Tag Archives: pole barn bracing

Temporary Bracing to Avoid Under Construction Mishaps

Temporary bracing in post frame buildings come without a prescription – there is nowhere which spells out “do it this way and all will be good”. There are some things which can be done to minimize the potential of mishaps similar to the one in the photo.
Buildings in their framing stages are the ones which are most vulnerable to wind forces. Once the roofing is properly installed, everything is tied together and works as a unit, rather than as independent and unrestrained pieces.

I’d been involved, to some extent, in two similar situations with large clearspan buildings, all or partially framed up, and high winds.

The first was when I was selling post frame building kits for the long defunct Mac Truss Company in McMinnville, Oregon. Our builder client had framed up a 60’ wide 22’ eave hay barn which the wind unceremoniously planted on the ground.

The second was not the Wreck of the Edmund Fitzgerald, but it went down as fast (read more of the story here: http://www.hansenpolebuildings.com/2014/03/wide-span-trusses-2/).
The building under construction in the photo is 80’ wide by 240’ long with an 18’ eave height. Along one side of the building is a 36’ wide shed row which sloped from the 18’ eave down to 9’ at the low eave.

Over the Christmas weekend the area experienced some high localized winds, resulting in what you see above. There are some things which might have either prevented or minimized the current situation:
Diagonal bracing to the columns. Please note the 2×4 braces. When a 2x member is loaded in compression (as in wind pushing from the opposite direction towards the braced column), it tends to buckle in the weak (2x) direction. As such 2x bracing members over 10 feet in length should be strong backed with another 2x member to form a T or an L to prevent buckling.
It is also essential to adequately affix the braces to the columns, as well as having an immovable stake in the ground for anchorage.

Included in the Hansen Pole Buildings’ Construction Manual is BCSI-B10 “Post Frame Truss Installation and Bracing” which details two industry recommended methods to resist racking of interior trusses/columns. These include using diagonal wood braces attached to the columns as well as truss top and bottom chords or the use of chains or cables with come-alongs to form an X in the direction of the trusses.

Trusses of spans 60 foot and greater also have some specific requirements for bracing, which can be read about in detail here: http://www.hansenpolebuildings.com/2013/12/wide-span-trusses/.

Pole Barn Design for Free

Please Structurally Design My Pole Barn for Free

This is one of those POLE BARN GURU questions which results with a lengthy enough answer I feel I must devote a whole column to it.

DEAR POLE BARN GURU: Could you please help clarify, for a 40 ft. wide x 64 ft. long x 15 ft. high Pole Barn Building,

What size & kind of posts are needed?
How you would recommend connecting posts to trusses?
Footer depth & construction?
Lateral Wind bracing & Uplift measures?

Would greatly appreciate hearing your recommendations.  Thank you! EILEEN in CENTERBURG

DEAR EILEEN: What you are asking for is to have a building engineered, without knowing the parameters the building is being engineered for.

Without the knowledge of your wind loads (including exposure), snow and seismic loads, any answers I would give to you for your pole barn design would most likely be incorrect.

post-frame-construction-150x150Post frame buildings also work as a system, so individual components or connections might possibly be adequate, however the entire building fails due to a weak link. This is why I always, always (did I say always) recommend ONLY to invest in a building which is designed by a registered design professional (RDP – engineer or architect) – especially for your particular site.

Some general answers to your questions (answered as if I was going to build this building for myself):

Posts

I would use true glu-laminated columns (not nailed up columns), as they have a high strength to weight ratio, are lighter to work with and tend to be less prone to warp and twist.

Trusses

The post to truss connection would have double trusses set into a notch cut into the top of the column. This prevents the trusses from being able to “slide” down the column in the event of a high snow load. To avoid uplift challenges, the trusses can be bolted or a combination of threaded hardened nails and bolts could be used. In high uplift situations, appropriately sized Simpson HST brackets may prove to be the best design solution.

Footer

Footer depth and construction – the holes need to extend at least below the frost line, and I tend to use 40 inches as a minimum depth into undisturbed soil. The columns should be floated eight inches above the bottom of the hole then no less than a total depth of 16 inches of premix concrete poured into the hole. The diameter of the holes will depend upon the loads being placed upon them, as well as the assumed bearing strength of the soil at the site.

Do not attempt to use concrete “cookies” – http://www.hansenpolebuildings.com/2012/08/hurl-yourconcrete-cookies/ or bags of sackcrete – http://www.hansenpolebuildings.com/2012/11/concrete/
Siding

Provided there are not excessive door openings in endwalls, in most cases the utilization of the proper screw for attachment of steel to framing the steel skin should be able to adequately transfer the imposed loads:                                           (http://www.hansenpolebuildings.com/2012/08/this-is-a-test-steel-strength/

Bracing

Here is some reading on bracing which you might find helpful: http://www.hansenpolebuildings.com/2016/03/diagonal-bracing/ and http://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/

Good luck with your pole barn design.

Mike the Pole Barn Guru

Dear Pole Barn Guru: What is the Proper Wind Shear Bracing?

New!  The Pole Barn Guru’s mailbox is overflowing with questions.  Due to high demand, he is answering questions on Saturdays as well as Mondays.

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday or Saturday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

Dear Pole Barn Guru: What is the proper wind sheer bracing for a 60’W x 80’L by 20’H monitor pole barn with a 20′ center aisle and a second story? The raised center portion has 20 foot walls, then another 6 feet to the center at the ridge.

The 2 sheds on either side are 10′ at the edge and intersect the center at about 15′. The entire structure is made of poles on 20′ centers, Lvl beams and ladder trusses for floor and trussed roofs. It is unprotected from the wind. We are in central Texas. TEETERING IN TEXAS

DEAR TEETERING: This is why it is such an excellent idea to order complete pole building packages from a company who can run all of these calculations accurately in advance. Then buildings are designed to resist the proper loads, including wind shear, without having to search for solutions in the middle of the game.

Provided all of the columns are adequately sized and embedded …..

Steel roofing should be 3′ width, minimum 29 gauge, with high ribs every 9″, attached to 2x purlins on edge spaced no more than 28″ o.c. Roofing should attach to purlins with #12 x 1-1/2″ diaphragm screws at 9″ o.c. at each purlin. At eave and top edges of panels place screws on each side of every high rib.

Provided you attach the endwall steel the same as the roof steel, you should be able to have up to 19 lineal feet of openings on each endwall without further reinforcement.

All of this should be reviewed by a Registered Design Professional (RDP – engineer or architect) for structural adequacy.

DEAR POLE BARN GURU:  Is it possible to get a quote to have it assembled? MINDFUL IN MORRIS

DEAR MORRIS: We are not contractors, however fair market value for labor is typically about 50% of materials costs.

I recommend placing an ad on Craigslist under “labor gigs” such as:

Contractor needed to assemble pole building kit package on my clear level site in Morris County. 24’x40’x14′ includes 12″ overhangs, a 12’x12′ overhead door, entry door and wainscot. I will provide all materials except for nail gun nails. Willing to pay $4000-5000 depending upon experience and references.

DEAR POLE BARN GURU: I have a metal building constructed of 2×4 square tubing and 4×4 metal posts. 3″ × 1.5″ c purlin is welded with the c side down spanning across my 2×4 square tubing roof beams. I have a metal roof screwed to the c purlin. The building wraps around an existing building and looks like an L from a top view and has a 2 on 12 shed roof with a hip. The building is “stand alone” and attached to the other structure only with a side wall transition piece. The metal roof slides under the eve of the other structure with the side wall transition on top. I also used the vented enclosure under the sidewall transition for ventilation. I also have a ridge vent at the hip with the vented enclosure under the hip cap. I have a 12″ soffit around the outside perimeter of the metal structure with soffit vents every 5 ft. I have a 4 ft cedar picket half wall around the outside perimeter with the remaining height of the wall in screens….basically a screened in party room but I plan on switching out the screens for heavy plastic sheeting in the winter. I have a hot tub inside and I want to insulate the roof and install a ceiling. 1st question: do I have to install a vapor barrier IF I am using 3/8 marine plywood for the ceiling and the attic side of the sheathing is covered in heavy vinyl….sheathing was once election signs. I am attaching the ceiling directly to the bottom of the 2×4 roof beams following the slope of the 2 on 12 pitch.

2nd question…..because I only have the 4″ depth of the 2×4 sq tubing + 1.5″ depth of the c purlin = 5.5″ total for insulation AND vent space, how would you insulate? Spray foam is too expensive for me. I want to reduce the radiant heat in the summer and I am concerned with the humidity from the hot tub especially in the winter. Any help would be greatly appreciated. TOASTY IN TEXAS

DEAR TOASTY: My guess is you are going to be creating an inadequately ventilated dead attic space. You need to have 1/150th of the “foot print” of your space, as ventilation, equally divided between the eaves and the ridge. In your case, you have no ability to adequately vent the high side of your roof, as it abuts another building.

Even though the best solution might well be to tear everything down and construct a new building, chances are you would not look favorably financially upon it as the end all.

Probably your best bet is to install an A1V reflective radiant barrier beneath the roof purlins (http://www.buyreflectiveinsulation.com) with the reflective side up. Make sure every seam is tightly sealed. This should help reduce the thermal gain in the summer. If you are going to create a dead attic space between a ceiling and the reflective radiant barrier – powered attic vents in each end could be a good investment.

As for humidity from your hot tub, install air inlet vents near the floor and exhaust vents near the ceiling line. You may also need to have one or more powered vents in the walls of this area.

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