Im thinking about renovating my garage. I already asked one plumber about adding a bathroom. He said that it would be too difficult and too expensive to install a sewage line because: 1 - the garage is on a slab, 2 - under the slab are large roots from a tree, and 3 - the garage is detached from the house. My question is there any other method to avoid the slab and root problem? Also he said he could do it for $5,000.00 however the bathroom would not be permanent.