Painting a room: quantities, order of work and timing

The room we will paint

To keep the numbers real, this guide follows one room from shopping list to finished walls: a 12 × 12 ft bedroom with 8 ft walls, one door and one window, sound painted walls getting a new light colour, a white ceiling and white trim. Every figure comes from the calculators linked along the way, and every step applies to a room of any size.

What to buy

Three products, each with its own coverage, and each calculated on its own:

The wall area is the perimeter times the height less the door and the window, from the wall paint calculator. The ceiling is the floor area, from the ceiling paint calculator. The trim is the baseboard less the doorway, plus one door casing and one window casing, from the trim paint calculator. If you are also painting the door itself, the door paint calculator adds it.

Then the tools: a 9 in roller frame and covers, a tray and liners, a 2 in angled brush for cutting in, a mini roller for the door, painter’s tape, drop cloths, filler, caulk, and an extension pole for the ceiling. The supplies calculator sizes the list to your job. Most of it lasts for many rooms; covers, liners, tape and filler are the consumables.

Which sheen where

The usual choice is flat for the ceiling, eggshell or satin for the walls, and semi-gloss for trim and doors. Flat hides the ceiling’s imperfections and does not show roller marks overhead. A low sheen on walls balances washability against hiding. Semi-gloss on trim stands up to shoes, vacuum cleaners and hands. The paint sheen comparison covers each room.

The order of work

The rule is top to bottom, and the reason is drips and spatter. Each stage covers the mess of the stage before it.

1. Clear and protect. Move furniture to the middle and cover it, lay drop cloths along the walls, remove switch plates and outlet covers, and take down curtains and pictures.
2. Prep. Wash greasy or grubby areas, fill nail holes and dents, sand the fillers flush, caulk gaps where trim meets wall, and spot-prime the fillers. Prep is where the finish is won.
3. Ceiling. Cut in around the edges with a brush, then roll the field in sections, working away from the window so you can see the wet edge. Two coats, with the recoat wait between.
4. Walls. Cut in at the ceiling line, corners and around trim, one wall at a time, then roll that wall while the cut-in edge is still wet. Wet edges blend; dry ones leave a visible frame. Second coat after the recoat time.
5. Trim and doors. Last, with a brush, once the walls are dry. Tape the wall edge if your hand is not steady, or cut in freehand with a good angled brush.
6. Clean up and cure. Pull tape while the last coat is still slightly soft, replace covers and furniture, and treat the walls gently for a couple of weeks while the paint cures.

Some painters do the trim before the walls, because it is easier to cut a wall colour against glossy trim than the other way round. Either works as long as the ceiling comes first.

How long it takes

The production rates behind these figures are in the production rates table, and the guide to painting production rates explains where they come from and how to time yourself.

Drying between coats

Latex wall paint is usually ready for a second coat after about 4 hours at 77 °F and 50% humidity. In a cold or damp room it can be twice that or more. The ceiling’s second coat, the walls’ first coat and the trim can be juggled so that something is always drying while you work on something else, which is how a painter gets two coats of everything done without long idle waits. Dry, recoat and cure covers the conditions in detail, and the drying and recoat calculator adjusts the times for your room.

Two people, or a bigger room

With two people, split the work by tool rather than by wall: one cuts in with the brush, the other follows with the roller a few feet behind. The cut-in edge is still wet when the roller reaches it, which gives the best finish, and the job takes a little over half as long. In a larger room, the quantities and hours scale with the area but the door and window time does not; a 15 × 18 ft living room has twice the wall of a small bedroom but may have the same two doors. For several rooms at once, the project planner sequences them so that one room dries while another is painted.

The things that make the difference

• Light. Paint with strong light raking across the wall, a work light on the floor pointed along it, so you see missed spots and thin areas while you can still fix them.
• Load the roller properly. A dry roller leaves a thin, patchy coat. Roll in a W or M shape about 3 ft wide, then fill it in without lifting the roller.
• Keep a wet edge. Finish one wall before a break, not half of it.
• Box the paint. If you have more than one can of the wall colour, mix them together first so the colour is identical; see paint can sizes and the leftover problem.
• Do not chase the ceiling line. If the ceiling is uneven, a straight line a fraction below it looks better than a wavy line exactly on it.

Common mistakes

• Painting walls before the ceiling. The ceiling spatter lands on your fresh walls.
• Skipping the second coat. The first coat always looks better wet than dry.
• Cutting in the whole room first, then rolling. The cut-in edges dry and show as a frame; cut in and roll one wall at a time.
• Recoating too soon. It drags and lifts; wait for the time on the can, longer in the cold.
• Pulling tape when the paint is fully dry. It can tear the paint film; pull it while the paint is slightly soft, at a low angle.
• Putting furniture back against the walls the same day. Latex is dry to the touch in an hour but soft for weeks.

To work out quantities for a different room, start from how much paint do I need; for the trim and door quart arithmetic, trim, doors and windows.