Hello Jeff,I am currently soundproofing a friend’s garage at the moment, he has given me permission to share images of the build. So hopefully I can give you some useful tips. I know this is a late response, but it is also likely you have not finished yet.
My friend is converting his garage into a bar. He was also concerned about making too much noise, as he will be playing music through a Sonos wireless speaker system in there. He wanted a bar that not only looks good, but offers good soundproofing qualities. This means it was a trade-off between lovely bar features, and soundproofing qualities. For example, a stylish composite door with windows were chosen as it looks good, but is probably not the most ideal door for soundproofing.
However, I must say, a band is a different level of noise. Please note that when people refer to something as soundproofed, it does not mean literally, as if no sound will escape. The best you could expect is a substantial reduction in sound outside of the garage, compared to the inside. Reducing band noise is a challenge due to the amount of decibels it produces.
However, you will need to go even more over the top then this to significantly reduce band noise! You could almost copy what I done for my friend, but you will need to do the following to have a good chance of reducing the sound significantly. Remember that sound will always take the easiest route, especially through windows and doors.
Ensure you have no windows. If you really must have a window, then go for windows designed for soundproofing. I believe windows that are thick and laminated offer the best soundproofing qualities.
Buy a solid thick door, which is narrow in width, and smallest in height. The bar I done for my friend uses a composite door. The composite door used for his bar has a hollow construction. It is great for thermal insulation, but mass is the key to blocking sound, hence having a solid door.
Things to remember:
Have the mentality of building a room within a room, and isolating both rooms as much as possible.
A combination of mass (such as thick dense walls) and absorption (such as heavy Rockwool) helps to block sound.
There are many offer things you can do to soundproof your garage, but I am assuming you want to make the project cost effective as possible. Soundproofing can get crazy expensive, depending upon the materials and techniques used.
I hope this reply helps. Feel free to ask any questions about the project.
Kind regards,
Jon