Hard8s

So I take it that there is a lip where the curtain is? Or is it just flat and sloped back to the drain? Either way I think you're going to have to put a frame in for the door. Why not just build over the pan and flash it or caulk it? Notch the bottom studs of the wall for the pan height so they have a footprint and marry it to the wall studs for support. Its not like the little wall is going to be load bearing.

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