How to Skim-Coat Walls
A new approach for smoothing rough walls that's easy to master
IntroductionSmooth 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.
- 4-in-1 screwdriver
- Mud pan
- Paint roller
- Roller sleeve
- Safety glasses
- Sanding pole
- Squeegee knife
- Taping knife
- 120-grit sandpaper
- Drywall compound
- Masking tape
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. Make sure you know about these tips before you paint plaster walls.
Before you start on this project, if you’re having some issues with your drywall check out this video:
Project step-by-step (6)
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.
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.
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.
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.
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.
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.