I’m trying to do a part of a roof and I can’t make flatten face from this

Make face.skp (273.7 KB)

The edges in your model file don’t lie on the same plane. You could find figure that out simply by orbitig the camera a little. Basic geometry. The edges of the face have to lie on the same plane.

Roofs simply are planes set at the correct angle (pitch). Draw adequately large faces, grouping each plane so they don’t stick to each other and are easy to move.

Think in terms of creating the planes of the roof, move into place, and find the intersection. Not trying to draw the intersections.

Make sure the planes intersect each other once you have them in place. Explode each set of planes intersecting with each other. Once intersected, select both of the planes by triple clicking on one of them, to fully select them.

Right click on them and pick “intersect faces”. SU will draw the intersections for you. Then just erase the excess stuff left over. Regroup.