This is part 2 of a 2-part project. To view part 1 on Apron and stepped flashing, click on the link.
Recommended lead to use is Code 4 / 5 depending on the mass of weight above the lead tray.
A lead DPC tray when used in a chimney is a water proof barrier which stops water penetrating down into the brick structure from above. They are normally inserted in the construction stage of a building as this is an expensive procedure to under take with an already constructed chimney.
Whatever the location of your chimney structure the lead DPC tray should be positioned 150mm above the lowest point of the chimneys front flashing where possible, or on the sides if the chimney is positioned on the ridge. Lead DPC trays should also incorporate an upstand where the tray meets the flue. This should be a minimum up turn of 50mm. The up turn is necessary to keep moisture that may collect on the tray from crossing below. The lead DPC tray should also be painted on both surfaces with Bitumen Paint and weep holes should be placed to let out any build up of moisture above the lead DPC tray.
An optional lead DPC tray can be installed just below any chimney capping as a secondary line of defence against water penetration your structure.