At this point of the build, the outer room was basically complete. I had finished hanging the plasterboard that formed the outer room ceiling, so now it was time to finally begin on the inner room - the actual studio space. The first thing to do was to join up all the individual pieces of stud framework that I had already built - this would form the wall structure of the inner room.
Here are the frames for the stud wall lined up in position:
You may notice the black material underneath the bottom plate: this is actually two separate components. On the very bottom, I used a
damp proof course (basically a thick plastic strip that prevents moisture from getting into the wood through the floor).
On top of this I then used an
EPDM resilient strip, which was intended to provide some acoustic separation between the stud wall and the concrete floor. In hindsight now, having done lots of research an the subject, this might have actually not improved the acoustic isolation as really you need to perform lots of calculations on the stiffness of the resilient layer and the weight put onto it by the walls (accounting for whole inner room structure) in order to be sure that you achieve the low frequency isolation. This is also why lightweight "floating floors" don't actually work in terms of the low frequency isolation - in some cases they can even amplify the transmission of the low end. When I was building the frame I did some tests using denser solid neoprene, which is what was recommended by Sound on Sound
in this article. Comparing the two materials, I found that the less solid EPDM performed better at reducing impact transmission (albeit in my very crude "hit it with a hammer" test), so I went with this as it was also significantly cheaper.
After I had put both materials under the frame, I then began positioning them, and connecting them together, initially with screws, and then using M8 bolts. The bolts added a huge amount of strength, and made the whole structure much more rigid. Here's an example of the section by the window, which I had aligned to make sure that the studs lined up with the window framework.
And here is a closeup of the bolted section (this picture was taken later on in the project):
In the above picture you can also see the "crown plate" - the additional wooden plate above the frame's top plates. I added this the whole way around the room, and this tied the frame sections together really nicely, ensuring a flat and level top surface to build the roof rafters onto.
You may also have noticed some wooden "ties" that go toward the wall: these formed part of a support column that I build to reinforce the longest wall section. This was necessary because this part of the wall was a ~5m long run, and didn't have any corners providing the necessary lateral restraint. The support column tied to the frame at the bottom, middle, and top, and added a great deal of stiffness. If you are building long straight sections of stud wall I would greatly recommend using something similar.
Once I had connected all the studwork sections together, I then had to build the front structure to connect the two sides of the room. This needed to be a different height as it had to hold the inner door frame - you can see me building this below:
And here is the completed front end - you can see how I tried to match the profile with the shape of the ceiling to maintain a constant 5cm, air gap between inner room and outer room:
The actual door lining would then go in the large aperture I had left, but I will discuss hanging the door later on as it was a whole process in its own right!
Next up - Acoustic Isolation Frame Mounts
