Knauf is enough........

Hi, Looking for some more advice on my project build.. Can you tell me if Knauf Rocksilk would be good enough? I want to use the product for; 1. Insulation for the stud walls and between floor joists 2. Use the material for bass hangers behind the walls 3. Use the product to make my own DIY bass traps (use 2 or 3 slabs together to make a 4" or 6" bass traps) I know from searching the forum that the "pink fluffy stuff" is not really good enough.. From the information on the label and the web site it looks like the product I bought is Rocksilk Flexible Slab RS33. Web site link http://www.knaufinsulation.co.uk/products/rocksilk_slabs/rocksilk_universal_slab.aspx I found the product at my local hardware store (B&Q) and costs 50 Euro (approx 40GBP or 80USD) for 10 slabs of 1200mm x 600mm x 50mm The web site also shows RS45, RS60, RS80 and RS100. Is there much of a difference? I can only see that the RS33 has a Thermal conductivity of 0.037 and a Thermal resistance of 1.35 for the 50mm thick slab, the RS45, RS60, RS80 and RS100 all have a Thermal conductivity of 0.035 and a Thermal resistance of 1.40 for a 50mm slab? What do you think? Paul

check Bob Golds absorption coefficient page for comparative values but generally you want 48kg/m3.

Thank you Glenn, I checked out Bob Golds page and found a link for absorbtion data but the link would not work for me. I then found the following link regarding the Knauf Rocksilk on a datasheet on their web site. http://www.knaufinsulation.co.uk/PDF/Datasheet%20-%20Rocksilk%20Universal%20Slab%20Feb%2007%20RD86107.pdf Quote from the site,

Rocksilk Universal Slabs are unfaced, rock mineral wool slabs, available in a range of densities from 33 to 200 kg/m3

I'm taking it that the number in their product code refers to the kg/m3 density Example - RS33 = 33 kg/m3, RS60 = 60kg/m3 all the way up to their RS200 = 200kg/m3 I'll give their technical team a call tomorrow to confirm. Thanks again for your help, Regards, Paul

prkm123 wrote:

Rocksilk Universal Slabs are unfaced, rock mineral wool slabs, available in a range of densities from 33 to 200 kg/m3

I'm taking it that the number in their product code refers to the kg/m3 density Example - RS33 = 33 kg/m3, RS60 = 60kg/m3 all the way up to their RS200 = 200kg/m3

Yes, your assumption looks correct. Many European manufacturers use a similar scheme with the kg/m3 in their name, afaik. Most slabs of the same density and thickness are more or less comparable when it comes to absorption (the difference is usually only minor and not possible to hear).

Yeah your right. i used RS80 on my build and emailed knauf to enquire the RS80 = 80kg/m3

Hi Guy's Thanks for the reply's.. medboyle How much did it cost you for the RS80? Do you buy the 50mm size? From B&Q? Regards, Paul

Hi, I used the Universal Slab Rs80 and went for 60mm Thickness. I got it at cost price as i pulled in a few favours i was due so i was paying £13 sterling a pack but it retails at about £35 sterling. Here's a link to the page on the Knauf website http://www.knaufinsulation.co.uk/products/rocksilk_slabs/rocksilk_universal_slab.aspx Cheers Alan

Thanks Alan, Is there any difference between the Rocksilk Universal Slab and the Rocksilk Flexible Slab? It looks like the only difference is that the Flexible Slab only comes in 33kg/m3. Where there are more density options with the Universal Slab. Paul