any cracks that would allow air, and subsequently audio waves, to seep through. But you can prevent this as much as possible. One quick and easy solution is to purchase pre-hung, exterior doors instead of interior doors to use for your studio. These are made to stop outside drafts from coming inside, and will help you in the same way for your studio. The prehung doors come complete on the frame with seals, frame and threshold. The overhang between the door and frame helps with the STC rating and then the weather stripping helps to achieve air tightness.
The second problem with doors is the construction of the doors themselves. As we discussed before, more mass is typically better for sound attenuation. Layers are typically better. Decoupling is always better. The typical construction grade interior door is hollow and made out of some sort of light, pressed wood product.
One final note on doors: Typically wider is better, not from a sonic standpoint, but from a "how the heck are we going to get that piano in there" standpoint.
Windows - Line of sight, not just sound
So you have built your air tight studio with a zillion layers to your walls, and all the right materials: Now cut big gaping holes in them for windows! That is the cruel joke of building an isolation room. But they are necessary (although I have seen a couple of interesting designs using closed circuit cameras that are interesting). First let's talk materials:
- Plexiglass - scratches too easily, you want to be able to see inside after a couple of years....
- Float glass - can be up to 1 inch in thickness - readily available and can be cut on site at most local glass places but not as effective in isolation as other types
- Heat Strengthen or Tempered glass - often found in sliding doors for it's durability, but cannot be cut once it is made - better isolation than float glass
- Laminate Glass - Made with an inner plastic layer (the laminate) between two pieces of glass which significantly reduces sound transmission - lab test have shown this to be the best glass for sound isolation
Before this article turns into a book, I will get to the point. A typical studio will use two of these pieces of glass, suspended each in their own frames, without touch one another. Creating an air tight frame is important. The more density and stiffness to the glass, the more it will be like an extension of the wall and create good isolation. In my study, angling one piece of glass may help reduce the sound transmission between having parallel pieces on one hand, but may actually increase sound transmission by decreasing the air spring between the pieces of glass. Before going out and having glass cut, which can get quite expensive, consider these options:
1. Sliding doors between the studios: If they are made with tempered glass and you double the doors up, this might double as an entrance as well a line of sight - better than cutting an extra whole in your airtight room since you will need a door anyway
2. Double pre-framed exterior windows. I was trying to finish my studio within a reasonable budget and so I found six foot long exterior house windows that were being recycled. They used laminate glass have seemed to do the trick. See the picture below. We framed each window into each wall and used black material between them to keep the dust out and give it a nice finish. You'll want to make sure the inside windows are very clean before installing them! A friend told me about a studio that had a fly sitting dead between the panes of glass...I won't tell you the new nick name for the studio.
Conclusion: Hopefully that helped as a quick overview. Do your best. You can always do more, but don't let the size of this project keep you from doing at least SOMETHING!
