Music studio in a basement with a party wall
Posted: Mon, 2020-Nov-23, 08:52
Hi everybody,
First, thank you Stuart and all of the great contributors of this forum. There's a massive amount of great and useful information!! I started being interesting in soundproofing music studio for a while now looking at forums and reading books ( Rod Gervais, Marshall Long,...). Continuing to learn about it, I'd like to introduce you my project.
I am planning to build (and make build with an architect) a « soundproof » music room in the basement of my house (built in1910) that has a limestone common wall with my neighbours house.
I have an appointment with the architect in January to plan the design of the project, the way to construct it and the budget for this. So, I need to be the more accurate as possible in my requirements and objectives for this room within a room.
I post my project here and share it to you because I have a lot of questions regarding studio designs and soundproofing processes. I'd like to discuss with you about this project and the realistic requirements and objectives that I can come with for the pre-project with the architect. And to resolve some of my misunderstanding of “soundproofing” concepts.
Objectives and environment
This studio room will be used to rehearse and recording/mixing (for preprod uses) live bands (drums, bass, guitars, voices, average level of noise : 110 – 120 db). The budget I can have for this project is 15k€.
The house is located in a houses neighboorhood with two streets (level of noise outside in daytime : 50db). The basement walls are underground/below grade with the fourth wall (at right)being common with my neighbours' basement. The environment sound level in my basement without noise (washing machine, etc,...) is around 30-35db (measured by iphone app...). With the washing machine on, it rises to 55db. The sound level in the neighbour's house is approximative because I won't be able to do measurements in... because of bad relationship with my neighbours...
Assuming I don't want to annoy my neighbours in their house (especially their living room), can we say the sound level in their basement should not rise over 35db ?
Here's some views (the red area labelled 110 db is where I plan to build the studio in the basement) :
Here's the existing top view of the basement:
The red line is the delimited space for the studio (room in a room).
The space is limited by:
_ the well. It will stay in place. It's a 4,5m concrete hole where there's 3m of water. It is used to drain the foundation. I've never noticed any water coming in the basement floor and it is safe. Architect and mason confirmed it.
_ the ducting and the pipes that go to the ground floor through the basement's ceiling. The gas pipe and the heating water pipe paths are quite weird and need to be moved away. They go through the middle wall by 2 holes. This should be useful for the HVAC system and the electrical installation.
The basement window (in the bottom wall) will be closed and could be used for the HVAC system design.
So the global idea to keep the area free for this “room in a room” little studio is:
_ move the ductings. Use the remaining holes in the wall for HVAC/electrical paths ?
_ knock down the 10 cm concrete block wall partition.
_ break a part of the 8 cm concrete slab.
_ remove interlocking concrete pavers.
_ dig 30-40 cm off the ground to have height from 2,1m to 2,4-2,5m. Regarding the height, the mason and architect tell me I could dig 40-50 cm high off of the soil without any risks to damage the building structures of the house.
Here's a more detailed picture for the foundation and new ground level:
And here's the project global view:
Dimensions are (LxWxH in cm) 480x380x(250-260).
I'm currently trying to figure out what is the best design and how to define some requirements. So, let's do the calculations using some math from Rod Gervais and/or Marshall Long. (Please let me know if I'm wrong).
First, I want to now the sound transmission loss in the 55 cm limestone common wall:
_resonant fundamental frequency for a single panel: fr = 0,45*vl*h*((1/L)² + (1/H)²)
where, h is the thickness of the panel (m),
L its length (m),
H its height (m),
vl (m/s), the longitudinal velocity of sound in the partition
vl = (E/pm*(1-s²))^(1/2)
E is Young's Modulus in (N/m²) or Gpa or Mpa
pm is the density in (kg/m3)
s is Poisson's ratio (0,2-0,3) in construction material
In my case,
_ h = 0,55m, L= 7,4m, H = 2,1m,
_ vl = [2553 – 2054] m/s where
pm for limestone is between [1800-2780] kg/m3
E = 11.10^9
s = 0,3
_ fr = [154 – 124] Hz
_ the critical frequency about bending waves and coincidence effect (from Rod Gervais);
fcr = c0^2/(1,8*h*vl)
where, c0, speed of sound = 344m/s
So, fcr = [46 – 58] Hz
Why fr is much higher than fcr since fr is the fundamental frequency ? Shouldn't it be the opposite way ?
If I refer to the mass law formula,
_ at fr, TL = 20*log(fr*m) – 47 (db), where m is the surface mass density in kg/m²
TL = [46 – 51] db, for limestone where density is between [1800 – 2780] kg/m3
_ at fcr, I read the formula in Marshall Long book but it's too far for my math skills...
About the minimum amount of insulation requirements:
_ if L0 is the level of sound in the red room, L0 = 115db
_ L1 the level of sound in my basement
_ L2 the level of sound in my neighbours basement (max 35 db)
_ T1, the transmission loss between the red room and the basement
_ T2, the transmission loss between my basement and the neighbours basement.
_ L1 = L0 – T1 and L2 = L1 – T2 (and T2 = TL)
→ L2 = L0 – T1 – T2, so T1 = L0 – L2 – T2:
T1 = 115 – 35 – [46 – 51] = [34 – 29] db.
Is it right ? And is it correct to say that I need to achieve a minimum of insulation with a transmission loss of [29 – 34] db for the red room ? (IMO, it's too low for the goal I want to achieve)
I consider 3 options for the main design of this room in a room and asking myself a lot of questions to know which one to choose (with the correct calculated data to make decisions and compromises with my budget):
(the door will be installed in front of the common wall. I'm aware this part of the room with the door will be the weaker part and where I need to put all the effort in designing and building).
After reading a lot of thread and just to be sure, can you confirm me that:
_ option 3 is a kind of triple leaf MSMSM system and this can be worse for my sound insulation. Moreover the building of this can be very complex (inside out ceiling,...).
_ option 2 looks like the best option but, is the new partition wall, the inner leaf and the common wall would act as a triple leaf wall?
_ option 1 is the less expensive one and allowing the more space but... Since I'm not sure at all about my calculations, I don't know how to mae the right decision...
For example with option 1:
_ for the 3 existing walls and the wood studs facing them:
The resonant frequency for double panels for MSM systems:
fr = 84*((1/d)(1/m1+1/m2))^0,5
where d the distance between panels, m1 the surface mass density of 1st panel, m2,...
d = 0,25 m because of the 10 cm of foundation wall, a gap of +/- 5 cm to the concrete (or wood) floor and 10 cm long wood stud):
m1 = [1800 – 2780]*0,55 = [990 – 1529] kg/m²
m2 = 24 kg/m² (2 layers of gypsumboard)
→ fr = 34 Hz
f < fr, TL = 20log (f*M) – 47, where M is the mass surface density of the entire construction: TL(f=fr) = 47,4 db
f > fr, TL = TL1 + TL2 + 20log(f*d) – 29
TL (f=63 Hz) = 158 db !!!!
_ for the remaining partition
d = 2,3m then
→ fr = 2,3 Hz !!!
f < fr, TL (f=fr) = 24 db
f > fr, TL = TL1 + TL2 + 20log(f*d) – 29
TL (f=63 Hz) = 177 db !!!!
These results sounds really weird and I should miss something... And that's where I'm stucked...
I don't think yet about HVAC because I'd like to know first which design of the room in a room I need.
I compile here my questions and others thoughts about my project to summarize it a bit:
Global:
Assuming I don't want to annoy my neighbours in their house (especially their living room), can we say the sound level in their basement should not rise over 35db ? So, does it mean I can have an acceptable sound level in my basement between 55 – 60 db?
About MSM systems and calculations formulas:
Why fr is much higher than fcr since fr is the fundamental frequency ? Shouldn't it be the opposite way ?
Is it right ? And is it correct to say that I need to achieve a minimum of insulation with a transmission loss of [29 – 34] db for the red room ? (IMO, it's too low for the goal I want to achieve)
Option 2 looks like the best option but, is the new partition wall, the inner leaf and the common wall would act as a triple leaf wall?
About construction:
_ For the new floor, I hesitate to ask the architect for a new concrete slab. She said to me that we could think about the solution of having prefab concrete little slabs using them as foundation for a wood floor. I'm not sure if we talk about putting the wood frame on it or not and this floor subject was just an informative talking, no decisions were made about it now.
_ I will have to put a new coating on the walls because the coating was made with concrete and the masonry stones in the basement require a “breathable” coating. I read that having a coating make transmission loss higher than without it. Should I put insulation on it (and how to not damage the walls or the insulation for the future) or to the wood studs' side? The kind of stones the basement is made of, need to “breathe” and act as the opposite of concrete regzarding water paths.
_ What would be the minimum recommended space between foundation wall and new floor to hope having a good decoupling between the new room and the existing structure?
Supplementary notes:
_ The main goal is to be able to make a compromise with budget/reachable objectives/design/building to bring with me accurate requirements for the architect preproject appointment.
_ First is to determine the sound transmission loss in the common wall and in the basement (resonant frequency and critical frequency as well). This will conduct me to choose for a particular type of design: the room in a room (and even more questions about the MSM system).
_ According to the acoustics math formulas, I'm trying to determine what would be the best option to reach the objective of the required sound transmission loss level. This is where I'm a bit confused. For my calculations in Option 3, I don't know if I need to use the triple leaf theory with the stone wall or use the double leaf theory first for the double wall studs and then use it again with double wall system and the stone wall. The same for options 2 with the double wall facing the common wall.
_ In my case, I think the weaker part of this MSM system will be the part of the room that will face the common wall and that have the door. The building of this will have a particular attention.
I hope I don't miss anything and that you would be able to give me some help and advices about my project. Please let me now if I miss details. I'm facing some confusion about the calculations in acoustics domain and I think I misunderstood some general concept. Especially for the MSM system and the triple leaf effect...
And I apologize if I made some mistakes in English. It's not my native language and it's quite difficult to try to explain a technical context without knowing all the vocabulary of construction.
Best regards
First, thank you Stuart and all of the great contributors of this forum. There's a massive amount of great and useful information!! I started being interesting in soundproofing music studio for a while now looking at forums and reading books ( Rod Gervais, Marshall Long,...). Continuing to learn about it, I'd like to introduce you my project.
I am planning to build (and make build with an architect) a « soundproof » music room in the basement of my house (built in1910) that has a limestone common wall with my neighbours house.
I have an appointment with the architect in January to plan the design of the project, the way to construct it and the budget for this. So, I need to be the more accurate as possible in my requirements and objectives for this room within a room.
I post my project here and share it to you because I have a lot of questions regarding studio designs and soundproofing processes. I'd like to discuss with you about this project and the realistic requirements and objectives that I can come with for the pre-project with the architect. And to resolve some of my misunderstanding of “soundproofing” concepts.
Objectives and environment
This studio room will be used to rehearse and recording/mixing (for preprod uses) live bands (drums, bass, guitars, voices, average level of noise : 110 – 120 db). The budget I can have for this project is 15k€.
The house is located in a houses neighboorhood with two streets (level of noise outside in daytime : 50db). The basement walls are underground/below grade with the fourth wall (at right)being common with my neighbours' basement. The environment sound level in my basement without noise (washing machine, etc,...) is around 30-35db (measured by iphone app...). With the washing machine on, it rises to 55db. The sound level in the neighbour's house is approximative because I won't be able to do measurements in... because of bad relationship with my neighbours...
Assuming I don't want to annoy my neighbours in their house (especially their living room), can we say the sound level in their basement should not rise over 35db ?
Here's some views (the red area labelled 110 db is where I plan to build the studio in the basement) :
Here's the existing top view of the basement:
The red line is the delimited space for the studio (room in a room).
The space is limited by:
_ the well. It will stay in place. It's a 4,5m concrete hole where there's 3m of water. It is used to drain the foundation. I've never noticed any water coming in the basement floor and it is safe. Architect and mason confirmed it.
_ the ducting and the pipes that go to the ground floor through the basement's ceiling. The gas pipe and the heating water pipe paths are quite weird and need to be moved away. They go through the middle wall by 2 holes. This should be useful for the HVAC system and the electrical installation.
The basement window (in the bottom wall) will be closed and could be used for the HVAC system design.
So the global idea to keep the area free for this “room in a room” little studio is:
_ move the ductings. Use the remaining holes in the wall for HVAC/electrical paths ?
_ knock down the 10 cm concrete block wall partition.
_ break a part of the 8 cm concrete slab.
_ remove interlocking concrete pavers.
_ dig 30-40 cm off the ground to have height from 2,1m to 2,4-2,5m. Regarding the height, the mason and architect tell me I could dig 40-50 cm high off of the soil without any risks to damage the building structures of the house.
Here's a more detailed picture for the foundation and new ground level:
And here's the project global view:
Dimensions are (LxWxH in cm) 480x380x(250-260).
I'm currently trying to figure out what is the best design and how to define some requirements. So, let's do the calculations using some math from Rod Gervais and/or Marshall Long. (Please let me know if I'm wrong).
First, I want to now the sound transmission loss in the 55 cm limestone common wall:
_resonant fundamental frequency for a single panel: fr = 0,45*vl*h*((1/L)² + (1/H)²)
where, h is the thickness of the panel (m),
L its length (m),
H its height (m),
vl (m/s), the longitudinal velocity of sound in the partition
vl = (E/pm*(1-s²))^(1/2)
E is Young's Modulus in (N/m²) or Gpa or Mpa
pm is the density in (kg/m3)
s is Poisson's ratio (0,2-0,3) in construction material
In my case,
_ h = 0,55m, L= 7,4m, H = 2,1m,
_ vl = [2553 – 2054] m/s where
pm for limestone is between [1800-2780] kg/m3
E = 11.10^9
s = 0,3
_ fr = [154 – 124] Hz
_ the critical frequency about bending waves and coincidence effect (from Rod Gervais);
fcr = c0^2/(1,8*h*vl)
where, c0, speed of sound = 344m/s
So, fcr = [46 – 58] Hz
Why fr is much higher than fcr since fr is the fundamental frequency ? Shouldn't it be the opposite way ?
If I refer to the mass law formula,
_ at fr, TL = 20*log(fr*m) – 47 (db), where m is the surface mass density in kg/m²
TL = [46 – 51] db, for limestone where density is between [1800 – 2780] kg/m3
_ at fcr, I read the formula in Marshall Long book but it's too far for my math skills...
About the minimum amount of insulation requirements:
_ if L0 is the level of sound in the red room, L0 = 115db
_ L1 the level of sound in my basement
_ L2 the level of sound in my neighbours basement (max 35 db)
_ T1, the transmission loss between the red room and the basement
_ T2, the transmission loss between my basement and the neighbours basement.
_ L1 = L0 – T1 and L2 = L1 – T2 (and T2 = TL)
→ L2 = L0 – T1 – T2, so T1 = L0 – L2 – T2:
T1 = 115 – 35 – [46 – 51] = [34 – 29] db.
Is it right ? And is it correct to say that I need to achieve a minimum of insulation with a transmission loss of [29 – 34] db for the red room ? (IMO, it's too low for the goal I want to achieve)
I consider 3 options for the main design of this room in a room and asking myself a lot of questions to know which one to choose (with the correct calculated data to make decisions and compromises with my budget):
(the door will be installed in front of the common wall. I'm aware this part of the room with the door will be the weaker part and where I need to put all the effort in designing and building).
After reading a lot of thread and just to be sure, can you confirm me that:
_ option 3 is a kind of triple leaf MSMSM system and this can be worse for my sound insulation. Moreover the building of this can be very complex (inside out ceiling,...).
_ option 2 looks like the best option but, is the new partition wall, the inner leaf and the common wall would act as a triple leaf wall?
_ option 1 is the less expensive one and allowing the more space but... Since I'm not sure at all about my calculations, I don't know how to mae the right decision...
For example with option 1:
_ for the 3 existing walls and the wood studs facing them:
The resonant frequency for double panels for MSM systems:
fr = 84*((1/d)(1/m1+1/m2))^0,5
where d the distance between panels, m1 the surface mass density of 1st panel, m2,...
d = 0,25 m because of the 10 cm of foundation wall, a gap of +/- 5 cm to the concrete (or wood) floor and 10 cm long wood stud):
m1 = [1800 – 2780]*0,55 = [990 – 1529] kg/m²
m2 = 24 kg/m² (2 layers of gypsumboard)
→ fr = 34 Hz
f < fr, TL = 20log (f*M) – 47, where M is the mass surface density of the entire construction: TL(f=fr) = 47,4 db
f > fr, TL = TL1 + TL2 + 20log(f*d) – 29
TL (f=63 Hz) = 158 db !!!!
_ for the remaining partition
d = 2,3m then
→ fr = 2,3 Hz !!!
f < fr, TL (f=fr) = 24 db
f > fr, TL = TL1 + TL2 + 20log(f*d) – 29
TL (f=63 Hz) = 177 db !!!!
These results sounds really weird and I should miss something... And that's where I'm stucked...
I don't think yet about HVAC because I'd like to know first which design of the room in a room I need.
I compile here my questions and others thoughts about my project to summarize it a bit:
Global:
Assuming I don't want to annoy my neighbours in their house (especially their living room), can we say the sound level in their basement should not rise over 35db ? So, does it mean I can have an acceptable sound level in my basement between 55 – 60 db?
About MSM systems and calculations formulas:
Why fr is much higher than fcr since fr is the fundamental frequency ? Shouldn't it be the opposite way ?
Is it right ? And is it correct to say that I need to achieve a minimum of insulation with a transmission loss of [29 – 34] db for the red room ? (IMO, it's too low for the goal I want to achieve)
Option 2 looks like the best option but, is the new partition wall, the inner leaf and the common wall would act as a triple leaf wall?
About construction:
_ For the new floor, I hesitate to ask the architect for a new concrete slab. She said to me that we could think about the solution of having prefab concrete little slabs using them as foundation for a wood floor. I'm not sure if we talk about putting the wood frame on it or not and this floor subject was just an informative talking, no decisions were made about it now.
_ I will have to put a new coating on the walls because the coating was made with concrete and the masonry stones in the basement require a “breathable” coating. I read that having a coating make transmission loss higher than without it. Should I put insulation on it (and how to not damage the walls or the insulation for the future) or to the wood studs' side? The kind of stones the basement is made of, need to “breathe” and act as the opposite of concrete regzarding water paths.
_ What would be the minimum recommended space between foundation wall and new floor to hope having a good decoupling between the new room and the existing structure?
Supplementary notes:
_ The main goal is to be able to make a compromise with budget/reachable objectives/design/building to bring with me accurate requirements for the architect preproject appointment.
_ First is to determine the sound transmission loss in the common wall and in the basement (resonant frequency and critical frequency as well). This will conduct me to choose for a particular type of design: the room in a room (and even more questions about the MSM system).
_ According to the acoustics math formulas, I'm trying to determine what would be the best option to reach the objective of the required sound transmission loss level. This is where I'm a bit confused. For my calculations in Option 3, I don't know if I need to use the triple leaf theory with the stone wall or use the double leaf theory first for the double wall studs and then use it again with double wall system and the stone wall. The same for options 2 with the double wall facing the common wall.
_ In my case, I think the weaker part of this MSM system will be the part of the room that will face the common wall and that have the door. The building of this will have a particular attention.
I hope I don't miss anything and that you would be able to give me some help and advices about my project. Please let me now if I miss details. I'm facing some confusion about the calculations in acoustics domain and I think I misunderstood some general concept. Especially for the MSM system and the triple leaf effect...
And I apologize if I made some mistakes in English. It's not my native language and it's quite difficult to try to explain a technical context without knowing all the vocabulary of construction.
Best regards