This is some lovely rotating clouds we saw from our front porch during a severe thunderstorm. Fortunately the rotating never organized into anything, but it sure makes you think.
The roof needed to be made in advance and so we made it from 2 sheets of 3/4 inch plywood. These were glued together and attached to a frame of 2X4s.If we decide to upgrade to an F5 suitable shelter we will add 1/4 inch steel sheets. I don’t think we’ll bother though. The cost would be huge and the risk, while not zero, is extremely low.
The space for the shelter is here under the main beam and near the stairs. Naturally Klinger supervises everything,
We have a very high water table anyway and with heavy rain we get a lot of water. If the sump pump fails the basement fills with water to the height of the black on the bricks. So the flooring has a one inch space for water to flow to the sump pump. During a severe thunderstorm, a space like this can swiftly fill with water from inches of rainfall so we have to plan on being wet. Because of the wet, the bottom most layer and everything that touches walls is made from treated “preserved wood foundation material” lumber. We have also purchased an emergency back up sump pump that will run on DC power since any severe weather will likely mean the electricity is out. There will be a deep cycle marine battery in the space. We will also have lights from the battery.
We originally were planning on bracing the roof into the beam of the house itself. But according to FEMA it’s better for the box to be self contained and not attached to the house in case the house gets moved off its foundation. So the box frame is bolted to the concrete with special 1/2 inch concrete anchors at six points on the floor and four on the roof where it attaches to the cinderblock wall that will act as the fourth wall. Each concrete anchor can take 1000 pounds of force with ten bolts we have 10,000 pounds. It’s not going anywhere any time soon. It would hold very nicely for an F2, F3, the kind typically found in Manitoba) and probably an F4. It might even be good enough for an F5 providing the tornado passed over very quickly and didn’t sit on us churning, since we are also below ground level.
Now the roof is in. It’s all framed with temporary frames and bolts until the main interior framing is completed. I can’t say we worked all that hard. We took lots of breaks, had a rather leisurely dinner and we didn’t start until after noon. Plus we had an afternoon nap. We finished to this stage by 9:00 pm.