I am building a walk in shower that measures 56x46 with a ft wide bench along the back wall. This gives me a floor that is 56x34. I bought a 48x48 shluter presloped floor and have cut enough away so that it is 48x34. This means i have to fill in each end about 4 inches. The sluter directions say do this with mortar, but, I was wondering if i could just use the strips of the floor pan I cut off to fill this in? I was thinking I could butter them up with mortar and stick them in place. I think it would work fine, but, was concerned they might move around a bit. Has anyone done this, or should I just head back to the building supply store nd buy a bag of mortar nd do it the right way?