Best Practices for Drywall Layout
The general concept of drywall hanging is very simple. The goal is to cover all metal or wood studs with sheets of gypsum panels. It can be likened somewhat to sheathing the exterior of a building using plywood or other exterior sheathing panel. However, the pattern in which sheets of drywall are laid-out on the studs is very important for at least the following two reasons. First, properly laid-out drywall is easier to tape and finish and second, it is stronger and better at resisting cracking at the seams. What are some things to consider when planning the laying-out of drywall before installation?
1 - Bound Edges should pair with Bound-Edges and Butts with Butts
The bound edge is the long edge of a sheet of drywall. The drywall paper continues along the front of the sheet and wraps over the edge to overlap with the paper from the back side of the sheet of drywall. Thus the edge is bound together with drywall paper instead of leaving the gypsum exposed.
Approximately 3 inches from a bound edge, the drywall thickness decreases slightly on the face of the sheet so that the final few inches of a bound edge are approximately 1⁄16 of an inch thinner than the rest of the sheet. This means that when two bound edges meet, they create a trough slightly below the surface of the rest of the sheet of drywall. This means that when taping a bound edge seam, the tape rests in the trough of two bound edges. Even after it is coated with drywall mud to smooth over the tape, the finished surface of a seam rises to just about the same plane as the rest of the sheet of drywall. By keeping bound edges paired with bound edges, taping and feathering seams is much easier.
A Drywall butt is the short edge of a sheet of drywall where the paper does not wrap around the edge. The gypsum within is exposed. Unlike on a bound edge, the drywall thickness does not change as it approaches the edge. Therefore, when paper tape is applied to the seam of two drywall butts, it rises above the surface of the surrounding drywall. Tapers must be careful not to put too much mud over the surface of paper on drywall butts while feathering out the seam to match the plane of the field of a sheet of drywall.
When a drywall butt is hung paired next to a bound edge, this creates two uneven surfaces. The bound edge is at least 1⁄16 of an inch lower than the butt and therefore, taping and finishing is much more difficult. Professional tapers are able to feather the joint so that it is nearly level with the surrounding surface; however it requires more coats and extreme care to create a flawless joint. Therefore, the first thing to consider when laying-out drywall is to keep the bound edges paired with bound edges and the drywall butts paired with drywall butts.
2 - Hang Drywall Sheets Perpendicular to Studs
Do describe this point we will speak specifically about walls however the principles carry over to ceilings and soffits. Wall studs whether metal or wood, are framed perpendicular to the floor. When hanging over wooden studs, sheets of drywall should always be hung perpendicular to the direction of the studs. Metal studs allow for a degree of flexibility in this regard however the principle holds true in many cases with metal stud construction as well.
Take for example a room with a ceiling height of eight feet. The simple thing may appear to be to take an eight foot sheet of drywall and stand it up length-ways so that one sheet reaches from ceiling to floor. Working from left to right sheets would be hung one next to another. This would limit the number of butt seams however this type of layout should be avoided with wood stud construction.
What is wrong with hanging sheets parallel to wood studs? When drywall is hung parallel to the studs, the bound edges fall directly on a stud. Because wood studs are not perfectly strait, the bound edge may or may fall directly in the middle of the stud along the entire distance of the stud. Perhaps the top of the stud is curved slightly to the left and therefore the bound edge of the perfectly strait sheet of drywall will not follow the crooked stud and therefore not have sufficient backing. Other wood studs may be proud to the room and therefore the entire length of the seam will end up sticking out into the room. Either situation makes the drywall seam more difficult to tape and finish and compromises the strength of the joint.
Sheets that are hung perpendicular to the direction of studs create more even holding power across the entire wall. Seams that land directly on a stud have less cross sheet holding power and the chances of seams popping or cracking is increased. For this reason, when hanging drywall over wood studs, you should always lay them out "railroad style", or perpendicular to the direction of the studs.
As mentioned above, metal stud framing allows for more flexibility in the direction of sheet layout for the following reasons. First, Metal studs are perfectly strait and therefore if a bound edge lands on a stud, it is much easier to ensure that it falls along the entire length of the stud evenly and has sufficient backing throughout. Second, metal stud framing is generally used in commercial construction therefore the entire structures have more consideration given to expansion and contraction. If drywall is going to crack in a commercial job, it is probably because of forces beyond the help of the layout of the sheets of drywall. In commercial building with suspended ceilings at heights of under 12 feet, drywall is often stood up lengthwise parallel to the direction of the studs because this creates a situation with almost no butt joints. This is usually fine considering the factors of commercial construction.
3 - Stager the Butt Joints
Drywall butt joints should always be staggered. This makes it easier for taping and finishing and increases the overall strength of the entire wall. When hanging drywall over wood studs and laying the sheets out "railroad style" or lengthwise across the direction of the studs, it is almost impossible to avoid butt joints at some points along the wall. However by planning where butt joints will land you can improve the quality of the finish job and long-term holding power.
Take for example a wall with an eight foot ceilings height and a length of 13 feet. If you are using 12 foot long sheets of drywall, one sheet will not cover the distance from wall to wall. The first sheet should be hung flush with the ceiling starting from the left hand side of the wall. Depending on how the studs are laid-out, it will stop about 16-24 inches, from the right hand side of the wall. This 16-24 inch section can be filled in with a small sheet of drywall. The lower sheet will be hung flush with the bottom of the first sheet and should be hung flush with the right hand side of the wall leaving the remaining section to be filled in with a small piece of drywall on the left hand side of the wall. This leaves one butt joint at the upper right hand and one on the lower left hand end of the wall.
The butt joints of a wall are generally one of the weaker areas that are prone to cracking. By staggering the butt joints, you limit them to no more than 4 feet long and therefore decrease the chance of cracking when settling. This same principle of staggering the sheets applies to ceilings and commercial steel stud framing where the ceiling height requires several sheets stacked on top of each other.
4 - Ceiling to Floor and Left to Right
This principle is less important for the strength of the finished product but it does make for an easier tape and finish job. In rooms that have a drywall ceiling, the ceiling should always be the first thing that is hung. By hanging the ceiling before the walls, the wall sheets will butt up flush along the edges of the ceiling and hold the ceiling sheets in place. Primarily, this makes the joints at the ceiling angles tighter and easier to finish.
Once the ceilings (lids) are hung, the walls can be hung starting from the ceiling down. This helps keep the ceiling angle tight and easier to finish. Walls should generally be hung from either left to right or right to left. Doing this, the first wall can be measured 1⁄4 of an inch short which allows the installation to be much easier. The sheets on the second wall will hide the edges of the sheets of drywall on the first wall and you will have a very tight corner between the first and second wall.. The sheets on the third wall hide the edges on the second wall and the only wall that must be measured tightly is the fourth or final wall. The final sheet must be measured exactly to fit between the first and third wall so that both inside corners are nice and tight.
When hanging drywall in rooms with suspended ceilings the top to bottom rule is not necessary since the top sheet will be hidden behind the drop-ceiling. However the principle of hanging left to right is still good to follow. By keeping this principle in mind when laying out drywall it helps you to create the tightest seams and corners at all critical parts of the wall.