Roofing Repairs: Tiles
Laying or replacing tiles involves a similar operation, though these are heavier than slates. Tiles are again laid in courses, working from the eaves up to the roof ridge. Each course overlaps the one below, and vertical joins are staggered in adjacent rows, so that a tile partly covers two in the row beneath.
A slate ripper is helpful but not essential on tile repairs.
There are six basic types of tile: plain, pantiles, double pantiles, interlocking tiles and Roman and Spanish tiles. Unlike slate, tiles cannot be cut to size. The most common is the plain tile, measuring 265mm x 165mm x 13mm. These are slightly curved to ensure that tail ends bed evenly on the tiles below and to prevent water from creeping up, by capillary action, under the eaves.
There are three sizes of tiles – a standard tile for the main area; a tile half as wide again, called a tile and a half, at the end of alternate rows; and a shortened version of the tile and a half for the course along the eaves and along the ridge.
Tiles may be nailed to roof battens at intervals with 30mm galvanized; usually at every fourth course. Some have small projections called nibs, which fit over the battens. When replacing the odd tile, it is not normally necessary to use fixing nails. Nibbed tiles may be nailed, but unnibbed ones must always be nailed.
Try to match your tiles but if this is not possible, remove tiles from an inconspicuous area, using these to replace tiles in the visible area, and use the new ones in the less noticeable place.
If several tiles in an area are broken, it is a good idea to strip out the-entire area and retile, with new ones in one patch. Broken tiles near a verge, ridge or hip are more difficult to replace. Verges, ridges and hips are usually bedded in mortar. This bedding must be picked out with a cold chisel and tiles removed until the re-placement can be effected. When reinstating the bedding do not use too strong or sloppy a mortar mix. Use a 1:3 cement/ mortar mix sufficient for a solid, watertight job.
To take out a broken tile you just push it back slightly, lift it and withdraw it. Slipping the trowel beneath an adjacent tile, and lifting this slightly, will assist the operation.
If tiles are nibbed, prise the sound ones up with a trowel and lift the damaged ones over the batten. Nailed tiles should be rocked gently from side to side to loosen them. Use a ripper, if necessary, to remove the nails. You can also use a tiler’s hammer which has a head designed for knocking in tile nails and shaped on the other side for lifting tiles.
Tile from the eaves upwards, and to fit the last tiles, wedge up one of the tiles and lift the others and slide in the new tiles.
The under-eaves tiles measure 165mm x 150mm, and comprise the first and lowest course. These tiles are sometimes called half tiles and may be used to form the last course beneath the ridge. Verge tiles, which measure 230mm x 255mm, are used at edges and also for cutting to the mitre angle of hips and valleys. If any of these are broken or missing, water can get be- hind the fascia board. This course is completely covered by the second row of tiles.
Valley junctions are shaped tiles which interlock with each other to form tiled.
Tiles are usually fixed to sawn deal battens, though you may encounter feather-edged board.
On some roofs, narrower tiles, called creasing tiles, may be used at gable ends. These are laid beneath the end to tilt the edge of the roof slightly, so that rainwater does not run down the gable wall.
Alternatively, you can remove the two tiles above, which will expose the nails, pull out the nails and then the tile, substitute a sound one and slide the other back, over the batten then down until the nibs engage.
If the new tile is too large, nibble off an edge with pincers, a little at a time, until it is the right size. You can rub the edge smooth with a coarse carborundum stone. Allow a 12mm gap between tiles.
Pantiles, sectionally shaped like a flattened letter V, also interlock or lap over each other. These are pointed along the verge and may have nibs or hooks and are also nailed. First, chip away pointing where necessary, lever this slightly to loosen the bed and then push and twist sideways to remove the tile. If these are nailed, a ripper may be used to remove them.
Ridge and hip tiles may deteriorate through stresses or inherent weakness, or flake and spall through combined water and frost action. This may expose the ridge timbers. A broken ridge can also slip down a roof and do a lot of damage.
Ridges are generally right-angled or semi-circular, with a 230mm diameter. The edges formed by two sloping surfaces, called hips, have semi-circular or bonnet-shaped tiles.
Chip out the old ridge and remove all bedding material. Clean the adjacent edges of ridges and try the new ones for fit. If the tile is too long, allowing a 6mm overlap on each side, mark a line, then nibble off with the pincers.
You can cut a section by bedding the ridge solidly in damp sand and chipping a groove all round with a sharp cold chisel. Concrete ridge tiles are more difficult to cut than clay ones.
A new ridge must be bedded solidly along the edges. The joints should be firm and when the cement has slightly dried, the joints should be trowelled smooth. On the end ridge, the ‘open’ section must be filled in with mortar and tile slips. These are small pieces of tile to reinforce the mortar.
Pieces of tile must be used to reinforce the mortar of the ridge tiles and in the tiles on the verge.
Sarking (bitumenized) felt is laid on modern roofs, primarily to keep out dust. This felt tears easily. Always fit new felt if the existing cover is torn.
Felt should be overlapped by 150mm at both horizontal and vertical joints. The bottom run of felting on a roof should be overlapped at the front to provide a drip into the, while the top should always overlap the ridgeboard to form a watertight seal.
10. November 2011 by admin
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