Our contractor did a lump-sum bid on retiling the shower (76 square feet) that is in our walk-out basement. We said we would buy all material, but not tools. Basically, he bid on his labor cost, The contractor is installing new DryBoard/ tile shower back board. When removing the tiles on two of the walls, he found that the walls were cement block. He spent quite a bit of time removing the tiles on those two walls, and then getting the new dry board to lay flat on the cement block. Should he expect more money from us to cover this unforeseen aspect? I know for sure that he is a beginning contractor, but his price was very competitive with an established contractor; there was only a $200 difference between the two. I'm wondering if the established, more experienced contractor would have asked us for more money, or if because of his experience, would not have let the cement walls delay him. Is this just part of the "risk" when bidding by lump-sum and just part of the learning process for the newer contractor? I need some advice on how to proceed, but really, how to feel about the pricing: do I compensate him for his extra time?