Polystyrene tiles both decorate and insulate. Although they can be used in any room they are especially suited to kitchens and bathrooms where they combat condensation. They are an ideal covering for a poor, though stable ceiling. Sizes are normally 300mm and 600mm square.
A clean, dry, sound surface is needed so any paper or flaking paint must be removed. A special adhesive paste is used and this must be spread evenly over the complete back of each tile before it is pressed into place.
Find the centre of the ceiling by stretching a string line from the mid-points of opposite walls. Tiling can begin where the lines cross but check first to see if an unsightly narrow strip of tiles will be left at the perimeter. If so, the starting point should be moved half a tile’s width to one side. Fluorescent strip lighting can also be a deciding factor when establishing the starting point.
As each tile is laid in place use a square of hardboard to press it to the ceiling for a few seconds until the adhesive grips it. If a tile is pressed with the fingers the surface will be indented.
Continue hanging the tiles until only part tiles are needed to fill the gaps at the edges. Measure out and mark each tile carefully before cutting it with a sharp knife. Place the tile on a flat surface, with the decorative face uppermost, hold a straight-edge on the tile and then cut through it with firm pressure. Make a cardboard template as a guide before cutting tiles to fit awkward shapes.
The tiles can be painted with emulsion paint if preferred. This job is easier if the tiles are painted before they are hung. Never paint expanded polystyrene with gloss paint — it breaks down the material and makes it highly inflammable.
The edge of the ceiling can be finished with polystyrene coving.
A textured ceiling is achieved with a thick, paint-like compound sold under various brand names. These compounds can be used on any sound, dry, clean surface and are especially useful for covering a cracked ceiling. The cracks should be filled first with cellulose filler.
There are two types of compound. One is self-texturing — it is applied using either a brush or roller and leaves a stippled surface automatically. A roller gives a deeper texture. Patterned rollers are also available.
The other type is applied with a brush over a small area. It is then given a texture in one of a number of ways. A basic stipple effect is created by wrapping a sponge in polythene and bouncing it up and down on the compound. Other effects can be created
by, for example, twisting a comb on the compound to leave a series of swirls. It’s best to practise first on a piece of hardboard before tackling the real thing.
Ceiling centrepieces and other mouldings made of polystyrene can be used to enhance a plain ceiling. These are easy to fix using a special adhesive.
Cracks which continually reopen at the angle of the ceiling to wall are caused by normal, seasonal movement of the house. There is little chance of any filling material keeping the crack sealed permanently. The only real solution is to hide it behind coving.
Gypsum plaster coving is available in two girths, 100 and 127mm. The 100mm size comes in 3m lengths; 127mm size is in 3, 3.6 and 4.2m lengths. The special coving adhesive is sold in 5kg bags. This is mixed with water to a creamy consistency; mix up enough for only one length of coving at a time as it sets quickly.
The first stage is to draw guide lines on the ceiling and wall. The lines enclose the area to be occupied by the coving. For 100mm coving the guide lines should be drawn 67mm from the angle; for 127mm coving each line should be 83mm from the angle. The area between the lines should be cleaned and any wallpaper or loose paint removed. Finally, score the area with a filling knife to provide a good key for the adhesive.
Supplied with the coving is a template which is used for marking out mitres at the coving ends to suit internal or external corners. Cut the coving with a fine-tooth saw then lightly sandpaper any rough edges.
Butter adhesives on to the back of the , coving along the two surfaces which will be in contact with the wall and the ceiling. Fix the coving in place immediately. Though light in weight, longer lengths should preferably be handled by two people to eliminate the risk of breakages. Dampen the fixing area then immediately press the coving between the guide lines. The adhesive should grip the coving after a few seconds. If it doesn’t, then knock a couple of nails into the wall tight to the bottom edge, with another midway between these two – but tight to the top edge. Pull the nails out later and fill the holes.
Scrape off any adhesive which squelches out from behind the coving and use it to fill gaps at the edges or between lengths of coving. Use a wet paint brush to remove any last traces of adhesive.
For Victorian style houses, decorative plaster coving, mouldings and ceiling centrepieces would fit better into the style. Fitting is as for plain types.