How to Mud and Tape Drywall Corners

Whether you’re finishing a new construction project or repairing existing walls, properly mudding and taping corners can make the difference between a professional-looking result and a DIY disaster. This guide walks you through the process of mudding and taping both inside and outside drywall corners with tips courtesy of This Old House’s Tom Silva.

Understanding Drywall Corners

These are the two main types of drywall corners you’ll encounter in your home:

• Inside corners: These are the corners where two walls meet at a 90-degree angle, forming an inward-facing corner.
• Outside corners: These are the corners where two walls meet at a 90-degree angle, forming an outward-facing corner.

Materials for Finishing Corners

To properly finish drywall corners, you’ll need the following materials:

• Corner bead (for outside corners)
• Drywall hawk
• Drywall knives (4-inch, 6-inch, and 12-inch)
• Drywall tape (paper or metal-reinforced)
• Joint compound (also known as drywall mud)
• Sandpaper (120-grit)
• Corner trowel (for inside corners)

Preparing for Mudding and Taping Drywall Corners

Before you begin mudding and taping your drywall corners, you need to prepare your workspace and materials. Clear the area around the corners you’ll be working on, removing any furniture or obstacles. Lay down drop cloths to protect the floor and any nearby surfaces from drips or spills. 

If you’re using powdered joint compound, mix it according to the manufacturer’s instructions. For pre-mixed compound, stir it thoroughly before use to ensure a smooth consistency. 

Pro Tip: When opening a bucket of pre-mixed compound, take the lid far away before scraping off the dried mud caked on the underside. If any of these hard specks — known in the trade as “boogers” — fall into fresh mud, they will rake annoying grooves under your taping knife as you work.

Inspecting the Corners

Carefully examine the corners for any protruding screws, loose tape, or damaged drywall. Address these issues before proceeding with the mudding and taping process. This minimizes interruptions and leads to uniform application.

Mudding and Taping Outside Drywall Corners

Outside corners are more prone to damage and require more specialized attention than inside corners.

Installing Corner Bead

Cut the corner bead to the appropriate length using tin snips. Position the corner bead on the outside corner, making sure it’s straight and level, and secure it using drywall nails, screws, or a corner clincher tool.

Pro Tip: Tom Silva, This Old House general contractor, prefers nails over screws for attaching corner bead: “I like to apply the metal bead with a nail, a drywall ring, shank nail… I can control it better with a nail.” He recommends nailing one on each side of the bead to keep the corner true and straight.

Applying the First Coat of Mud

A proper first coat establishes the foundation for subsequent layers. Follow these steps to apply mud:

1. Scoop some joint compound onto your drywall hawk.
2. Using a 6-inch drywall knife, apply a generous layer of compound to both sides of the corner, covering the corner bead completely.
3. Smooth out the compound, feathering the edges to blend with the surrounding wall.

Sanding and Applying Subsequent Coats

To build a strong, smooth corner, multiple coats and sanding are necessary. Once the first coat is dry, lightly sand the area with 120-grit sandpaper. Apply a second coat using a 10-inch drywall knife, feathering the edges further out from the corner. After the second coat dries, sand lightly and apply a third and final coat using a 12-inch knife for the smoothest finish.

Pro Tip: Tom Silva recommends a patient, iterative approach to building up coats: “Let it set up, let it dry. Do it again, just clean away your high spots.” Resist the urge to overwork the mud while it’s wet — as Tom notes, “If you work it too hard, it actually becomes harder to work with.” Big voids in the first coat aren’t a crisis; just catch them on the next pass.

Mudding and Taping Inside Drywall Corners

Inside corners require a different approach than outside corners, but the goal remains the same: achieving a smooth, seamless finish.

Preparing the Corner

Preparation differs slightly for inside corners. Clean the corner of any dust or debris. If using paper tape, fold it lengthwise down the middle to create a crease.

Applying Tape and Mud

Using a 4-inch drywall knife, apply a thin layer of joint compound to both sides of the corner. Press the creased tape into the wet compound, checking that it is centered in the corner. Use your 4-inch knife to embed the tape, removing excess compound and air bubbles.

Smoothing Technique: When smoothing tape into the compound, start halfway along the joint and pull the knife to one end in a single stroke, holding it at a 25-degree angle to the wall. Then return to the midpoint and pull in the opposite direction. Working from the center outward prevents the tape from pulling away from the wall.

Smoothing and Feathering

Achieving a seamless finish involves meticulous smoothing techniques. Apply another layer of the compound over the tape, using your 4-inch knife to smooth it out. Feather the edges of the compound, applying more pressure to the outer edge of the knife for best results. Use a corner trowel to smooth the compound and create a clean, crisp corner.

Technique Detail: When feathering compound in an inside corner, concentrate your mud load on only half the knife blade — scrape clean the half that will be farthest from the corner. On your smoothing stroke, grip the handle so your index finger rests on top and directs the blade. Place one side of the knife in the corner and angle it slightly so the compound disperses away from the corner. Hold the blade at a low angle, with your knuckles nearly touching the wall, and twist your wrist as you stroke to concentrate blade pressure on the side away from the corner. This action confines the compound to a fine feathered edge.

Tips for Professional-Looking Drywall Results

To achieve the best possible finish on your drywall corners, keep these expert tips in mind:

• Allow proper drying time: Follow the manufacturer’s recommendations for drying times between coats.
• Keep your tools clean: Regularly clean your knives and trowels to prevent dried compound from affecting your work.
• Practice on scrap drywall: If you’re new to mudding and taping, practice your technique on a piece of scrap drywall before tackling your actual project.
• Work in thin layers: It’s better to apply multiple thin coats than one thick coat.
• Sand lightly between coats: This helps create a smoother surface for subsequent layers.

Common Drywall Mudding and Taping Mistakes to Avoid

When mudding and taping drywall corners, be aware of these common pitfalls:

• Insufficient feathering: Properly feather the edges of your compound to avoid visible seams.
• Rushing the process: Trying to complete the job too quickly can lead to poor results and extensive repairs later.
• Neglecting corner beads: Inadequately securing or aligning corner beads can cause uneven edges and less durable finishes.

Advanced Techniques for Seamless Drywall Corners

There are several advanced techniques you can learn to take your drywall skills to the next level.

Using Paper-Faced Corner Beads

Paper-faced corner beads combine the benefits of metal corner beads with the ease of paper tape. They’re perfect for creating smooth, resilient corners that integrate seamlessly with the drywall surface. Here’s how to install them:

1. Cut the corner bead to the desired length.
2. Apply a layer of joint compound to the drywall corner.
3. Position the paper-faced corner bead and press firmly into the compound.
4. Smooth the edges with a drywall knife, and make sure the corner bead is flush and aligned

Applying No-Coat Corner Beads

No-coat corner beads offer increased flexibility and durability, which is especially beneficial in high-traffic areas. Measure and cut the no-coat corner bead to the needed length. Apply the corner bead with a combination of joint compound and adhesive backing. Secure the corner bead with additional compound, and smooth the surface using appropriate drywall knives.

Mastering Curved Corners

Flexible corner beads are great for curved corners, but they can be a bit tricky. Take the following steps to install beads on curved corners:

1. Select a flexible corner bead designed for curves.
2. Attach the bead using joint compound, following the curve of the wall.
3. Layer multiple thin coats of compound, sanding between coats to create a smooth, continuous curve.

Our Conclusion

Mudding and taping drywall corners is a skill that takes practice to master, but with the right techniques and tools, you can achieve professional-looking results. By following the steps outlined in this guide and paying attention to detail, you’ll be well on your way to creating smooth, seamless corners in your home improvement projects