Plastering walls in a renovation: old walls, holes and glue residue

When do you choose plastering in a renovation?

Plastering is the route if you want a smooth, painted wall after the renovation and the wall is too uneven for paint alone. Think of walls where pipes have been chased in, where a wall has been taken out or where old plasterwork has been repaired. A layer ready for painting brings all those spots back into one flat surface.

If you would rather have wallpaper on the wall, renovation fleece in a renovation is often the quicker route. In homes that have stood for years, the risk of new shrinkage cracks is smaller than in a new build, which makes plastering a good choice there. If you are still undecided, compare plaster and renovation fleece for your walls.

What preparation does each old substrate need?

In a renovation there is rarely just one type of substrate in the house. Brick next to plasterboard, old lime plaster next to a freshly filled chase. Each substrate needs something different before the new layer will bond to it.

All the data sheets begin with the same requirement: the substrate must be dry, clean and stable, free of dust, grease and other contamination. In a renovation, with demolition dust everywhere, that is the point that needs the most attention.

If there was wallpaper on the wall, first thoroughly remove all the wallpaper paste residue. And if an old layer has to come off completely, we take it off the wall first.

How are holes, chases and broken-out sections repaired?

After laying new electrical wiring or pipes, moving a door or removing a chimney breast, there are often deep holes and chases in the wall. These are filled first until flush with the surrounding wall, before the layer ready for painting goes over them.

We fill deep spots in stages. In the MP 75 data sheet, Knauf specifies that a layer thicker than 25 mm is applied in two passes, with the second layer only going on once the first has hardened. That is why we fill a deep chase in stages and not in one go.

At the joint between the filled chase and the old wall, two materials that behave differently meet. According to the same data sheet, fibreglass reinforcement belongs in the fresh plaster there, to limit new cracks. If such a transition cracks later anyway, the question is whether to touch up cracked plaster or have it redone.

On external corners created during the renovation, such as a new doorway or the opening to an extension, we fit a corner bead. We count corner beads per running metre.

Can’t you just put a thick layer over everything?

No, that actually costs you money later. A thick layer seems to solve everything, but it only hides what is underneath. If there is a hollow spot, a layer of glue residue or a dusty substrate underneath, the new layer clings to that, and comes away with it again.

The opposite misconception exists too: that everything has to be stripped bare first. Old plasterwork that is firmly attached everywhere can often stay, even in a 1930s house. That saves the cost of removal, and it saves demolition work and rubble in a house that is already full of dust.

You make the difference by tapping the wall. If the wall sounds solid everywhere, a new layer can go over it. If it sounds hollow, that section has to come off first. We make that assessment wall by wall, not house by house.

What does plastering walls in a renovation cost?

The plaster layer itself has a fixed price per m². What differs from one renovation to the next are the items before it: removal, corner beads and covering the floor.

Prices exclude VAT. For renovation work on a home over 10 years old, VAT is usually 6%; otherwise it is 21%. The VAT rate is stated in the quote.

An example for a ground floor with 80 m² of wall, of which 15 m² has a thin loose layer, 6 metres of new external corner and 70 m² of floor to cover: removal 15 × €14.99 = €224.85, plastering 80 × €22.99 = €1,839.20, corner beads 6 × €16.00 = €96.00 and the floor protection runner €274.99. Total €2,435.04.

If it concerns the whole house, use the example for a complete home. And if you want to see all the other rates side by side, take a look at our price overview.

How does the plastering fit into your renovation schedule?

The work is done by one of our 32 plasterers, from a team of 97 permanent tradespeople, which also includes 40 wallpaper hangers and 25 painters. We plan the plastering, the painting or wallpapering afterwards and the drying time in between ourselves.

Plan the plastering after the rough work: demolition, pipework and new openings in a wall must be finished, otherwise the plasterwork gets damaged again. A plasterer plasters 100 m² a day on average. The layer then has to dry; according to Knauf, gypsum plaster can be dry enough for paint after about four weeks under good conditions.

If your renovation falls in winter, plastering in the cold needs extra attention in the planning.

In your request, tell us what is happening in the renovation: which walls are being opened up for pipes, where a doorway is going and whether there is still wallpaper or old plasterwork on them. With those items in view, you receive a free quote within 24 hours. During the site visit we tap the walls, look at the substrates and take measurements.

Not every wall needs the same layer: there are different types of interior plaster, and during the site visit we look at which suits your walls. Our plasterers plaster walls and ceilings across Belgium, and in a renovation we take care of the rest of your renovation too.