Corners are where amateur drywall work gives itself away — wavy edges, cracks, and dinged-up beads. Inside and outside corners each need a different technique, and both reward patience.
Two Kinds of Corners
Every room has two corner types. Inside corners are the concave 90-degree joints where two walls (or a wall and ceiling) meet inward. Outside corners are the convex edges that stick out — at a wall return, a window reveal, or a bulkhead.
Inside corners are finished with creased tape; outside corners are protected with a corner bead. Mixing up the methods is a recipe for cracks and chipped edges.
Corners also take more abuse than flat walls — vacuum cleaners, furniture, and foot traffic all find the outside edges — so getting the method right is about durability as much as looks.
A surprising amount of a room's perceived quality lives in its corners — crisp, plumb edges make the whole space feel custom-built, while wavy ones cheapen even an otherwise excellent finish.
Taping Inside Corners
Use paper tape for inside corners — its centre crease folds to a clean 90 degrees that mesh can't hold. Apply compound to both walls of the corner, fold the creased tape, press it into the joint, and run a corner trowel or knife to seat it and squeeze out excess mud.
The trick is to finish one side of the corner at a time on the following coats. Trying to coat both walls of an inside corner at once drags the knife through the wet mud on the adjacent side and ruins the edge.
A dedicated inside-corner trowel, which has a fixed 90-degree angle, seats both sides of the tape in one pass and is well worth owning if you're finishing more than a closet's worth of corners.
Outside Corners & Corner Bead
Outside corners take a corner bead — metal, vinyl, or paper-faced — to create a straight, impact-resistant edge. Metal bead is nailed or screwed on; paper-faced bead is bedded in compound and is popular for its dead-straight lines and crack resistance.
The bead's raised nose sets the finished plane. You build compound from the nose out onto each wall, feathering it flat, so the finished corner is crisp at the edge and invisible where it blends into the wall.
Paper-faced bead has largely won over many finishers because it resists the chips and dents that plague bare metal bead, while still giving a dead-straight line — a good default for high-traffic outside corners.
Off-Angle & Bullnose Corners
Not every corner is 90 degrees. Cathedral ceilings, angled bulkheads, and bay windows create off-angle inside and outside corners. Flexible tape-on bead bends to any angle and is the cleanest way to handle them.
Bullnose (rounded) corners, common in some newer Waterloo Region builds, use a special rounded bead and rounded transition pieces at the top and bottom — a detail that takes extra care to finish smoothly.
Flexible tape-on bead comes on a roll with a thin metal or plastic spine down the centre, so you simply set the angle you need and bed it in compound — far cleaner than trying to mud an off-angle corner freehand.
Coats, Drying & Sanding
Corners need the same three-coat discipline as flat seams: a tape/bead-bedding coat, a fill coat, and a finish coat, each dried fully and each feathered wider than the last. Sand lightly and check the edge for straightness under raking light.
Go easy sanding the very edge of an outside corner — it's easy to cut through to the bead and create a shiny line that shows through paint. A few light passes is all it takes.
Run a straightedge or level down a finished outside corner before you call it done. A corner that's straight to the eye can still have a subtle bow that a long, raking shadow will reveal.
Crisp Corners Every Time
Good corners are the signature of a skilled finisher: straight, sharp, and crack-free, with no waves you can see when the sun rakes down the wall. They take practice and the right bead for each situation.
D&D Interior Services finishes inside corners, outside beads, and off-angle transitions across Kitchener, Waterloo, Cambridge and Guelph. Get a free consultation for clean, durable edges.
Because corners are the first thing to chip or crack as a house settles through Ontario's seasons, the right bead and a proper three-coat build aren't just cosmetic — they're what keeps those edges looking sharp for years.
Key Takeaways
- Inside corners use creased paper tape; outside corners use a metal, vinyl, or paper-faced bead.
- Finish one side of an inside corner at a time so the knife doesn't drag the adjacent wet side.
- Flexible tape-on bead handles off-angle corners on cathedral ceilings and bay windows.
- D&D Interior Services serves Kitchener, Waterloo, Cambridge, Guelph and surrounding areas
- Get a free no-obligation quote — call or book online anytime
Sources & References
- Ontario Building Code — Relevant Standards & Guidelines
- D&D Interior Services field experience across Waterloo Region
