A common wall / fence exists between my house and my neighbors. The wall was built before my house was constructed. Neither my neighbor or myself were property owners here when constructed. Best guess is the wall is 25 years old. The wood w/ stucco wall has been bowing slightly (4-6" in the center of a 100 ft wall) for years. We have noticed it, but the wall seemed tost be resonably structurally sound Due to a concrete restoral project in my backyard, I just had two trees removed along the fence line and it is pretty evident that the lean is indeed due to roots from the removed trees. Prior to the tree removal, my neighbor has never noted or complained about the leaning, but did wake up and notice when I removed the trees.
Since we are doing some backyard remodelling, we actually tried to be good neighbors and say that we would remove the wall and replace with high quality vinyl fencing (matches the fencing on the rest of our property and asthetically much nicer than the generic stucco wall) but she feels that it would not look good with her back yard.
Now she is suggesting I replace the wall (108 ft, large $$$ cost). In addition, there is a wall extension that corners back onto her property with a gate. She is assuming I will replace that as well to match the new wall, but it is not damaged / in perfect shape. I believe that the undamaged section should not be demoed and the replacement wall joined at the corner where the extension continues back onto her property.
So my questions are:
1. Is the wall replacement my responsibility or a 50 / 50 shared if the trees on my side were the source of the bowing of the wall? Is there specific California civil code that dictates this in the above scenario (i.e. not just aging / deterioration of the wall).
2. If it is my responsibility, who dictates type of wall replacement and contractor? She is assuming she can dictate type of wall and contractor. My fear is that I will get totally hosed by the contractor she selects (likely). I believe we should get competitive bids and the lowest cost bid for equivalent replacement construction should be selected. Is there legal guidance here?
Thanks...

