For decades, plaster ceilings have been suspended using 1-1/2” and 3/4” channel. The 1-1/2” is suspended from the deck, beams, or joists using 8ga. hanger wire and is usually spaced around 3’oc. I say usually because the spacing must be changed based on the span and the weight of the ceiling to be suspended from it. The 3/4” channel is then wire-tied to the 1-1/2” channel at a spacing determined again by the ceiling to be hung from it. These spacings are dependent on each other and the spacing of the members from which they are to be suspended. After the framing members are tied together, the metal lath is then tied to the 3/4” channel.
ASTM—C 1063 – 03 is the Standard Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster. Refer to it to find the specific spacing for your application.
“Standard” channel suspension system at the South campus Miami Valley Hospital.
As an option, a grid ceiling which is engineered for stucco and plaster have been developed. I will refer to the Armstrong system, although I am aware other manufacturers have systems which are similar.
The Armstrong Stucco/Plaster grid system has mains with routed slots at 13.5”oc so the cross tees snap together. This eliminates wire-tieing the channels together and it makes the spacing 100% accurate. The lath is then screw applied to the bottom face of the 1-1/2” tees. I recommend paper back lath so the thickness of the applied Stucco/Plaster is kept even. With standard suspension, paper-back lath cannot be used as the paper inhibits the ability to tie the lath to the channel.
“Snap-in” grid system used at the Franklin County Courthouse in Columbus, Ohio.
This exterior ceiling is 220’ above street level.
Note the studs laying on the framing - they will be put in as upright braces as part of the engineered uplift system. The carpenters are working off Hydro-lift mobile.
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