Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
(OP)
Hello:
Would like to know if any of you has any experience with structures in hurricane area [Southwest Florida]regarding Fla Building Code requirements for a foundation depth. I am thinking of overturning resistance or uplift forces. Walls to be 4" or 6" reinforced CMU. Owner wants to do only concrete slab on grade. Shed 10'x20'
Any thoughts appreciated.
Rarebug
Would like to know if any of you has any experience with structures in hurricane area [Southwest Florida]regarding Fla Building Code requirements for a foundation depth. I am thinking of overturning resistance or uplift forces. Walls to be 4" or 6" reinforced CMU. Owner wants to do only concrete slab on grade. Shed 10'x20'
Any thoughts appreciated.
Rarebug






RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
I have to confess limited knowledge of the Florida code in particular (Ron are you out there?), but in general, a flat mat foundation might work as long as you check the 0.6D + W uplift combination and verify that the slab is stiff enough to account for loading on the portion that would participate in holding down the load bearing walls or columns.
A thin slab, getting pulled up by its edges, may not have enough dead weight tributary to the walls to work. The amount of slab you use as tributary to the walls would depend on the slab stiffness.
General comments but I'd need to see the actual code language to help you any more than that. Perhaps others out there - anyone?
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Regards!
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
The foundation/slab must also be designed for lateral bearing/movement. This is to determine the minimum depth of the foundation, based on lateral sliding resistance.
As for the depth of foundation for vertical loads according to the Florida Building Code....for monolithic slab/foundation systems, the minimum depth is 12 inches....but you still have to check for sliding.
A 4-inch masonry wall might give you a bit of a problem under the wind loads in that area. You will be limited to a wall height of less than 7 feet for a 4" bearing wall.
Also, ...no need to be snarky. Ron9876 gave you good advice if you are not a structural engineer; and presumably you're not since you asked these questions. We commonly get contractors asking such questions hoping to save some money....keep in mind that the building department will require signed/sealed drawings and in some cases, calculations. For these reasons, Ron9876's comment was right on target.
Now be nice and apologize!
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Didn't realize this was a residential shed. Requirements are less for the slab edge. Can do 8" depth for utility shed, particularly if less than 450 sf. Still need to check for sliding, overturning and other high wind considerations.
Geez...now we have a municipality practicing engineering without a license!!
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Design for that.
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
But I think most failures occur well above the concrete slab, not within it. Or maybe the attachment to the slab. If concrete is good at nothing else, it provides a lot of mass for very little money. With enough reinforcing to activate the mass, you can at least move on to the next weak link. Run the overturning and sliding numbers and see what kind of slab you need. But I suspect that other things will control.
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Thanks for your valuable input!. Initially, I was exactly thinking on the sliding and overturning resistance, but was curious how the foundation depth component played in all these.
It would be worthless to figure out steel anchoring to the slab or foundation wall or detail the roofing attachment to the wall,and have the building roll over altogeter, and I think the foundation depth plays an important role in both sliding and overturning resistance.
Thanks!
RE: Shed Structure Foundation Depth Hurricane Area [130 mph] Wind
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.