I suggested speaking to a atty for a reason, if it is your property that is 3 storys and the other property is the one story and you had to tear down your building in order to create a parking lot, to tear down the entire so called joint wall would harm the other owner, so you would only have the upper parts removed because then it makes sense to leave it and a good arguement to abandon your interest in the wall since its not likely code would allow you to rebuild onto it. if that common wall between you began to crumble and crack down in the basement and had to be repaired it would make sense that you both share the repair cost since doing nothing could permit a fire to spread from one to the other more easily. Ill tell you my logic is if the part that serves only you is in need of repair then why would it be fair for other owner to assist you with money to repair it ? Your still free to speak to a atty or even try to get the neighbor to assist with the repair cost. ( If I was the owner of the one story I would take a look my self at the condition of the first couple of feet up from where the wall served as common wall and likely have a pro look at it and if that area didnt need repair- was solid and would cause no risk of water damage to the joint wall I would decline to share the cost & tell you that your repair crews had permission to use my roof as a staging area to complete your repairs. ( there is 3 story building in town here with a one story attached too that had to have many of the upper courses of brick were failing so they were removed and is in the process of being redone now) No work was needed to the common wall.
