We have a 1970s built smallish four bedroom detached house on an estate in south east England (Kent, just outside the M25). The house has with a pitched roof. I am advised that the pitch on the roof is quite low but it is not noticeably lower than other houses on the estate. Previous owners put four vents in the roof a couple of feet from the edge of the roof, two on each side of the house. Last winter (2023/2024) we started having leaks into three bedroom ceilings. Each leak is in the approximate vicinity of a vent in the roof. I am advised that it is unlikely that three of the four vents will have failed at about the same time and be letting water in.
Last summer a builder replaced the felt beneath the first couple of rows of tiles on each side of the house and reset the tiles. The gutters were cleaned at the same time.
As soon as we had heavy rain this autumn the leaks reoccurred in exactly the same places as previously. I’ve had a number of roofers around and they have given me a number of solutions including: installing ventilation in the loft, increasing the pitch of the roof a bit, replacing the felt overhang where the roof meets the walls and resetting the first couple of rows of tiles (again).
It has been pointed out to me that the cement between some of the ridge tiles has gone. This is visible from the ground. One roofer has quoted around £2,000 (including VAT) to repoint the ridge tiles. This doesn't include scaffolding. This seems to be very high for the job.
So my question is: is it likely that the ridge tiles are letting water in which is running down the roof felt and coming out where the vents have been cut into the felt. If so, will repointing the ridge tiles fix the problem or do they need rebedding as well to ensure that leak can’t reoccur?
Does £2,000 seem reasonable price for repointing the ridge tiles?
I've added photos to show the location of the leaks and an internal photo of the worse leak. If you enlarge the images from the front and back you can see where the leaks are in relation to the vents. You can also see the missing mortar between the ridge tiles in the front photograph.