Tag Archives: bookshelf girts

Metal Building Insulation

Building Has Metal Building Insulation

Hansen Pole Buildings’ Designer Rachel received an inquiry from a client whose existing post frame (pole) building has metal building insulation.

Rachel sent this to me:

“STEVE would like some advice on insulating.  He has a Cleary Building which has blanket insulation in the walls and roof and he would like to insulate over the top of this insulation and wondered if there would be issues.   

Steve mentioned that as your standing in the building you see the white vinyl on the inside.  Is there vinyl on both sides?  If not, shouldn’t the vinyl by facing the steel?

Any information or assistance you can give him would be appreciated.”

Mike the Pole Barn Guru writes:

I am not much of a vinyl faced metal building insulation fan to begin with (read more here: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/]. Even though I have it in roofs of my two older personal post frame buildings, it isn’t a product I would use if I were to construct a new building for myself.

Problems would come from having insulation sandwiched between two vapor barriers.

I would do this personally –completing each wall individually, I would remove wall steel, remove  wall metal building insulation. Cover each wall with a Weather Resistant Barrier (like Tyvek) and reapply wall steel. Spray two inches of closed cell foam insulation upon the inside of the wall steel. If full wall thickness bookshelf girts were not used in the walls (flush or extending inside of columns), another set of girts should be added to the inside surface of columns. Your engineer of Record (engineer who sealed your building plans) should be consulted to determine proper size and spacing of girts. Once installed, fill insulation cavity completely using BIBs. Glue two inches of rigid closed cell foam insulation board, taping all seams, to the inside face of girts. Glue interior finish (typically gypsum drywall) to the inside of foam boards.

PBG NOTE ADDED: Hansen Pole Buildings’ Designer Rick Carr aptly pointed out to me WRB (Weather Resistant Barrier) purpose would be defeated by spray foam application. Correct application should be one only, however only after metal building insulation removal.

For your roof, provided trusses are adequate to support applicable dead loads, I would install a truss bottom chord level ceiling. This would allow insulation to be blown into dead attic space. In order to achieve adequate insulation above the sidewalls, it may prove necessary to use closed cell spray foam insulation above the ceiling in areas closest to the sidewalls. If eaves have ventilated soffits, ensure an inch or more of free air space exists between insulation and roof deck (or metal building insulation). Appropriate ventilation must be provided in dead air area above insulation.


Net Zero Post Frame Homes

Net Zero Post Frame Homes

Energy efficiency has become a huge focus in every type of home construction. Post frame homes can be net zero, just as well as stick frame.

Our environmental commitment allows us to design post frame homes to reduce environmental impact. High performance design and advanced engineering make it easier and more attainable to build a home producing as much energy as it needs through renewable energy, known as net-zero energy.

A net-zero home will be more than a house with solar panels. It’s a house designed to put energy conservation first: from framing to finishing. An airtight structural shell paired with additional options – such as highly insulated wall systems, high performance windows, passive solar design and more – mean any Hansen Pole Buildings’ post frame home can be designed to achieve net-zero energy.

Reader IAN from MIDDLETON writes:


First, I want to let you know how much I have enjoyed reading your blog. I started reading through it topically to answer some of my questions, but because I have been finding so much good information, I resolved to start at the beginning and read through chronologically to make sure I don’t miss anything. Thank you for sharing your lessons learned from decades of experience.

I’ve been exploring options for a cost effective and energy efficient single family home. Reading on your blog has convinced me of the advantages of post frame construction, but I have also been reading about ways to achieve high energy efficiency. In particular, I’m interested in ways to incorporate thorough air sealing and extra insulation (in particular for walls) into a post framed structure. I have found numerous references on the internet to the ways that post frame construction is generally moderately more energy efficient that stick framing, but I have only found a few examples that specifically address trying to achieve a very high level of energy efficiency in a post framed house. The clearest example I’ve found is the following short video that profiles the construction of a net zero single family home in upstate New York: https://youtu.be/PKXNwdvUNj4

My questions for you:

Have you designed a post framed home with high energy efficiency in mind? What kinds of strategies did you use to achieve high energy efficiency?

Have you ever designed a super-insulated post framed home, and if so, how did you incorporate the additional insulation? Some approaches used in stick framing are double stud exterior walls, or supplemental rigid foam insulation between the sheathing and siding (likely not ideal for a steel clad post framed building). Have you seen these or other super-insulation strategies used on post framed buildings?

Finally, have you ever had a post framed home blower door tested for airtightness, if so, how did it perform? Do you have any recommendations for air sealing strategies specific to post frame construction?

Thank you for considering my questions; keep up the good work!”

Thank you for your kind words. Sadly, most post frame home clients are just not savvy enough to be willing to make an extra upfront investment to super insulate their buildings.  I have designed several post frame residential buildings for my own use, so I have learned from mistakes. Also, technologies have improved greatly in recent years, making energy efficient designs more practical.

For walls, my current best recommendation would be to use two inches of closed cell spray foam against siding insides. Walls would be framed with bookshelf style girts to create a deep insulation cavity. BIBs insulation would be used to entirely fill the wall cavity. Inside of the  girts, covering columns as well, two inches of rigid closed cell foam board would be applied with glue, and all seams sealed. Gypsum wallboard (sheetrock) would be then glued to the foam board. Using rigid foam board inside eliminates any thermal bridging as well as creating a vapor barrier.

With 2×8 bookshelf girts, a wall system of over R-50 could be obtained using description above.

I am not yet sold about creating a warm attic – so I’d use 22 inch raised heel trusses and blow in 20 inches of fiberglass to go R-60 and beyond.

I haven’t seen any post frame air tightness tests, however even 25 years ago (when I was building post frame buildings) we had instances where our post frame homes and commercial buildings were so tight, a window had to be opened in order to close exterior entry doors!

Good Luck! And let me know how it all turns out. I’d love to see pictures of your progress!


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.


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/


Supporting Drywall in Post Frame Construction

Loyal reader SCOTT writes:
“Good Morning,
First, thank you for the amount of information you post through the Pole Barn Guru section.  There have been a wide variety of questions, and thoughtful responses posted.
One of the points my father had was, why do a post frame if you have to go back and stud to support drywall?
I am still curious about the proper finishing of the interior or perimeter walls, but I can see you spoke much to deflection and making sure the building was engineered to withstand natural forces.
All this said, I am close to Fort Wayne, IN, and was curious if you offer and service this far away, or if you have knowledge of a reputable company that has tacked post frame residences.
The design we have in mind is quite simple, as we are really only looking at post frame due to the simple fact we could have half (or more) of our house completely open.
We like the idea of having our kitchen, dining, entryway, and living room all part of one open space.
Thanks for the great info on the site, and good luck in your future projects!”

Mike the Pole Barn Guru writes:
Thank you very much for your kind words, they are appreciated. If we are able to inform and entertain you then our mission has been successful.

Even if one decided to stud frame to support drywall (there is a one-step framing method for exterior walls: https://www.hansenpolebuildings.com/2017/08/bookshelf-girts-insulation/) there is a huge savings to be had from post frame construction (https://www.hansenpolebuildings.com/2011/10/buildings-why-not-stick-frame-construction/).

For interior walls – they can be studwall framed and since they are not supporting a roof load, they can be placed wherever you desire (or large portions can be left open). In our own post frame home, 3/4 of our floor plan is wide open without interior walls. Our home happens to be entirely on a second floor, and given the challenges of accessibility I normally encourage clients to keep their home designs on a single level and for comfort and ease of living construct them over a crawl space.

We provide post frame homes in every state in the United States, including Alaska and Hawaii – so Indiana almost feels local!

One of our Building Designers will be in contact with you to further discuss your needs.

It Is Exactly the Same Building: Part II

Well, maybe not exactly the same building.

Yesterday I ran a beginning list of comparison’s between a Hansen Building quote and a quote by one of our competitors espoused to be “exactly the same” by a client of ours.

The saga continues:

Powder coated diaphragm screws vs. #10 diameter painted screws . Those who are familiar with the properties of paint and powder coating know the first is far superior. Some more information on powder coated screws is available here: https://www.hansenpolebuildings.com/2012/08/lobular-powder-coated-screws/. There are structural challenges which occur when using industry standard small diameter screws, which we found out about only when we went to test a building roof: https://www.hansenpolebuildings.com/2012/08/this-is-a-test-steel-strength/.


Recessed purlins vs. stacked purlins. Stacked purlins go over the top of the interior roof trusses, which effectively lowers the truss by the thickness of the roof purlin, hence reducing interior clear height – you get less volume of usable space! Stacked purlins also attach to the trusses via “paddle” blocks, which are highly problematic: https://www.hansenpolebuildings.com/2012/05/paddle-blocks/.

Bookshelf girts vs. flat girts. Wall girts placed flat on the outside of columns rarely meet with the deflection criteria of the Building Code as can be found here: https://www.hansenpolebuildings.com/2012/03/girts/.

Inside closures at eave vs. no eave closures. Inside closures keep the flying critters out of your new post frame building. https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/.

True doubled trusses vs. Single trusses each side of columns. When two trusses are spaced apart by blocking, they no longer act as an integrated pair, each truss functions on its own. In the event of a critical roof load, if the weakest link is a flaw in one of the trusses, the entire roof could easily land on the ground. With true double trusses, they load share – and since the probability of two trusses having the exact same weak point is extraordinarily small, an overloaded roof is more likely to stay standing after the single truss roof has gone boom.

Engineered steel hangers to attach purlins and truss bracing vs. Nailed connection. There is a reason Building Officials like engineered steel connectors – they are a stronger connection! https://www.hansenpolebuildings.com/2013/08/simpson/

Ledgerlocks to attach trusses to columns (eliminates drilling huge through bolt holes) vs. Bolts. We are into providing buildings which are structurally sound as well as easily constructed by the average person who can and will read English. This truss to column connection is both!

Engineer sealed plans and calculations vs. not sealed plans. My long term readers have read my harping on engineered plans. Here is why: https://www.hansenpolebuildings.com/2016/10/engineer-stamped-pole-barn-plans/

500+ page Construction Guide. Let’s face it, it does not matter how good the design or materials are, if there are not explicit instructions on how to get everything together right. I’ve seen plenty of post frame building kit packages instructions in my nearly four decades in the industry. Absolutely nothing compares to what we provide.

Getting a better “deal” on a post frame building than what was quoted by Hansen Pole Buildings? And of course it is “exactly the same building” – let us review any competing quotes you are considering. The service is absolutely free of charge and if it is indeed an equal to or better building, and a better price, we will be the first ones to tell you so!

The Straight and Narrow of Fascia: Hansen Building Disaster Part III

The Straight and Narrow of Fascia:  Building Disaster Part III

Look at the board on the far right. The one which resembles the coastline of New Jersey. It is what is known as a fascia board and it is pretty important it be straight.


Because not only do vinyl soffit panels attach to the underside of it, but steel trim covers the face of it. Steel trims are very happy to be installed on straight boards.

But other worries are looming in this photo.

The roof trusses were manufactured in a plant which seemingly has some challenges with plumb cutting (which was specified on our order) Read about plumb cutting here: https://www.hansenpolebuildings.com/2015/09/trusses-9/. None-the-less the builder might have stumbled upon reading in the plans or the Hansen Pole Buildings’ Construction Manual and seen the necessity to have cut the tails plumb. He instead has opted to just nail the fascia board onto the ends of the square cut tails.

This creates more problems – such as the inability to install the soffit panels. Which, since he left the framing off the sidewall to support the soffit panels, might have been why he quit where he did.

Notice, if you will, how the outside face of the bookshelf wall girts and the wall columns are in the same plane.

They are not supposed to be. The wall girts should extend outside of the columns by 1-1/2 inches. This allows for the outside of them to be flush with things such as the skirt boards, which the builder has installed on the face of the columns! I suppose the thought was the wall steel would just curve to make up the difference?

Tomorrow, the client proposes some solutions to some of the issues and I will give my take on why those solutions may, or may not work.

Insulating a Barndominium

Residential post frame buildings are becoming more and more prevalent as consumers are beginning to realize they can save thousands of dollars in foundation costs and actually build their own beautiful and well insulated barndominium homes.

Steve from Northglenn posed this question:

DEAR POLE BARN GURU: Now that the “Barndominium” style home is more popular than ever, have standards and practices been developed for creating a well insulated/air sealed pole structure?

Particularly, how would you recommend designing well insulated/air sealed pole barn home with cathedral ceiling/exposed joists in climate zone 5b?
I would like at least r49 in the ceiling and r28 in the walls, but the more the better. I would like to avoid spray foam due to the costs, and the steel replacement factor; replacing damaged exterior steel which has been sprayed with foam insulation sounds like a nightmare.

Mike the Pole Barn Guru:

My thought is bookshelf girts with BIBS(blow in blanket insulation), plus 1.5″ of XPS sheathing (fully sealed/taped) outside of the posts, then either attach the steel to the girts through the XPS, or place 2x4s on the XPS and attach the steel to that to maintain an air gap.


The ceiling I am less sure of. How is the ceiling finished if exposed trusses are desired? Is drywall screwed directly to the underside of the girts? If so, what supports the edges of the drywall on the 2′ span between girts? What is the largest girt size that is reasonable? In order to get a r49+, the roof would need 2×12 girts with BIBS plus 1″ of XPS, then steel, or 2×10 girts with BIBS then 2.5″ of XPS.

Have you ever used roof SIPS to get higher R-values? If so, how are they attached to the girts?

What is the best way you recommend to accomplish this?

Thanks! Steve

Dear Steve: Might as well start at the end and work forward.
SIPS – (Structural Insulated Panel System) No, I have never used them. They would provide high R values, however they appear to be extremely expensive. As far as I can surmise, the savings in energy costs will never offset the added cost of the SIPS. I had done some preliminary research on the use of SIPS for post frame. However the people “in the know” never shared the information I needed to be able to write further about them:


I would think to use SIPS would require the use of very long screws to attach them to the underlying roof system adequately enough to maintain structural integrity of the building.
For the roof, you are not going to want to place XPS (Extruded Polystyrene rigid foam board such as Owens Corning FOAMULAR®) between the roof purlins and the roof steel, as this will compromise the shear values of the roof steel.
SIP PanelWithout going to the expense of deep I joists or prefabricated parallel chord trusses for roof purlins, the largest readily available dimensional lumber would be 2×12, which even with BIBs is only going to net you about R-45. Plus the upper foot of the roof trusses would then be “buried” by the thickness of the purlins.
If your goal is to have an exposed truss, you might want to look at doing parallel chord scissor trusses to create an attic space in which you could blow in even R-60 insulation, then use a non-structural truss below to create the look you are after. Our friends at Timber Technologies are just one possible source of this type of truss:

On the walls, you have the same potential challenge with attempting to place XPS between the girts and the siding, as on the roof. The best results are going to be obtained when as much of a thermal break as possible can be created. Bookshelf girts can provide for a deep insulation cavity, then the XPS panels can be placed on the inside of the girts, and GYB (Gypsum Wall Board) can be installed on the inside of the XPS panels. You will want to have a quality Weather Resistant Barrier between the wall framing and the steel siding. Read more here: https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/
The XPS panels will serve as a vapor barrier on the inside of the walls, so you will not want to have another vapor barrier (such as Visqueen) on the inside of the wall insulation.
Looking for a super insulated new home? Post frame construction is most likely the answer!


Book Shelving? Ceiling Insulation

DEAR POLE BARN GURU: Do you have to set laminated pole so you see the 1.5 side of the 2×6’s while looking in or out of the building? I was thinking of using 4ply 2×6 post 10′ out of the ground every 8′ while book shelving with 2×6’s in between posts. I thought it would be a lot faster to notch both sides of the post for the 2×10’s to sit in, just cutting out one 2×6 off of each side leaving 2 in the middle seems a lot faster than notching all 3 plays on a standard laminated post. My building won’t be very high and I heard book shelving greatly improves racking from side to side. Was planning on the book shelf being 2’OC didn’t know if going 16″OC would improve this design or if it is just unheard of turning the post sideways. I do understand that this makes the post 5.5″x6″ but the extra .5″ is of no concern since it is for a garage and I will just be sheeting it with 7/16″ OSB anyway.

Thanks in advance Mike CHRIS in DUNCANSVILLE

DEAR CHRIS: If by laminated you mean a true glulaminated column – then you can set it any direction as it has become a true one piece unit. If you are talking nailed up columns, or ones which use nails and construction adhesive (or through wires), those must be set with the 1-1/2″ sides of the 2x6s towards the wind. A 4ply 2×6 glulam will measure 5-1/2 inches by 5-3/8 inches, so there is no extra 1/2 inch to worry about.

Now I will totally upset your apple cart – how about doing away with the truss carriers entirely? And place the columns every 10 or 12 feet, instead of every eight? You can use a double truss system, with purlins on edge between the trusses and eliminate about 50% of the pieces you would otherwise need to handle and install – with the added benefit of not having to drill so many holes!! You can view sample plans for post frame buildings constructed in this fashion here: https://www.hansenpolebuildings.com/sample-building-plans/.

Book shelf girts are going to be far stronger against wind loads, I’ve used them on all of my current buildings and wouldn’t do them any other way. Two foot centers will adequately support far greater loads than will ever be imposed on most buildings.

DEAR POLE BARN GURU: Can a cloth type material like is used with BIBS or house wrap be used as a “ceiling” to hold up the insulation above it, or would there be excessive sagging or other problems? Not so concerned with aesthetics given my needs. Thanks. DAVID in MARYVILLE

DEAR DAVID ~ Depending upon how far you are spanning between trusses or ceiling joists there may be a fair amount of sag – however it should work as long as you can adequately attach the material. I’ve seen people use chicken wire stapled to the underside of double trusses which were spaced every 12 feet to support unfaced insulation batts.

DEAR POLE BARN GURU: How can I become a certified contractor/builder of Hansen Pole Buildings? BRANDON in BALTIMORE

DEAR BRANDON: Here is the link to the application on the Hansen Pole Buildings website, please fill it out completely in order to be considered: https://www.hansenpolebuildings.com/hansen-buildings-contractor-program/.



Pole Building Wall Girts

Movin’ On Up!

Well Leroy will never be confused with Sherman Hemsley of the iconic TV series “The Jeffersons” but his crew was certainly movin’ on up!

Leroy mentioned the man he works for provides neither plans nor a materials list for his crew to build from. They just make the building “work” from the materials which are dropped off. Somehow, this seems less than scientific, especially as they cut all of the notches in the columns for the single trusses spaced every eight feet, then had to go back and cut them all again! It seems they had forgotten to compensate for the purlins, which would run over the tops of the trusses. The crew easily burned several hours in this adventure!

It was of interest to hear Leroy espousing how much money was being saved by his employer using rough cut 5×6 (yes, 5×6 for those in most of the rest of the country) for posts instead of surfaced 6x6s.

At 4-3/4” x 5-3/4” the Section Modulus of the rough 5×6 is 26.17, as compared to the slightly greater 6×6 at 27.73 (within 6% anyhow). As long as the site of this building was Exposure B or C for wind, either size would work – Exposure D, either is a failure (assuming we are talking about Southern Pine lumber, not some lesser species).

For more fun with posts: https://www.hansenpolebuildings.com/2014/08/lumber-bending/

What I found particularly interesting was the attempts to cut truss notches in the posts, while they will settle further into the ground due to the lack of an adequate footing underneath. If you didn’t read the past two days’ blogs, go back and find out how much concrete was put in the posts, and why it’s nowhere near adequate to keep this building from settling (or heaving due to frost).

I’ve always built by doing the roof first, it made things easier to square up. Leroy’s boys were putting up wall girts as quickly as they could, however. I was impressed by the use of 2×4 1650 msr lumber for the wall framing. This was the first good idea I found my neighbor’s pole building experience.

Learn about msr lumber here: https://www.hansenpolebuildings.com/2012/12/machine-graded-lumber/

Pole Barn Wall GirtsOn this building, the girts were unusually spaced – 31 inches from the top of the pressure treated skirt board, to the bottom of the first girt, then 25-1/4 inches on center above. This means the bottom girt has to carry a tributary load of 29 inches.

With an Exposure B wind condition, they will carry the bending loads (https://www.hansenpolebuildings.com/2012/03/girts/), however with spans of greater than 24 inches on center, which they all are, results in excess deflection beyond the limitations of the building codes. Adding two more rows of wall girts would have at least been something to even things out.

Now the clincher –only the 40 foot sidewalls were framed prior to all of the windows and the entry door being installed. No apparent attempt was made to insure the corners were plumb, and no apparent connection to the other walls was constructed. The entry door was installed without adding a post on one side for stability! It just sort of “hung there” on the one post.

On the windows, if the wall has to be racked very far to have a plumb corner, undue stresses will be placed upon the frames, resulting in windows which bind when being opened, or possibly cracking from the stresses induced! I’d not want anyone standing below this building if they do decide to square it up.

Come back next week and we’ll see if this saga comes to a close!

I Love Pole Building Photos

My wife, not so much – because she says I manage to pick out things which are wrong in nearly every one of them. Weirdly enough, when I do find errors, it is nearly always on buildings which have been constructed by “professional” barn builders. More often than not, when our clients do the work themselves – the pole building photos prove they followed the directions!



I have made this statement repeatedly for years – the average building owner who can and will read instructions will construct a better finished building for himself, than most contractors will erect for them.

Read more about doing it yourself here: https://www.hansenpolebuildings.com/blog/2012/01/build-it-yourself/

We don’t make a fortune on the buildings our clients invest in. The little we do get paid for, is because we have spent decades going over minute details to make construction as easy as possible for the average Joe (or Jane) to arrive at a successful result.

pole building frameOne of those “maybe simple” things is the overall footprint of our buildings. In the photo is a partially framed 30 foot wide by 48 foot long building. When we measure those dimensions, it is from outside of column, to outside of column. All of the wall framing is to extend out 1-1/2” past the posts. Done correctly, the finished framework of this building will be 30’3” by 48’3”.

Why might this make things easier?

Steel panels have a net coverage of three feet (36 inches). They also have an overlap. This means 10 sheets of steel will cover approximately 30’2”. The Hansen Pole Buildings Construction Manual has the first panel of wall steel starting ¾” outside of the pole, so at the far end of the wall, the last panel of steel does not have to be ripped to fit. So much easier to avoid the extra cutting!

Now, take a gander at the pole building photo. Look close – notice the wall girt framing does not extend out past the poles. Bookshelf girts, as described and shown in the Construction Manual and on a specific “blown up” detail on the plans, should project 1-1/2″ outside the building line. This client’s builder took it upon himself to disregard the building plans and instructions. He created a lot more work for himself, by cutting all of the 2×8 pressure treated skirt boards (https://www.hansenpolebuildings.com/blog/2013/08/composite-grade-board/) and headers to fit between the columns, instead of applied (more easily) to the outside face of them. He also ended up having to rip steel panels which would not have been otherwise cut lengthwise.

The Hansen Pole Building kit is the product of easily 100,000 pole buildings of experience. The great majority of folks follow the instructions and avoid extra work and pitfalls…..the few others, not so much!

Them Girts, They Be a Bending

In order to follow the deflection criteria of the International Building Codes, other than for fairly small wall column spacings with low wind speeds, pole building wall girts need to be installed in a “bookshelf” fashion.

What even is “deflection criteria”?

Dictionary.com defines deflection as, “the deviation of the indicator of an instrument from the position taken as zero.”

In layperson’s terms, when you push on something with a known force, how far does it bend (or deflect)?

Prior to the adoption of the International Building Codes, wall members which did not support a brittle finish material (e.g. drywall), were not limited in how far they could deflect.

Not so with the new code.

For those of you who care to look it up and read along, Table 1604.3 lists deflection limits. For walls with brittle finishes, the limitation is L/240 (where “L” is the span or length of the supporting member). For flexible finishes, the limit is L/120. Footnote A includes, “For secondary wall members supporting formed metal siding, the design wind load deflection shall not exceed L/90.”

The smaller the value L is divided by, the larger the allowable deflection is.

Ignoring the width of nominal six inch building columns the allowable deflection of wall girts for an 8’ bay (with steel siding) would be 1”; a 10’ bay 1.27”; 12’ bay 1.54”.

Using the least possible loads allowed by code – which would be 85 mile per hour winds, B wind exposure and a building Occupancy class of I (I = a building which represents a low hazard to human life in the event of failure) combined with the stiffest possible commonly used lumber (Douglas Fir or Southern Yellow Pine #2) and spaced 24 inches on center, some problems occur.

Using 2×6 lumber on 10’ bays the actual deflection is 1.507” and on 12’ bays 3.226”. On 8’ bays IF 2×4 #2 is actually used (it is rarely available in lumber yards), then it would deflect 0.924” and be OK. Another issue with the 2×4 girts on 8’ bays, is this style of construction is most prevalent in areas where the minimum wind speed is 90 mph.

Keeping all variables the same, except increasing the wind speed to 90 mph, increases the deflection of a 2×4 #2 to over an inch on an eight foot bay!

Shopping for your new ideal dream pole building? If so, ask specifically how the wall girts are placed. Anything other than “bookshelf” style pretty much guarantees the building being proposed, is not code conforming!