Drywall is fairly easy. If you have some talent and patience, you'll do just fine mudding.
- Build the walls
- install electrical boxes and wiring
- insulate the walls
- install vapor barrier on the bathroom side of the wall
- hang the drywall, doing your best to keep the sheets vertical
- as much as possible, use natural butt joints, especially where door and window trim will be; put cut sides in corners
- use drywall screws for initial 'holding'
- use either screws or long drywall nails to finish attaching it, spaced about 6"
- screw and nail head should be just below the surrounding surface; the hammer head should make the slightest depression on the surface.
- Try not to break the paper with the screw/nail heads, as that's where a good deal of the holding strength comes from
- apply adhesive mesh tape or apply a medium layer of mud, then paper tape on top
- apply a thin layer of mud atop the tape
- let dry
- sand lightly
- wipe with damp cloth
- apply another light-to-medium layer of mud, let dry
- repeat until tape is well-covered and depression is nicely filled.
- On the screw/nail holes, put on as little mud as you can; let dry, sand lightly, and repeat as necessary until the holes are all smoothly flat.
- natural butt joints should be smooth and flat
- cut joints need to be tapered out 8"-12" or more from the seam
Be sure you have a supply of new blades for your drywall knife. You can use a shop vac with a drywall sanding attachment; this will keep the dust to a minimum. A couple gallons of water in the tank will also help minimize dust. Also buy a drywall sanding sponge; with a light touch, you can smooth out remaining unevenness you find with it dry. If you don't have a good hammer with a good head, buy a new one; nothing's worse than hanging drywall using a 40 year old hammer that's been used for construction and destruction. Buy or borrow good, true mudding tools. Have a good 6" knife for corners and edges, and a 12" (or so) trowel for butt joints; the trowel will be slightly U-shaped so that it can apply the mud either slightly raised or flat, depending on the pressure used.
Shine a light along the wall's surface; the shadows will reveal where you need more or less mud. For example, if you see obvious shadows in a natural butt joint, that depression will be painfully obvious once you have it painted.
Above all, before you do anything, stand in front of the wall and stare at it, going through each step you will take until you have the wall finished in your mind. Then take it one step at a time. And inspect your work after each step. Don't rush; work on accuracy/precision first, and efficiency second: you have to learn to walk before you can run. Patience is your friend.
In the bedroom, you can hang plastic wall-to-wall and ceiling-to-floor with tape. 2"-3" painter's masking tape should be good enough on the walls and ceiling and should remove easily enough. Leave yourself a 'sealable' door and you will minimize dust travel. Put old rugs/towels inside and outside the 'door' to wipe your feet.
If you are installing a new tub surround, you can use regular drywall everywhere. If it's just a tub and tile, use concrete board for the walls above the tub. Green board may be nice, but it ain't good enough.
Put one foot in front of the other, carefully and deliberately. You'll finish the job, it'll be done right, and you'll've caught your worst mistakes. When done, it may not be laser flat, but it'll've been by *your* hand. And after a month or three, you won't even notice the little mistakes you didn't catch.
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