Pole Barn Tips for High Wind + Humidity (Florida)

[chamjoe]

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]

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

 

[Tractor X]

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]

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]

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]

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. I知 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 can稚 seem to find the data to back it up.

On the insulation side I think youæ±*e right and I知 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]

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]

Permanentpostsystems.com

Engineered posts and post bases. You will need to decide if regular trusses or �ole 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]

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

 

[BoylermanCT]

I just ordered a 30x40x12 pole barn kit and they have standard trusses every 4 feet. I did not like the design that only had trusses at the posts.

 

[fried1765]

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

Can't be a very wide pole barn if you "put rafters between" the trusses.
Longest length rafter material readily available is 18'.
Maybe max. 32' wide building?

 

[RNeumann]

Can't be a very wide pole barn if you "put rafters between" the trusses.
Longest length rafter material readily available is 18'.
Maybe max. 32' wide building?

Watch the videos I posted above- you have missed something.....but when you quote half a sentence it can happen.

 

[AllByteNoBark]

The link above took me to their Youtube page. This should be a direct link to one of the pole barn build videos mentioned above.
Building A Large Post Frame Garage Full Time-lapse Construction: NEVER BEFORE SEEN FOOTAGE - YouTube

I believe he was referring to the purlins as rafters.

 

[aczlan]

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

Posts every 12 feet seems far apart to me, around here they go about every 8 feet, but we have to deal with snow load which isn't usually a big deal in FL.

Aaron Z

 

[chamjoe]

Posts every 12 feet seems far apart to me, around here they go about every 8 feet, but we have to deal with snow load which isn't usually a big deal in FL.

Aaron Z

Snow would be better down here as it would help keep the barns from flying away in 140mph hurricane wind gusts. As for the 12' spacing this is somewhat typical but the trusses that I've seen aren't your regular 2x4's they are 2x6's or larger when wood. The metal ones are more common but to me they are what scare me with regard to spacing but I'm lacking real specs on those data points.

 

[EddieWalker]

Trusses in an area where you don't have snow are not that complicated. The biggest thing to remember is the farther apart you put them, the bigger the purlins will have to be. I like them every 4 feet so I can use 2x4's on the flat. That means more trusses. If you are going to use shingles for the roof, you HAVE to put the trusses every 2 feet so you can deck it with OSB or Plywood. If you want to put metal over decking, the trusses have to be 2 feet apart. You can easily put your trusses every 6 feet, 8 feet or ten feet apart. Probably 12 feet too, but that's getting more in the area of when they build with metal. Off the top of my head, I believe that for 6 feet apart you have to turn the 2x4 purlin on edge, then for 8 feet you have to use 2x6's on edge, for 10 feet you use 2x8's on edge. I've never seen it done any farther then that, but would guess that using 2x10's on the edge for purlins would work for every 12 feet, but I wouldn't do it.

Back to your original question about strength, having trusses every 4 feet will give you the most strength with the best value for your dollar without any complicated engineering or construction issues.

 

[RNeumann]

The link above took me to their Youtube page. This should be a direct link to one of the pole barn build videos mentioned above.
Building A Large Post Frame Garage Full Time-lapse Construction: NEVER BEFORE SEEN FOOTAGE - YouTube

I believe he was referring to the purlins as rafters.

I was actually referring to joists or rafter ties as rafters. OP’s question was about how to insulate the building. If you build with a pole barn style truss you will need to span between the truss bottoms with some type of joist so you can insulate with batt or blown insulation.
So to be clear- perlins would go on top of the truss and support the roofing.

Back to the insulation- if you the insulation right up against the roof in “typical” pole barn fashion you run the risk or rot- especially with the humidity in Florida. That’s another reason to go away from a pole barn style truss and toward the standard style truss.

Strength, either way, isn’t an issue. The trusses and roof system are all engineered and would work fine. The issue is overall cost and time. Say you go with the pole barn truss and it saves $1500. Then two years from now you want to insulate, add lights and drywall the ceiling. The cost and time to add back in what is needed would quickly eat up the $1500.

Same goes for the posts. You can do quick and cheap- just set the wood posts in concrete. Or you can spend a bit now and use a column base as mentioned in a post above.

 

[aczlan]

Snow would be better down here as it would help keep the barns from flying away in 140mph hurricane wind gusts. As for the 12' spacing this is somewhat typical but the trusses that I've seen aren't your regular 2x4's they are 2x6's or larger when wood. The metal ones are more common but to me they are what scare me with regard to spacing but I'm lacking real specs on those data points.

Our 40' wide pole barn has 2x6 trusses, our 30' wide pole barn has 2x4 trusses.
Both have poles every 8 feet and trusses every 4 feet with 2x4 purlins nailed flat on the trusses to mount the metal roof to.

Aaron Z

 

[AllByteNoBark]

I was actually referring to joists or rafter ties as rafters. OP’s question was about how to insulate the building. If you build with a pole barn style truss you will need to span between the truss bottoms with some type of joist so you can insulate with batt or blown insulation.
So to be clear- perlins would go on top of the truss and support the roofing.

Back to the insulation- if you the insulation right up against the roof in “typical” pole barn fashion you run the risk or rot- especially with the humidity in Florida. That’s another reason to go away from a pole barn style truss and toward the standard style truss.

Strength, either way, isn’t an issue. The trusses and roof system are all engineered and would work fine. The issue is overall cost and time. Say you go with the pole barn truss and it saves $1500. Then two years from now you want to insulate, add lights and drywall the ceiling. The cost and time to add back in what is needed would quickly eat up the $1500.

Same goes for the posts. You can do quick and cheap- just set the wood posts in concrete. Or you can spend a bit now and use a column base as mentioned in a post above.

My mistake, that makes sense. Our most recent is all galvanized steel with 20 foot bays, so, totally different animal. Been a while since I was around true pole barns.

 

[RNeumann]

My mistake, that makes sense. Our most recent is all galvanized steel with 20 foot bays, so, totally different animal. Been a while since I was around true pole barns.

My haste too! I tried to make a quick response while doing something else. I wasn’t clear.....I think the OP gets it now.