How To Tape and Mud Drywall

Most walls and ceilings in modern construction are made from sheets of drywall, also known as gypsum board. Drywall is a plaster-like substance sealed between two sheets of heavy duty paper and attaches to the walls or ceiling using special drywall screws. Each sheet of drywall has chamfered edges to allow you to seal the seam between the boards, making your walls nice and smooth. In this wikiHow we'll look at the basic techniques needed for mudding a room that has been drywalled. The process is done in several stages and does require some specific tools.

Step 1  

Know that drywall board comes in a variety of sizes, types and widths.  

• Typically walls are covered in 1/2 or 5/8 inch thick drywall board bought in 4x8 or 4x12 foot sheets. There are also many different specialty products on the market, such as larger 4x16 sheets, specialy ceiling boards called "CV" boards that are more resistant to sagging, and there are sheets that are 54"x8 or 12' for specialty applications such as 9' ceilings.

Step 2  

If you find you need to cover walls that are in poor shape and past the typical amount of repair, you can also get 1/4 inch drywall sheets, but they may be as or more expensive than regular thicknesses.  

• Ceilings and walls unless as regulated by specific firecodes are usually covered in 1/2" dryall sheets. In ceilings you usually use "CV" rated or ceiling boards. In some instances you may be required to place 5/8" drywall on your ceilings or outside walls, 5/8" drywall is usually classified as "Fire-rated" drywall and stands up to fires longer than traditional 1/2" drywall does. A special lift (easy to rent) can hold these large sheets against the ceiling while you attach them.

A 'drywall lift' can also be made using 2 x 4s nailed into a T-shape that is placed under the dry wall to hold it against the ceiling as you place a few screws into the panel to secure it. However, if you are installing drywall on your own or don't think you have the upper body strength to manipulate the drywall, a lift is well worth considering renting.

1. • Drywall that will be installed in wet locations is called green board or MR board meaning moisture resistant (for example, behind bathroom tile) must be the type that can withstand water. Usually these sheets are covered in green paper, not the usual gray.

Drywall should not be used for tub surrounds or showers. The correct material would be cement board with an 8 mil vapor barrier behind it. The seams of the cement board need to be finished with a fiberglass mesh tape which is then covered with a "setting type" joint compound or "thin set" tile adhesive.

1. • Drywall that is to be installed in areas where fire is a concern, for example around a water heater enclosure, is required to be much thicker.
     • In some municipalities you can double your drywall in fire risk areas, rather than buy far more expensive thicker sheets.
2. Check your local planning department and municipal building codes for drywall rules and regulations in your area.
3. Check that the drywall is attached to the wall studs correctly.
   1. Wall drywall should be screwed to all the studs it covers every six to eight inches. Ideally, it should be supported at each edge and every 12 inches in the middle of the panel in a wall framed 24 inches on center, giving you top to bottom 5 screws; in a more usual wall with studs on 16 inch centers, you will have a row of screws on each edge plus two rows spaced 16 inches in from each edge.
   2. Drywall screws must be correctly countersunk. Invest in a counter-sinker designed for drywall applications. This tool attaches to the end of your drill and perfectly countersinks every screw you place.
      • Run the blade of your trowel over the screws to make sure none are sticking out. Remove, countersink or otherwise deal with any screws that are sticking out even a little bit. You want the screws to dimple but not tear the paper coating of the drywall.
   3. Do not use drywall nails unless you have been hanging drywall for years as a professional. The chances of a nail bending, putting your hammer through the drywall or simply an incorrect countersink on the nail head are great. Drywall screws are far easier to work with, but you will need a power screwdriver.
   4. Drywall boards should meet at chamfered edges only and be no more than 1/8 to 1/4 inches apart.
   5. To cut drywall sheets follow the instructions here.
   6. If two pieces of board do not meet at a chamfered edge you can use a utility knife to cut a rough chamfer all the way down the edge if you have a steady hand. If not, you will have to adjust the seam to accommodate the difference in thicknesses, placing the bulk of the mud on the chamfered side.
   7. If your local municipality requires an inspection before mudding your drywall, schedule the inspection.

Begin with the tape coat

1. Buy ready-mixed mud and make your life much easier in one single step!
   • Do not use Spackle. Mud is not Spackle, it has no "glue like" quality.
   • Don't dilute or mess around with the mud mixture. You can do so, but there is no reason to in the vast majority of applications. Spackle is intended primarily to patch nail and other holes in drywall.
   • There are several brands and grades of mud. Use the "all purpose" mud for your base (first) coat to seat or cover the tape, and light mud for the final coat. You can also use what is called brown or topping mud; it's actually beige and dries to a very pale color, and has a more plastic texture than regular mud. It dries smoother, has less of a tendancy to bubble, and is intended for the final top coat.
   • You can buy mud in square plastic boxes, or in tubs. It's cheaper in the boxes, if that is an issue. Try getting one tub and then boxes and use the tub with the mud from the boxes when it is empty. or use another clean plastic container that is easy to handle.
2. Stir the mud a little, but not too much. Stirring ready-mixed mud can introduce air bubbles that will result in an uneven finish.
3. Plastic knives (trowels) intended for use on walls have a tendancy to get burrs on their edges over time, so check if you are using plastic tools to see that they have smooth edges. Metal knives can rust, so make sure to clean them well at the end of your work session and dry them carefully.
4. Using a trowel place a generous amount of mud onto your knife.
5. Press the mud into the seam between the drywall boards.
   • You only need to press hard enough to fill the seam and leave smooth mud on the wall. The chamfered edge on a sheet of drywall tapers from about 2.5 inches to the edge, so you want to cover the entire six inches of drywall from edge of the chamfer on one sheet to the edge of the chamfer on the other. Use a bright light held at an angle to better see the chamfer area that must be covered.
   • When using the wide blades loaded with mud the best bet is to place the loaded blade perpendicular to the wall, at a 45° angle. As you draw the mud and blade down the wall sharpen the angle until the blade and the wall are almost flat together.
   • Leave plenty of mud on the wall, at least three inches on each side.
6. Cut the paper drywall tape to the correct length, with a little extra on each end.
   • Some people recommend soaking the tape in water first. While this may make it a little easier to work with it greatly increases the mess and awkwardness of the tape when actually mudding.
   • Only use plastic, mesh or specialized tapes for their specific applications. They can be harder to work with and may require three, four or more coats of mud. If you are doing inside or outside corners, for example, mesh tape is not the best choice as the tape is not intended to fold. If you are careful mudding, you can use mesh tape on seams with two coats, but you may find that you spend more time getting a good final coat.
7. Press the tape into the freshly mudded wall with your hands.
8. Be sure the center of the tape is as even as possible with the seam between the drywall boards.
9. Clean your knife. Pay attention to the back as well as the front of your knife; when you are using the knife on the wall, if you see streaks pulled in the mud, you may have a bit of dried mud or something else on the back of your tool.
10. Pressing as hard as practicable (you don't need to break your knife doing this, but you still want to press most of the mud out from under that tape), pull the knife along the seam removing extra mud as you go.
    • The goal at this stage is to get mud into the tape, not finish the job.
    • If your tape starts to buckle simply flatten it out with your hand.
    • Be sure all parts of the seam and tape are mudded.
11. Once all the tape is covered in mud use a wide knife to smooth out and remove as much of the extra mud as possible.
    • At this stage you are not going for perfection. It doesn't have to be super smooth. The important thing is to make sure the tape is covered in mud and correctly positioned in the seam. However, try not to have a large hump over the seam, or high edges. These will require sanding out later.
12. Leave this to dry. Overnight is best.
13. While waiting, fill the screw holes with mud using your palette knife. Just apply some mud and then take it all away again, if you countersunk your screws properly you should have a small dot the size of a screw head of mud without seeing your screwhead. If you leave lines of mud behind while doing this all you're doing is creating more sanding for yourself later. Mud shrinks as it looses moisture, so you may have coat these 2 or 3 times, although small cracks can just be filled with paint.

Corners

1. Corner seams require special attention. You will need to use a 45° knife while working in the corners.
2. Fill the corner seam with mud and, once again, leave some mud on the wall.
3. Cut the tape to the right length.
4. Fold the tape down the middle. You will find a crease there to make this easier.
5. Push the tape into the corner seam as neatly as possible.
   • Often the tape will "disappear" into the corner seam. Your goal is to make the nicest 90 degree angle possible, and this is controlled by the tape, so pull it out and start over.
   • Once the tape is in place in the mud, mud over it again using your 45° mud knife.
   • Carefully remove any extra mud from the corner and walls.

Outside corners

1. Outside corners do not use tape, rather they use a metal corner strip. You can also buy plastic or fiberglass corner bead although this is difficult to work with.
2. Cut the corner strip to the right length using tin snips. Be careful not to bend the corners out.
3. Nail or screw the corner strip to the wall.
4. Load plenty of mud onto the 6 inch knife.
5. Pull the mud down the wall, one part of the blade resting on the metal and the other on the drywall.
6. Make it as smooth as you can and leave to dry.
7. Corners typically take two coats to cover the metal, but remember that your paint will also cover some of the metal.

The second coat

1. Run your dry clean blade over yesterdays work, rubbing away obvious burrs and bumps.
2. Use a larger blade, 8 to 12 inches in width.
3. Understand that the goal of this coat is a smooth finish, not filling anything in, so take time and care.
4. Load your blade with mud.
5. Pull the mud over the seam a second time.
6. Feather out the mud as smooth as possible to a width of about four to six inches on either side of the seam, using the knife horizontally rather than vertically, then go over the body of the seam vertically for a final smoothing.
7. You are done when you can no longer see the tape.
8. The idea of this second coat is to fill up the bevel of the drywall so if you were to take your drywall knife and place the edge on the seam at a 90 degree angle you wouldn't see any light between the joint and knife, ideally on the second coat you should have a small hump in the middle of your seam to allow for the shrinkage of the mud as it dries.
9. Feather the edges again if necessary.
   • Use quick but hard swipes of the blade to spread the mud out to the thinnest coat possible.
10. After this coat has dried, inspect your work. Look for pits and holes in the mud that are too large to be filled with paint to a smooth surface. If you find such marks, do a third coat, or if the pits and holes are few, fill them to the surface of the rest of the dried mud.

Sanding

1. Do not sand after the first coat; the tape is still too close to the surface and you risk breaking it.
2. Always sand after the final coat.
3. Sanding during intermediate coats is optional and depends on how smooth you can get the mud. For very light sands between coats of mud consider a wet sand.
   • Find the smoothest surfaced sponge you can and wet it down so it is damp, not dripping.
   • Rub the sponge over the mud. The sponge will re-wet the surface of the mud, filling in gaps.
   • Continually clean your sponge.
   • Be very careful not to use too much water or you could dislodge your previous work.
4. Sand using a sanding block and fine sandpaper, at least 150 grit.
5. You can also use a hand-held "orbital" sander so long as you keep it in constant movement.
6. Seal the room as best you can and wear proper breathing protection. The dust created from sanding gypsum is very fine and unhealthy.
7. Use a shop vacuum to clean up, after having attached a hose to vent outside.

Tips

• After the mud is dry, do not sand. Use a clean trowel and just scrape off the lumps and bumps.
• Keep the side of the tub clean by frequently moving the mud off the sides and corners into the middle. Thin mud will dry quickly forming chunks that will cause streaks.
• Do not use fiberglass tape, it's too expensive and the joints crack easily.
• Shine a light across the wall, it will show any imperfection.
• Tape vertical joints before taping horizontal joints. Horizontal tape joints will cover the ends of the vertical tape.
• Take your time. It will take two to five coats to get a perfect finish, depending on your experience, and each coat needs to dry fully.

Warnings

• Do not let dried mud fall back into the tub or bucket. Dried mud stays dry and will introduce bumps and problems into your work. If you do see lumps in your wall mud, remove them with your fingers or a trowel before the mud dries, otherwise you will have to sand them off and start over.
• Before it dries mud is water soluble, so remove drips and splashes promptly. On carpet it can work better to leave the mud to dry and then remove it.

Things You'll Need

• All purpose joint compound
• Paper tape
• 6 inch taping knife
• Corner knife
• Utility knife
• Mud tray
• Power screwdriver with drywall countersink attachment.
• Straightedge.
• Sponge
• Sand paper
• Hand sander
• Dropcloths
• Facemasks