Different wall surfaces and different types of damage can require different repair methods. The first difference is in the type of filler you choose; there is a vast range. Small holes, like the ones left after a picture has been moved, simply require a premixed cellulose type filler, just clean any loose material from around the hole first and give sand it to remove any unevenness. Push frayed plasterboard surface paper into the hole with a small blunt tool and the apply in a small amount of filler with a putty knife. Scrape off the excess. Leave a small amount over the hole, as it will shrink as it dries. These types of filler dry in about 30min. Hand sand and dab on a little touch up paint to finish.
Large shallow blemishes such as scraps and gouges require very fine plaster surface filler or a joint topping compound. Sand the area first then squeeze an amount of the filler onto a scrap of flat board, use a wide putty knife to collect amounts of the filler from the board and apply it over the scrape. These fillers may take a couple of hours to dry before sanding, be sure to use a sanding block when you finish off the job so you don’t hollow out your patch. You should paint larger repairs with a primer/sealer before touching up with your topcoat.
Gaps along joints where the skirting boards or architraves meet walls require movement so a flexible acyclic gap filler is important as it will expand and contract with this movement rather than cracking. These are applied with a caulking gun but are also available in applicator tubes. Push the applicator away from you and run a bead along the gap, this will help force the filler deeper into the gap. As you finish each section clean up the bead by wiping away the excess, the best tool for this job is a basic one, your finger. Clean up any mess with water and wait at least half an hour before painting.
Before filling cracks in masonry it is best to scarp the crack with the tip of a sharp object first to widen it slightly, vacuum out loose dust and slightly dampen it before filling. Apply a flexible filler, wipe away excess with a damp sponge and then tap the surface of the repair with the sponge to add slight texture, this will help disguise the repair once touch up paint is applied.
Fixing Large holes
Larger holes, like the ones that mysteriously appear in teenage boy’s rooms, will need a patch. Gather up a cordless drill, a keyhole saw, a sharp utility knife and a short length of 2x1 pine. You’ll also need a small piece of plasterboard and some jointing compound; these can be purchased at a hardware store for around $20. Cut a square patch from the new plasterboard, a fraction larger than the hole in the wall. Use the patch as a template to mark around the damaged part of the wall then use the keyhole saw to remove that area. Use your knife to cut a bevel around the front edge of the hole and the outer edge of your patch. The patch wont stay in the hole by itself so that short length of timber, around 20cm longer than the width of your hole, needs to be fed into the hole and secured by driving a screw through the wall on either side of the hole into the ends of the timber. Now the patch can be placed in the hole and also screwed to the timber, be sure to use plasterboard screws and only drive them deep enough to pull the surface paper of the plasterboard down to form a dimple, try not to penetrate that paper. Finally apply a thin coat of jointing compound over the seams and the screw heads. Once that is dry, use a sanding block to smooth it off; you’ll probably have to apply a repeat coat of the compound to achieve a smooth finish.
Proprietary hole patching products, such as ‘Vothole,’ are available from hardware stores. These replace the timber and plaster board plug as they are inserted straight into the hole and then topped with jointing compound. A temporary brace is removed from the front of the product once compound has dried and a final sand and fill smoothes the job before painting.