Finishing work should be clean and result in all edges and junctions being properly sealed against water penetration.
Sarking should be trimmed around all roof projections such as chimneys, shafts, vents and abutments. The edges should be turned up to divert water around the projections and from under flashings.
All flashings are to be installed by other trades. Either lead or copper may be used for metal flashing (unless otherwise specified). It should be sufficiently pliable to be dressed down well into the tile profile but at the same time have sufficient mass to retain its position under wind pressure.
Side flashing should be dressed to fit closely into and against the profile of the roof tiling and be a close fit to the vertical wall. Top edges should be firmly secured into raked joints or machine cut grooves in masonry.
Flashing against vertical framework must be suitably supported.
The waterproof junction between the brickwork and tiling may be either by concealed gutter and stepped flashing, or stepped cover flashing. Stepped cover flashing must be carried over the tiles and dressed down into each watercourse.
Cover flashing must be carried over the head of the tile to a minimum distance of 115mm and properly dressed down into the tile profile.
All overlaps must ensure that water cannot penetrate.
The lower edge of wall sheeting over a tiled roof must finish 90mm above the top of the tile batten to allow clearance over the tiles. The distance must be maintained for all batten sizes.
Minimum clearance between top of rafter and bottom edge of raking, stepped or cover flashings should be as follows:
INSERT TABLE HERE ROOF TiLES
Junction of Flat Roof with Vertical Tiling
The minimum overlap for metal flashing at the head of vertical tiling must be 115mm. Tiles must be fixed in accordance with Tile Laying.
The minimum overlap for metal flashing at the junction must be 115mm. Metal flashing must be dressed well down into the tile pattern.
Valley boards should be a minimum 19mm thick, be below the top of the tile batten and extend the full width of the valley.
Tapered valley boards having a section of 175x19x6mm can be used, with the 6mm thickness to the outside of the valley for 50x25mm battens. An outside thickness of 25mm applies where tile battens are 38mm in thickness.
Sarking at Valleys
Where sarking is used, it should overlap the valley by 25mm and be held in place by a valley batten fixed parallel to the valley board.
Valley Protection (where applicable)
Under normal conditions a gap of 100mm between tiles is acceptable.
Where birdproofing is specified, a strip of galvanised wire mesh can be installed between the tiles and valley.
In high rainfall areas the valley tiles should be bedded and pointed and the gap between the cut tiles may be increased to 180mm.
Valley irons should be treated with corrosion inhibiting material prior to bedding and pointing.