Black Gravel in Clay Ridge Tiles Information, help and tips on many areas of roofing including trusses, tiling, venting, insulation etc....

[Partly Cloudy]

I thought I'd replace some damaged clay angled ridge tiles on the roof of my house built in 1936.
There is a black crumbly filling, like gravel under all the ridge tiles. I've added some photos. This gravel is damp because the mortar had mostly dropped out over the years and the tiles had holes in them.
The roof doesn't look like it has been touched since the house was built.
What is this gravel and what purpose was it meant to serve?
Thanks!

[stoneyboy]

Hi partlycloudy,
It is there to stick the ridge tiles in place so they do not blow off in high winds.
Regards S

[Partly Cloudy]

Thanks for the info Stoneyboy. It's obviously degraded from being mortar to soft gravel over the years. It didn't have any adhesive quality left at all, so I brushed it out where I replaced ridge tiles and will rely on the mortar I used to bed in the new ridge tiles and their own weight. The original Acme Sandstorm roof tiles on one side of the roof are so frost-damaged now, that I'll have to have the whole roof retiled this summer, so my ridge tile replacements are only temporary.

[stoneyboy]

Hi partlycloudy,
Thanks for responding.
Use a weak mortar mix so the ridges can be easily removed for the re-roof.
You will never know the conditions when the ridges were laid but if it was a hot sunny day it’s fairly certain that the mortar will have dried out and not set properly.
Regards S