I have a shed which I need to anchor down. I found a kit which states you would need 1500 pounds of force for the object it is holding down to move. What does 1500 pounds of force equal per MPH?

It doesn't equal anything. It only works when you have surface area. Just think, if you held 1 square foot of wood into a 50 MPH wind, you could most likely do it. Now try to hold a 4X8 piece of plywood into the same wind. Can't do it! Same MPH but a lot more force. Hate to do this to you but: Taylor's formula gives the following:

Fw = 0.003 A V^2

Where:
Fw = the force of the wind acting normal to a surface facing the wind in lbs
A = the area of the surface facing the wind in square feet
V = velocity of the wind in miles per hour

The answer isn't straightforward, because it depends on the size and shape of the shed. There are a variety of online resources to help you calculate the wind loading and uplift forces.

Here's a good starting point:

http://www.documents.dgs.ca.gov/dsa/pubs/IR-16-7_WindLoad_12-18-07.pdf
(http://www.documents.dgs.ca.gov/dsa/pubs/IR-16-7_WindLoad_12-18-07.pdf)

The answer isn't straightforward, because it depends on the size and shape of the shed. There are a variety of online resources to help you calculate the wind loading and uplift forces.

Here's a good starting point:

http://www.documents.dgs.ca.gov/dsa/pubs/IR-16-7_WindLoad_12-18-07.pdf
(http://www.documents.dgs.ca.gov/dsa/pubs/IR-16-7_WindLoad_12-18-07.pdf)

6X8X8 with a 1 foot pitched roof. If I calcualted correctly I came up with 87 MPH. Let me know how close I came. I appreciate the answers guys.

I haven't done the calculation, but that certainly sounds pretty reasonable. The question is, do you ever get winds higher than 87mph? If so, remember that any weight you keep inside of it will add to the 1500 lbs. anchoring it to the ground.

And I thought Taylor's formula was complex!

You have the weight of the shed and weight of things in it. A couple of mobile home screw anchors should be satisfactory. You never mention the construction, a wood shed of that dimension weighs at least 500#. I have a 10X12 frame shed, 5/12 roof, in the GA Mountains, sitting on PT 4X4 runners. It is unanchored and despite Hurrican Ivan, has never moved. Probably has 200-300# inside.

I live in South Florida so we can get Category 5 hurricane winds. The weight in the shed does not matter because it has nothing to do with the roof.

I will ask the question a different way. What anchors and cable thickness would I need to withstand 140 MPH winds for 3 seconds. Believe it or not the inspector told me this is what the city requires.

Thanks again for your help

Now you are talking roof. Lateral wind loads are different than a roof which is rated in uplift. So are you talking about anchoring the roof to the ground not the structure base?

Now you are talking roof. Lateral wind loads are different than a roof which is rated in uplift. So are you talking about anchoring the roof to the ground not the structure base?

I need to show code enforcement the building will not fly away in a cat 5 hurricane. The shed is not up to code but I figured if I can show the City I anchored the structure down using a product which is code within the Cities parameters I could pass inspection. Any suggestions?

I believe they will require an anchor that goes from the roof joists to the ground. We have friends in Ft. Pierce who just built a new house and they have steel cable up the walls and across the roof to tie the house down. If you just tie the foundation, the walls and roof will blow away. I would use 4 Mobile home anchors, 4-6" in diameter, 1 in each corner, screwed 3-4 ft' into the ground and run 3/8 aircraft cable up over the roof or through the floor and then across the collar ties on the roof joists. The anchors are cheap and should each hold at least 2000#. Breaking strength of 3/8 cable is about 2400#. Using that, you should get way more than 2000#. Hope this works for you.