Design Weight of Acoustical Plaster

[JAE]

We have a project from the 1960's where we are checking the roof joists for added mechanical units.

In trying to determine the roof dead loads we have a situation where the original plans (and the current condition) call out a ceilng of 1 1/8" Acoustical Plaster on Metal Lath .

We typically assign about 8 psf for 3/4" lath and metal plaster ceilings.

But having trouble finding information on 1960's era "Acoustical Plaster".

Does anyone have any information on this? Some online searches suggest a lighter density than typical plaster but no direct values.


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[Ron247]

I have no idea about plaster that old. The only acoustical plaster I dealt with weighed about 3 psf or less. That weight did not include the metal lath. Look at "USG® Acoustical Plaster Finish" to see if it is similar. I would assume older stuff would weight more though.

 

[WARose]

One source I have puts it at 9 lb/ft² surface weight per 1 in. thickness. But that is for "dense" plaster. For acoustic/lightweight stuff, I'm use to seeing about half that.