How does one set up a deck slab template when the profile is not located at the alignment? In my case the cross-sectional shape of the deck is shaped like a simple gable roof but the grade line is not located at the peak (where the alignment is) but rather…

Is there any way to allow the Top face of the slab to follow the curvature of the alignment (horizontal and vertical), but for the Soffit of the slab to remain level (horizontal, but vertical is fixed). Or for the slab to be placed to follow the horizontal…