When installing drywall flat against a stud, there are two types of drywall joints, or seams, you can make: the butt joint or the tapered joint.
A joint is created when two pieces of drywall are placed next to each other and attached with drywall tape and compound.
- Defined: The edges of the two sheets of adjoining drywall have the same thickness as the rest of the drywall sheet.
- Example: If the sheet is 1/2 inch thick, the edges are also 1/2 inch thick.
- These edges are located on the 4 foot long ends of the drywall sheet.
- Defined: The edges of two sheets of adjoining drywall taper from the rest of the sheet's thickness to a reduced thickness.
- Example: If the sheet is 1/2 inch thick, these reduced thickness edges will be about 1/4 inch thick.
- These edges are located on the 8 foot long ends of the sheet.
Which to Choose
Whenever you have the choice, choose the tapered joint.
Tapered joints allow you to fill in the "valley" created by the tapers with drywall tape and drywall compound, thus creating a smooth, seam-free joint.
Butt joints will always produce a ridge. With careful application of compound and sanding, butt joints can be made to disappear.
Butt Joint Installation
The name "butt joint" comes from an installation process when two non-tapered sheets of drywall are "butted up" next to each other.
A thin coat of drywall compound is laid down, then drywall tape is embedded in the compound. Then another thin layer of compound is spread over the tape.
Tip: use a flat type of drywall tape such as ordinary paper tape or FibaTape Perfect Finish tape to avoid bulges after application of joint compound.
Making a Tapered Drywall Joint
If you look carefully at the long edge of drywall, you will notice that on each side there is a taper. It is nearly always preferable to choose the tapered joint over the butt joint in flat (i.e. not a corner) seam installation. This is because joint compound can be used to fill in the taper.
A drywall taper is formed when the tapered edges of two sheets of drywall are adjoined.
Together, the two tapers form a triangle. This triangle drywall taper will allow for drywall tape and joint compound to be filled in, without leaving any kind of bulge. Whenever possible, you should make tapered joints because the seam is nearly invisible.
Note that the drywall taper is only for flat installations, not corner installations.
Filling the Tapered Drywall Joint
The tapered drywall joint results in nearly invisible seams because the mudding compound perfectly fits in the "valley" and does not rise above the level of the drywall facing.
With the tapered drywall joint, you can even use a stronger type of tape, such as mesh fiberglass drywall tape. You would not want to use fiberglass mesh on butt joints because it is fairly thick and will result in bulges.