Tile planning for kitchens and bathroom

Tile planning for kitchens and bathroom

tile planning kitchen bathroom

Planning on paper

The best possible way to start planning for a large expanse of tiling is not on the wall, but on paper. Graph paper is ideal, particularly if you intend including a mix of plain and patterned tiles, or a large motif that needs building up. Of course, advance planning is also essential if you’re tiling round major features like windows, doors, mirrors, shower cubicles and so on. You need separate pieces of graph paper for each wall you intend tiling. Allow the large (1 cm) squares on the paper to represent your tiles — one for a square tile of any size, two for a rectangular tile; this will give you a scale to work to.

Now mark up sheets of greaseproof paper with your actual wall sizes using the scale dictated by the tile size on the graph paper. Measure and outline on the seethrough paper the exact position and in-scale dimensions of all fixtures and fittings . At this stage, the objective is to decide how to achieve the best symmetrical layout for your tiles — the ‘ideal’ is to have either whole or equal-size cut tiles on each side of a fixture. First you have to mark in the central guide lines. For instance, on walls with a window draw a line from the sill centre to the floor, and from the centre of the top of the window to the ceiling. If there are two windows also draw in the central line from floor to ceiling between them.

Mark the centre point above a door to the ceiling and also indicate the horizontal line at the top of the door. In the same way draw in a central line from the top of a basin or vanity unit to the ceiling. For all these lines use a coloured pen for you have to be aware of them when deciding where whole tiles should be positioned. But they’re only the starting point — other potential problems have to be looked at too. Place the see-through paper over the tile sizes on the graph paper so you can see how the tiles will fall in relation to the guide lines. Now take into account the following important points:

• The first row above the lowest level — either the floor, the skirting board or a wallto- wall fitting — should be whole tiles. If necessary, change this to prevent a thin strip being cut at the ceiling.
• Check where tiles come in relation to fittings. If very thin strips (less than 38mm/ 11/2in) or narrow ‘L’ shapes would need to be cut, move the top sheet slightly up, down, left or right till the tiles are of a cuttable size — areas to watch are around windows, doors and where one wall meets another.

Placing patterns

When you are satisfied that you have a symmetrical and workable arrangement you can tape the top sheet in the right position on the graph paper, then start to plan where you’re going to position your patterned tiles. Use pencil this time in case you change your mind and want to make adjustments. These are the points to watch:

• Don’t place single motif patterns at internal corners where they would have to be cut — you won’t find it easy to match up the remaining piece on the adjacent wall.
• If the pattern builds up vertically and horizontally over four or more tiles, ‘centre’ the pattern on the wall so that cuts are equal at both ends. If pattern loss can’t be avoided with designs of this type at least it can be kept to internal corners. • Whole tiles should be used on both faces of external corners. Now butt each of the wall plans up to the other to make sure that the patterns relate both vertically and horizontally.

Planning on the wall

tile gauge

When there are no complicated tiling patterns involved and walls are free of interruptions such as windows, it’s often easier to do the planning directly on the wall itself. Here, the simple objective is to place the tiles symmetrically between the corners. And to do this, all you need is a tiling gauge which you can make. A tiling gauge is like a long ruler, except that it’s marked off in tile widths. Use a long, straight piece of timber ideally about 25mm square (1 in square) and remember to include the grouting gap between tiles as you rule off the gauge. If you’re using rectangular tiles, mark the widths on one side, the lengths on the other. Holding the gauge against the walls first vertically, then horizontally — tells you instantly where the whole tiles will fit in and where cut tiles will be needed. But first you must find the centre of each wall.

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Measure the width — doing this at three places will also tell you if the corners are vertical (hang a plumb line or use a spirit level to make absolutely sure) — and halve it to find the centre point. Use the tiling gauge to mark this vertical centre line with a pencil, then hold the gauge against it. Move it up or down until you have at least a whole tile’s width above the floor or skirting board — this can be adjusted slightly if it avoids a thin piece of tile at ceiling height — then mark off the tile widths on the vertical line itself.

Now hold the tiling gauge horizontally, and move it to left or right of the vertical line if thin pieces of tile would have to be cut near windows or fittings, or to make cut tiles at both ends of the wall equal. Following this adjustment, mark the wall and draw in a new vertical line if necessary.The wall can now be marked horizontally with tile widths. Keeping to the same horizontal, mark up adjacent walls in the same way. At corners, whether internal or external, don’t assume they’re either square, vertical or even. An internal corner is the worst place to start your tiling for this very reason, but it doesn’t matter if you position cut tiles there. On external corners use the tiling gauge to work inwards in whole tile widths. You can also use the tiling gauge to check that your graph plan is accurate, and make any necessary adjustments.

Putting up battens

Once you have determined that your plan is correct, fix a length of perfectly straight 50mm x 25mm (2in x 1 in) battening across the full width of the wall — use a spirit level to ensure that the batten is horizontal. Use masonry nails to fix it in place but do not drive them fully home as they will have to be removed later. If using screws the wall should be plugged. The batten provides the base for your tiling and it’s important that its position is correct. If more than one wall is being tiled, continue to fix battens around the room at the same height, using the spirit level to check the horizontal. The last one you fix should tie up perfectly with the first. If there are gaps, at the door for example, check that the level either side is the same, by using a straightedge and spirit level to bridge the gap. Once the horizontal battens are fixed, fix a vertical batten to give yourself the starting point for the first tile. Use a spirit level or plumb line to make sure it’s positioned accurately.

Fixing tiles

Begin tiling from the horizontal base upwards, checking as you work that the tiles are going up accurately both vertically and horizontally. Work on an area of approximately 1 sq metre (1 sq yd) at a time, spreading the adhesive and fixing all the whole tiles using card or matchsticks as spacers as necessary. Make sure no excess adhesive is left on the surface of the tiles. Next, deal with any tiles that need to be cut. You may find the gap into which they fit is too narrow to operate the adhesive spreader properly. In this case spread the adhesive onto the back of the tiles. When all the tiling above the base batten has been completed wait for 8-12 hours, before removing the battens, and completing the tiling. Take care when removing the base batten that the tiles above are not disturbed — the adhesive is unlikely to be fully set.

wall tiles

Dealing with corners

Your original planning should have indicated how many border or mitred tiles you will need for tiling external corners or for the top line of tiles on a half-tiled wall. You will find external corners, those which project into the room, in virtually all tiling situations — around boxed-in pipework , or around a window or door reveal, or in an L-shaped room. Where you are using universal tiles at an external corner, start at the corner with a whole tile — it should project by the depth of the mitre so that the mitre on the other face neatly butts up against it with a fine space for grouting in between.

With window reveals the correct method is to tile up the wall to sill level, cutting tiles if necessary. Fit whole tiles either side of the reveal, then again cut tiles to fill the space between those whole ones and the window frame. Attach whole border or mitred tiles to the sill so they butt up against the wall tiles. If using square-edged tiles the ones on the si should cover the edges of those on the wall so the grouting line is not on the sill surface. If the sill is narrower than a whole tile, cut the excess from the back — not the front. If the sill is deeper than a whole tile, put cut tiles near the window with the cut edge against the frame.

Continually check the accurate lining up of tiles with a spirit level. Some vertical external corners are not as precisely straight and vertical as they should be and this can lead to problems of tile alignment. The use of a thick-bed adhesive will help to straighten out some irregularities where a corner goes inwards (a thin-bed helps where the wall leans outwards). Buying a ‘flexible’ adhesive will give you both qualities.

As a general rule it is better to concentrate on lining up your border or mitred tiles perfectly vertically with only minute ‘steps’ between tiles, then bedding spacer or ordinary tiles behind to correspond with the line. Don’t forget that if you do have to create a very slight stepped effect, you can reduce the uneven effect between the corner tiles and others by pressing in extra grouting later.
Internal corners seldom cause serious problems as cut tiles can be shaped to suit fluctuations from the truly vertical. Don’t assume when cutting tiles for a corner that all will be the same size — the chances are that they will vary considerably and should be measured and cut individually.

Another point: don’t butt tiles up against each other so they touch — leave space for the grouting which will give the necessary flexibility should there be any wall movement.

Tiling around electrical fittings

When tiling around electrical fittings it is better to disconnect the electricity and remove the wall plate completely so that you can tile right up to the edge of the wall box. This is much neater and easier than trying to cut tiles to fit around the perimeter of the plate. Cut tiles and fit them in the normal way with the plate being replaced on top, completely covering the cut edges of the tiles.
This same principle applies to anything easily removable. The fewer objects you have to tile around the better, so before starting any tiling get to work with a screwdriver. You have the greatest control over the end result if at the planning stage you work out where you want to place fittings such as towel rails and soap dishes, shelves and the like.

Tiling non-rigid surfaces

On surfaces which are not totally rigid or which are subject to movement, vibration or the odd shock, tiles should not be attached using adhesive which dries hard as most standard and waterproof types do. Instead use adhesives which retain some flexibility. These may be cement-based types with a latex rubber content, or acrylic adhesives. You may have to surround a non-rigid surface with wooden lipping to protect the tiles.
Bathroom Fitters, Kitchen Installers

Tiling bathrooms and kitchen walls

Tiling bathrooms and kitchen walls

Tiles are an ideal decorating material for they make a room look good for years and require virtually no maintenance. But covering several walls with tiles is a large-scale job which needs a methodical and careful approach if you are to achieve the best results.

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The all-in-one look that wall-to-wall tiling can give has to be planned carefully to avoid expensive and time consuming mistakes. How to do this may depend on whether you want to include special patterns in the design, but following certain rules will give a desirable symmetry to the look. One of the hardest tasks will probably be choosing the tiles for there’s a vast array of shapes, sizes and colours available.

Having picked out the ones you want though, don’t buy until you’ve done the planning – for the plans of each wall should tell you whether the pattern will work in the room or would be lost in the cutting or amid the fittings. Plans on paper also give you an instant method of working out how many tiles to buy (counting each cut one as a whole, and adding 2-5% for unintended breakage) including the number which will need to be border (two glazed edges) or mitred (on square or rectangular universal tiles) for the top row of half-tiled walls or external corners.
Buy all the tiles at once, but do check each carton to make sure there’s no variation in the colour (this can occur during the firing of different batches).



Square or oblong areas

• measure lengths and width of the area
• divide each measurement by the size of tile you’re using, rounding up to the next whole number if you get a fraction • multiply the two figures to give the number of tiles needed Awkwardly-shaped areas
• divide area into convenient squares or oblongs
• work out each one as above adding up the area totals to give the final figures Patterns using two or more different tiles
• sketch out design on graph paper, one square for each tile (two for oblong tiles); use colours to mark where different tiles fall
• count up totals needed of each pattern, counting part tiles as whole ones Add 10% to your final tile counts to allow for breakages

ADHESIVE/GROUT For each square metre of tiling allow:
• 1.5kg (about 1 litre) of adhesive
• 150g of grout
TIP: AVOID NARROW STRIPS Less than about 25mm/1 in wide is very difficult to cut. When planning, if you see narrow strips are going to occur you can:
• replan the rows to use one less whole tile with two wider cut pieces at either end
• or increase the grouting space slightly between every tile in the row

Ceramic tiles for kitchens and bathroom

Ceramic tiles for kitchens and bathroom

Ceramic tiles are easy-clean, hygienic and hard wearing.

kitchen tiles wall

Modern ceramic tiles are thin slabs of clay, decorated on one side with coloured glazes. These are baked on to give the tile a hard, glassy surface resistant to water, heat and almost all household chemicals. The clay from which tiles are made, which is known as the biscuit, varies and you need to know the differences before you choose the tile to use.

Kitchen fitters, Bathroom installers

The thinnest ones with a pale coloured biscuit are good on all vertical surfaces (including doors where extra weight puts stress on the hinges). If the biscuit is reddish/brown it has been high baked (vitrified). The thicker and darker coloured it is the more strength the tile has — floor tiles, for example, are usually big in size as well as thick in biscuit., Work surfaces need tiles that are strong to withstand weights of heavy pots, while splashbacks and bathroom surfaces can take lighter, thinner ones. Types of tiles Within each range of tiles there are usually three types.

Spacer tiles have small projections on each edge called lugs which butt up to the neighbouring tile and provide the correct space for grouting (with these it is very hard to vary the width of the grouting). Border tiles are squared off on all sides but are glazed on two adjacent edges — these give a neat finish to outer corners and top or side edges. Universal or continental tiles have no lugs and are square on all edges.

All three can be used successfully in small areas, but do remember that if tiles do not have lugs you have to include grouting space in your calculations — the thinnest tiles need to be spaced by nothing more than torn-up pieces of cardboard, 6mm (1Ain) tiles are best with a matchstick width in between. Tiles are sold by the sq metre, sq yd, boxed in 25s or 50s, or can be bought individually. Boxed tiles usually advise on adhesive and grout needed for specific areas. When buying, if there’s no written information available always check that the tile is suitable.

How to plan the layout

When tiling small areas you don’t have much space to manoeuvre. The idea in all tiling is to create a symmetrical effect, using whole tiles or, if any have to be cut, making them equal. Knowing about the different sizes of tiles helps in the planning. For example, if you know the width and height or depth of the surface you intend to tile, you can divide this by the known size of tiles until you find the one that gives the right number of whole tiles.

Remember that the width of grouting has to be added to the measurement with non-lugged tiles – and except with the very thinnest tiles this can be slightly widened if it saves cutting a tile. If you’re prepared to incorporate cut tiles into the planning remember:
• on the width of the tiled area, place equal cut tiles at each end • on the height, place cut tiles at the top edge • on the depth (eg, window-recesses) put cut tiles at back edge
• frame a fitting by placing cut tiles at each side and the top

A mix of patterned or textured with plain tiles is best done first on metricated graph paper. This will help you see where you want the pattern to fall. Fixings should be made in the grouting lines where possible. Some tile ranges have soap dishes, towel rails etc attached to tiles so they can be incorporated ina scheme, but if these don’t suit your purposes, you can drill the tiles to screw in your own fitting (see page 58).

A working plan

All tiles should be fixed level and square so it’s important to establish the horizontal and vertical with a spirit level. Draw in the lines with pencil. If you plan to tile where there is no support (eg, on either side of a basin or sink) lightly pin a length of 50 x 25mm (2 x 1 in) timber below the tiling line – the batten will prevent the tiles slipping. On doors you may have to consider adding a timber surround to keep the tiles secure as they will be subjected to movement (see section on Adhesives).

Adhesives and grouting

The choice of both of these depends on where the tiles are to be fixed. In a watery situation (eg, a shower cubicle or a steamy kitchen) it is important to use a waterproof variety of both, even though you might have to wait for 4-5 days before exposing the tile surface to use.

All ceramic tile adhesives are like thin putty and can be bought ready mixed in tubs or in powder form to be made up with water. They are what is known as thin-bed adhesives in that they are designed to be applied in a thin layer on a flat even surface. The spread is controlled by a notched comb (usually provided by the manufacturer but cheap to buy where you bought the tiles) to make furrows of a specified depth.

When the tiles are pressed on with a slight twist, the adhesive evenly grips the back of the biscuit. Special latex-jbased adhesives (usually, two-part products which have to be mixed before using) have much more flexibility and are good for tiles where there is any movement (eg, on doors).

Spread the adhesive on an area no more than 1 sq metre (1 sq yd) at a time, or it will lose its gripping power before you have time to place the tiles. If you remove a tile, before refixing comb the adhesive again.

Grout gives the final finish to the tiled area, filling the spaces between the tiles and preventing moisture getting behind them and affecting the adhesive. Grouting can be done 12-24 hours after the last tile has been pressed into place. Grout can be standard or waterproof (with added acrylic), and both are like a cellulose filler when made up. If you only make up one lot of grouting, you can colour it with special grouting tints – but remember that it’s hard to make other batches match the colour.

Waterproof grouting cannot always take these tints. Press grout between the tiles with a sponge or squeegee and wipe off excess with a damp sponge. Even up the grouting by drawing a pencil-like piece of wood (eg dowelling) along each row first vertically, then horizontally. Do this within 10 minutes of grouting so it is not completely dry. Leave the tiles for 24 hours before polishing with a clean dry cloth. Wash clean only if a slight bloom remains. Tiles should never be fixed with tight joints for any movement of the wall or fittings will cause the tiles to crack. Similarly where tiles meet baths, basins, sinks etc, flexibility is needed – and grout that dries rigid cannot provide it. These gaps must be filled with a silicone rubber sealant Techniques with tiles To cut tiles, lightly score th’e glaze with a tile cutter to break the surface.

Place the tile glazed side up with the scored line over matchsticks and firmly but gently press the tile down on each side. If using a pencil press on one side, hold the other. Smooth the cut edge with a file. Very small adjustments are best done are best done by filing the edge of the whole tile.

line heavily by drawing the tile cutter across the tile more firmly several times in the same place. Then use pincers to ‘nibble’ the waste away in small pieces and smooth the edge. Glaze on broken tiles is as sharp as glass, so be careful not to cut yourself. Templates for awkwardly shaped tiles are not difficult to make. Cut the shape in card, place on a tile and score a line freehand with the tile cutter. Any straight score marks can be deepened afterwards, using a straight edge for support. Then nibble away the waste with pincers. If there’s a large amount to be cut away, score the waste part to divide it into sections, then nibble away. A good tip is to do this on a soft or padded surface so the tile doesn’t break in the wrong place. 2 Another type of cutter has’jaws’which clasp the tile during breaking. (It also has a small ‘wheel’ for scoring through the glaze on the tile). 4 Place pencil centrally under tile and score line, hold one side and press firmly I on other. With thin tiles, press lightly both sides.

Suitable surfaces

The ideal surface for tiling is one that’s perfectly flat, dry and firm. Small irregularities will be covered up, but any major hollows, bumps or flaking, need to be made good.

Plastered walls and waterproof sheets: perfect for tiling, but wait a month after any new plastering to allow the wall to dry out completely. Unless surface has been previously painted, apply a coat of plaster primer to prevent the liquid in the tile adhesive from being absorbed too quickly.

Plasterboard: again, ideal for tiling as long as it’s firmly fixed and adjacent boards cannot shift. (If they did the joins would probably crack). To prepare the surface, remove all dust, wipe down with white spirit

Laying plywood over a timber floor

Laying plywood over a timber floor

A floor which is subject to movement will disrupt tiles laid over it so if you intend tiling over a suspended wooden floor you will first have to make the surface as firm as possible by covering it with a layer of man-made boards. Water-resistant resin-bonded plywood is a suitable material as it will resist penetration by the damp adhesive you will be spreading over it and you will avoid the problem of rotting boards. The boards should be at least 12mm (1/2in) thick. To prepare the floor to take the plywood you should punch any protruding nails below the surface at the same time checking that the floorboards are firmly secured. You can then go ahead and fix the sheets of plywood to the floor using nails spaced at 225mm (9in) intervals across the middle of the sheets and at 150mm (6in) intervals round their perimeter. You will have to cut the boards to shape round any recess or alcove , and where there is a pipe run, fix narrow strips of plywood over the pipes to make access to them easier. Make sure you stagger the joints; this will prevent any floor movement causing the tiles to break up in a run across the floor.

Levelling a concrete floor for bathrooms and kitchens

Levelling a concrete floor for bathrooms and kitchens

A concrete floor which is out of true can be levelled using a self-levelling flooring compound so it is suitable for tiling. For the compound to form a smooth, even surface it should only be applied to a floor which is clean and free from dust, oil, grit or grease so you should first sweep the floor and then scrub it thoroughly (1). You may find you have to use a proprietary cleaner to remove stubborn greasy patches. The compound comes in powder form and you will have to mix it up according to the manufacturer’s instructions so it forms a runny paste

If you try covering the entire floor in one operation, it’s likely the compound will set into large pools which are difficult to join up. It’s better to work in small areas; you can delineate your working area by forming a bay using timber battens. Pour the compound onto the floor and then spread it out as evenly as possible using a steel float, any marks from the float will disappear quickly. The compound will set within a couple of hours. If you want extra thickness you can apply a second coat once the first is hard.

Grouting the tiles

Grouting the tiles

Mix the grout according to the manufacturer’s instructions; make up only a small amount at a time and, as with adhesive, work in areas of 1 sq metre (11 sq ft). Apply it with the straight edge of a rubber float, or a sponge or squeegee, making sure the joints are properly filled.

shower grouting

Pack the grout firmly into the joints and smooth off using a small rounded stick-don’t try using a finger as the grout is likely to irritate your skin. It’s best to remove excess grout (and adhesive) as soon as possible. If it sets it will be difficult to remove.

Laying tiles

Laying tiles

Finding the starting point

The first whole tile you lay will determine where all the other tiles are laid, so it is important that you get this positioning correct. Choose the corner in which you wish to start tiling and, laying your tile gauge parallel to one of the walls, measure how many whole tiles will fit along that side of the room. There will almost certainly be a gap left over. Measure this gap, and divide the answer by two to find the width of the cut tiles that will fill the gap at each end of the row. (These should be of equal size.)

bathroom floor tiles

If these cut tiles turn out to be less than one quarter of a tile-width across (and therefore tricky to cut), reduce the number of whole tiles in the row by one. The effect of this is to increase the width of each cut tile by half a tile – much easier to cut. Return to the corner and with your tile gauge parallel to the wall along which you have been measuring, move it so the end of the gauge is the width of one cut tile away from the adjacent wall. Mark this position off on the floor – it indicates where one edge of the first whole tile in that row will fall. Repeat this same measuring process along the adjacent wall to establish the positioning of the row at right angles to the one you’ve just set out; you will then be able to mark off where the other edge of this same first tile will fall, and so fix its position precisely.

Once that is done, every other tile’s position is fixed right across the floor. You can then place thisfirst tile in position. Mark off and cut the boundary tiles between it and the corner. Remember to allow for the width of the grouting gap when measuring each cut tile. Each cut tile should be measured individually because the wall may not be perfectly straight. You may then go ahead with laying whole tiles, starting from your original corner.

In the corner area spread adhesive evenly on the floor over an area of about 1 sq m (11 sq ft) – it is important to work on only a small area at a time, otherwise the adhesive may have begun to dry out by the time you reach it. With a gentle, twisting motion, place the first tile in the corner, and use light hand pressure to bed it firmly in the adhesive. Place the second tile alongside the first, using the same gentle pressure, and placing spacers of cardboard or hardboard between the tiles if they don’t have spacer lugs.

Continue laying tiles, building up a rectangular area, until you have reached the edge of the adhesive bed. Use a spirit level to check that the tiles are level; if any are too low, lever them off the bed as quickly as possible with a wide-bladed trowel, add adhesive and re-set them, pressing them down gently. With the first square metre of tiles laid, you can spread another layer of adhesive over a further area, and lay the next area of tiles. As you lay the tiles, it is worth checking every now and again that adequate contact with the adhesive is being made and that there are no voids beneath the tiles – any gaps or hollows under the tiles will become weak points later on. You can proceed with the tiling in 1 sq m sections until all the tiles are,in place, then leave them for at least 24 hours. The tiles must not be walked on during this time so that any risk of them being knocked out of place or bedded too deeply is avoided.


If you have to walk on the tiles, lay a sheet of plywood or chipboard over them first to spread the load. When 24 hours – or longer; check the manufacturer’s instructions – are up, you can remove the spacers. Check with the adhesive manufacturer’s instructions to see whether you need to allow extra time after this before you begin grouting. Cutting tiles You will have to cut each tile individually since you will almost certainly find variations around the room. Place the tile which is going to be cut against the wall and on top of the adjacent whole tile.

Mark it off for cutting. Using a straight edge as a guide, score the tile surface and edges with a scribing tool. You can use a hand tile cutter to cut and break the tile along the scoreline; but its probably worthwhile hiring a special floor tile cutter to make the job easier. To cut a tile to give an L-shape you will need to use tile nips to nibble away at the waste area. You can use a tile file, carborundum stone or coarse glasspaper to smooth off the rough edge. For curved shapes (eg, to fit round a WC pedestal), you will need to make a template and again use tile nips to nibble away at the tile.

Preparing the floor surface for tiles

Preparing the floor surface for tiles

Surfaces to be tiled should be dry, flat, stable, clean and free from grease, dirt and unsound material. A flat, dry, level concrete floor can be tiled without special preparation. If, however, there are small depressions in the concrete these should be filled with a mortar mix of 3 parts sharp sand and 1 part cement.

A more uneven floor should be screeded with a proprietary brand of self-levelling flooring compound. The screed should be left for two weeks to allow it to dry thoroughly before fixing tiles. If the floor is a new concrete one, it should be left for a minimum of four weeks to allow all moisture. to disperse before you begin covering it with tiles.

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Existing ceramic floor tiles, quarry tiles or terrazzo surfaces can be tiled over. They should be checked to ensure that there are no loose or hollow-sounding areas. Any defective sections must be made good before you lay new tiles on top. You can tile on suspended wooden floors, but it is important that the floor should be made as rigid and firm as possible.

To achieve this, cover the floorboards with a layer of water-resistant resin-bonded plywood at least 12mm (1/2in) thick. Alternatively, you can use chipboard of the same thickness. Before laying tiles over timber floors cover the surface thoroughly with a priming coat – either a special priming agent from the adhesive manufacturer, or else diluted PVA building adhesive.