A Igloo type magazine is the structure that after building the structure on the ground, covered on an upper slab. Exactly as covering with earth on the upper slab, even if it is the ground building, have character of heat environment like underground environment. A indoor temperature is less than the air and keeps a low temperature, but with the air, surface condensation is easy to be generated in the rainy season. This study is to analyze the natural convection to have an effect on condensation in the covered with earth magazines then present to the solution for reducing condensation from increasing the natural convections.