This loose and damaged ridge tile was found on a recent aerial roof inspection which had missing ridge tiles on the south side of the building.
Upon closer inspection of the below image, you can see shadows from one of the nails which indicate there is some ‘give’ on the roof tile which has been caused by wind. Unfortunately this ridge tile isn’t able to sit flat anymore as a stone as lodged underneath and the wind is now able to penetrate into the roof along the adjoining ridge tiles. If you look carefully you can see a missing nail, and what looks like a piece of debris lead flashing or debris of a roof tile along the roof gully.
Ridge tiles become dislodged and damaged due to high winds resulting in the breakdown of the original mortar after years of exposure to the elements, mostly rain and frost. Once this occurs, rain enters the small cracks resulting in the eventual crumbling of the mortar.