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Lead Valley - All Decra Tile systems:
1. Install noggins between rafters to support valley boards.
2. Lay 250mm girth valley boards flush with top surface of rafter or 6mm exterior grade plywood valley boards on top of rafters.
3. Ensure that valley boards provide continuous support for lead valley.
4. Install continuous valley batten to each side of valley gutter, approx 200mm from centre line of valley, to support tiling battens.
5. Dress lead over layboards and valley battens and provide welted end, min 275mm from centre line of valley.
6. If required install timber packing pieces to suit to support underlay and tile battens at intermediate position.*
7. Cut underlay/breather membrane to rake and dress over valley to lap onto lead valley. Ensure that underlay is not laid under lead.
8. Cut tile battens to rake, projecting over valley typically 65mm short of centre line (also allowing sufficient downturn of tile edge into valley).
9. Cut tiles neatly, fold down to cover batten, and fix to provide a gap typically 125mm wide centred on valley.
GRP Valley - All Decra Tile systems:
1. Install noggins between rafters to support the valley boards & GRP valley tray.
2. Lay valley boards flush with top surface of rafters or 6mm exterior grade plywood valley boards on top of rafters.
3. Ensure that valley boards provide continuous support for GRP valley tray.
4. Install continuous valley batten to each side of valley gutter, approx 200mm from centre line of valley, to support tiling battens.
5. Install GRP valley in accordance with manufacturer’s instructions.
6. If required install timber packing pieces to suit to support underlay and tile battens at intermediate position.*
7. Cut underlay/breather membrane to rake and dress over valley to lap onto lead valley. Ensure that underlay is not laid under lead.
8. Cut tile battens to rake, projecting over valley typically 65mm short of centre line (also allowing sufficient downturn of tile edge into valley).
9. Cut tiles neatly, fold down to cover batten, and fix to provide a gap typically 125mm wide centred on valley.
*Timber packing pieces: These are used to raise the tiling battens above the level of the rafters to create an upstand for the valley tray, and should be reduced from min 19mm thickness across three or more rafters to avoid a visible rise in the tiling.
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