In addition to the fire-proof and earthquake-proof structure, Hoan-den were requested to be equipped with heat-resistant and damp-proof structures by using asbestos for the inside and outside, as well as by laying boards made from empress tree or hinoki cypress inside.
耐震耐火構造とし、内外防熱防湿のために石綿材料を施し、内部はさらにキリまたはヒノキ板張りとするとされた。