The direction of the drywall can mean the difference between a beautiful finished home and one with sagging ceilings and obvious wall seams.
Walls: Vertical or Horizontal?
Is the job commercial or residential?
Commercial: Hang the drywall vertically. On commercial jobs, fire codes often require seams to fall on the entire length of the framing, so the drywall must be hung vertically.
Residential: How high are the walls? For walls nine feet high or shorter, hanging the drywall horizontally has a number of benefits.
- Fewer seams – Horizontal hanging reduces the lineal footage of seams by about 25%. Keeping the footage of seams to a minimum will result in less taping and a better looking finished job.
- Hides uneven studs – Hanging horizontally also allows the drywall to flow over the framing so that bowed studs create less of a problem. If the drywall were hung vertically and a seam placed on a bowed out stud, the seam would be magnified because of the bump in the wall.
- Easier to finish – A horizontal seam 48 inches or 54 inches off the floor is easier to finish uniformly, especially when compared to a vertical seam, which requires reaching up high and bending down low to finish. Also, don’t forget that drywall is available in long lengths so most walls can be covered in one length. CertainTeed Gypsum has drywall in lengths up to 16 feet and 54 inches wide to accommodate walls that are nine feet high.
Ceilings: Perpendicular or Parallel?
Most often I choose to hang the drywall on ceilings perpendicular to the joists. Yes, we are always trying to avoid butted seams, but an occasional butt seam is better than a ridged seam running the length of the ceiling, or sagged drywall between joists. Hanging drywall perpendicular to the overhead framing members is a good idea for several reasons:
- Less visible seams – A perpendicular orientation allows each sheet of drywall to float over the framing members, making uneven joists or trusses blend in. If the on center spacing of the framing is off when the drywall is hung perpendicular, then the panel is simply cut back to the prior framing member, which would not be possible when hanging drywall parallel.
- Structural strength – Drywall is typically stronger when hung in the long direction than it is in the short direction, which means less chance of sagging when attached perpendicular.
Exceptions to the Rule
I’m often tempted to hang drywall parallel if that is the shorter dimension of the ceiling, and in doing so would result in no butted seams on that ceiling. This can be done as long as the following conditions are met:
- The type of drywall being used is approved for that on center spacing when hung parallel.
- The ceiling joists are accurately spaced.
- Heavy insulation will not be installed later, since that could cause the drywall to sag, or even fail.
Regular half inch drywall ceilings can be hung perpendicular if joists are spaced 24 inches or less apart (*always refer to local codes). If hung parallel, the maximum spacing is 16 inches on center. These framing spacings are only acceptable for half inch regular board when no water-based textures are being applied to the ceiling. If water-based textures are being applied to the ceiling, then half inch interior ceiling board or half inch lightweight drywall, such as CertainTeed® Easi-Lite™, is required. The lightweight drywall panels meet the same performance standards as interior ceiling boards as they are more resistant to sagging.
Don’t Forget to Account for Insulation
An often overlooked factor is the insulation in the ceiling. Always consider the weight of the insulation: half inch regular drywall can support 1.6 lbs. per sq. ft.; half inch lightweight wallboard and half inch interior ceiling board can support up to 2.2 lbs. per sq. ft. For reference, blown-in fiberglass insulation is approximately 0.8 lbs. per sq. ft. for an R-49 insulation value, while loose fill cellulose is a little over 2 lbs. per sq. ft. for an R-49 value.
Build walls that matter with CertainTeed Gypsum Wall-to-Wall solutions, including AirRenew® drywall for healthy homes and SilentFX® QuickCut noise reducing drywall. For complete product information, visit CertainTeed.com/WallsMatter.