Here are my specs so far for the shed I am getting made. I plan to use it as a shed for my very large tools.

It is 40 ft × 24 ft, with 11 ft high walls. It is made from galvanized steel while the walls and roof are something like this photo.

This is what I have done to help protect it from hurricanes and increase the survival chances.

  1. I have made a strong concrete foundation that can handle 5 tons of tools and machines.

  2. I plan to screw the galvanized steel to the foundation.

  3. I plan to add shatter-proof windows and doors.

  4. Studies have shown that certain home shapes and roof types can better resist high winds and hurricanes, according to new research. I can share a link if you want. In the research it says that a gable roof with a 30° slope would be a good idea.

What can I do to make it stronger and what have I missed?

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    The exterior shell of the shed is fairly weak. What are your inside rails/joist spacing? Generally the idea behind seismic and wind resistance is tying everything together. In the past a lot of things relied on the weight of the material keeping it in place, now we have structural ties to tie the roof to the wall and the walls to the foundation. Can you talk about how each component is tied together? – Fresh Codemonger Feb 23 '20 at 18:08
  • I am getting it build, but I did not tie anything to make it stronger, how do I go about doing that? Where can I screws or special cables for this? – pumpum_bread Feb 23 '20 at 19:41

In Florida, I have seen many sheds like the one in your picture further supported with cable or strap tie downs. Heavy galvanized eye bolts embedded in each side of the concrete slab. Then straps or cables attached to one eye bolt, up and over the roof and down to an eye bolt on the opposite side. Hope this helps, and hope you never need it. You can get anchors similar to the ones pictured below at many home stores. They can be installed and then the slab poured over them for added strength.

enter image description here

Then steel cable or web tie downs can be fastened to the anchors. The web tie downs come in up to 50 foot lengths and steel cables in any length. They can go over the roof or attached to other structural points depending on the design of the shed.

enter image description here

  • I am getting it built, but I did not tie anything to make it stronger, how do I go about doing that? Where can I screws or special cables for this? – pumpum_bread Feb 23 '20 at 19:47
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    @pumpum_bread See my edited answer – JACK Feb 23 '20 at 20:11
  • Wait, as a retrofit? Seems like throwing a steel cable or strap over your roof is going to put inordinate stress on the roof corners, which it's really not made for... and a narrow steel cable across sheathing will be like using a straightedge to help tear a piece of paper. – Harper - Reinstate Monica Feb 23 '20 at 20:17
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    @Harper-ReinstateMonica not a retrofit but designed into the structure of his shed. He's getting it built and can have supports added as needed on the corners or where ever. – JACK Feb 23 '20 at 20:22
  • @Harper-ReinstateMonica, I am getting it built, thanks for the help man! – pumpum_bread Feb 23 '20 at 20:46

OK it's not made of galvanized steel, it's sheathed in galvanized steel. That sheathing is paper-thin and provides no structural value whatsoever. Seriously, ask your engineer how it would affect snow loads if you removed the sheathing and made it a carport. The engineer will say "Not at all, side sheathing provides no strength". It's a liability for wind loads, as it catches the wind and transfers it onto the building's structure (or fails to do so).

Except for the World Trade Center I and II, the visible surface of the building is not a contributor to strength, just as your own skin does not enable you to lift heavy loads. Behind it are the bones of the building. I.E. the wooden poles holding up the top rails on which the joists sit, or the steel skeleton, or whatever you selected when you specced the building.

That structure decides the strength of the building. It is chosen at design time.

I agree to be concerned the "default" specification may not be enough for hurricane country. (of course the city won't let you build anything below their standards). Now you are hoping core building strength can be retrofitted. This is not the worst time to do that, but it's still an awkward time.

That's a conversation you need to have with your engineer. Depending on the building type, sometimes a "knob can be turned" (e.g. ordering more trusses and putting them on 16" centers instead of 24"; speccing 20 ga. sheathing instead of 24) and sometimes it calls for a different building type or design.

This will have a price tag; or several price tags depending on the level of protection that you want; and e.g. twisting a knob vs blank-sheet respec.

Outside from that, keep the sheathing from falling off

Because loose sheathing in hurricane winds is a guillotine blade and will do unbelievable damage to whatever it hits. This just involves plenty of hold-down screws, positioned so they don't tend to tear down "seams". And it helps to have more carlins to screw into.

If it were tornado country I'd say build in some "blowouts" where parts will open up like a flap and let the air equalize; because replacing some sheathing is cheaper than having the building's structure be bent or broken. But that's not a hurricane problem, unless you have tornadoes too.

  • Hey mate! I did not buy anything, still looking around. Trying to decide thanks for the advice, I really appreciate it – pumpum_bread Feb 23 '20 at 20:31
  • @pumpum_bread oh good, you're working this problem at the right time, then. You might want to edit your other question to "How do I select a building for best hurricane resistance?" That'll yield some good answers. – Harper - Reinstate Monica Feb 23 '20 at 20:51
  • Lots of good info above. I'd ask about skinning the inside with something wood-esque, like plywood or OSB. That'll provide a ton of shear strength. Plus, you'd be able to through-bolt the siding in a few places to reduce the chance of flying guillotines. – Aloysius Defenestrate Feb 23 '20 at 22:42

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