How to Skim Coat Walls

Skim Coating a WAll

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Overview
  • Working Time: 1 hr - 1 hr, 30 mins
  • Total Time: 2 - 3 hrs
  • Skill Level: Beginner
  • Estimated Cost: $20 to $50

Over time, walls can develop surface imperfections such as shallow gouges, ripped drywall paper, or chipped paint. If you think that you will need to replace the drywall, you might be pleasantly surprised to learn that there is an easy, alternative wall fix: skim coating. 

What Skim Coating Is

A skim coat is a thin layer of drywall joint compound (also known as mud) that gives walls a glass-smooth finish. It’s used to repair damaged walls and smooth down intentionally applied wall texture.

Some walls have a coating known as orange peel or knock-down texture. Some homeowners may want smooth walls instead of textured walls. Skim coating is an easy, low-mess alternative to chipping away the texture material.

Skim Coat Application Methods

Paint Roller

Rolling drywall compound onto the surface with a paint roller cover and frame is a popular way to apply the product. The drywall compound goes on quickly, and clean up is easy.

Drywall Knife

The drywall knife, which is always used to smooth down the drywall compound for skim coating, can also be used in earlier steps to apply the compound to the surface. This offers the advantage of keeping your tool purchases to a minimum. The downside is that the application is laborious and slow.

Texture Sprayer

The fastest and most effortless way to apply drywall compound to the wall is with a sprayer. You cannot use an ordinary paint sprayer—you will need to rent a texture sprayer.

What You'll Need

Equipment / Tools

  • 12-inch drywall knife
  • Drywall mud pan
  • 9-inch paint roller cover
  • Paint roller frame
  • Paint roller extension pole, 4- to 8-foot range
  • Fine-grit drywall sanding screen
  • 5-gallon bucket
  • Paint rolling screen for the bucket

Materials

  • Lightweight all-purpose drywall compound
  • Clean water
  • Painter’s tape

Instructions

  1. Prepare the Work Area

    Cover up areas that will not be skim-coated. Shut off electrical circuits to outlets and light switches. Remove faceplates and then cover the outlets or light switches with painter’s tape. Lay down drop cloths and tape them up to the wall baseboard.

  2. Mix the Drywall Compound

    Use a light-body drywall compound. Since the compound serves almost no structural purpose, heavy body compound is not necessary. Plus, lightweight mud is easier to sand smooth.

    Mix the drywall compound according to the mix ratio on the product instructions. Often, it's better to short the water slightly to produce a heavier, stickier product. This gives the skim coat greater strength, plus it's cleaner to apply. Mix to a stiff, yogurt-like consistency.

    Tip

    When mixing drywall compound, determine the amount of water needed according to manufacturer's instructions on the product. Put slightly less water than needed in a mixing container or bucket and add compound to the water. After mixing, add the remaining water if needed. Adding the compound to the water is better for achieving a lump-free mixture than adding all the water to the compound at once.

  3. Roll Out the Drywall Compound

    Roll out a section about 2 feet wide by 8 feet high. Press the roller firmly into the wall to force out bubbles. Working time depends on the amount of drywall compound deposited on the wall, room temperature, and airflow. It's always better to maintain smaller working zones so that the drywall compound does not dry up on you.

    Be sure to keep the drywall compound consistent across the surface. Even though the drywall compound does get scraped off, inconsistent compound dries at different rates, so the process will be easier if you do a consistent application.

  4. Skim the First Section

    Skim out the drywall compound with the 12-inch knife. Scrape either upward or downward in columns, applying slightly more pressure to the left side of the knife than the right. This eases out imperfections on the left side, but leaves a low ridge on the right side.

    Tip

    Do not exert full force with the knife because you will end up scraping off too much drywall compound, and you risk gouging the wall with the corners of the drywall knife. Deposit excess in the tray.

  5. Skim the Rest of the Sections

    Make a second pass adjacent to the first column. Again, favor pressure on the left side. This eliminates the ridge on the left. Overlapping ensures that most of the ridges are taken care of by the drywall knife. This leaves less drywall sanding for later.

  6. Sand the Dried Skim Coat

    Allow the skim coat to dry. It should dry within an hour or two. Finish with a light sanding with fine-grit drywall sandpaper.

Wall Skim Coat Troubleshooting

Drywall Compound Is Hard to See on the Wall

Set up a work light on the floor to cast a low angled beam on the skim coat surface. This helps to identify high and low spots.

The Roller Slides on the Wall or Gums Up

When the roller slides, this means that the roller is stuck and is not turning. Knock off the roller cover, run water over the roller frame to clean it off, then replace it with a new cover.

Drywall Compound Is Not Sticking to the Wall

The compound may be mixed too thinly. Add a little more dry mixture and mix again to stiffen up the product. Also, walls painted in high gloss paint may not hold the drywall compound well. These walls should be lightly sanded before skim coating.