If you need to paint high walls and ceilings in a stairwell or a great room, you'll need to use an extension ladder and maybe build scaffolding to reach some of the farthest points. Below are a few tips and techniques for working in stairwells and building quick, improvised scaffolding with dimension lumber. If you don't want to deal with ladders, another method for painting a high ceiling while standing on the floor is also described here. This requires attaching a brush to an extension pole and using the same color paint on both the ceiling and walls.
To make using these improvised scaffolding safer, keep the lengths of dimension lumber as short as possible and be sure they are well supported by the ladders or other props used. Walk slowly and with care when standing on the scaffolding and where possible, clamp the boards to the supports.
To avoid tripping or slipping when walking over floors, covering them with canvas drop clothes, not plastic. Tuck the sheets into the corners at each step riser and other edges to form a clear, smooth surface for walking. Also tie or tape a drop cloth around any banisters or other rails to keep it in place while you work.
To reach stairwell ceilings for painting projects and other work, use an extension ladder as shown here. Set it on a stair tread and lean it against the stairwell wall. A 16 foot ladder will reach a two story ceiling but higher work may require a 20 or 24 foot.
Pad the ladder to protect the wall using a rag that won't transfer dye wrapped several turns around the ends. Keep it in place with a few turns of masking tape. To hold a paint pail while working from the ladder use a bucket hook and hang it from one of the rungs and off to the side.
In larger stairwells it may be impossible to reach the midpoint of some walls using an extension ladder alone. In these cases use two ladders, a sawhorse and dimension lumber like a couple 2x8's or several 2x4's to improvise scaffolding. Don't use 1x8's or other 1by finish lumber, these boards will not be thick enough to support your weight.
Keep the 2by board length to a minimum to avoid a lot of bowing and springing as you walk. If you must use longer boards then stack two together and use clamps or screws to join them for more stability.
To paint and repair vaulted and cathedral ceilings, use two 8 or 10 foot step ladders and a couple 2x8's to build a moveable scaffolding. Keep the ladders fairly close together and use a 10 foot boards to prevent bowing and springing as you walk across the scaffold. Too much vibration like this could cause the ladders to shift and the board to become unstable.
For standard eight and nine foot ceilings a smaller scaffolding can be built using a sawhorse or chair, and a step ladder to support the 2by boards. Here too, keep the scaffolding board fairly short to keep vibrations to a minimum.
Using one color for both the walls and ceilings will make it possible to paint the corners with a brush and then roll the remainder, all from the floor. Also, using flat latex paint will improve the results because it will not show brush and roller marks which are hard to avoid when working with a long pole. If you're choosing the colors for the job, using one that closely matches the existing color will make coverage easier. If you must have a white ceiling with an accent color on the walls, a ladder will be required to do the job, so use one of the scaffolding methods above.
To work from the floor use a roller extension pole long enough to reach to the ceiling. Twelve feet is usually the limit for these but this is long enough for most situations.
To do the painting fill a brush and tape it to the end of the extension pole using masking tape. Set the brush so the threads on the pole press against the metal band around the bristles and wrap the tape a few times around the two, near the tip of the brush handle. Wrap a couple turns of tape again, a few inches farther up the handle to hold it in two places.
Extend the pole and start at the farthest corner brushing the paint on as far as it will go. When the brush runs dry, compress the pole to pull it in and load more paint. Carefully dip the brush into the can while still attached to the pole and tap on the sides of the can to stop drips. Extend the pole again and coat more of the corner. Paint all the high corners along the ceiling and down the walls to a point where you can reach from the floor or a small ladder. Let the corners dry and apply a second coat if necessary. To finish, roll the ceiling first and then the walls using the extension pole and a roller. Use a shorter pole as you work your way down, to finish the walls.