PREPARING SURFACE
In your residential or commercial painting job, small cracks, dents, holes or gouges in plaster walls or ceilings can be repaired with interior filler. To search for cracks and gaps that need repairing, hold a torch to the wall and run it over the surface to highlight any flaws that aren’t obvious in natural light. Circle the problem areas with a pencil.
Corner cracks
These cracks tend to indicate movement between the adjoining walls, and require caulking, which is flexible even with a bit of wall movement, preventing the crack from reappearing.
1. Squeeze a narrow bead of flexible gap sealant directly over the crack, around 3 mm in diameter, but don’t overfill as it can make the square corner appear rounded.
2. Mould the gap sealant into the crack with a wet finger.
Nail pops
Fasteners driven too far through plasterboard paper during installation or gaps between the plasterboard and the wall stud can result in nail pops. Movement of the timber makes the Filler over the area pop out from the wall. 1. Add a screw near the first to hold the plasterboard firm. Tap on the pop with the handle of a broadknife to recess a hole,
2. then cover over both nail and screw heads with some wall filler.
External corners
Metal corner angles sometimes pop through the surface plaster. In other cases, vertical hairline cracks form slightly beyond the corner, usually because the angle wasn’t nailed securely or covered in tape.
1. Secure with extra 30 mm plasterboard nails through the loose edges of the corner angle to hold it flat to the wall.
2. Centre tape over the entire length of the angle and cover with two coats of joint compound.
Loose tape
Plasterboard joint tape tends to blister and peel when there isn’t enough joint compound under the tape to anchor it to the plasterboard.
1. Cut and peel the loose tape beyond the evident crack, and fill the hole with fast setting wall filler and leave to dry.
2. Embed a strip of paper tape into the joint compound to cover the patch, then overlay two wide applications of joint compound to blend the patch into the wall.
Damaged areas
If significant damage has been made to a large part of the wall, the damaged area should be skim-coated in a thin layer of joint compound. Begin by removing loose plasterboard poper then prime the remaining raw paper.
Use a brush to saturate the paper with paint and wipe any runs. When dry, lightly sand any raised nubs.
1. Trowel on the joint compound using overlapping vertical strokes.
2. Finish with overlapping horizontal strokes.
