Strange surfaces appear when applying SubD modifier

Hi everyone!

I’m having a little issue here I can’t seem to resolve. I want to create a hard surface at the edge indicated with the green arrow in the top image. I have tried beveling the edge aswell as increasing the crease parameter to no effect.

When I apply a SubD modifier, I get strange edges coming in from the side as indicated in the second image by the red arrows. I have tried everything I can think of to fix this so any advice would be appreciated.

Ideally, I want to achieve similar geometry to the below image.

try to resolve to quads. Ngons can cause problems with sub-div.

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Blender tries to resolve ngons best it can, but you’re leaving it with too many ngons, and concave ones at that. You need to split these ngons (using knife, vertex connect, etc…) so that your model ends up with only quads. Quads behave predictably in sudivision surfaces, ngons do not (they are actually implicitly triangulated).

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