When painting walls, the amount of necessary masking and covering depends upon whether you are spray painting, or rolling and cutting-in the paint. Spray painting walls almost always requires more masking than rolling and cutting-in with a brush.
Cutting-In and Rolling Interior Walls
The only masking and covering required for cutting-in and rolling a wall is in the area directly below where the paint will be applied. This can be accomplished using some combination of masking tape, masking paper, and painters drop cloths.
Keep in mind that when you cut-in paint against masking tape, it is possible to get paint seepage. This is when a small amount of paint works its way under the tape. Make sure the masking tape is firmly attached by sliding a small putty knife or your finger over the surface of the tape.
Masking Non-Painted Items
Consider non-painted devices that need to be protected while painting walls.
When painting walls with a brush and roller, paint drips and roller splatter should not land beyond 3-4 feet from the base of the walls. A few runners (drop cloths) are just the right size to cover the perimeter of most rooms. These are typically 4ft x 12ft or 4ft x 15ft.
For hard surfaced floors such as hardwood, tile, and vinyl, red rosin paper works well as an alternative to painters drop cloths. Place a single row of red rosin paper within one inch from the wall. Use a low adhesive masking tape to attach the perimeter of the paper to the floor. Make sure the masking tape is close to the baseboards or to the bottom of the walls.
At the bottom of the wall, carefully tape a layer of 6-9 inch masking paper along the top edge of the baseboards. Allow the paper to hang down to the floor overlapping the masking on the floor. If you are not using a hand masker, place a strip of 1 ½-2 inch masking tape along the top edge of the baseboard tight to the lower corner of the wall.
Masking ceilings and crown moldings
It is not necessary to mask the ceiling or crown molding when painting walls with a brush and roller. If you have a steady hand, you can cut-in the paint against the ceiling or crown molding without any overlap. If you want some protection, use a single layer of low-medium adhesion, 1 ½ inch masking tape. Place it on the ceiling or crown molding, tight to the upper corner of the wall.
Masking windows and doors
When painting walls with a brush and roller, only a limited amount of masking is needed to protect the doors and windows. It is a good idea to put a layer of masking paper on the top edge of door and window casings. Let the masking paper hang over the top casing. This will prevent roller splatter or paint drips from landing on the door and window trim. You can place a single layer of masking tape on the vertical casings for extra protection. This also allows you to roll very close to the casings without spotting them with wall paint.
Window stools are easily covered with a single layer of 6-9 inch masking paper and masking tape.
Spray Painting Interior Walls
When spray painting walls, the overspray can drift around a room. Therefore it is a good idea to cover everything in the room thoroughly. This is especially the case for any surface directly adjoining a wall. These surfaces include ceilings, crown moldings, windows, doors, baseboards, and flooring.
Place runner drop cloths around the perimeter of the room. Runners are typically sized at 4ft x 12-15ft. Red rosin paper is an alternative for hard surfaced floors. Lay a single row of paper within one inch from the wall. Use a strip of low adhesive masking tape to attach the paper to the floor. Make sure the masking tape is close to the lower corner of the baseboards or the walls. Use larger drop cloths, 9ft x 12ft or 12ft x 15ft, to cover other exposed areas not already covered.
At the bottom of the wall, carefully tape a layer of 9 to 12 inch masking paper along the top edge of the baseboard, tight to the corner of the wall. Allow the paper to hang down to the floor overlapping the masking on the floor. Tape the masking paper in a few spots to the floor cover so it does not flap around from the pressure of the spray paint.
Masking the ceiling
Start at the top of the wall. With a hand masker, place a row of 9-12 inch masking paper on the ceiling, tight to the corner where it adjoins the wall. Tack the masking paper to the ceiling so it does not hang down, using low-medium adhesion masking tape. It is a good idea to place a 2nd row of masking paper, overlapping the 1st row, so as to provide a little more protection from deflected overspray.
Masking crown moldings
Carefully apply a strip of low-medium adhesion masking tape to the bottom edge of the crown molding, tight to the corner where it adjoins the wall. With the use of a hand masker, place a row of 9 to 12 inch masking paper prepared with masking tape over the crown molding, attaching it to the first strip of masking tape. Attach the masking paper to the ceiling in a few spots to hold it in place. It is a good idea to place a 2nd row of masking paper, overlapping the 1st row, so as to provide a little more assurance from deflected overspray.
Masking windows and doors
Spray painting walls will impact the doors and windows. Tack a layer of painters plastic or attach a layer of masking film over the windows and doors. Leave about 3 to 4 inches exposed around the perimeter. Use 6 to 9 inch masking paper to finish off. Tape it carefully to the edges of the door and window casings or window sash and let it overlap the masking film. Tape the masking paper to the masking film so it does not flap around from the pressure of the spray paint.