What Do Plasterers Use To Fill Deep Holes?

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Most homes have a few holes in their walls. Often, these holes are very small – for example from nails or pins. However, if those holes are especially deep you may need to call in a plasterer to help fill them in.

So, how will a plasterer do this? Below we will take a closer look at the materials and methods a plasterer might use to fill in deep holes. We also look at when each method would be most appropriate to use.

Plasterers use a range of materials and methods to fill in deep holes in walls. The methods and materials to be used depends on the surface that the hole is in.

For example, is it a stud wall, is there a void behind it or is the wall rendered? All may require a different approach, and it can also depend on the tradesman’s personal preference.

Some popular ways to fill in deep holes include:

  • Plasterboard to patch the hole
  • Expanding foam to fill a deep hole behind the plaster
  • Using a deep repair filler

Patching Holes In Plasterboard Using More Plasterboard

One of the best ways to patch large holes in plasterboard is to simply use more plasterboard. This is usually the best option for stud walls.

Of course, it isn’t as easy as just jamming a spare piece of board into the hole. To do the job properly and to achieve a seamless result, you need to follow some steps.

Before you begin, you should inspect the area for any pipes and cables. If the hole is big enough you may be able to feel inside. Failing that, you can use a pipe and cable detector to ensure the area is safe to work on.

Then follow the steps below:

  1. Find the studs on each side of the hole, then mark where the centre of each stud is on the plasterboard.
  2. Draw straight vertical lines through those marks that extend beyond the hole (above and below)
  3. Next draw horizontal lines above and below, to create a rectangle shape.
  4. With a pencil, mark diagonal lines from each corner, then cut along them using a plasterboard saw.
  5. Also score around the rectangle. At this point you can easily snap the board and cut the back paper to remove.
  6. Once you have a clean rectangular hole, measure it, and cut a new piece of plasterboard to fit into the space.
  7. You should also add timber batons behind the plasterboard to help carry the new board. Measure between the studs to get the baton lengths and fix them through the plasterboard at the top and bottom. Make sure to leave some timber protruding past the plasterboard.
  8. Simply screw the piece of plasterboard in place attaching to the studs at each side and the timber batons above and below.
  9. Apply jointing tape carefully to overlap the join.
  10. Mix finishing plaster and apply it, carefully covering the jointing tape.
  11. When the plaster is dry, you can lightly sand if the surface is not completely smooth.

Using Expanding Foam to Fill Deep Holes Behind Plaster

For smaller deep holes with a void behind them, using expanding foam can also be a solution. The foam automatically expands once it has been sprayed. This means that it quickly fills up any gaps and holes.

Once it has fully set, it will be sufficiently strong, then you can simply remove the top layer to a few mm and apply a filler, for a nice smooth finish.

Just follow these steps:

  1. Clean any debris from the hole in the wall.
  2. If there is a void, you can stuff in some newspaper around the bottom of the hole to stop the foam from falling before it expands and sets.
  3. Make sure the applicator tube or gun is correctly fitted. Shake well before use.
  4. Spray the foam inside the hole. Fill it to about 75% of its capacity then allow the foam to expand. The foam should bulge out beyond the wall’s surface.
  5. Wait until the foam has fully hardened. This may take a couple of hours.
  6. Once the foam is hard, cut it down with a Stanley knife, so that it is just below flush to the wall’s surface.
  7. Next you can use a filler knife and some filler to create a smooth finish.

Once this is done you can either decorate, or if you are plastering, the wall would be ready for skimming.

Using A Deep Repair Filler

A deep repair filler can be used on its own to fill holes measuring as deep as 20mm. A lightweight ready-mixed filler can be used to rebuild the damaged area. Just follow these steps:

  1. Remove loose plaster and dust from the hole and its surrounding area.
  2. Dampen the surface so the filler bonds to the background.
  3. Push the deep repair filler into the hole.
  4. Smooth the surface using a scraper, and if necessary, sand it down for a smooth finish.


Although large holes in a wall may be unsightly, they can be repaired using the appropriate methods. Whether using expanding foam, filler or a piece of plasterboard, most large holes can be fixed quite easily. Simply follow the instructions outlined above and you’ll find your wall can be restored to its former glory.

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