TYPES OF ROOF TILE

Replacing roof tiles is a job you can tackle yourself as long as you take the necessary safety precautions, since working at such a height will otherwise be hazardous. The tiles you will need for your particular roof are made of either clay or concrete and fitting is a straightforward operation.

Before attempting repairs to a tiled roof, check what sort of tiles have been used and how they are laid out on the roof. There are basically two types of roofing tile – double lap, and single lap.

Double LAP TILES

Double lap. or plain, tiles are slightly curved with two holes for fixing nails and usually two nibs. or projections, on the underside at the top edge; some tiles, however, are continuously nibbed along the top edge. The tiles are normally fixed to battens with aluminium alloy nails and the nibs hook over the battens for extra security. THE camber, or curve, to each tile provides air spaces between tiles and battens for ventilation and to prevent water ingress by capillary action.

Once made by hand, plain tiles are now mainly machine-made from clay or concrete Many clay tiles are smooth-faced, although they are also available with a sand face. Concrete tiles are becoming increasingly popular because they are slightly cheaper than many clay tiles; they are also not so likely to laminate and are available in a wide range of colours, including brown, red. grey, green and buff. In some cases the colour is confined to the granule facing, although often the tiles are coloured throughout. Because there are many types, sizes and colours of plain tiles, take a sample as a pattern when ordering replacements to make sure you get the right ones.

In plain tiling, the tiles hook over roofing battens so each course overlaps the tiles in the course-but-one below it; this amount of overlap should not be less than 65mm. Tiles in each course are butted together side by side and do not overlap. In this way there are at least two thicknesses of tile in every part of the roof – and three thicknesses in most places.

The usual size of plain tiles is 265 x165mm, although some hand-made tiles are 280 x 178mm. In addition there are special tiles to maintain the lap and weatherproof the roof at the verge, eaves and ridge.

VERGE TILES AT the verges special lile-and-a-half tiles, usually 265 x248mm, are used in alternate courses. These tiles are normally bedded on an undercloak of plain tiles, laid face downwards and projecting 38-50mm over the gable walls or bargeboards. Sometimes the verge is finished with a clip-on plastic verge channel which holds the end tiles firmly and stops water penetration.

Eaves TILES These usually measure 190 x 165mm and are used as an undercourse at the eaves and as a top course just below the ridge tiles.

RIDGE TILES Half-round ridge tiles, bedded with mortar along their edges and at the joints between tiles, are used to weatherproof the ridge. Hog back. segmental and angle ridge tiles are also used. It is most important the bedding mortar is placed only along the edges and joints between the ridge tiles, since cracking can occur if the ridge tiles are filled with bedding mortar.

HIP TILES There are several ways in which hips may be finished. It is common to use third-round ridge tiles bedded on mortar in a similar fashion to the way a ridge is formed. Because third-round tiles are not secured by nailing, a galvanized hip iron is screwed to the foot of the hip rafter before the hip tiles are laid to give them support.

Hip irons are not necessary when bonnet hip or angular hip tiles are used. These are nailed to the hip rafter and are bedded on mortar at the tail; they should be fitted so they lie snugly against the plain tiling at each side.

VALLEY TILES In plain tiling, valleys are often formed with purpose-made valley tiles of similar colour and texture to the main roof tiles. Valley tiles butt against plain tiles on each side and are usually fixed by nailing or bedding in mortar.

SINGLE lap tiles

Single lap tiles are designed to overlap, or be overlapped by. adjacent tiles in the same course and in the course above and below. In most parts of the roof there is only a single thickness of tile – except at overlaps, when there is a double thickness.

Clay single lap tiles have been in use for many years, but are being replaced by interlocking concrete tiles which are cheaper. Although some clay patterns are still made, it may be difficult to buy replacements; if they are not stocked by your local builders’ merchant, try specialist roofing contractors or local demolition firms – but ensure second hand tiles are not flaking or cracking.

A commonly found single lap tile is the English pantile; you can also buy interlocking clay pantiles which are available in a range of colours and with a glazed or matt finish. In some situations only alternate pantiles are nailed to the roofing battens but, if you have to replace this type of tile, it is a good idea to fix each one with rustless aluminium alloy nails.

Other common single lap clay tiles are double and single Roman tiles, ‘interlocking Somerset tiles, Spanish tiles which have concave under-tiles. and Italian tiles which have flat under-tiles.

Interlocking concrete tiles are available in a wide range of designs and colours and in smooth and granule finishes. Some have an acrylic finish which gives the roof a lustre as well as promoting rainflow off the roof and inhibiting the growth of fungi and moss. Concrete tiles imitate many of the clay tile designs and some are patterned to look like roofing slates.

Some single lap tiles have interlocking head and tail joints as well as interlocking side joints; this enables them to be used on roofs with very low pitches – down to 15 degrees in some cases.

FITTINGS Fittings for use with interlocking concrete tiles include angle, half-round and third-round ridge tiles, as well as monopitch ridge tiles for monopitch roofs.

ROOFLIGHT TILES To give light in the roof space, rooflight tiles made from translucent reinforced plastic are available in the contours of the single lap roof tile patterns.

VALLEY TROUGH TILES Valleys can be formed with special valley trough tiles, with adjacent tiles neatly cut and bedded on mortar.

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