Plz convince me 4:12 pitch is perfectly safe in Augusta Me

I need help convincing a client that a standing seam roof with a 4:12 pitch will have no problems in the snows of Augusta Maine. He is convinced that it needs to be a min of 8:12. Unfortunately given his town's height restrictions and an existing foundation - 8:12 doesn't work. Can you speak from your experience that - if properly installed- 4:12 will work? Or am I too optimistic?

You are not too optimistic. Standing seam, if a mechanical double lock, can easily be run in pitch applications that are 1:12, let alone 4:12.

4:12 is plenty of pitch for any roof application and especially standing seam.

4:12 is more than adequate for a standing seam. I would recommend using a concealed fastened, clip system that snaps together. a high temperature peel and stick should be used at the eave (at least three feet beyond the interior side of the wall) and the valleys. Then covering the rest of the roof with synthetic vapor barrier.

Many thx, I should have also said they close the house in the winter - so there is no heat.

No reason that will have any impact. If you are concerned, full field Ice/water is easy security...but honestly its overkill.