Finishing Plasterboard: Skim, Plaster or Wallpaper?

Filling the joints and screw holes and skimming once is enough if wallpaper is going over it afterwards, or if it’s a loft nobody looks at closely. If you’re painting the wall, or it’s a ceiling that gets raking light across it, skimming isn’t enough. Then a thin plaster coat goes over the whole surface, so there’s no joint or screw dimple left to see anywhere.

Three levels of finishing plasterboard

Finishing plasterboard isn’t a yes-or-no job. There are three levels, and which one you need depends on what’s going onto the wall or ceiling afterwards.

Filling joints and screw holes

Every plasterboard wall or ceiling starts with the same work, whatever you do with it afterwards. Scrim tape goes over every joint between two boards first: a thin, perforated tape that stops the joint cracking again later from slight settling of the house. Filler goes over that, in a few thin layers, until the joint can’t be felt any more. The screws are driven slightly below the surface of the board, and I fill and sand those heads smooth too. Without this work, you’ll see on every board where the next one starts, and a small bump or dip at every screw.

Skimming plasterboard for a rough loft or under wallpaper

If you only fill the joints, a subtle difference in thickness stays across the whole board: the edge is built up, the middle of the board isn’t. You only notice that when you look closely, or when light hits it at an angle. For a loft that’s mainly becoming storage space, or a room that’ll be full of furniture, that’s not a problem. Skimming goes a step further: a thin layer of filler over the whole board, not just the joint. That flattens out the difference between the edge and the middle, and is exactly enough for plain wallpaper. Wallpaper with a bit of texture hides the last small unevenness itself. Want to paint the wall? This level usually isn’t enough: paint adds nothing and exposes every difference in thickness instead.

Why you see plasterboard joints on a ceiling as soon as the light goes on

This is why a ceiling is stricter than a wall. When you switch on a lamp, or daylight comes in at an angle through a window, that’s called raking light: light that skims flat across the surface instead of hitting it straight on. Raking light makes every small difference in height visible, even a difference of a fraction of a millimetre between a filled joint and the rest of the board. On a wall you’re less likely to run into that, because a lamp is rarely right next to it. On a ceiling there’s often a spotlight, and the daylight coming in changes angle throughout the day. Skimming alone keeps that thin line visible. A thin plaster coat over the whole ceiling evens out the surface in one go, so there’s no joint left to become visible.

For Niel in Gorinchem, it was a 68 square-metre living-room ceiling. Here’s his review, left in Dutch on Werkspot:

“Werkt echt super nauwkeurig en netjes, hij heeft bij mij een prachtige plafond afgeleverd. Een echte vakman en zeer aardig en vriendelijk. Top! Van harte aan te bevelen!” Source: Niel, Gorinchem (Werkspot review)

Finishing plasterboard for painting or for wallpaper

What you need depends on what goes onto the wall or ceiling after the finishing work. If you’re painting, a plaster coat that’s smooth and ready for paint is enough: smooth enough to give the paint an even texture, without the board joints showing through. If you’re wallpapering, especially with a thinner or glossy wallpaper, you want the wall or ceiling completely flat before you start. Under thin wallpaper, every unevenness comes back, even one that paint would have hidden. Not sure what you need? I ask beforehand, so the final coat matches the right finish straight away.

Having a plasterboard wall or ceiling finished

I plaster plasterboard walls and ceilings smooth and ready for paint, including the ceiling I fit myself for a suspended ceiling. Newly fitted boards don’t have a smooth surface straight after installation, and I finish them in the same job into a crisp, flat surface with no visible joint. For Tom in Sprang-Capelle, it was the loft and the bedroom walls. Here’s his review, left in Dutch on Werkspot:

“Zeer tevreden over het geleverde stucwerk. Reageerd snel en is oplossingsgericht. Bedank Osman” Source: Tom K, Sprang-Capelle (Werkspot review)

Not sure whether filling the joints is enough, or would you rather have a full plaster coat? Send a photo of the wall or ceiling through the form or on WhatsApp. I’ll quickly tell you what level it needs. The same approach applies for wall plastering and for a ceiling I lower or fit new: the joints first, then the coat that matches what’s going on top afterwards.