Low pitch / Stone tiles advice please.

[MJS2014]

This looks like a great community, only just signed up!

I am looking at a simple 4m x 5m extension for my neighbour. Due to the position of existing first floor windows, a roof pitch of only 15 degrees can be achieved.

Roof tiles to the existing roof are natural stone, something like this...

I have looked online and struggled to find any information on low pitch stone tiled roofs. It would be wrong to introduce another roofing material as the whole terrace is made up of the same roofing as can be seen below...

Does anyone know if stone tiles can be pitched so low? Would it need additional water proofing? I have seen low pitch clay and concrete tiles but have not found anything in stone - or something with a similar visual effect that goes as low as 15 degrees. Any thoughts or comments would be appreciated, thank you

 

[palaceray]

The pitch is to low for stone or slate.

There is a product called onduline that should help as a waterproofing layer underneath.

It should be possible to increase the pitch by forming a lead secret gutter detail between the existing house and the new pitch roof.

 

[hardmetalking]

Lead or copper wouldn't look out of place IMO.

 

[MJS2014]

Thanks both for the input. Much appreciated

 

[MJS2014]

Would a pitch of 25 degrees be sufficient for natural stone slates?