My studio is coming along well enough that I've to start thinking about doors and such. I have the luxury of a control room with 2" x 8" studs so the walls (and the door opening) are nice and thick. The wall to the common area has 1/2" on the common side and will have 2 layers of 5/8" on the inside with R30 in the middle.
My question is once I've got my second layer of 5/8" up, I'll have 9 1/2" between the inside wall and the outside wall so I was wondering if this was enough of a gap to make two doors worth it (I'm going to be building my own doors, by the way) or would I be better served with one more massive door (say 4 layers of MDF)? It would be nice if dBs added directly (i.e., an STC 36 door + and STC 36 door = STC 72 door, but I think it actually works out to STC 39 for the combination.
One other thing I should note is this is a single wall, not a double wall so that may make the idea of two doors moot.
len
One Door Or Two?
Originally posted at johnlsayers.com, topic 4742.
Looking at the floorplan, you essentially have a huge "air lock," and you're wondering if you need to isolate the control room from this air lock... :roll: it seems that two doors would be a waste for all the reasons you cited. But, I'm not the expert... Let's see what others have to say! 8)
Even on a common frame, two doors each consisting of two layers of 3/4" MDF with a 6" air gap between -
1 door - STC 35, low end TL of around 26 dB.
2 doors - STC 48, low end TL of around 35 dB. This is assuming perfect seals, so drop both figures by probably 3-4 dB.
Your walls are a 2-leaf system, even though they're on common studs; so a double door WOULD help; just not as much as a full double framed system with an actual air lock. The downside is twice the work/cost for doors and seals... Steve
Thanks guys. I think what I'll do is frame and install one door on the "hallway" side of the wall. I'll make it the best I can and if it doesn't quite cut it, I'll have the room to add another one on the inside. Hopefully the little "tunnel" made by the door way thickness won't cause me any reflection problems.
len