Plasterboard Question

JohnGardner · Post by **JohnGardner** » Wed Jul 21, 2004 7:39 am

Here in New Zealand 5/8"(16mm) plasterboard is really expensive compared to 2/8"(10mm)

the costs are:

10mm $16 per sheet 2.4x1.2m

16mm $50 per sheet 2.4x1.2m

I understand the thicker sheets are better for bass but:

Can use two sheets of 10mm in place of one sheet of 16mm, or three sheets of 10mm instead of two sheets of 16mm and expect approximatly the same isolation STC performance?

Thanks

JohnG

knightfly · Post by **knightfly** » Wed Jul 21, 2004 8:25 am

Calculation-wise, 3 sheets of 10mm is as good for bass as two sheets of 15mm, and the three thinner ones actually outdo the two thicker ones in the midrange by about 3 dB -

Only difference would be in the labor involved to do three layers instead of two - be sure and check the USG handbook and other stickies for how-to - you can use about half as many screws for all but the last layer and it will help isolation by a few dB... Steve

serge instrumental · Post by **serge instrumental** » Wed Jul 21, 2004 12:56 pm

So if I understand well, the less the screws, then "moore" is "unconnected" from the wall?(Xcuse my english this is not my native stuff)

knightfly · Post by **knightfly** » Wed Jul 21, 2004 3:20 pm

Yes, that's basically how it works - each screw causes a very slight loss of performance because it's a hard path through the wallboard and into the frame - as long as the two sides of the wall are isolated from each other by using either separate frames or some sort of resilient mounting, most of this transfer is absorbed by the insulation material that is placed inside the wall - however, the less screws you use to hold the wallboard onto the frame, the better the wall isolates sound.

If you take this too far, though, the wall will literally fall down. The practical limit is that you use half as many screws to mount all but the final layer of wallboard on the frame, then use the full recommended screw spacing for the top layer.

If you go to the USG download link at the top of the main Construction page, you will find that the entire USG gypsum installation manual is available in both English and Spanish - those are the only two languages I've seen that document in - I hope that helps... Steve