Replacing broken or missing ridge tiles is something that should only be attempted by an expert roofing contractor. It's a difficult job that requires a multitude of skills and a lot of expensive equipment, not things that your average homeowner usually possess offhand.
Re pointing the hips on buildings is even more difficult being as there is nowhere to hang a roof crawler safely, it is necessary to remove a number of tiles from the roof to enable safe access. It is important that safety is observed at all times when dealing with roof repairs, especially on taller buildings and when trying to reach the outermost sections of tiling.
When re-pointing ridge tiles, it's not just simply good enough to skim over the existing tiles with a pointing trowel, thinking that it will last forever. The tiles should be lifted carefully and cleaned, any old cement then given a good brushing to remove mosses and lichens, then given a quick brush over with uni-bond. The slates themselves need a little uni-bond applying to where the tiles are to go back, this will insure that the ridge and the roof tiles are bonded together with the cement that has been used to re-bed them.
It is always worth noting that the ridge irons should be replaced if the ridge tiles are to be re-bedded. Leaving old rusting iron work is a false economy and should be attended to at the same time as the roofing repairs. Matching of the ridges is paramount when the tiles have been blown from the roof in storms, as the old ones will probably be no good and matching replacements must be found, there are a lot of reclaimed building material yards in Nottingham to search for such replacements .
It is some times a good idea that when the tiles are in a conspicuous place like the front of the house, tiles may be removed from the rear roof of the property and moved to the front and the new tiles placed at the rear were they will in time catch carbons and dirt staining them the same color as those on the front roof.
when all the work is completed you should not really be able to see there has been a repair at all. When choosing a roof repairer in Nottingham always employ a time serviced man and do not be afraid to ask about public liability insurance. Lastly never employ a builder that finds you, by this i mean the stranger that knocks at the door with tales of how you are missing a slate, and he just happens to have one exactly the same in the van. Thank him kindly and tell him the matter is in hand and close the door never employ one of these traveling builders that finds you, today he is a roofer yesterday he was properly a tar-mack monster and tomorrow he will be selling pegs. I know of at least 100 tradesmen from Nottingham and none of which go out renting for work door to door a builder that does not own a land line telephone or have an address may be difficult to find again.