Where are arris tiles used?

[ey143]

What is the purpose of the Marley arris tiles when you can use bonnets? And what are granny bonnets compared with other type of bonnets?

Marley technical is banging on about mechanical fixing finials and ridge tiles. What's that all about?

Finally, are valley tiles exactly the same as bonnets but the other way around

 

[noseall]

oops

 

[noseall]

What is the purpose of the Marley arris tiles when you can use bonnets? And what are granny bonnets compared with other type of bonnets?

Bonnets are more versatile regards pitch but do require a decent mortar bed which requires pointing. Arris on the other hand are pitch specific but only require a little seating mortar, which is hidden from view.

Finally Marley technical is banging on about mechanical fixing finials and ridge tiles. What's that all about?

Vulnerable locations regards wind etc.

Finally, are valley tiles exactly the same as bonnets but the other way around

No. Hips have a fixing hole and are a different shape.