I want to replace the fiber tiles with drywall. The ceiling is made up of 2x2 16 on center, I plan to use 12' long pieces less seams. What thickness of drywall is safe to use. Thank you for any information you can provide.

  • 1
    You have 2x2 ceiling joists? Are you sure? Or are you talking about 2x2 furring?
    – Huesmann
    Commented Jan 21 at 19:35
  • 1
    Is that 2x2 furings on ceiling joists?
    – crip659
    Commented Jan 21 at 19:35
  • If they are ceiling ‘joists’ (as opposed to perpendicular furring), what’s the clear span? Commented Jan 21 at 20:44
  • And if you specified the size of the ceiling, we could offer opinions about 12’ vs 8’ sheets. Commented Jan 21 at 20:45

1 Answer 1


ASTM C840 specifies about everything for by-the-book drywall. For 16" support spacing and insulation supported by the drywall, Table 2 prescribes a minimum thickness of 1/2". Without insulation supported by the drywall, it's 3/8" minimum thickness. The long edge of the drywall sheets must run perpendicular to the support framing.

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