Wall erected on the dividing line of two contiguous lots and which belongs in undivided co-ownership to the owners of both of them. The maintenance, repair and rebuilding of the common wall are at the expense of the owners of these lots, in proportion to their respective rights in the wall. Other rules may apply in particular in the event of heightening (increase of the height of the wall). The Civil Code of Québec stipulates that partitions or walls that are not part of the foundations and main walls of a building but which separate a private portion from a common portion or from another private portion are presumed common.