Ensuring that your shed won’t be blown into the street or into the neighboring yard during a windstorm is an important part of shed ownership. Anchoring the shed firmly will help prevent this type of occurrence.
One of the best ways to secure your shed in place is to have a concrete pad foundation. Once the concrete is poured, after it has started to set for a while, you can insert anchor bolts into the still soft concrete.
Move them up and down slowly a little bit to encourage the concrete to fill in firmly around the whole bolt area that’s in the concrete. Make sure they are all level with each other, then let the concrete set. These bolts will enable you to secure your shed firmly to the foundation.
If your slab has already been installed, you can use a hammer drill and masonry bit to drill a hole into the sill plate of the shed and down into the slab. Insert sleeve anchors into the holes, then use the washers and nuts that come with the anchors to attach the shed. These are used every three to four feet all the way around the shed.
There are also T-shaped anchors that are meant to be attached to the sides of the slab, again requiring drilling. Two bolts are attached through the upside-down T to the slab, while the upright part is attached to the shed.
How Do You Prepare Ground for a Metal Shed?
Mark out the planned location for your shed, then measure out a foot wider all the way around. Insert a stake in each corner, attaching string between the stakes. Use the string to make sure that your corners are all square. Measure three feet from one stake on the string and mark it, then do the same on the other string attached to that corner, this time marking it at four feet.
If the distance between the two marks is five feet, you have a square corner. If not, you’ll have to do some adjusting of the relevant stakes and try again. Then do the same with the opposite corner. Dig out the defined area, making sure the walls of your dig are vertical and straight.
For a small shed, a depth of four inches is fine; for larger sheds, you may have to go as deep as eight inches. Fill the excavated area with crushed gravel to a depth of two inches, then compact it. Keep filling your space two inches at a time. Renting a compactor for this project is recommended, but you’ll need eye and ear protection, as the machine is quite loud.
Your shed can be installed or built over this foundation, and the extra gravel all around will help keep water from standing around your shed. If your shed does not have a floor, you may have to fill in some more gravel inside the shed and compact that also. Check out my article Should You Use a Permanent Foundation for a Shed? for more information.
How Do You Keep a Metal Shed from Blowing Away?
One of the best ways is to use a post-hole digger to dig round holes at least four feet deep near the corners and another in the center of the long sides if you have a long shed. Fill about six inches of gravel into the hole. Use tube forms set into the holes. These are usually made of cardboard.
The tops of the tubes should extend at least six inches above ground level, and the tops should all be level to each other. Pour concrete into the forms and set anchor ties into the tops in order to attach strapping. Once the concrete is fully set, toss a strap over the roof of the shed. Attach each end to the pair of anchors, then ratchet the strap taut. To prevent getting the strap too tight, test it while tightening.
It should be taught but you should still be able to slip a hand under the strap. Do this for the rest of the anchors. You can also use mobile home anchors and straps. If you know a bad storm is coming, you can add stability by putting a strap around the shed to make sure the door stays closed and doesn’t blow off.
There are also ground augers that look like a long rod with an eye hook on one end and a small auger blade near the other. They are screwed into the ground at a slight angle away from the shed and the straps are attached to them. They do take some work to insert and can be a problem if you have a lot of rocks in the ground.
How Much Wind Can a Shed Withstand?
This depends on how the shed is constructed and if it is wind resistance rated. This wind resistance factor refers just to the shed itself, not how it is attached to the ground, as that is the owner’s responsibility. Some locations require that sheds withstand certain wind speeds and have this written into their building codes.
Hurricane-prone areas, such as south Florida, have building codes requiring that structures be able to withstand 130 mph winds. If you have wind resistance in your local building codes, be sure to mention that when buying a prefab shed, ordering a shed custom-built or are planning to build one.
How Do You Wind Proof a Shed?
No shed can be made entirely windproof, but some guidelines from hurricane-prone areas will help. These include building a concrete foundation and anchoring the shed to it with the anchor bolts built into the concrete.
The more fasteners used in the construction of the shed itself, the sturdier it will be. Location is a factor, as a shed located at a high point in the yard will be more subject to winds. Make sure the roof doesn’t overhang the shed wall by much, as a longer overhang will give the wind something to grab to lift the shed.
If you’re concerned about wind proofing your shed, chances are your locality has something to say about it in the building codes. You should check with them to see what should be done. They may specify certain types of foundations and attachments, and certain fasteners for the studs and roof and other requirements.
If you have no guidelines, check out building codes for southern Florida, such as Broward County. If you build to their specifications, your shed will be as windproof as possible.