How to Prep Your Walls for Painting: The Perfect Canvas Awaits

Paint won’t adhere well to a dirty surface. You’ll need to get rid of dust, dirt, and grime—which could include tackling sticky kitchen grease or removing cigarette smoke residue. Fortunately, washing your walls doesn’t take much sweat equity. All you need is some warm water and a scrubby sponge. 

If walls are particularly dirty, you can ramp it up a notch with an all-purpose cleaner or degreaser that’s safe to use on painted walls. Don’t forget to clean the trim and moldings thoroughly. If you’re having trouble reaching or plan to paint your ceiling, attach your sponge to a telescoping handle for extra length.

How to clean walls before painting depends on how you use the room. Kitchens need a little more elbow grease to eliminate the literal grease from cooking. You may have to clean some mildew or mold in the bathroom that you won’t typically find in other rooms. This informs the type of products you should use to clean the walls. You may want to use:

• Degreaser for kitchen walls

• Mold and mildew remover for bathrooms and other moist areas

• All-purpose cleaner for general cleaning

“The average bedroom takes one to two hours to prepare, and a family or living room will take slightly longer, likely two to four hours,” says May. “Not all walls need to be sanded or cleaned, but many kitchen walls do. If you live in the western half of the U.S., most walls have significant texture (orange peel or knockdown) and require little to no surface prep. All rooms require covering of floors or furniture.”

Always choose high-quality primer and paint for rooms that experience temperature fluctuations. To get a perfect finish, plan your project based on the weather. For example, if you don’t have air conditioning, avoid painting on a hot and humid day, or the paint could bubble.

After you’ve washed your walls thoroughly, the next step for painting your walls and trim is to give them a good sanding with 80- to 120-grit sandpaper. However, sanding your walls is only necessary if you repaired significant drywall damage or your walls were previously painted with a semi-gloss paint. If you have textured walls, sanding is typically not needed. The other reason for sanding is if the previous paint had a lot of contaminants, resulting in bumps.

The goal is to get rid of any chips, knicks, divots, and deformations that might have accumulated on your walls in high-traffic, high-use, or high-humidity environments. Primer also adheres better to a textured surface.

Before you get your sanding on, it’s a good idea to cover doorways, HVAC registers, sinks, and fixtures with plastic sheeting. The last thing you want is to spoil your brand-new paint job with sinks and heating grates clogged with dust.

Sanding isn’t always enough to get the smooth surface you need for a pro-quality finish. Pictures, decorations, and shelving can leave deep holes and divots in your walls. Luckily, with some DIY drywall repair tips, you can fill in these stubborn imperfections with some spackling paste. 

Apply the paste per the manufacturer’s instructions. Once the spackle is dry, give your wall a light sanding with 220-grit sandpaper. Anything heavier is likely to leave streaks. Use circular motions to get the perfect canvas for your paint.

Before you prime or paint, you need to cover the areas you don’t want to paint. Make sure to give all your surfaces a final wipe-down with a damp cloth to remove any residue or debris from cleaning and sanding your walls. Then, cover outlets, trim, floor, and any other surface you don’t want primed and painted with plastic sheeting and painter’s tape.

Choose the best tape for your wall surfaces and for the length of time the tape will be left on. “Use a low-tack tape for any previously painted surface. Use a delicate

tape for any recently painted surface or surface that could peal up (like wallpaper or

paper-coated cabinet),” May says. “Only use masking tape on carpets or other surfaces that require more adhesion and cannot be damaged.”

Once you’ve cleaned and sanded your walls, there’s one last step you need to take before getting your color groove on. You guessed it: primer. Paint primer is important if you have drywall or you’re painting in a humid area prone to stains (think: kitchens, bathrooms, or laundry rooms). 

First, drywall is naturally porous, and primer helps stop bleed-through and uneven coverage and coloration. Second, humid environments are prone to bubbling, peeling, and cracks. You’ll need the paint to adhere as much as possible.