View Single Post
Old 24th June 2020
  #1
Here for the gear
 

Help understanding whether thickness of material affects GFR?

Hi,
Bit of a noobie question here, planning out my first DIY acoustic treatment project. Attached is an image I found on this forum that's shown up in a few threads which shows the GFR numbers published for each of Knauf Earthwool's products.
I'm just trying to make sense of the difference in GFR for the products that seem to only differ in thickness. It was my understanding GFR is irrespective of the material's thickness? For example if the product reports a GFR of 9000 MKS Rayls at 50mm, would it not still be 9000 at 100mm?
In this chart I'm also seeing the 14kg/m3 Ultra Acoustic Wall batt in the 50mm thickness has a higher value (14500) than the 75mm thickness variant (12400). Perhaps someone got the numbers mixed around.

Apologies if this is a tiring subject. I'm trying not to get overwhelmed by how much i'm reading, and how much different information I'm finding as well. I'm running the numbers into http://www.acousticmodelling.com/porous.php and I want to be sure whether varying the thickness of a given material (stacking layers of the insulation together for instance) affects the Pa.s/m2 value.
Attached Thumbnails
Help understanding whether thickness of material affects GFR?-earthwool_gfr.png