Walls

How To Repair Walls & Our Top Ceiling Repair Tips

From hairline cracks to damaged plaster, knowing how to fill holes in a wall is a simple skill that will save you from calling out a handyman. Whether you have plenty of DIY experience or none at all, this guide contains everything you need to know.

Before you get started, familiarise yourself with our handy video tutorial and read through these DIY safety tips.

What you’ll need:

Different types of wall will require slightly different materials and technique. To make things easier, we’ve added steps for each kind.

How to repair a plastered masonry wall

1. Prepare the damaged area

  • Use a bolster chisel and club hammer to remove all loose material round the area to be patched and undercut the edges.
  • Wire brush the brickwork to remove all traces of loose material.

2. Mix the new plaster

  • Mix the plaster according to the manufacturer’s instructions. Use a gauging trowel to sprinkle the plaster powder into the water, while stirring with a clean stick.
  • When the plaster is thick and creamy without lumps, turn it onto a dampened board.

Top tip: Always add the plaster to the water and not the other way round. This will ensure that the plaster isn’t lumpy.

3. Fill the hole with plaster

  • Thoroughly dampen the area that’s being plastered. Use the plastering trowel to slide a good amount of plaster onto the plasterer’s hawk.
  • Standing close to the patch, tilt the hawk towards you. With a continuous movement, lift half the plaster onto the trowel.
  • Hold the trowel horizontally but slightly angled towards the wall. Press the plaster into the patch and move the trowel up the wall, gradually flattening it. Don’t completely flatten the trowel against the wall as this causes suction and pulls the plaster off the wall.
  • Repeat this process until the patch is slightly overfilled. Don’t overwork the plaster as this weakens it.

4. Smooth off

  • Once the surface is covered, go back over it to smooth the plaster to an even thickness. Hold the trowel at a slight angle so only one edge touches the plaster at any one time.
  • The plaster will start to set after about 45 minutes. Go over it again lightly with a dampened trowel to smooth the surface.
  • After a further 20 to 30 minutes, splash the surface with cold, clean water then use the trowel to flatten to a fine, smooth surface.

5. Filling deep holes

  • If the hole is deep, you may need to apply two layers of plaster. Apply the first layer to half the depth of the hole. When it has partially set, scratch up the surface and leave it to set fully without drying out. Apply a second coat and rule it off. When set, smooth off.

How to repair a lath and plaster wall or ceiling

  • Tap the surface to determine the extent of any loose plaster. Mark the perimeter of the damaged area with chalk, then score this line deeply with a heavy-duty craft knife. Remove the loose debris and wire brush the laths and studs.
  • Dampen the laths and edges of the surrounding plaster, then apply a coat of plaster to half the thickness of the old plaster.
  • Use enough pressure to force plaster between the laths while still leaving a covering of plaster on them.
  • When this first layer is partially set, scratch up the surface and leave it to set fully without drying out.
  • Then follow steps 3 and 4 under ‘How to repair a plastered masonry wall’ above.

How to repair brick in-fill stud walls

  • Treat these in the same way as other walls, except where a wooden stud or joist is exposed:
  • Use galvanised clout nails to fix 150mm-wide galvanised expanded metal to the wooden studs so the metal extends over the damaged area to the solid brickwork either side (always wear thick leather gloves when handling exposed metal).
  • Then follow steps 3 and 4 under ‘How to repair a plastered masonry wall’ above.

How to repair small holes in plasterboard

1. Prepare the hole for repair

  • Feel inside the hole to check for concealed pipes or cables. If you find one, push it to one side. Make sure the electricity is turned off at the mains while you check for pipes and cables.
  • If there aren’t any, use a utility saw or pad saw to clean up and straighten the damaged edges of the hole.
  • Finally, without making the actual hole any bigger, gently chip away a 25mm strip of surface plaster from around the hole.

2. Fix a backing patch in place

  • Tie off the string until the adhesive has set and scrape off any excess adhesive. Cut off the string flush to the patch.
  • Holding the string, feed the patch through the hole in the plasterboard and pull it into position behind the hole to check it fits.
  • If it fits OK, pull the patch back through the hole and coat its contact surface with panel adhesive. Feed the patch through the hole again and pull it firmly into position.
  • Cut a piece of plasterboard 25mm wider and longer than the hole. This is your patch. Drill a small hole through the centre of the patch and thread a knotted piece of string through it.

3. Fill the patched hole

  • Cut another piece of plasterboard very slightly smaller than the hole. Glue it in place with panel adhesive and leave to dry.
  • Finally, apply strips of self-adhesive plaster scrim over the joints and tidy up with finishing plaster filler.

How to repair large holes in plasterboard

1. Locate the adjacent studs

  • First, use a steel rule or thin batten to find the adjacent studs to the hole and mark them on the plasterboard.
  • Make sure you feel inside the hole to check for concealed pipes or cables before doing anything and move them to one side.

2. Remove the damaged board

  • Mark a rectangular section around the whole area that’s damaged and use a utility saw or pad saw to remove the section.
  • Clean up the edges with sandpaper.
  • Remove a 25mm strip of finishing plaster around the edge of the hole.

3. Fix battens to the studs

  • Use 50mm plasterboard nails to fix sections of 25mm x 50mm sawn and treated batten to the studs. Keep the battens flush with the front edges of the studs.
  • Use a thin layer of panel adhesive to glue further lengths of batten horizontally behind the plasterboard. Hold the battens in place with G-clamps.

4. Fix the new patch in place

  • Once the battens are set, cut and fix a piece of plasterboard to fit the hole, leaving a 3mm gap round the edges. Fix the plasterboard in place using 32mm plasterboard screws.
  • Finally, apply strips of self-adhesive plaster scrim over the joints and tidy up with finishing plaster filler.
  • Remove a 25mm strip of finishing plaster around the edge of the hole.

Ceiling repair tips

Repairing a ceiling requires a similar technique to a wall. However, there are a few other things to take into consideration.

If you live in a modern house, the ceilings will probably be made from plasterboard. Older properties, however, may have ceilings built from lath and plaster. To repair a ceiling, follow the steps above, depending on what material your ceiling is made from.

With awkward angles and gravity working against you, repairing ceilings can be a messy task. It is a good idea to lay dust sheets beneath where you’re working – just in case!

And that’s how to fix wall cracks and repair ceilings without having to call out a builder. To find inspiration for your next DIY project, take a look at our Ideas & Advice page, or share your own top tips with us @Homebase_UK.



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