Tag Archives: wind load

I’d Rather Order My New Pole Building Myself

We humans want to do things ourselves. We love GPS because it keeps us from having to ask strangers for help or admitting we are lost.

I admit to, at one time in my life, being an extremist at “doing it myself”.

Then I learned….. by listening to experts I could learn so much faster.

Consider me – I’ve either personally made more mistakes or been a party to helping people fix theirs, than most can even begin to imagine.

Why should you repeat these sins?

Answer: You do not have to. Here is a case in point real life story thanks to reader ARNOLD:

“It would be really neat if when filling out information your page a potential customer could get the information without having to give name, email, and what all else.  Kind of a pain in the rear if you know what I mean.

Thanks”

Mike the Pole Barn Guru writes:

Thank you very much for your input. Certainly we could have our system set up so you could go online and actually even order a building, without ever having to talk to anyone. Think of it similar to be able to custom produce a massive set of somewhat Lego® like pieces online and have them delivered. We could do it……

And chances are you would end up regretting your decision forever.

Our system would allow you to make changes in climactic design. This could result in you not having a building meeting Building Code loadings. Worst case scenarios being you would either not be allowed to build, or (in jurisdictions with no plan reviews and field inspections) your building could fail and injure or kill someone. Decrease snow and/or wind loads or chose B for wind exposure instead of C could result in both savings as well as collapses. Your building department would also reject your plans…or even worse, your building, once you had constructed it. Planning on “doing it yourself” and not ever contacting your building department? In one word: Don’t!!! I’ve seen far too many customers snagged on their buildings after they were built. Worse case, the building department made them tear it down.

About Hansen BuildingsFace it, we humans are dimensionally challenged. Even though we have an idea a basketball hoop will be at 10 feet, we think our car needs a door this height. We want to make certain you design a building with adequate spaces for your activities. This includes properly sized doors, properly spaced, to actually allow prized possessions in or out without damage to your building or something treasured.

Our having you interact with a real live person has a goal of keeping you (as much as possible) from making crucial design errors causing you to hate your pole building forever. One of those mistakes would be us allowing you, as a serious future building owner, to order a post frame building from someone else. We firmly believe we have the absolute best value in a complete, engineered post frame building kit package – enough so we offer to go comparative shop for any client prepared to invest in a building. Call 866-200-9657 and ask us about this service. It’s free!

Wall Girts Are Not Sexy

Wall Girts Are Not Sexy

Thought I had forgotten about Features and Benefits? Guess again!

My 1990’s salesman Jerry was proud of his ability to rattle off a litany of features, without explaining to clients benefits of any of them. This one feature I can imagine meant little or nothing to clients, as wall girts are not sexy!

FEATURE: Bookshelf style 2×6 #2 and better, kiln dried wall girts

Interior StairwellBENEFIT: Set flat like shelves, girts oriented this direction are strong enough to withstand wind loads, stiff enough to meet Code deflection requirements and keep finishes such as gypsum wallboard (sheetrock) from cracking. Spaced 24 inches on center, they create a deep wall cavity for insulation.

EXTENDED READING ABOUT THIS SUBJECT:

On deflection limitations: https://www.hansenpolebuildings.com/2012/03/girts/

For insulation: https://www.hansenpolebuildings.com/2018/09/making-framing-work-with-bookshelf-girts/

WHAT OTHERS DO: Most often, “barn” style girts placed flat on outside of wall columns.

pole spacingConcept of girts being nailed to column exteriors is they (in theory) do not have to be trimmed therefore saving labor (as well as any need to measure). Being ignored in this is lumber typically comes approximately 5/8 inch over specified lengths, making trimming needed anyhow. Most common column spacings are multiples of exactly two feet – eight, 10, 12, etc., and those 5/8 inches add up across a very long or wide post frame building.

Usually girts as specified upon plans (or plans themselves) have never been checked by an engineer and they sail right through most plan checks, in part because they are done “how we’ve always been doing them”.

In some cases every other girt will have another member attached to form a “T” or an “L” – however intermediate member (one between T or L girts) still fails to meet Code deflection limitations and often proves insufficient to resist wind loads.

Generally, little or no consideration has been given to additional forces upon girts when buildings are partial enclosed or three sided: https://www.hansenpolebuildings.com/2014/03/three-sided-building/

WHAT WE DID IN 1980: Remember, Lucas Plywood & Lumber was in a region where low grade green lumber was king! We used green 2×6 #3, barn style, spaced upon two foot centers. Ignorance was bliss and we were happy, as this solution was cheap, however not structurally adequate.

If you are not well versed regarding issues surrounding green lumber, you will want to read this information: https://www.hansenpolebuildings.com/2011/09/499green-lumber-vs-dry-lumber/

 

Both Ends Open, Pole Barn Wind Load Challenge

The Both Ends Open, Pole Barn Wind Load Challenge
There are plenty of people who just do not understand the basic concepts of how wind loads are transferred through a pole barn (post frame building) to the ground. Included amongst these would be those who desire buildings which are enclosed on both long sidewalls and open on both ends. This is one of the worst possible design concepts one can come up with in a new post frame building.

Of course somewhere along the discussion between the Building Designer and the client this statement always seems to come up:
“Well Joe Blow has one down the road and his is still standing”.
My response to this is – “Joe has just been phenomenally lucky”.

In my years living in Eastern Washington, we made numerous trips from Spokane to Seattle. Driving across Interstate 90, one passes through the towns of Moses Lake and Ellensburg. This is prime grass growing country, where numerous hay storage buildings have been constructed over the years, with both ends open. The majority of these now have complex systems of braces and/or extra diagonal columns added to their sidewalls in attempts to maintain them standing vertical. More than a few of them only remain standing up because they are full of hay – the contents alone are what is keeping the buildings standing.

I’ve hashed through this challenge in the past, however it is apparent too few people have read and grasped the situation (read more here: https://www.hansenpolebuildings.com/2017/04/open-endwalls-hay-barn/).

For those of you who enjoy audience participation, please go find an empty shoe box and a pair of scissors.
Remove the lid (and the shoes) from the shoe box. Place it open side down on a table top. Push down on the box – pretty stable, isn’t it?
Next, cut both of the narrow ends completely out of the box. Again place it open side down on the table and push on it…..
Flat as a pancake, isn’t it?

The very same concepts work to keep buildings standing. Remove too much or all of the ends and the building does a fall down, goes boom.

Just because Joe happens to have a building standing which sound engineering practice says it should not be, does not make it right. Most folks are going to make a significant financial investment into a new post frame building and my personal preference is for them to not have their insurance company paying to replace the building.

Builders Who Make No Upgrades in Twenty-Five Years

Builders Who Make No Upgrades in Twenty-Five Years.

Why?

We’ve Been Building This Way for 25 Years
In the event you happen to hear this from a pole builder – run away from them as quickly as possible.
Why?
Because every three years there is a new version of the Building Codes and often those new Codes come with changes in the way wind, snow and or seismic loads are applied to the building. New methods and materials seem to appear on the market so fast they make one’s head spin. Technology moves at a breakneck speed and to be doing things exactly the same for 25 years means your proposed erector is pre-internet in thinking!!

COREY in BILLINGS writes:
“Good Morning,
I was speaking to Rachel and she gave me your email to see if you might be able to answer a question for me. I hired complete a 50’x 80’ x 12’ pole barn here in Huntley, MT. The company showed up on the job yesterday and drilled the holes and started setting posts. Posts are 8’ center. They set the corner posts and maybe 6 sidewall posts and 4 endwall posts. The other posts were placed in the drilled holes and left for completion today/tomorrow. When I inspected the posts that were placed but not set (no backfill) I noticed that there was no footing or no cleats attached to post base to prevent uplift. When I questioned the owner of the company what he was using for footings he stated nothing added just solid tamped. I immediately called him and questioned his reasoning and got the I have been building these like this for 25 years. My question is on average what is the post load in psi on the 50’ x 80’ x 12’ pole barn with a 40# snow load? My soil has a bearing capacity of 2100 psi.”
In my humble opinion, you need to stop them immediately. Just because they have been doing them this way for 25 years does not make it correct.

Mike the Pole Barn Guru Writes:

Assuming a 40# design roof snow load and minimal design dead loads (usually 3.3 psf top chord and 1 psf bottom chord) gives a total of 44.3 psf X 8′ on center X 50’/2 = 8860# downward If they are using 6×6 posts (5-1/2″ nominal) they are placing over 42,000 psf on the base of the column!!

Roughly 21 times the soil bearing capacity.

Each post should probably have a concrete pad 30 inches or so in diameter underneath and at least 6 (if not 8) inches thick.

If I were you, I’d be requiring the building contractor to submit engineer sealed plans for your building to you (even if you have to pay for the cost). Otherwise you are pretty well hung out to dry.

Dear Pole Barn Guru: How to Replace a Sliding Door with an Overhead

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: Have pole barn with sliding doors which are being wedged with weather changes. Looking for overhead door option for door that is 16′ wide and 12′ tall. Do you provide these and conversion labor to install? LOOKING IN LEBANON

DEAR LOOKING: Switching from sliding doors to an overhead door is going to pose a massive challenge to do correctly. This, in itself, is reason enough to spend the generally few dollars up front to use a sectional steel overhead door.

To begin with, the openings are not framed to the same size. It is easier to frame smaller than have to try to hack out and replace one or more columns. This will probably entail framing down to a finished hole 13’10” in width and 10’11” in height (measured from the top of the concrete floor) and installing a 14’ x 11’ residential overhead door. In order to get things looking right from the outside. All of the steel on this wall should be replaced, to give uniform color and no splices.

We can certainly provide a wall’s worth of steel siding, color matched powder coated screws, the appropriate steel trims, the overhead door and hardware to hang it. We are not contractors in any state, so we do not and cannot provide any labor to install.

You may want to look at what the real problem is – sounds like you have frost heaving, which is pushing the ground, or concrete, up at the location of the door. Just switching doors is not going to take away the problem.

If heave is the root cause of the problem, then remedial action can be taken by installing a French drain along the side of the building in front of the door. The sliding doors can also be taken off, and their overall height shortened enough to keep them from binding when the heave occurs.

DEAR POLE BARN GURU: How do I calculate what size of purlin I need based on my snow load, and the bay spacing of my pole barn? Thanks. CURIOUS IN CULDESAC

 

DEAR CURIOUS: From the ground, a roof purlin looks pretty simple – it is usually a piece of 2x material, fastened on top of or attached to the side of rafters or roof trusses. Roof sheathing (typically OSB – oriented strand board, plywood, or steel roofing) is then attached to the top of the purlins.

Purlins are not simple at all. They must carry all applied dead loads, live loads from snow as well as wind loads. They need to be checked for the ability to withstand bending forces (both compressive and from uplift), to not have too much deflection and be adequately attached at each end.

In snow country, purlins near the roof peak need to be checked for the added drift loads which are applied.

I could spend several thousand words and numerous pages to teach you how to be able to properly calculate the purlins for your individual case, however it is far more information than the average person wants to, or is able to, absorb.

The best recommendation – hire a registered design professional (RDP – architect or engineer) who has the ability to run the calculations to adequate design your purlins based upon the climactic (wind and snow) loads being imposed upon them at your building site. Or better yet, order a complete pole building kit package which has been designed by an RDP.

Building Code: Or Not?!

Things Which Scare the Pooh Out of Me

And we are not talking about things which go bump in the night or hide in closets waiting to jump out.

Hansen Buildings’ Designer Rick recently ran up against an interesting situation.

One of the responsibilities of clients is to verify the code information with their Building Department prior to ordering. As there are, at times, only questions which can be answered by the client, we have found it to be the best solution for all involved if the client checks out building code requirements with his local jurisdiction.

Building Code Snow LoadsThis particular client lives in the far northern United States, where it tends to snow…a lot.

Client does his part and gets this response:

“We don’t enforce the building code in Xxxxxx County, so you will have to have whoever designs your building refer to the xx State Building Code. We have a link for that on our County Website it is as follows: xxxx”

So Rick gives it a try and comes back to me with:

“You are sure right on this.  I just got off the phone with the county.  He actually used the words “we don’t care if it is built of straw” as long as your setbacks conform. 

This is my first encounter with a county that doesn’t even have a snow load, and I didn’t think there were any.

The link in the e-mail below gives me an error code and the link on the county web site for the XX State Building Code gives me Chinese.”

Now this particular building is going to be constructed where there is snow in the winter….lots and lots and lots of snow.

Personally, I am not a fan of government intervention, however I am a fan of people not being hurt or killed when under designed buildings collapse.

For people who are going to build in areas where the Building Code is not enforced – do due diligence, make every effort to find or calculate loads which will be adequate for your structure.

If you need help understanding your local building code, ask me.  I’m all about safety first.

 

 

 

 

 

 

Fabric Covered Building and Wind

One of the Hansen Buildings designers recently asked me what I knew about fabric covered buildings. He was speaking with a client who was comparing one of our post frame buildings versus a fabric covered structure.

My only up close and personal experience with a fabric structure was with the United States pavilion at the 1974 World’s Fair in my home town of Spokane, Washington. The original covering of the pavilion was a thick vinyl sheeting. It was allowed to remain until it began to deteriorate, become unsightly and was thought a safety hazard.

As I started to do more research, I found article after article about the May 2, 2009 failure of a fabric covered building with steel frame practice facility owned by the National Football League’s Dallas Cowboys. This structure collapsed under wind loads significantly less than those required under applicable design standards, according to a report released October 6, 2009 by the Commerce Department’s National Institute of Standards and Technology (NIST).

Located in Irving, Texas, the facility collapsed, during a severe thunderstorm. Twelve people were injured, one seriously. Based on the national standards for determining loads and for designing structural steel buildings, NIST researchers studying the Cowboys facility found the May 2 wind load demands on the building’s framework—a series of identical, rib-like steel frames supporting a tensioned fabric covering—were greater than the capacity of the frame to resist those loads.

Assumptions and approaches used in the design of the Cowboys facility led to the differences between the values originally calculated for the wind load demand and structural frame capacity compared to those derived by the NIST researchers. For instance, the NIST researchers included internal wind pressure due to the presence of vents and multiple doors in their wind load calculations because they classified the fabric covered building as “partially enclosed” rather than “fully enclosed” as stated in the design documents.

Even more damning, the NIST researchers determined the building’s fabric could not be relied upon to provide lateral bracing (additional perpendicular support) to the frames in contrast to what was stated in the design documents and the expected wind resistance of the structure did not account for bending effects in some members of the frame.

“Our investigation found that the facility collapsed under a wind load that a building of this type would be expected to withstand,” said study leader John Gross. “As a result of our findings, NIST is recommending that fabric-covered steel frame structures be evaluated to ensure the adequate performance of the structural framing system under design wind loads.”

The NIST report recommends such evaluations determine whether or not: (1) the fabric covering provides lateral bracing for structural frames considering its potential for tearing; (2) the building should be considered partially enclosed or fully enclosed based on the openings which may be present around the building’s perimeter; and (3) the failure of one or a few frame members may propagate, leading to a partial or total collapse of the structure.

Shortly after the Cowboys facility’s collapse, NIST sent a reconnaissance team of three structural engineers to assess the failed structure and wind damage in the surrounding area, and collect relevant data such as plans, specifications and design calculations. Using the data acquired during the reconnaissance, the NIST study team developed a computer model of a typical structural frame used in the practice facility and then studied the frame’s ability to resist forces under two wind conditions: the wind loads based on the design standard wind speed of 90 miles per hour (mph) and the actual wind loads based on conditions at the time of the collapse.

NIST worked with the National Oceanic and Atmospheric Administration’s (NOAA) National Severe Storms Laboratory to estimate the wind conditions at the time of collapse. The researchers determined, at the time of collapse, the wind was blowing predominantly from west to east, perpendicular to the long side of the building. Maximum wind speed gusts at the time of collapse were estimated to be in the range of only 55 to 65 mph!

In the conversion of actual wind speeds to pounds of force applied to a building the wind speed is squared. A 65 mph wind speed creates a force of 10.816 pounds per square foot (psf), whereas the required load carrying capacity of 90 mph would be 20.736. The structure failed to carry much more than half of the wind load force it should have carried!

This evidence could lead one to be highly skeptical about the ability of a fabric covered structure to adequately support wind loads.  If one is considering such a fabric covered building, my advice would be to carefully gather evidence (backup data) to clearly substantiate the building supporting wind loads…in all circumstances.