Finishing Drywall Joints: Tape Coat

Taping Before starting the taping process, make sure corner bead is installed on all outside corners.

Also make sure that all the fastener heads are sunk below the surface of the drywall. You can check them by running a taping knife over the drywall. If you hear a "click" you've got a nail or screw that needs to be sunk deeper. Just give the nails an extra tap, or give the screws a twist with a phillips-head screwdriver.

Professional tapers sometimes notch out the butt joints so they have more space for the first pass of joint compound. This helps eliminate the "hump" that you might get when taping these joints.

The entire finishing process is about a 4- step, 4-day process. The first step is called the "tape coat." This is when you apply joint compound to the seams and embed paper joint tape in it.

First Pass of Tape Coat

Mix up your joint compound. If you're working with pre-mixed compound, don't mix it too much, this can work air into the mixture and then you can get little bubbles and craters on the surface of the wall.

Starting on the ceiling, first spread out a layer of "mud", as the professionals call it, over the joints. For this first coat use a 5" or 6" taping knife.

Be generous with the mud at this point. Spread out more than you need to fill the seam.

TIP: The trick to spreading out mud is to hold the knife almost vertical to the drywall when it's full of mud, and press it flatter as you move along the joint. This spreads the mud evenly over the whole stroke of the knife.

Embedding Joint Tape

For the second pass, lay a piece of joint tape over the center of the joint. Press it lightly with your hand--just to make it stick for now.

Then go back and flatten the tape into the mud, working from the center of the joint out to the sides.

You can use pretty firm pressure with this stroke. You'll end up scraping off some of the excess mud, just leave some mud under the tape.

TIP: As you tape, keep your knife clean. Constantly scrape it off the side of the pan. Mud that stays on your knife will dry out faster.

The last step for the tape coat is to spread a very thin layer of mud out on top of the tape.

This requires a gentle touch. The layer should be thin enough that the tape is still visible through the mud.

Don't worry too much about a few grooves and streaks on the surface for now. There'll be more coats to smooth it out later.

Inside Corners

Inside corners also get treated with joint tape. There may or may not be tapered edges here, but it doesn't really matter too much. Slightly uneven walls won't be as visible in the corners as on a flat wall.

First apply a thin layer of joint compound inside the seam and on both sides of the corner.

Measure and cut off the length of joint tape you need. Then fold the tape in half and press it into the corner. Most brands of tape come with a crease in the middle to make this easier.

Press the tape into corner, then run a knife down each side to set it into the mud and to work out any excess mud.

Lightly coat both sides with joint compound again.

Outside Corners

The outside corner bead will have a little valley between the metal ridge on the corner and the surface of the drywall. Now you want to fill this with mud.

With mud on your knife, run it down each side of the corner bead. Hold the knife at about a 45 degree angle; it should be touching the wall and the ridge at the corner. Scrape off anything that rises above that level. Clean off any bits of mud left on the ridge.

You should end up with about a 4" wide band of mud on either side of the corner.

Mudding Fastener Heads

The last thing you have to do for the tape coat is to cover all of the screw and nail heads.

It just takes a small amount of mud to cover these, but start by troweling on more than you need. And cover an entire row of screws with one stroke.

Gently scrape off the excess mud with the taping knife almost perpendicular to the surface. This will leave a very thin layer of mud all the way up and down the wall.

The mud over the screw and nail heads will shrink a little, so you'll have to repeat this step with each of the next two coats.

Wrapping up for the day

When you finish the tape coat, you need to let it all dry at least overnight.

Clean all your tools real thoroughly. If you have any dried mud left on your knives it'll cause little gouges when you do your next coat.

Throw out any mud left in your pans. Scrape down the sides of the mud bucket, and pour a little water on top of it to keep it from drying out. Pour this water off before using the mud the next time.