I am building a storm shelter in my new house. It's underground on 2 sides. The design has 8" concrete walls on all sides, 4 steel beams in the roof in pockets on the wall and bolted all the way through with welded steel angles. Roof is welded metal decking on the beams with 4 inches of concrete poured on top. The concrete on top was not as nicely finished as my slabs, and during construction when it rains I can see water seeping down inside on some parts of the wall. The concrete roof will be covered by a room above it so it won't leak when done, but do you think the fact that water can get in means tornado winds could pull the roof off?
Of course normal inspections are done and have all passed. But there's no code for storm shelters per se. I believe this is and issue with the finish of the concrete roof (which will be the floor of the 1 room in the house, which will be covered by 2x4, floor sheathing and be surrounded by a regular house frame.
The concrete walls where poured with a 4 inch lip (versus the 8" thickness) at the top so the roof would be poured inside. I think the edge of the roof pour and the lip ended up with some small gaps along the edges.
I am thinking of having them use epoxy crack filler in a few visible cracks. Or is that even necessary?
It was designed by an architect and a structural engineer. But I have constantly pushed them for a more belts and suspenders approach. Originally they just place the steel beams in pockets only (a 4" ledge on each side). But I had them welded to a steel angle and which was then bolted through the wall and tthough another steel plate with 3/4" bolts. They are also ok with the seepage as it will no be exposed to water once the structure is complete. But am thinking of the event when the structure has failed. I guess the final question is: is the dynamics of water and the suction produced by a tornado similar in the sense that if water can drip in, can that suction exploit the cracks and pull air from inside the shelter with enough force to pull the concrete/metal deck ... off. BTW above the decking, in the concrete, i had them place #5 rebars that were drilled into the lip.
Meeting him tomorrow to look at this issue - want to have a second opinion. But I can get another engineer locally to review. Thanks
I'm just saying that it doesn't sound like you have a concern with the wind ripping off the roof of this thing, based on what you have described.
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