Is it permissible to open a door onto the non-thoroughfare alley for a purpose other than passage, such as boarding it up or installing a window?

Primary text

If the owner wishes to open a door onto the alley for a purpose other than passage, or desires to have a door that can be boarded up (samara), or wishes to install a window, it is permissible. This is because the right to alter the entire wall implies the right to alter a portion of it first.