What are the different types of plasterboard joint?
The way in which jointing tape is used varies slightly depending upon the type of plasterboard joint being worked upon. There are four types of joint: tapered joints, butt joints, internal corners and external corners.
Plasterboard is manufactured with either square edges or tapered edges. Whether or not a plasterboard sheet has tapered edges determines the kind of joint that is created when it is installed.
Tapered joints occur where two long, tapered edges of plasterboard meet and a small ‘valley’ is formed.
As a result of the small dip created by the tapers which allows room for the tape and jointing compound, these joints can be more easily hidden.
Either paper joint tape or scrim tape can be used on tapered plasterboard joints.
For more information, see How to conceal tapered plasterboard joints with plasterboard joint tape.
Butt joints form when non-tapered edges are joined together.
As the edges of the plasterboard are square, this type of joint is not recessed like tapered joints so any tape or jointing compound applied to the joint will sit proud of the surface of the plasterboard.
This makes it more difficult to bridge the gap between the plasterboard sheets and conceal the seam.
Because it is thinner, paper jointing tape is recommended for butt joints as thicker scrim tape would create a more pronounced bulge at the join.
However, paper tape will still result in a slight bump and wider coats of jointing compound are required to cover this and give the appearance of a flat wall.
For more information, see How to hide butt joints with plasterboard joint tape.
Wonkee Donkee Tip: ‘If you are planning to skim- coat your wall, hiding the joints completely is not as important as it would be if you were taping and jointing.’
Internal Corner Joints
Joint tape is also used to reinforce corners, where two sections of plasterboard meet.
Internal corner joints appear either horizontally, along the top of the wall where it meets the ceiling, or vertically, connecting the floor and ceiling.
Paper tape is usually used to strengthen these joints because it can be more cleanly creased along its length.
This helps to keep it centred and straight against the inside of the corner.
External Corner Joints
External corners are approached differently to the other types of plasterboard joint.
Instead of jointing tape, either metal or plastic corner beading is secured to the joint with plasterboard screws.
To conceal corner beading, setting compound, which is stronger and harder when dry, is used, rather than ordinary jointing compound.
Walls with external corners are usually skim-coated before they are painted or wallpapered, as it can be difficult to effectively blend the beading into the plasterboard like you would jointing tape.