It depends on how much risk of a noise complaint from neighbours you want to carry
The sketch is on the basis of a dual leaf masonry external wall, with a metal frame stud lining with partial Rockwool fill in the void, and a plywood and plasterboard dual leaf partition. This, plus the corner trap, and potentially a ceiling trap, depending on the roof design, should provide enough LF absorption.
As you suggest, it can be possible to replace the internal masonry layer with a lightweight layer, and avoid the third layer, but it needs some thought on attenuation of inside to outside. It looks like the plan has described it as a “leisure room”, so they may get away with it, but planners and EHOs can get a bit nervous about noise breakout from AV or cinema rooms, mainly due to the thunderous BASS most will have.
“Then and there a base was laid for the GIP 9700 pair previously shown in Munich to find a final home in Holland. That Suzuki-san shipped the system of course wasn’t the result of a simple yeah, let’s see what you do with it. Some hard negotiations were involved before the €200.000,- system was allowed to change hands.” https://6moons.com/industryfeatures/roadtourburen2/3.html
My friends had a music showroom, that they had to make the best of, concerning noise leakage, to other units. They had so much bass loss, due to all the panels they had to put in, they had very little left.
I have a sealed room, with five of the six surfaces, made of concrete. I don’t have a real bass problem.
count to 10 for incoming suggestion about buying a few metres of land from next door’s over endowed plot in order to double the size of the house for suitable mahusive horn system…
Ironically, I went to talk to the neighbour last week to ask him if we could slide out the fence panels for a couple of days during the construction, to finish/point that side of the brickwork. He was fine with it.
I also mentioned his massive garden and he said it was a pita…the upkeep was killing him…
Don’t think it would be quite that simple. The fence we’re talking about is the back fence of his garden and it’s in a straight line about 200 metres long. So, we’d have to buy a 200m x say 2m strip or he would end up with a notch in his back fence.
How far down that 200m fence, is your back property line?
I doubt a small deviation of the fence would bother him. Why not buy a more useable amount, like 10m. It would only be for the length of your garden, so not many extra fence panels would be needed.
Well, he has given you a helpful hint, in that he finds all that garden, a pain to deal with. Maybe the people behind you, would like to extend their garden?
We would have a lot more space to play with on the other side of the house, where the existing garage is. I want to have a garage for pork reasons. The other possibility was to extend the existing garage and build a new garage in the space we’re now going to build the new extension.
Thing is, the existing garage would need to be mostly demolished then rebuilt + plus the cost of the new garage. I did get quotes for this but it was well over twice the cost of just building a new extension on the other side and leaving the existing garage as it is.
The ideal solution would be to build a new listening room in the gravel area behind the garage - this is all part of our plot and is about 30’ square.
The garage door would need to be transferred to the front. But the architect says planning would not allow this because the garage door would end up too close to the footpath.
Why not use that nice large space, leave the garage, and build a much cheaper building, on the other side, just to protect the car. All you need is shelter for the car.
Ironically, I went to talk to the neighbour last week to ask him if we could slide out the fence panels for a couple of days during the construction, to finish/point that side of the brickwork. He was fine with it.
