How to Skim-Coat Walls

A new approach for smoothing rough walls that's easy to master

Introduction

Smooth over rough or damaged walls with a skim-coat of mud, applied with a special squeegee knife. It's easy to do and delivers great results.

Tools Required

Materials Required

  • 120-grit sandpaper
  • Drywall compound
  • Masking tape
  • Primer

How to Skim-Coat Walls

If you're a skilled drywall taper or plasterer, you probably use a hawk and trowel to skim-coat walls. We don't expect to change your mind if you use those tools as second hands. But if you're a remodeler who does only occasional skim-coating to fix wrecked walls, you know it's a tough skill to master. Plus, here's how to choose the right joint compound for your project.

The method we show isn't faster than traditional skim-coating — you have to do two or three coats and let each one dry in-between. But it's idiot-proof, and the walls will end up flat and smooth. So if you're a contractor who's given up on skim-coating and you always call in a taper for the task, you can save on labor by tackling it yourself next time. It only takes a regular paint roller and a squeegee knife. The 14-in.-wide squeegee knife we used is called a Magic Trowel.

Before you start on this project, if you're having some issues with your drywall check out this video:

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Project step-by-step (6)

Step 1

Start by Prepping the Walls

  • With this method of how to retexture a wall, you don't just spot-prime; you roll the entire wall with a stain-blocking sealer.
    • Pro tip: If you've always used solvent-based sealers like traditional BIN and KILZ, it's time to try one of the water-based stain killers. Zinsser's Bulls Eye 1-2-3 primer works well, and you'll avoid any griping from your customers about the smell.
  • Roll a fast-drying, stain-sealing drywall primer on the walls. The primer seals loose paper and promotes better adhesion of the joint compound.
  • These are thin layers that won't fix holes or torn-away paper, or make uneven sections level. Patch these problems with setting-type joint compound.
  • Let the compound harden (it doesn't have to be dry) before you start skimcoating.
  • Don't rush on to the next step; let the sealer dry thoroughly before applying any joint compound.

skim coat paint primer

Step 2

Roll on the Mud

  • Mix all-purpose joint compound to about the same consistency as mud you would use for bedding tape (the consistency of mayonnaise, or just thin enough to roll on the wall).
    • Pro tip: You'll get shrinkage if you mix it too wet.
  • Spread a layer of slightly thinned all-purpose joint compound on the walls with a heavy-nap roller.
  • Work in small sections so you can smooth out the joint compound before it starts to dry.
    • Pro tip: Don't worry if you get cracking on the first coat; just mix the next coat a little thicker by spooning in some fresh mud from another bucket.
  • Use a 1/2-in.-nap roller to roll mud on an area about four feet square.
    • Pro tip: Try to keep it as even as you can so the squeegee work will go better for you.

Roll on the Mud

Step 3

Trowel the First Coat

  • Smooth the joint compound with the squeegee knife.
  • Keep a damp rag and a mud pan handy.
    • Pro tip: Use the rag to wipe the blade after every few strokes and the mud pan to wipe off excess mud that builds up on the blade.
  • Starting at the top corner, set the squeegee knife against the wall and pull it down.
  • Overlap each vertical pass until you finish the section.

Trowel the first coat

Step 4

Pull up from the Bottom

  • You may have to go over some areas a few times. It won't take you long to get the hang of using the squeegee knife.
  • When you're done with the top section, roll joint compound on the lower half and smooth it by pulling the trowel upward.
  • Pull the squeegee knife from the bottom up.
  • Touch up along the edges as you go.

Pull up from the bottom

Step 5

Scrape Off Lumps

  • Let the first coat of joint compound dry.
    • Pro tip: To speed up drying time, especially if the air is humid, bring a space heater and a box fan or two.
  • You don't have to sand between coats; just knock off lumps or proud mud lines with a 5- or 6-in. putty knife to avoid streaks in the next coat.
  • Brush off the wall and you're ready for the next coat.

Scrape off lumps

Step 6

Change Directions for the Second Coat

  • It sounds like a lot of work to apply two or three coats of joint compound, but the process is quick and the thin layers dry fast.
    • Pro tip: Give this squeegee-like taping knife a shot for smoothing out tape joints next time you tape. It tapers the edges and you'll have no trowel or taping knife marks.
  • As you know, the smoother you get the wall, the less sanding you'll get stuck with.
  • Trowel off each successive layer at a right angle to the previous one.
  • If you still see indentations or imperfections after the second coat dries, trowel on a third coat.
  • After the last coat dries, pole-sand the wall with 120-grit paper.
  • If you have too many peaks and valleys, hit the walls with 100-grit first.

Change directions for the second coat

Originally Published: June 16, 2020