Ceilings Once the ceiling has been stripped fsee p. 84-7), fill any minor cracks with cellulose filler, as for walls fsee p, 88-9). You may find that a large crack runs right across a ceiling, opening and shutting as the house moves slightly with the changing seasons. This type of crack is virtually impossible to seal and, unless you want to replace the ceiling, you may have to disguise it with ceiling tiles. Plasterboard ceilings are particularly prone to forming cracks in the finishing coat along the joins between the boards. To minim ize this, newly plasterboarded ceilings should be formed with small lath” sections of board, and a plaster undercoat as well as a finishing coat applied.
You can decorate the ceiling with a thick, textured paint to cover up these fine cracks. However, if you prefer a smooth finish, your best chance of a lasting repair is to work a fine-surface filler – or even a finely textured paint – into the cracks and smooth off with a dampened sponge. Stains On a ceiling, stains will sometimes bleed through new decoration if they are not treated beforehand. Seal the stained area with either an aluminium primer-sealer or with a proprietary stain block. Stain-sealers are now available in easy-to-use aerosol form. Textured surfaces If you wish to remove a textured coating from a ceiling, beware: the coating may well have been applied by a previous occupant of your home – or for that matter by its builder- to conceal a ceiling in poor condition. If you want to remove a textured coating, use a steam stripper to soften the compound, or apply one of the special stripping prepar- ations that are now readily available.
Either way, you will not find it to be an easy task, since you will have to scrape the compound away a little at a time and then wash the ceiling clean. Hairline cracks • The first step in repairing a hairline crack is to widen it slightly using the corner of a stripping knife. Unless you do this, it will be impossible to work sufficient filler into the crevice to repair it. e After you have widened the crack and removed any loose debris, the crack should look like this detail in cross section – a slightly V-shaped crevice. The point of the V will be on the inner surface. Plasterboard cracks o When you have to fill a large hole in a plasterboard ceiling, use expanded metal mesh stapled behind the hole.