Great project. So, are those precast chimney sections? The table top extension is a great idea; I can see it provides a handy work surface as well as a place to congregate. These planchas are a large heat sink, and now that the occupants aren't breathing in all that smoke it makes it possible to seal the room better and thus keep the cocina nice and cozy. I built a Lorena Stove in my PC shack, and it kept me comfy on those cold rainy days and windy winter nights.