Skimming vs re-plastering: which do you need?

Skimming puts a couple of millimetres of finish plaster over a sound surface. Re-plastering strips the old plaster back to the masonry and rebuilds it. Choosing the wrong one is the most common reason a plastering job disappoints.

Three checks you can do yourself

1. Tap the wall with your knuckles. A dull, solid sound is good. A hollow drumming sound means the plaster has parted from the wall and should come off.
2. Press firmly. Any give, movement or powdering means the plaster has failed.
3. Look at the low level. Salt staining, bubbling paint or crumbling within half a metre of the floor usually points to damp rather than plaster failure.

When skimming is enough

• Sound plaster that is simply uneven, patched or covered in textured coating.
• New plasterboard that needs a flat finish.
• Walls with minor cracks that can be raked out and filled first.

When to re-plaster

• Hollow or blown areas across a significant part of the wall.
• Historic damp damage where salts have contaminated the plaster.
• Old lath and plaster that is sagging or has lost its keys.
• Walls being taken back for rewiring, replumbing or insulation.

What each involves

A skim is a one to two day job per room with modest mess. Re-plastering means removal, waste, base coats and a longer drying period before decorating — often a week or more before paint. Prices differ accordingly, so ask each plasterer to say which they have quoted for and why.

Getting comparable quotes

Plasterers sometimes quote for different jobs on the same wall — one for a skim, one for full removal. Ask each to state the method, and then compare. Our guide on comparing quotes covers how to normalise them.