Pole Barn Tips for High Wind + Humidity (Florida)

chamjoe · Oct 21, 2019

I've scoured the forum and internet and apparently I'm getting old as I can't seem to find the answers.

I'm in central florida and need to build a pole barn that I will probably close in myself doen the road. I don't need permits as I'm ag exempt.

While I don't need permits I'm trying to find a kit or some sort of specs or even friendly advice on what the minimum specs should be to provide some hurricane resistance. Online kits that I've seen don't get into details and when I ask them about Florida and wind loads the usual response is that they don't service the area. Assuming ~40'x48'x12' I'm thinking about 6x6 posts every 12' for the sides but what about sinking the posts in sandy soil and probably most importantly what about trusses and whats the best was to insulate the metal roof?

I'm also open to CFL contractor recommendations.

Thanks

boomer1025 · Oct 21, 2019

Here you go, check out this site
Pole Barn Cost Estimator | APB Pole Barn Design Center

Tractor X · Oct 21, 2019

did a lot of rebuilding and building (06-09) in the gulfport ms area after katrina. the gulf coast has some of the strictest building codes (International Building Code) in the US.
normal we set post (marine grade) in a 30dia X 3'-6'D hole depending on local codes. we drove #4 or #5 rebar (perpendicular) at 2' and 1' from bottom of posts sticking out 6"-8" on each side. not sure if this would apply to a pole barn... definitely use the rebar.
continuous strapping from ground to header/beam at all 4 corner posts.
trusses need X3 continuous rat runs (gable to gable) for gable bracing at each end. all trusses got hurricane clips and both end gables strapped to header/band at 32" .
i can't remember the screw pattern for metal roofing 16" oc and 8" at eves? decking was 1/2"-5/8" plywood (nailed every 8") with ice and water shield as underlayment. screwing metal directly to OSB voided warranty, not sure about FLA. never did any jobs with purlins on the gulf coast.
ask around! most subs, lumber salesman and code enforcement guys are happy to help. i will NEVER forget the devastation after katrina... codes have changed since then.

EddieWalker · Oct 21, 2019

I'm in East Texas, so I don't know anything about building in your area other then what little I've read about it. I have seen a lot of effort put into different ways to keep posts in the ground, but haven't actually seen any pictures of evidence of posts coming out of the ground during a storm. If it was me, I'd just drill the holes and fill them with concrete unless I found solid evidence that they actually come out of the ground during a storm.

I think your real issue is the roof. Overhangs and eaves catch the wind and seem to be the first place that damage happens.

Metal is attached to purlins. Purlins are normally 2x wood material that is attached to the posts and the trusses. I like to attach them on the flat so you have more surface area. Never use nails since they become loose over time as the wood dries out. For every outdoor structure, I only use screws and bolts. I also like to put my trusses every 4 feet and then use 2x4's 16 feet long or longer for my pulins so they are connected to as many trusses as possible. Then use long screws to hold your metal on. Inch and a half or longer with 2 inches being ideal. You want maximum holding power and going all the way through the purlin will give you that. Also be sure to install three screws per purlin the full length of your metal.

If you go 12 feet apart for your posts, your purlins need to be 2x6 and at least 24 feet long. Again, you want them to be attached to as many posts as possible. Stagger your joints too. Your header should be two 2x10's or 2x12s with one of them notched into the top of your posts and bolted into place.

Your trusses need to be held in place with hurricane straps.

The best insulation is closed cell foam. Never put open cell foam on a metal building, it will hold moisture and rust out the metal from the underside.

Install diagonal bracing everywhere possible!!!!!

hawkeye08 · Oct 21, 2019

You might want to pay an engineer to design it.. even though you are ag exempt. We had our enclosed pole building designed for 40lb snow load, 70 mph winds.

chamjoe · Oct 21, 2019

EddieWalker said:
I'm in East Texas, so I don't know anything about building in your area other then what little I've read about it. I have seen a lot of effort put into different ways to keep posts in the ground, but haven't actually seen any pictures of evidence of posts coming out of the ground during a storm. If it was me, I'd just drill the holes and fill them with concrete unless I found solid evidence that they actually come out of the ground during a storm.

I think your real issue is the roof. Overhangs and eaves catch the wind and seem to be the first place that damage happens.

Metal is attached to purlins. Purlins are normally 2x wood material that is attached to the posts and the trusses. I like to attach them on the flat so you have more surface area. Never use nails since they become loose over time as the wood dries out. For every outdoor structure, I only use screws and bolts. I also like to put my trusses every 4 feet and then use 2x4's 16 feet long or longer for my pulins so they are connected to as many trusses as possible. Then use long screws to hold your metal on. Inch and a half or longer with 2 inches being ideal. You want maximum holding power and going all the way through the purlin will give you that. Also be sure to install three screws per purlin the full length of your metal.

If you go 12 feet apart for your posts, your purlins need to be 2x6 and at least 24 feet long. Again, you want them to be attached to as many posts as possible. Stagger your joints too. Your header should be two 2x10's or 2x12s with one of them notched into the top of your posts and bolted into place.

Your trusses need to be held in place with hurricane straps.

The best insulation is closed cell foam. Never put open cell foam on a metal building, it will hold moisture and rust out the metal from the underside.

Install diagonal bracing everywhere possible!!!!!

Thanks. Youæ±*e right on the brackets/roof being the most important. IçŸ¥ just struggling to find the technical bits. Prices are all over the place from $5k for the kit to $9k-$21k installed. The wood truss guys (more expensive) say itç—´ much stronger but I canç¨š seem to find the data to back it up.

On the insulation side I think youæ±*e right and IçŸ¥ ready to close the book on it. I was just holding out hope that there was a reasonable DIY option via an insulated metal roof panel but being open I know it will be a raccoon/rat habitat if I go fiberglass or foam board.

RNeumann · Oct 21, 2019

Permanentpostsystems.com

Engineered posts and post bases. You will need to decide if regular trusses or “pole barn” trusses at every post is how you want the roof done.

chamjoe · Oct 22, 2019

RNeumann said:
Permanentpostsystems.com

Engineered posts and post bases. You will need to decide if regular trusses or è�Ÿole barn trusses at every post is how you want the roof done.

can you elaborate on what you mean by "pole barn" trusses or "regular" for that matter?

RNeumann · Oct 22, 2019

A typical truss manufacture for houses and structures makes trusses that are spaced 2’ on center. A pole barn style truss would be spaced at every pole- say every 10’ and then you put rafters between. You would probably pay a bit more for standard trusses but if you plan to sheet the ceiling and or insulate it may be easier to go with typical trusses.

Check out this guy. His post method isn’t something that would be my first choice but overall he builds a good product. He does the pole barn style truss.

RR Buildings
- YouTube