Metal tiles are press-formed to provide a variety of shapes resembling clay tiles, wooden shingles, or shakes. They are interlocked or overlapped laterally and longitudinally and are clipped or fastened to timber or steel battens.

Metal tiles, shingles, and shakes are normally manufactured from metallic-coated steel, although other metals can also be used.

Pressed steel tiles invariably have an additional protective and decorative coating applied over the metallic-coated steel. This may be an organic paint coating applied by either the steel manufacturer before the tiles are formed, or by the tile manufacturer after the tiles are formed. An alternative (and traditional) coating can be provided by applying crushed stone or ceramic granules (“chip”) to the base metallic-coated steel, which is attached by an adhesive coating; normally, a clear acrylic coat over the chip coating. Post-applied coating also provides cut-edge protection.

Pressed metal roofing tiles are installed by nominated agent fixers, trained and appointed by the manufacturers or their representatives. They are not normally supplied to other installers.

Valleys are installed so water discharges over the fascia and into the eaves gutter. The valleys are held in position by clips specially designed to allow for expansion, or by compatible nails and washers placed alongside the valley or bent over the top lip of the valley.

Under no circumstances must the fasteners penetrate the sole of the valley. The top end of the valley should be turned up against the hip or ridge battens to the height of the batten. Where two valleys meet over a dormer, they are cut, shaped, joined, and sealed so that they form a continuous valley.

The tile edge should be bent down to a minimum of 5 mm from the valley floor.

The gap between tiles on opposing sides of the valley must be a minimum of 70 mm.

Valley boards must be H3.1 treated and separated from metal by underlay.

• H1.1 boric-treated when used in attic roof construction;
• H1.2 treated when used in skillion roof construction.

• a minimum of 50 mm x 40 mm for 900 mm rafter spacing; and
• a minimum of 50 mm x 50 mm for 1200 mm spacing.

Battens in contact with tiles must not be treated with copper-based preservatives. Battens required for rafter spacings greater than 1200 mm must be specifically designed and spaced to suit the tile module.

N.B. Battens at different centres may require different values.

 Battens must have square cut ends and must be butt jointed over the centre line of the rafter.

• Adjacent rows of battens must not be joined on the same rafter and must span at least three rafter spacings at the roof edge.
• A batten must be installed immediately behind the fascia as fixing for the eaves tiles.

Because an eaves-tile batten is installed directly behind the fascia, the position of the next batten up the rafter will be less than that of the normal tile batten spacing. The position of this batten may vary depending on the pitch of the roof.

The batten layout is marked on the rafters by placing nails at the line of the batten fronts. The roofing underlay is laid over this, onto the rafters. The battens are then laid from the lowest part of the roof upwards, using the marker nails to locate the front edge of the batten. Remove the marker nails before laying the tiles.

Standard flashings are supplied for most locations on a roof. They come in two styles, only one of which is used on any one roof. All flashings and roofing accessories are made of the same base metal as the tiles and are coated the same way.

• Long accessories are typically 2 m long and fixed every 500 mm and there are specific accessories for ridges, hips, barges, aprons and walls.
• Short accessories are typically 400 mm long trims and can be used for most flashing applications on a roof.

Special flashings are made as required by the manufacturer or the roofer from uncoated steel, and subsequently factory coated using the same coating process as used for tiles.

The roofing supervisor will establish when the roof may be installed after all sub-trade work has been completed.

If substantial work, such as texturing walls, is to be carried out on a wall above or adjacent to where metal tiles are to be laid, they should be installed after such work has been completed.

Tiles should be inspected and selected, as tiles of a different colour match should not be installed on the same plane of a roof. If more than one pallet of tiles is required for one job, the colour uniformity should be checked.

Tiles damaged during installation must be removed and replaced, and any deformed tiles or tiles with surface damage must be rejected.

The eave gutter tiles should project over the edge of the fascia to ensure that water discharges directly into the gutter system, and tiles should be laid so they prevent any water from penetrating the roof cavity.

Before tiles are laid, the direction of lay should be determined, taking into account whether the profile can be laid only one way or both ways.

Direction of lay may be influenced by a desire to face laps away from major lines of sight, direction of prevailing weather, or sequencing of construction.