im hanging 4' x 8' x 5/8" firex type drywall on my garage ceiling and plan
to pump in 8-10" (max) of loose insulation on top of it.
rafters are 24" apart. am i good with 12" screw spacing to hold this up?
for a 4x8 sheet this basically puts 5 screws across the width, every 2'. or
25 screws for a whole board.
everything ive read seems to point to 12" spacing, and ive been told it
meets code. i just want to make sure before i pump the stuff in and watch
my ceiling fall due to the weight.
USG calls for 12" OC screws as maximum spacing. Don't be pennywise.
Go with 8" OC. It'll cost you an extra fifteen minutes of your time
and a few bucks for the screws.
USG also "strongly" recommends double-nailing ceilings to prevent pops,
but does not require double-screwing.
The 5/8" board is maxed out with joist at 24" OC if run perpendicular -
if you run it parallel, it's only good for 16" joist spacing. You
could go with the 1/2" sag-resistant ceiling board - good for 24" joist
spacing either way, and you'd save some of the weight. I'd contact USG
and ask their recommendation on which board to use with that much
but why is there such a discrepancy? my local inspector told me that 12"
centers is good enough for up to 12" of blown in insulation on top of the
5/8 firex. code normally has some fudge factor built into it... if code
says x is enough, why does everyone seem to suggest using x+1?
have you seen an actual failure when someone used 12" spacing?
i mean you don run 10 gauge wire when 12 will do, just to stop from being
pennywise... you dont make fishing poles out or rebar either...
ah man. now i remember why i unsubscribed before.....
come on richard. why 8 inches? you got any info about the structural
strength of sheetrock that i cant find on the back of a cereal box?
anybody? buhler? buhler?
Spanning 24" with 5/8 sheetrock seems a little far.
I'd me more concerned about the 24" than the 12" screw spacing
not necessarily, code making involves a fair amount of compromise & is
very dependent on the personalites invloved, some times it's just
worng, some times un-conservative, some times overly conservative
because "the code is a minimum standard"........kinda like a doctor
who just barely passed med school.
For example, the allowable joist spans (esp for long spans) will yield
a floor that, for many people, is jsut too bouncy, but it's code. A
Put the extra screws in, you'll be glad you did. hink about about it,
if a screw fails the closest screws in one direction is 24" away, in
the other 12".
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