The plastering of a complete wall is not likely to be required in many households. New work is more easily carried out with plasterboard, but there are times when repairs arising from problems with damp or resulting from alterations such as the moving of a doorway leave fairly large areas to be plastered. Plastering of this sort can be tackled by the non-professional, although some previous experience, such as patching up damaged plaster, would be an advantage. The key to success is to divide the wall into manageable areas.

Applying the Plaster

Using the face of a plasterer’s trowel, scrape a couple of trowel-loads of plaster on to the hawk and start undercoat-plastering at the top of the wall, holding the trowel at an angle to the face of the wall and applying the plaster with vertical strokes. Work from right to left if you are right-handed and vice versa if you are left-handed.

Using firm pressure to ensure good adhesion, apply a thin layer first and then follow this with more plaster, building up the required thickness. If the final thickness of the plaster needs to be greater than 9mm (3/ain), key the surface with a scratcher and let it set, then apply a second or ‘floating’ coat.

Fill the area between two screed battens. It is not necessary to work tight up against them. Level the surface with a rule laid across the battens, sliding the tool from side to side as you work from the bottom upwards. Fill in any hollows and then level the plaster again. Scratch the surface lightly to provide a key for the finishing coat and let the plaster set. Work along the entire wall in this way, then remove the battens. Fill the gaps left by the battens, again levelling the plaster with the rule.

With gypsum plasters the finishing coat can be applied as soon as the undercoat is set. Cement undercoats must be left to dry for at least 24 hours because of shrinkage, then wetted when the top coat is applied.

PREPARING TO PLASTER

In addition to specialized plasterer’s tools, you need a spirit level and some lengths of 9mm (3/ain) thick planed softwood battening. The battens — known as screeds — are nailed to the wall to act as guides when it comes to levelling the plaster. Professional plasterers form ‘plaster screeds’ by applying bands of undercoat plaster to the required thickness. These can be laid vertically or horizontally.

Prepare the background and fix wooden screeds vertically to the wall with masonry nails. Driving the nails fully home will make it easier for you to work the trowel, but it can also make it more difficult to remove the screeds afterwards. The screens should be spaced no more than 600mm (2ft) apart. Use the spirit level to get them truly plumb, packing them out with strips of hardboard or wood as necessary.

Mix the undercoat plaster to a thick, creamy consistency and measure out two bucketfuls to begin with, though you can increase this to larger amounts when you become more proficient.

Cover the undercoat with a thin layer of finishing plaster, working from top to bottom and from left to right  using even, vertical strokes. If you are left-handed, work from right to left. Hold the trowel at a slight angle so that only one edge is touching.

Make sweeping horizontal strokes to level the surface further. You can try using the rule to get the initial surface even, but you may risk dragging the finish coat off. Use the trowel to smooth out any slight ripples.

Wet the trowel and work over the surface with firm pressure to consolidate the plaster. As it sets, trowel it to produce a smooth matt finish, but do not overwork it. Wipe away any plaster slurry which appears with a damp sponge.

The wall should be left to dry out for some weeks before decorating.