Plaster Wall Repair – Corners

Repairing chipped plastered corners 

Modern plastered external corners usually incorporate a metal corner strip and are so protected from damage. However, in older properties external corners were often made using render and plaster alone and can suffer damage from knocks and scrapes. Repairing such damage can be easily repaired using a suitable filler. 

• Start by brushing the damage clean of all loose dust and dirt. 
• Dampen (but don’t soak) the area of damage using a moistened paint brush or water spray. 
• Use a wide filler knife to apply filler to the damage, work it into the damage to make sure that there are no air holes or voids in the filler. 
• Use the knife to get the filler level with the surrounding plaster. 

 When the filler has started to harden, use a wet finger to shape the corner to the profile above and below the damage. 

Te filler used may shrink as it hardens, and the surface may need to be built up using repeat coatings of filler. Between each coat, lightly sand the surrounding surface and moisten the previous filler. 

Repairing Outside Corners of Plaster Walls

Tack a length of wood that exceeds the vertical dimension of the corner flush with on of it corners, making sure the length of the wood extends past the hole on both the top and the bottom (A). This acts as a guide when you patch the outside corner to produce an edge that blends in with the undamaged portion of the corner. 

Remove loose plaster, going slightly beyond the hole to provide a good seat for the plaster patch. Smooth the patching plaster away from the wooden guide with a trowel, overlapping the existing wall slightly. 

After it has dried, switch the position of the wooden guide to the other side (B) of the damaged corner and repeat the process. Sand and smooth once the patch has dried completely. Fill in any holes used to tack the piece of wood with joint compound.