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Should drywall used in a ceiling be of a different weight/grade than drywall used in walls?

We are demoing a closet this weekend, and will need to repair the remaining drywall in a few places.

  • Is this an apartment, a condo, or single family home? If it is a condo or apartment, it needs to be fire rated, if it is a single family home there is no specific requirement – Jack Feb 7 '15 at 2:08
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First you need to figure out if the ceilings are considered a firewall. If they are they must be 5/8 inch type X.

If not I would suggest one of the two:

  • 1/2" gypsum ceiling board - ceiling board is simply drywall rated to have less sag and less pulling properties. This is normally what we use on jobs. It is not always available at big box in all lengths but we usually find it. And then you can always order it and they will deliver. See this PDF to compare ceiling board to regular wall board.

  • 1/2" lightweight wallboard. This is your stock lightweight drywall. Given its light weight it will have less sag and pop out issues.

I would never use anything less than a half inch. It just bends too much. Given that there is more flex during your install could cause issues down the road at the seams.

  • "Firewall" has a very specific technical meaning because firewalls divide a structure into two buildings. That's serious business...as serious as it gets in terms of rated construction. As such, firewalls can only run vertically [they are walls]. Various fire ratings can be achieved for horizontal assemblies using standard gypsum board in lieu of type 'X'. Many building codes list prescriptive construction which meets the requirements. – ben rudgers Feb 7 '15 at 0:42
  • @benrudgers I've seen fire rated drywall needed for ceilings when there's an undivided attic above, in a utility room, and I suspect it's also used in garages depending on the local code and floor plan. This is mostly a concern for multi-unit dwellings. – BMitch Jul 10 '15 at 2:40
  • @BMitch All gypsum board affords fire protection because it is non-combustible and has a low heat conductance. Type 'x' affords more per fire protection per unit thickness than normal gypsum board and at scale this reduces materials and labor. International Residential Code for one and two family dwellings, prescribes methods of achieving fire resistance rather than specifying assembly ratings. Nevertheless fire resistance is an area of code concern even in single family dwellings. – ben rudgers Jul 10 '15 at 15:53
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Depends on the ceiling/wall function. In most cases for repairs you want to replicate what was there, unless you are ripping the entire wall/ceiling or it's too hard to track down matching replacement drywall.

If the wall/ceiling is a firewall, you normally need to replace the structure that was there, which may be double-layer 5/8 type X ("firecode") gypsum. I prefer it for ceiling applications anyway (single layer where double-layer is not needed), as it's far less prone to sag than the thinner grades. It's also heavier, which you may not be fond of - and it is sometimes used on "acoustic" walls for that reason.

I've dealt with old walls that use as little as 1/4" drywall. 1/2" is what's normal/standard in new construction - 1/4 and 3/8 may be available from a supplier but I would only use those for repairs of a wall starting with that thickness where replacing the whole wall doesn't make more sense.

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My home has a mix of 1/2 and 5/8 drywall on the ceiling and it is completely related to the spacing of the ceiling joists. If they are 16 on center, the builder used 1/2. If they are wider than 16, then they used 5/8. The 5/8 will prevent sagging between wider ceiling joists.

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If one can afford, I would recommend go for the best - protection, performance and build quality of your home. If it was my own home, where I wish to live for a long time, I would get it built with the finest material. Using a 5/8" drywall makes sense in so many ways, so go with the best available, after all you don't rip drywall now and then. Once installed, follow the manufacturer's guidelines as to how it needs to be finished if you want that excellence in paint finish etc. Thank you

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