i want to build a dome-based house but differently to most designs, i want it to be a full sphere, using a base of steel pipe and a pair of different joiners (hex and penta) and then grid mesh over each face, except for the truncated hexagon of the center row (think like football grid with each being a hexagon/pentagon made of triangles) , the "ground" level is then a nice neat flat shape to put a giant doorway into, and the triangles at the top around the top pentagon (iirc, if i point one hexagon as our "front" then at the top is a pentagon, the top pentagon then becomes a vertically closable cap that can be dropped down to seal the whole structure up water tight, with screw bolts and spring-based metal multi-layer seals. the whole thing would then, with concrete, and multiple layers of hydroisolation, likely handle handle full immersion for ~1 week without significantly leaking, and a "plug" in the base that once the water starts to drain back down, the "plug" can be opened.

the lower half, also, would be water storage, so when it's used as a refuge, the majority of the stored water underneath is drained out in order that the whole structure potentially has buoyancy, as well as keeping it vertically oriented and if made of a suitable ratio of weight, would even float, and for good measure, below the structure under the "plug" opening to the down drain, it has a long, heavy chain, and an anchor, which will keep it from moving.

that's my ultimate space survival disaster earth-ship design. probably also, it would use tensegrity in the structure so that there is heavy springs holding cables linked through the steel pipes at the core of the structure, making it resistant to fracturing by distributing the tension from impact equally so there is no loss of symmetry.