I am not sure if the valley is leaking or the mortar either side of the valley is leaking.Is it best to remove all the mortar and replace?What mix and additives should you use?Can you use flashing tape along the length of the valley.Unable to see leak due to valley boards and draft excluder any ideas without ripping everything out?

john, December 2006

DO WHAT JHON SAYS , ALSO CHECK FOR ANY BROKEN TILES AROUND THE VALLEY AERA AND CHECK FOR ANY LOOSE OR BROKEN RIDGE TILES . WATER COULD BE COMEING IN FROM THE RIDGE AN RUNNING DOWN BEHIND THE VALLEY

RICH THE ROOFER, October 2007

It looks like youve got a tiled roof. Go up on the roof, clean the zinc or lead of the valley with a stiff brush, remove any loose mortar, dry the valley with old rags and if possible a hot air gun, patch up any obvious holes with flashing tape ideally warmed up with the hot air gun the coat the valley with Acrypol, starting at the top. later replace missing pointing, 4 to 1 fine sharp sand/ cement with plasticiser and maybe some pva in the water keep the mix dryer than you think, and press well in

JOHN COUGHLAN, December 2006