Shed roof with tile or metal covering?

Hello everyone,

I am currently planning for our new home. Today the architect called me and asked what kind of roof covering I would like to have. He is currently working on the structural calculations and needs to know this.

After a long phone call, I unfortunately did not come to a decision! The choice would be a tiled roof or a titanium zinc roof with standing seam. The problem was that he could not tell me which roof covering would be the most cost-effective. Maybe you can give me some arguments that can help me with my decision.

Our case:

We are building a bungalow with two staggered shed roofs. One shed roof is oriented to the south and has a slope of 13 degrees. The second shed roof is oriented to the north and has a slope of 10 degrees.
The architect said it doesn’t matter which covering I choose because under both coverings a bituminous membrane (or similar) must be installed for sealing. Is that correct so far?

I am leaning towards the titanium zinc roof, but the questions are: what does it cost? How durable is it? What if something needs to be repaired? And is the substructure more complex than with a tiled roof? Does the titanium zinc roof have to be fully supported to be walkable, or is a battens system underneath sufficient? Is a metal roof always a cold roof?

I hope you can make some sense of the information for now. I look forward to your suggestions and the discussion.

Best regards

Florian