All of the preceding writeups have good information, but none of them tell you…
How to hang and finish drywall
These instructions presume you are going to be working on bare, unfinished, interior walls. In other words, you are staring at nothing but studs. I will leave it to others to tell you how to do exterior walls. I’ve never done that.
What you will need
- Drywall. Duh. It comes in sheets of 4 feet by 8, 4 by 10, and 4 by 12 feet and thicknesses of ½ inch and 5/8 inch. Panels with other dimensions are not unheard of. (Metric users will need their calculators to follow this writeup.)
- Joint compound. Here in Kentucky we also call this mud; joint compound has too many syllables. This plaster-like stuff comes in powdered form or in pre-mixed buckets of various sizes.
- Tape. No, not duct tape, but paper tape used to cover the seams. It comes in adhesive and non-adhesive forms.
- Drywall knives. These are also known as putty knives. These should be somewhat flexible. You want sizes from a couple inches up to 10 inches or so.
- Utility knife.
- Tape measure
- A chalk line. This is a spool of string encased in a container along with powdered, colored chalk. When you pull the end of the string out, it’s covered with chalk. By means of this, you can mark straight lines.
- Drywall screws or nails. I prefer screws
- A hardy, reliable cordless drill with screwdriver attachments (if you’re using screws) or a hammer (for nails.)
- A countersink drill bit is helpful if using screws (thanx cbustapeck)
- Corner beads.
- Various sanding tools (see below)
- A good sponge
How to hang it
Hang areas where you can use full sheets first. Take a piece of drywall and place it where you want it on the wall or ceiling. Most people, myself included, recommend hanging the ceiling first. The procedures for walls and ceilings are nearly identical; I won't distinguish between the two. Also note you will need at least one other person helping you. A sheet of 4 by 8 drywall, 1/2 inch thick, is about 50 pounds, but it’s so clumsy to carry it feels like 200. A buddy helps. Once you have the panel where you want it, begin screwing it in. Some people, myself included, like to start from the top down. Since a standard American wall is eight feet tall, and most panels are four feet wide, two panels are usually hung horizontally, one hung above the other. I prefer to hang the topmost sheet first. My reasoning is that it is more important for the top sheet to look good. The bottom sheet, at least the bottom several inches, is usually covered with baseboards or other wooden trim. You are screwing the panel into the studs, so your screws will be 16 inches apart horizontally (assuming standard 16 inch studs.) Screws should be spaced about 18 inches vertically apart and slightly “sunk” into the panel. In other words, the head of the screw should be slightly below the plane of the sheet.
Repeat the process of attaching panels until your area is completely paneled in. What? You have a panel that’s too long? And you have an electrical outlet or whatever? Well friend, you are going to need to cut. Carefully measure the space. Carefully measure any spaces you are going to have to knock out (light switches and so on). Then go to your panel and start marking off your measurements. Think of it as you are drawing the lines on which you are going to cut to make the shape you need. Use the chalk line to make long, straight lines. Once your shape is drawn out, cut out the shape using a utility knife. Be very careful. You are cutting through a piece of heavy paper glued to gypsum. All sorts of bad things can happen, not the least of which is that you could cut off your fingers and toes. All you need to do is cut about 1/8 or 1/4 inch into the panel, then you can break the panel along the cut and finish cutting the paper on the opposite side. What I call knockouts, holes for light switches and outlets are tricky. These require extra careful measurement, but cutting them out is just the same. You draw your shape and cut it out. There is a special saw you can buy with a sharp point and serrated edge designed for this very purpose. Now that your panel is cut into the proper shape, screw it on.
Outside corners are parts of the wall that stick out. They are the corners you stub your little toe against rather than the corner your mom made you stand in for saying dirty words. Outies rather than innies. For these, you will need corner beads. These are strips of plastic or metal that you screw onto the corner to make a nice, clean edge. Without these, your corners would have huge chunks gouged out of them every time you stubbed your toe against them. Screw your corner beads onto all of your outside corners from floor to ceiling.
Inner corners, joints, and seams
Can you imagine what it would look like if you started painting your walls now? There would be these depressed valleys running along the width of the room and sharp, thick lines running vertically. Your corners would have gaps into which your 2 year old could stick all of your credit cards. This is where the tape comes in. The idea here is to put a tough material across the seams and cover it with joint compound to smooth it out. There are two kinds of seams. There are the seams along the tapered, long edges of the panel, and there are seams where the thicker short edges, or edges you’ve cut, are butted against each other. These are also known as butt joints, which is just fun as hell to say aloud. Most people tape the butt joints first. Stop snickering.
With a thin (2 to 4 inch) putty knife, run a thin layer of joint compound along the seam. By thin, I mean thin enough for the tape to adhere but not so much it’s goopy. Lay the tape onto the mudded seam and press on it just enough to make sure it sticks. Then, with a wider (4 to 6 inch) knife, lay a thicker layer of mud on top of the tape. What you want to do is “feather” the mud out from the center. In other words, the mud should taper very, very gradually outward from the middle of the seam (see diagram below). The seam, obviously, is going to be thicker than the nearby drywall because it has the tape and all that mud atop it, but by gradually feathering the mud out, it becomes difficult to tell where the seams are. That's the goal anyway. One technique that works well, if you can imagine a horizontal seam, is to apply the first layer of mud atop the tape with your index finger putting pressure on the middle of the knife. Then go back over the strip of mud with your index finger to the left of center so that more pressure is applied to the left side of the knife than the right. Start with the left edge of the knife in the middle of the seam and go over the mud a second time. As you can probably imagine, this has the effect of mashing mud from the thicker middle to the thinner area above the tape. This is the essence of feathering. Repeat on the lower edge with your finger applying pressure more on the right side of the blade.
For the inner corners, the procedure is somewhat similar. But with the corners, you will have to fold the tape in half before sticking it onto the mud. Most drywall tape has a subtle depression in the middle of it to facilitate folding. Once the tape is in place, you apply mud over the tape and feather it out like before, from the inside of the corner outward. Don’t forget to do the seam between the wall and ceiling too. Use the same three stroke procedure to feather the mud out.
Now we’re ready to paint, right? Wrong. Don't be impatient. You still have to cover up the screw holes. Stop snickering, perv. Simply slap a bit of putty into the hole and feather out the mud, and you’re done. After about 24 hours, the mud will have dried. There are types of joint compound out there that dry faster, but I've never used them.
Once dry, you will have to sand the areas on which you've applied mud. There are several products out there for sanding joint compound. First, there is good, old sandpaper. I use a medium grain (80 - 120 grit) paper on a hand sander. There are sanding blocks, which are sandpapers affixed to foam blocks. There are sanding boards with broom handle attachments for doing walls very quickly. I've also seen various power tools for this purpose, but I've never used them. Given my experience with power sanders, I'd tear huge gouges into the wall and probably sand my lips off if I used one of them for this purpose. Different people use different tools based on personal preference so experiment until you find something you like. You are still going to end up doing the same thing: sanding the dried joint compound to a satiny smoothness.
OK, maybe not satiny. What you are going for after your first coat is an imperfect sort of flatness. Chances are there will be strange divots and holes that sort of look like the surface of Mars. Don't worry about sanding these out totally. You will mud over these in subsequent coats. You are basically flattening things out rather than making a work of art. Some people don't even bother sanding the first coat since it is going to be so rough no matter what you do. The risk of over sanding is that you will expose the tape or rub off the paper on the drywall itself. Neither sanding too much nor not sanding at all is a big deal with the first coat, but you could have extra work in covering problem areas in the subsequent coats if you royally foul up this base coat. Use judgement.
When sanding, go over the screw holes, inside and outside corners, and all the seams. You will kick up a lot of very fine, white dust as you sand. Get used to it. Some sort of filter is a good idea. I use cheap paper filters that go over the nose and mouth with an elastic band. If you are doing overhead work, as in the ceiling, wear safety goggles. Seriously, do.
Rinse and repeat
After you've sanded your first coat, take a damp sponge and wipe down the walls. Don't go nuts with it. You're just trying to keep the dust on the walls down to a reasonable level, which will help considerably when it's time to paint. Time for your second coat of mud. Like the first time, you are going for a feathered effect except this time, you want the mud to splay out farther and thinner. I'll try to illustrate the concept with ASCII art.
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
3 2 1 T T 1 2 3
Similarities to the Mid-Atlantic Ridge
notwithstanding, this is the effect you are going for. The T
stands for tape, and the space between the two 1
s represents the first coat of joint compound. This area is going to be area of the thickest mud, but hopefully the feathering in subsequent coats (the areas between the 2
s and 3
s) will be so gradual that it will appear flat when painted.
To achieve this progressively wider feathering effect, it is very helpful to use progressively wider putty knives. You can find knives 12 inches or wider at hardware stores. It is not unreasonable for your seams to have strips of mud 12 to 18 inches wide. The wider and more gradual the seams are, the less they will be visible when painted. Nothing looks worse or more amateurish than a wall with obvious humps where the seams are. Gloss paints make these humps stand out like crazy.
In the second sanding, and especially in the third, you want to pay close attention to those pesky irregularities that looked like Mars. Carefully smooth out any hard lines or obvious depressions or ridges. Use lighter grit sand paper to fine tune things. Remember, at the end of the third coat, you want all this mud you've slathered on to be totally smooth.
I haven't said anything about screw holes or corners in the second and third coats. Screw holes ought to be smoothed over and invisible after the first coat. If not, then certainly by the second they ought to be perfectly smooth. Both inside and outside corners are sanded just like the joints are. Extra care needs to be taken with the corner beads. Be sure and knock off any extra mud on the edges and don't sand them too hard or you'll scratch them, which could be visible when you paint. Inside corners can be tricky because sanding them is just plain clumsy.
After sponging down the walls after the third coat, you are ready to prime and paint the walls. Or are you? Look around. Chances are you have piles of fine white powder all over the place. Before you paint, you'd do yourself a favor
by vacuuming it all up. Don't make the mistake I made and use a broom
. If you do, stand by to have Lando Calrissian
spank your Wookie
because you will be in Cloud City
. Rent a high powered vacuum cleaner (shop vac
) and invest $20 in what's called a three stage HEPA
filter. This will take care of particles as small as 0.3 micron
s, good enough for drywall dust. Don't make the mistake I did and use your regular household vacuum. It will simply suck up and trap the larger particles and blow the finer stuff, the stuff that will really give you problems, all over your house. And from then on, every time you start your vacuum, a little white cloud of plaster dust will burst forth from your bag. Once all the dust is up, and once you wipe down the walls one more time, you are ready to prime and paint.