Skim Coat

A thin layer of finishing plaster applied over plasterboard or existing plaster to create a smooth, paint-ready surface.

A skim coat is a thin layer of finishing plaster — typically 2-3 mm thick — applied over plasterboard or existing plaster to create a perfectly smooth surface ready for painting or wallpapering. It is one of the most common finishing tasks in UK and European renovations, though in the US it is more common to tape and joint drywall seams instead of skimming the entire surface.

Why skim coating is done

  • New plasterboard — fresh plasterboard has a paper surface and visible joints between sheets. A skim coat covers everything with a seamless finish
  • Repair work — old walls with cracks, uneven patches, or damaged plaster can be skimmed to restore a smooth surface without stripping back to brick
  • After removing wallpaper — if the paper has pulled away surface plaster, skimming creates a clean base for new decoration

The skim coating process

  1. Preparation — the surface is cleaned and a bonding agent (PVA) is applied to help the plaster adhere
  2. First coat — a thin layer of finishing plaster is spread across the entire surface with a trowel
  3. Second coat — once the first coat has firmed up slightly, a second thin layer is applied and worked to a smooth finish
  4. Drying — the skim needs to dry completely (usually 2-3 days) before painting. It transitions from dark pink to a uniform light colour when dry

Skim coat vs. dry lining

In the US and increasingly in modern UK builds, an alternative to skimming is “taping and jointing” (also called dry lining). This involves taping the plasterboard joints, applying a filler compound over the tape, sanding smooth, and painting directly onto the plasterboard. It is faster but does not produce the same hard, solid finish as a plaster skim.

Practical tip

Skimming is a skilled trade — the quality of your painted walls depends heavily on the quality of the skim underneath. When getting quotations, ask whether walls will be skimmed or taped and jointed, and factor in drying time before decorating can begin. A good plasterer working on a typical room will complete the skim in a day, but you will need to allow additional time for drying.