This project is about transformation of a surface, and it will be a complete sucess with the first image of a plant emerging through your grafitti wall. I have reservtions about the long term durability of the sytem as burlap degrades, and soils shift, but this is completely irrelevant if you can acheive transformation!! By transformation i mean the metamorphosis of a grafiti surface into a vegetative surface. The idea of a breathable building surface has been a visionary notion in architecture since the invention of performative building materials and beyond, so I would encourage you to not worry about waterproofing and other impermeable materials.. Instead, focus your attention on the breathability of the proposed system. I would encourage you to research evaporative cooling techniques, and high perfomance fabrics as a precedent. There are large scale evaporative coolers that function by saturating a textile such as a tensile shade structure and cool an outdoor area. You may be on the path to invent a vegetative version of this system, where a building can ventilate and cool itself by using your adaptation of an "air filter". I would also research large scale evaprative airconditioners used in arid regions, there may be some insprations there.