ᐅ Sound Insulation: What Thickness for Cavity Wall Insulation on Interior Walls?
Created on: 9 Jul 2018 16:26
D
Don_Mikele87
Hello everyone,
Today, I want to discuss sound insulation. We are currently building the walls for our single-family house in cooperation with a local carpenter. There are some differences of opinion between our architect and the craftsman regarding the insulation of the interior walls:
The wall structure is as follows (from left to right):
12.5 mm (0.5 inch) gypsum board
15 mm (0.6 inch) OSB
120 mm (4.7 inches) wooden studs including cavity insulation
15 mm (0.6 inch) OSB
12.5 mm (0.5 inch) gypsum board
Mineral wool is being used as insulation.
The issue:
The carpenter wants to fill the cavity completely with 120 mm (4.7 inches) thick insulation, meaning the full depth of the stud. According to the architect, however, for better soundproofing, it’s preferable to fill the cavity only partially, with 40-60 mm (1.6-2.4 inches) max.
As a layperson, I’m caught in the middle and trying to understand the situation. Searching online yields varying arguments:
1. In favor of 40-60 mm: insulation that doesn’t fully connect both walls, leaving an air gap, absorbs sound better from an acoustic standpoint.
2. In favor of 120 mm: more insulation means more mass; more mass absorbs sound better.
Are there any experts who can confirm or refute either position? Any personal experiences? This question is solely about the thickness of the cavity insulation, not about other soundproofing measures such as vibration-free suspensions, etc.
Thank you in advance!
Today, I want to discuss sound insulation. We are currently building the walls for our single-family house in cooperation with a local carpenter. There are some differences of opinion between our architect and the craftsman regarding the insulation of the interior walls:
The wall structure is as follows (from left to right):
12.5 mm (0.5 inch) gypsum board
15 mm (0.6 inch) OSB
120 mm (4.7 inches) wooden studs including cavity insulation
15 mm (0.6 inch) OSB
12.5 mm (0.5 inch) gypsum board
Mineral wool is being used as insulation.
The issue:
The carpenter wants to fill the cavity completely with 120 mm (4.7 inches) thick insulation, meaning the full depth of the stud. According to the architect, however, for better soundproofing, it’s preferable to fill the cavity only partially, with 40-60 mm (1.6-2.4 inches) max.
As a layperson, I’m caught in the middle and trying to understand the situation. Searching online yields varying arguments:
1. In favor of 40-60 mm: insulation that doesn’t fully connect both walls, leaving an air gap, absorbs sound better from an acoustic standpoint.
2. In favor of 120 mm: more insulation means more mass; more mass absorbs sound better.
Are there any experts who can confirm or refute either position? Any personal experiences? This question is solely about the thickness of the cavity insulation, not about other soundproofing measures such as vibration-free suspensions, etc.
Thank you in advance!
D
Don_Mikele8712 Jul 2018 20:26Regarding decoupling the ceiling joists, I will speak with the carpenter tomorrow. The ceiling assembly is as follows (from bottom to top):
- 12.5 mm drywall
- 15 mm OSB
- 50 mm battens (installation space)
- wooden beam ceiling
- cavity insulation between the studs
- 22 mm OSB
- 20 mm thermal insulation
- 35 mm impact sound mineral fiber insulation
- PE foil
- 65 mm screed
If the joists need to be decoupled from the load-bearing wall, wouldn’t the 22 mm OSB also need to be decoupled with sealing tape? Or not, since that would create a cavity?
The interior walls will be double-layered anyway – on the studs, 15 mm OSB plus 12.5 mm drywall.
For the exterior walls, a 15 mm OSB panel attached to the studs on the inside will have a 6 cm installation space added behind it. This will also be double-layered – first OSB, then drywall. I’m not sure yet whether the installation space will be insulated. Too much insulation can sometimes cause moisture issues. I will also need to discuss this with the carpenter.
- 12.5 mm drywall
- 15 mm OSB
- 50 mm battens (installation space)
- wooden beam ceiling
- cavity insulation between the studs
- 22 mm OSB
- 20 mm thermal insulation
- 35 mm impact sound mineral fiber insulation
- PE foil
- 65 mm screed
If the joists need to be decoupled from the load-bearing wall, wouldn’t the 22 mm OSB also need to be decoupled with sealing tape? Or not, since that would create a cavity?
The interior walls will be double-layered anyway – on the studs, 15 mm OSB plus 12.5 mm drywall.
For the exterior walls, a 15 mm OSB panel attached to the studs on the inside will have a 6 cm installation space added behind it. This will also be double-layered – first OSB, then drywall. I’m not sure yet whether the installation space will be insulated. Too much insulation can sometimes cause moisture issues. I will also need to discuss this with the carpenter.
Hello, so in our case the installation layer on the exterior walls is also insulated, and otherwise we have similar wall and ceiling constructions.
We have been living in the house since early March, and acoustically we have no complaints. Of course, everyone perceives noise differently, but we have really active boys and we simply enjoy the “quiet” in the house.
We have been living in the house since early March, and acoustically we have no complaints. Of course, everyone perceives noise differently, but we have really active boys and we simply enjoy the “quiet” in the house.
D
Don_Mikele8713 Jul 2018 09:11Do you possibly have some details? How and where was it decoupled? Especially in the ceiling area?..
Don_Mikele87 schrieb:
- 15 mm OSB (0.6 inch)
- 50 mm battens (installation layer) (2 inches)
- Timber beam ceilingHow is the connection between the OSB and battens, as well as between the battens and cross beams, constructed? Is there a tongue-and-groove rail or suspension system in between? I would personally prefer it that way.Hi, sorry for the delay.
In the granny flat, the drywall sheets are screwed onto spring clips instead of battens (don’t ask me exactly what they were called). You don’t hear anything from the guys there, unless they’re doing sack races or something like that.
Since we still had some of the rubber underlays left, we placed them under the battens in the living room and kitchen. The drywall sheets on the walls were also pulled up and insulated all the way to the top.
The drywall sheets were fixed normally with screws, and no special attention was given to the joints.
In the granny flat, the drywall sheets are screwed onto spring clips instead of battens (don’t ask me exactly what they were called). You don’t hear anything from the guys there, unless they’re doing sack races or something like that.
Since we still had some of the rubber underlays left, we placed them under the battens in the living room and kitchen. The drywall sheets on the walls were also pulled up and insulated all the way to the top.
The drywall sheets were fixed normally with screws, and no special attention was given to the joints.
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