Dealing with existing internal walls.

[dannyc123]

Hi there,

I have been lurking around on this forum for a few weeks, reading books and trying to gather all the information that I can. I have learnt an insane amount of information from here alone and I am really thankful for it. This is my first time posting and I may be missing some glaringly obvious things so please be gentle!

I am looking to move house so have been trying to find somewhere with some outbuildings or similar that can be converted into a small studio mostly for my own band but looking to work with some other local musicians. I am hoping to have a separate live room and a control room.

One place I am looking at is pretty perfect but I seem to have come up against a brick wall (pun totally intended) with how to do the layout. I have attached two images to try and help explain. My drawing skills leave a lot to be desired, but I think they sum up my problem pretty well.

The 'studio' building is in fact a series of small connected outbuildings. This means that the walls which connect them are both structural and immovable. They are made from fairly thick brick (I don't have the dimensions). I understand the principles of mass-air-mass and would build inside of the existing structure to have the rooms decoupled.

The problem I have is that to keep the rooms decoupled, I would be in fact creating a three leaf wall (as shown in attachment 1). If I was to retain a two leaf design then my control room is coupled to the main structure of the building; the existing brick wall (attachment 2).

Am I missing something and being really stupid, and if not then which is the preferable design? I would need a reasonable amount of sound isolation as like most of us I am sure, I work stupid hours and don't want to disturb the nearest neighbours (around 200 metres away).

Thanks!
Danny.

brick wall problem1.jpg

brick wall problem2.jpg

[Soundman2020]

Hi Danny, and Welcom!!!

You are stuck with on of those cases where you really don't have much of a choice: you have to go with 3-leaf.

However, you are actually in luck there. With a three leaf system, you get the best performance where most of the mass is on the middle leaf, and since your wall is brick, there's plenty of mass there! I assume you'll be building your inner-leaves with drywall on stud frames? If so, you should be fine. The surface density of a brick wall is many times higher than the surface density of drywall (plasterboard), so I wouldn't worry about it.

On the other hand, something you might want to consider: If you wanted sight lines between the two rooms, you could probably cut a hole on the middle of that wall, leave it empty, then put glass in your two inner-leaf walls, and you'd be back to two leaf! You'd have to check with a structural engineer, and you'd need to put a lintel in to support the load overhead, but if you did want to have a direct view between the rooms, that would be the way to do it, and kill two birds with one stone.

But three-leaf sometimes is a workable only solution, and as long as you compensate for the 3-leaf effect in your design, you'll be fine.


- Stuart -

[dannyc123]

Hi Stuart, thanks for your reply!

I assume you'll be building your inner-leaves with drywall on stud frames?

Yes of course, my drawing wasn't great but the two little lines represent a stud frame, insulation and probably 2 sheets of plasterboard (drywall).

If you wanted sight lines between the two rooms, you could probably cut a hole on the middle of that wall, leave it empty, then put glass in your two inner-leaf walls, and you'd be back to two leaf!

I hadn't drawn windows & doors in because I thought it easier to just convey my point. I would be putting a window in and I am having an engineer come and look at the house with me in a few days. Am I right that what you're saying is with a hole in the wall and windows only on the drywall sides that it returns to acting as though a two leaf? Is this because you are allowing the air to move freely through the brick wall?

I would imagine (though some of these rules about acoustics have seemed a little counter intuitive to me) that it would bring it closer to a two leaf system, but would you still get some reflections from the brick wall resulting in a sort of compromise between the two in terms of isolation.

Thanks again Stuart, some of the threads I've read on here have had so much useful input from you! My next step is to get my head around sketchup and try and get a basic design up and going when I have the exact dimensions. I will definitely be coming back for some advice with that when it's in good shape!

Danny

[xSpace]

You are going to fill up the cavity between the new walls and the brick wall with insulation, both sides, to damp the cavity and lower the resonance of the wall. Does that address your concern?