I guess you will need. Kajiado you need approvals that one am sure. To be save visit mavoko offices and enquire. Was the wall in the initial approved plan for the house, if yes then the approvals should have been granted together and hence you have nothing to worry about. If not then they demand for architectural drawings of the fence.
"The trouble with not having a goal is that you can spend your life running up and down the field and never score". - Bill Copeland