For the D12 there is a limitation on the minimum height and there will always need to be 2 sets of flights.
1 000
-
1375
=
2
1380
-
1860
=
3
1865
-
2340
=
4
2345
-
2685
=
5
2685
-
3000
=
6
After around 2500mm, but depending on the aesthetic and considering all the variables - we normally suggest installing a beam(cross-bar) and closing the remaining gap with a Maxigrill product.