Tag Archives: engineer

Typical Wall Bracing Details for Pole Barns

There are many ways to permanently brace walls of pole barn (post frame) buildings. Most of these methods are utilized in buildings not designed by a Registered Professional Engineer (RDP). A RDP who has a great deal of experience with post frame building intricacies would first be looking at a structural design to utilize steel siding and roofing’s shear strength.

Hansen Pole Buildings’ independent third-party engineers use values obtained from actual full scale testing of steel panels done under supervision and auspices of engineer Merl Townsend: https://www.hansenpolebuildings.com/2012/08/this-is-a-test-steel-strength/. These test results, and those of other tests, are published in the NFBA (National Frame Building Association) Post-Frame Building Design Manual https://www.hansenpolebuildings.com/2015/03/post-frame-building-3/.

Recently reader JOSE from GONZALEZ asked:
“What are the typical wall bracing details for pole barns? Best locations?”

In utilizing steel skin strength, in many cases, needs for other wall bracing is eliminated. This makes for no extra expenses and ease of assembly. When wall bracing is needed, it is usually added closest to corners, where shear load forces are greatest.

For cases where strength of steel skin is not adequate to support loads, the International Building Code (IBC) provides for wall panels to be braced by adding either Oriented Strand Board (OSB) or plywood. This most often occurs when a wall (or walls) have large amounts of openings (doors and windows) or in cases where buildings are tall and narrow, or very long (usually width of three to four times building length). An engineer can determine the applicability of this as a design solution. Installation of added sheathing is generally fairly simple and requires (in most cases) minimal extra framing materials.

X bracing is often found in non-engineered buildings and can be either of dimensional lumber or steel strapping. Actual effectiveness of either of these is limited by an ability to add enough fasteners to resist loading: https://www.hansenpolebuildings.com/2016/03/diagonal-bracing/.

Rural Renovators recently constructed a very tall post frame building where they utilized a triple set of 2×6 X bracing at building corners: https://www.facebook.com/ruralrenovators/videos/2089528207814164/

In any case, my recommendation for proper post frame building correct structural design is to only use plans designed by a RDP (engineer).

Overhead Door Header Problems

Overhead Door Header Problems (and More)


Reader MITCH in NASHVILLE writes:

“I recently purchased a property that the previous owner had just built a 30×50 pole barn on. It has foil faced double bubble on the roof and walls. I need to heat and possibly cool the space. What are the options for insulating the ceiling? The ridge is vented. There is no soffit and thus no vent there. The trusses are 5ft apart. Your all-seeing wisdom is appreciated.”

There are times I wish I was not what Mitch feels is “all-seeing”, because I find lots of problems in photos building owners are unaware of. 

Back in my post frame building contractor days I would go visit some of our newly constructed buildings, as time and logistics allowed. I generally had very, very good crews and we had an extremely high satisfaction rate from our clients. I would find things wrong (in my eyes anyhow) and send crews out to make repairs. More than once I would field phone calls from clients asking what was going on. They were perfectly happy with their buildings. I would explain to them they might be satisfied, but I was not!

Mitch’s photo shows a frequent challenge posed with post frame buildings where headers (in this case more appropriately known as truss carriers), support trusses between columns. I am not a gambler, but would place money on this not having been an engineered building. Just guessing, this builder used the same size truss carrier for all locations. Usually these truss carriers would be sized to support a single truss centered between two columns. Here, due to door location and width, this carrier supports two trusses, or double what it should have been carrying. 

Look back at this photo – there is a noticeable sag across overhead door top! This same sag will be evident along sidewall eave line outside.

Before any thoughts of insulating are considered, a competent professional engineer should be engaged to design an appropriate repair for this header. Engineer should be advised this header will also need to be capable of handling the weight of a ceiling without undue deflection occurring.

Moving forward, contact the roof truss manufacturer to get a truss repair to upgrade trusses to support at least a five psf (pounds per square foot) bottom chord dead load, with 10 psf being even better. Each truss should be stamped with information of who fabricated them.

Once header and truss repairs have been completed, use white duct tape to seal all gaps present in your roof’s radiant reflective barrier. Without these being sealed, there is a potential for warm moist air to get between barrier and roof steel and condensing.

Place ceiling joists on hangers between roof truss bottom chords every two feet. Your previously engaged engineer can verify if 2×4 Standard ceiling joists will be adequate.

Install vents in each gable end. Placed in the top half of each gable, a net free venting area of 360 square inches or more will be required for each endwall.

Hang 5/8” Type X gypsum wallboard on bottom of ceiling joists, leaving an attic access somewhere towards building center. Have a spray foam insulation installer apply closed cell foam along a two foot strip closest to each sidewall. Blow in fiberglass, cellulose or rock wool insulation across remainder of ceiling surface.

Responsibilities Where the Legal Requirements Mandate

Responsibilities where the Legal Requirements Mandate a Registered Design Professional for Buildings (Section 2.3 of ANSI/TPI 1)

MPC is Metal-Plate-Connected; RDP is Registered Design Professional (architect or engineer).

In preparation for specifying MPC wood trusses, every section of Chapter 2 and ANSI/TPI 1-2007 (NOTE: ANSI/TPI 1-2014 retains same language) standard should be carefully studied by the RDP. In preparing this article, we assumed that the RDP will view a complete copy of Chapter 2 for a full understanding. Specific sections selected for discussion are cited by paragraph and subparagraph numbers.

Under Section 2.3.1 Requirements of the Owner, we note three sections that can help prevent truss erection accidents, and in some cases improve in-service truss performance. Over the past two decades, industry safety documents recommended that for truss spans over 60 feet, the Contractor should “See a registered professional engineer” for temporary bracing information. In many cases, Erection Contractors failed to follow the advice, and some accidents and performance problems stemmed from inadequate temporary and permanent bracing. The new ANSI/TPI 1 standard now requires action by the Owner and RDP as given in the following paragraphs:

2.3.1.6 Long Span Truss Requirements.

2.3.1.6.1 Restraint/Bracing Design.

In all cases where a Truss clear span is 60 feet (18m) or greater, the Owner shall contract with any Registered Design Professional for the design of the Temporary Installation Restraint/Bracing and the Permanent Individual Truss Member Restraint and Diagonal Bracing.

2.3.1.6.2 Special Inspection

In all cases where a Truss clear span is 60 feet (18m) or greater, the Owner shall contract with any Registered Design Professional to provide special inspections to assure that the Temporary Installation Restraint/Bracing and the Permanent Individual Truss Member Restraint and Diagonal Bracing are installed properly.”

The importance of these new paragraphs to truss safety and reliability cannot be overstated. When executed by the Owner and RDP, these provisions for long span trusses should be effective in preventing truss erection accidents and ensuring in-service truss performance. “

Monitor Barn Truss Challenge

When All Else Fails a Monitor Barn Truss Challenge.

Monitor style buildings are a popular post frame building design (for background on monitor barns please read: https://www.hansenpolebuildings.com/building-styles/monitor-building-designs/). In most cases, design, ordering, delivery and construction of monitor buildings goes off without a hitch. On rare occasions a hitch glitch happens – so when all else fails I get to jump in.

Now I am highly qualified to solve post frame building challenges.

Why?

As a 1990’s era post frame building contractor, my company had as many as 35 building erection crews working at a time across six western states. We paid our crews very well, so we attracted a group of subcontract builders who we felt were a cut above most. Even with this, challenges could and would occur.

Over several years I have had DIY clients call and tell me, “You won’t believe what I have done, it may very well be among the worst mistakes ever”! I would relate my experience as a contractor and then assure them, “If an error could be made, one or more of my crews could figure out how to do it. Tell me your challenge and let’s work together for a solution”.

In these photos, please note on an end of these monopitch trusses it appears the pressed in steel connector plate at truss heel (low end of truss) is beyond the line of columns. At truss high end, seemingly just truss top chord is attached to column…leaving bottom chord hanging out in space!

Our client did not even realize a truss challenge had occurred. They had sent these photos in regards to an entirely different issue and we found it when looking at them.

Putting on my best Sherlock Holmes hat, it was time for some sleuthing. Our request transmitted to the truss manufacturer asked for a 12 inch overhang on these trusses. It turns out our truss people decided to put the overhang on high end of trusses, rather than low end. Sure enough, we missed this when we approved their drawings. Client (and/or his builder) somehow also missed this and installed trusses as shown in photo!

This one actually had a reasonably easy fix. Truss company’s engineer was able to design a repair using a solid block of 2×12 to fill in the space and attach truss and columns.

There exists a solution to every post frame challenge.

Oklahoma, Is it OK?

Oklahoma, Is It OK?

Last weekend my lovely bride and I attended an event hosted by her first husband’s sister and her husband. Event purpose was to celebrate this couple’s upcoming 40th wedding anniversary.

Adding to this fun, at least for me, was a new Hansen Pole Building being erected onsite (D.I.Y. husband doing some nice workmanship). Like most new construction this attracted a fair number of looky-lous who wanted to check everything out and offer their ‘armchair expert’ opinions.

One of these lookers was aforementioned husband’s brother, who (as I later found out) had his old pole barn collapse due to snow last Winter. Rather than contact us about a replacement building, he ended up buying a post frame building to be delivered from Oklahoma (keep in mind we are in Northeast South Dakota).

Now I happen to know these folks in Oklahoma who provided this kit package. I hadn’t visited their website in quite some time, so I went browsing.

Here are some things I found:

“Building codes and permits

In our recent annual post-frame construction industry survey, one of our questions to builders was about code enforcement in their areas. Of the 134 post-frame builders who answered this question, 55% said they have needed on occasion to change their construction to meet a code. Codes can be problematic if not clearly understood. Start with your local planning and zoning office or your local building inspector. They will be able to tell you the standards for your community.

Know the rules in your area:

  • Some cities will not allow a steel skin building – you must have a brick veneer.
  • Almost all residential areas will have a setback requirement, meaning the building must be so many feet from the property line.
  • Many neighborhoods have a restriction on how tall you can make the building.
  • Many areas want to inspect a building at each stage of construction, starting with the depth of the holes, then they will inspect the wooden framework, then the completed structure.
  • Some communities insist on bolting the trusses in place, adding hurricane clips, beefing up the top plate, digging the holes deeper and providing longer poles or adding gravel or a concrete footer in the hole.

Bonus Tip: Some local code expectations may seem over-engineered when it comes to equating cost with necessity. In our view, codes generally foster a better quality building and we have found it is best to give the inspector what he or she wants. Life, and your project, will go easier that way.”

Now I agree total with starting a journey to a new post frame building with visits to your local Planning  (https://www.hansenpolebuildings.com/2013/01/planning-department-3/) and Building (https://www.hansenpolebuildings.com/2013/01/building-department-checklist/) Departments.

What amazed me was “55% said they have needed on occasion to change their construction to meet a code”. Thinking back over nearly 40 years of post frame buildings, I can only think of two sets of circumstances causing a change in construction to meet Code. First – not submitting plans prepared by a RDP (Registered Design Professional – architect or engineer), second would be not having correct design criteria (snow, wind and seismic loads, along with frost depth) provided.

In my humble opinion, a majority of these builders who had to change their construction were probably not building Code conforming structures! Think about this if you are considering investing in a post frame building from ANY builder.

While some jurisdictions will not allow steel roofing and/or siding, I have yet to have any demand a “brick veneer”. There are numerous alternatives to steel, they just happen to be less economical and less durable.

Only insistence from communities regarding how buildings should be assembled comes from those who have prescriptive requirements for non-engineered pole buildings. Read about challenges of prescriptive requirements here: https://www.hansenpolebuildings.com/2012/02/prescriptive-requirements/.

Path to best value for one’s post frame building investment nearly always involves having RDP sealed plans. Make everyone’s life easier (you, your building kit provider, any contractors, as well as your Building Department) and insist upon only using RDP sealed building plans. Headaches saved, will be yours!

 

 

 

What To Do With an Old Dollar General Pole Barn

What to Do With an Old Dollar General® Pole Barn

In the fall of 2016 the town of Reading, MI purchased the pole barn which had previously been the home of a Dollar General® store. The original plan was to convert the pole barn into a new city hall, but, after seeing the estimated price tag the idea was set aside.

The city’s maintenance man, Bob Jepsen, suggested tearing down the walls, replacing the building’s leaky roof and converting the building into a pavilion. It turns out the city’s planning commission thought this would be a great idea and held a public meeting to discuss.
In the early days of railway transportation, the brakemen rode in the last car of the train – the caboose (seen many of these lately?). He had one of the deadliest jobs in America, as the brakeman had to work from the tops of the railway cars in all sorts of weather.

In the case of the old Dollar General® pole barn, I am going to act as brakeman on the runaway train which is the remodel of the building into a pavilion.
Tearing the walls off of an existing post frame (pole barn) building sounds relatively easy – and from a labor standpoint it may be. Where it all gets dicey is when it comes to structural engineering.

When a post frame building has its walls removed, the columns (posts) now act as cantilevers. They are functioning similar to a diving board, where the end is very flexible. With the walls on the building, the columns are, in most cases, acting as beams supported at one end by the ground and the other by a relatively rigid roof diaphragm.

The difference in the loads which the columns must resist are increased by a factor of four without the walls present, as the posts become the sole structural members for transfer of wind loads from the roof to the ground. This potentially not only impacts the design of the columns, but also of their embedment into the ground.

Whether it is this particular Dollar General® pole barn, or any other post frame building where exterior walls are being considered for removal, a RDP (Registered Design Professional – engineer or architect) should be engaged early on in the process to make a determination as to what upgrades are necessary to result in a structurally sound building.

18 Foot Span Roof Purlins?

The Possibility of 18 Foot Span Roof Purlins?

Reader CHRIS writes:
“I have a building I want to build but I am not able to add the height I need on the side walls.  My plans are 24 deep by 30 wide with 8 foot walls.  Roof trusses would be 24 ft.  My problem comes from overhead power lines.  They are right in my way.  I really need 10 or more feet of ceiling.  The wall structure will be 2×4 residential style build with double top and bottom boards this should spread the weight out on the concrete well.

The span of the 1st section (north side), would need to be 18ft.   If I used a triple truss at 18 ft. and 2×8 purlins would I be able to get this to work.  I will be using a metal roof the 30 ft. wall will have a 16 ft. door and 9 ft. door Eve entry.  I know it’s not optimal.  But to get a lift inside the garage it will be a must to get this span.  Also my garage door will follow the roof line. In the 18 ft. area it will be hung from the purlins.  A winch will be used as an opener.  Also attached to the purlins but boxed to prevent movement.”

Mike the Pole Barn Guru writes:
In most jurisdictions you are not allowed to build under power lines – you need to be consulting with your local power company and your Building Official first. Even if it is allowed, you would be wise to have the lines relocated, or buried so as to not have a future issue. A live wire comes down on your nice new steel roof and poof!

Depending upon your roof load and wind load, it might be possible to span 18 feet between trusses with purlins, however they are probably going to need to be larger than 2×8. With the proper truss design, it might very well be able to carry the end of the purlins with a double truss.

What you are proposing is well outside of the prescriptive portions of the Building Codes, so whether stick framed or post frame (post frame will be far more economical) you should be utilizing the services of a RDP (Registered Design Professional – architect or engineer) in order to make sure you have a new building which is adequately designed to support the imposed loads.

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.

A Retro-Fit, Truss Support? and Sliding Door Installation

The pole barn Guru looks at a Retro-Fit, truss supports, and installing a sliding door.

DEAR POLE BARN GURU: I have a question about Retro-Fit insulating my pole barn. I live in Southwest Michigan and bought my house with an existing 40’x60′ building, just used for storing farm equipment before I acquired it. Steel roofing straight to the roof purlins and steel siding straight to the wall purlins. Can I put a metal ceiling in with blown fiberglass insulation above and metal walls with Batts between the inside wall and outside wall, or do I need to have some sort of vapor barrier? MITCH in MICHIGAN

DEAR MITCH: First things first, in order to retro-fit the trusses, confirm the trusses are capable of supporting the weight of the steel liner panels and insulation. Most post frame building trusses are not designed to support a ceiling. There should be a stamp on every truss which identifies the truss manufacturer as well as the design loads. You need a minimum three psf (pounds per square foot) bottom chord load to support the ceiling. If it is less, and you can contact the truss manufacturer who should be able to provide an engineered repair to upgrade the trusses, for a nominal fee.

You will need to have some form of thermal break below the roof steel – my choice would be closed cell spray foam. On the walls, you should really have a building wrap between the steel and the framing, however an inch or so of closed cell spray foam would work, filling the balance of the cavity with unfaced fiberglass, then a well sealed vapor barrier on the inside.

 

Engineer sealed pole barnDEAR POLE BARN GURU: Pole Barn Guru, do you have to have girt under end trusses. End trusses setting on 2×12 from header and nailed to 6×6 pole with 2×6 blocking below trusses 24″o.c. sheated header 3 2×12 notch blocked and clipped. STEVE in CHEYENNE

DEAR STEVE: In order for me to answer your question, I would need to see the engineered plans for your building. If you are unsure of how to determine from your plans, you could contact the engineer of record who designed your building and ask him or her.

DEAR POLE BARN GURU: On a sliding 4×8 walk in door, on the barn exterior are all 4 sides flat or is the top out the thickness of say 1.5 inches? If it is out will it not seal? If all is flush with it not roll easy? Joe

Figure 27-5

DEAR JOE: The sliding door track needs to be mounted to a ‘track board’ which is typically a 2×6 placed on the face of the sliding door header. This puts the top out 1-1/2″ which allows the door to be able to slide past the adjacent siding without banging against it. Sliding doors do not and will not seal air tight, so this should not be an issue unless you had some sort of unrealistic expectations.

Pole Barn Footings

Some things in life amaze me – magicians are one of them. I have no idea how the do what they do, but I am totally fascinated by them (you can read about my college experience with a magician here: https://www.hansenpolebuildings.com/2014/08/lumber-bending/). One of the other things which amaze me are how clients will invest tens (or hundreds) of thousands of dollars on a new post frame building, only to cheap out on the footings!

Anything of high quality requires a good foundation.  In post frame buildings, the measure of a good foundation’s investment is small in comparison to the overall picture.

Reader CHRISTINE from SPOKANE writes:

“We see all these posts about footings. It seems here they just pour concrete around post with no footings. Is that due to the nature of our rocky soil. Our posts are in the ground, no footing and ready for concrete, architect plans, say “bottom of all footings to bear on undisturbed ,native, inorganic soil 1′ min below grade. Extend all footings 4′ min below finish grade.” Did I assume wrong and he’s calling for an actual footing? TYIA! ASAP”

Dear Christine;

For years we designed our post frame buildings without a concrete footing below the columns, instead relying upon the concrete encasement around the posts to adequately bond to the pressure preservative treated column. The bond strength between concrete and wood is documented and more can be read about it here: https://www.hansenpolebuildings.com/2013/04/pole-barn-post-in-concrete/. There were some Plans Examiners who did not look kindly upon this as a design solution.

The Building Codes do specify the requirement for a concrete footing, and as such we moved several years ago to a design which placed eight inches thick of concrete below the column.

As an architect designed your building and placed his seal upon the plans, you are obligated to construct the building per his/her solution. There should be a detail on the plans which shows exactly what the architect had in mind. If there is not, request a clarification as this is something you paid for in your fee for the work.

Mike the Pole Barn Guru

Looking for a post frame building with a column embedment design which both makes sense and works structurally? If so, only consider a building which comes with plans done specifically for your building, on your site, and sealed by a Registered Professional Engineer.

Spot the Post Frame Problem

Spot The Post Frame Problem – Reprised

In our last episode, I left you all with a cliff hanger. I did clue you into it being a structural issue, which rules out our builder in the air with his safety harness hooked to an invisible sky hook.
While you all ponder the photo and look at it closely, I will mention a few items which are not necessarily a problem, just maybe not what I would call “best practices”.

Note the trusses. One is on each side of the column. Chances are good this builder is marketing his product as a double truss system. What they actually have are two single trusses spaced 5-1/2 inches apart. These trusses do not act as a pair, because the blocking between them will not transfer the load from one truss to the other.

Each of those trusses is bearing on a block. The trusses are depending only upon the nails or bolts driven through the end of the truss and the blocks to keep them up in the air. There was a time when I did buildings this way also. Until the day I saw a set of trusses and the blocks below them driven down the sides of the poles by excess snow! They were only stopped from hitting the ground by the vehicles which were crushed inside.

Paddle blocks – if you do not know what they are, or their potential for future challenges, you will want to read here: https://www.hansenpolebuildings.com/2012/05/paddle-blocks/.
Okay, time to get serious here. Look at all the pretty wall girts. Nailed flat on the outside of the columns. They all fail due to not meeting the required deflection criteria set by the Building Codes: https://www.hansenpolebuildings.com/2012/03/girts/.

Now the particular jurisdiction where this building is being built has their own prescriptive solution to this problem. I’ve railed against prescriptive requirements in this forum previously: https://www.hansenpolebuildings.com/2012/02/prescriptive-requirements/. Look closely at the wall in the back of the photo. Look at the right hand bay. Note how every other wall girt has another board nailed to it to form an “L” as a stiffener. Truly wonderful as this solves the deflection issue for these particular girts only. The girt in between, without the stiffener, still fails!

Again I preach and beseech – please, if you are going to construct or have constructed for you a new post frame building, only do so with plans which are design specifically for your building and your building only, which are designed by a Registered Design Professional (architect or engineer).

The Argument Against Building Codes

The Argument Against Building Codes

The argument against building codes isn’t a haphazard attempt to loosen restrictions. Instead, it’s often made by experienced contractors and other industry veterans who are frustrated by certain trends and aware of hazards or risks the general public may not realize.

When construction teams “build to code,” what does this really mean? Unfortunately, it often means complying with the bare minimum of legal requirements.

Building-Plans2Ponder this one carefully – “the bare minimum”. Or, in other terms just enough to get by. Would you prefer to fly in jet aircraft designed by engineers who were 4.0 students in college, or ones who barely scored high enough to graduate? How about buying a new car, with a highest speed capability which is equal to the speed limit, and no greater?

No reputable builder or building supplier will defy codes intentionally, but if the only goal is to make sure a property isn’t illegal, they may not have incentive to go above and beyond with quality or safety.

You don’t have to see into the future to know what happens when only the bare minimum requirements are followed. Martin Holladay, who serves as a Green Building Advisor (GBA) Senior Editor, points to historic Vermont homes with rotten sills, undersized rafters and bulging foundations as examples of corner-cutting craftsmanship which only barely complied with the building codes of the time.

Of course, safety is still the primary purpose of building codes. However, because construction crew training isn’t required and building owners aren’t necessarily savvy about the best materials and building practices, construction teams can continue to neglect the quality of their work.

What can the average post frame (pole building) future building owner do about it?

Don’t buy to minimum standards.

Repeat – don’t buy to minimum standards.

Just.  This.  Simple.

Oftentimes the investment to upgrade climactic loads (wind and snow) to standards more rigorous than the minimums is negligible.

I see lots of proposals from pole barn suppliers and builders, which do not even specify the design loads of the buildings being proposed! And even more amazing – PEOPLE BUY THESE BUILDINGS!!

Don’t be a fool, for a fool and his money are soon parted. Know what the minimum loading requirements are (https://www.hansenpolebuildings.com/2013/01/building-department-checklist/).

Demand to have the design wind and snow loads specified on any quotation and most certainly upon any order.

Ask – how much more would it be to increase the design wind speed by 5, 10 or even 20 miles per hour. Ask – about the extra investment to increase snow load capacity.

And after all is said and done, don’t invest in a building which does not come with plans and calculations specific to your building, at your site and sealed by a registered design professional (RDP – engineer or architect).

For more reading on engineered buildings: https://www.hansenpolebuildings.com/2011/12/engineered-buildings/

Storage in Trusses

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: My shop is in a 30×40 pole barn. I would like to put storage up in the trusses, and have some of the shelves that hang from the ceiling also (really there is no ceiling right now, just the trusses and roof). The trusses span the 30ft and I am worried about putting too much weight on them. I really would rather not have any supports in the middle of my floor…I was wondering if I could just sister up to the truss with some 2x6s or bigger to strengthen them…or should I just limit my upper storage? ONLY IN OHIO

DEAR ONLY: Unless specifically ordered for light storage loading, pole building trusses are rarely constructed so as to support any weight from their bottom chords other than limited electrical and lighting.

As you are considering “beefing up” the existing trusses, you should consult with the company which manufactured the trusses. There is typically a stamp on every truss with the truss company’s name on it. For a nominal fee, they can usually provide an engineered “repair” to upgrade your trusses.

In the event the truss company cannot be located, a Registered Design Professional (RDP – engineer or architect) should be hired to design a repair for you.

Only with one of these two solutions would I be able to recommend placing anything for storage in the truss system.

An alternative may be to build a raised “loft” floor in the building, at the level of, but not supported by the trusses. Again, this is a design best accomplished by a RDP.

DEAR POLE BARN GURU: Hello, I am contractor assembling one of your pole building kit packages.
Would you send me details for flashing the building please?
Need:
-Corner flashing.
-End capping the cut ends at top.
-Where do the corrugated foam strips reside?
-Roof panel overhang on the sides and ends.
-Door trim flashing

Thank you, WISHING IN WASHINGTON

DEAR WISHING: All of these are covered in depth in the Hansen Buildings Construction Guide which was provided to your client after purchase. If your client has not shared it with you, you should ask him for the big white binder which was sent to him. Every piece of trim has a diagram showing what it is along with the code used by the steel company. Detailed drawings show where each piece goes on the building.

Building Code: Things Which Make My Head Hurt

International Building CodeThe International Building Code (IBC) is the resultant of years of practical experience and sound engineering practice. The authors are a collective group of Building Officials and engineers, whose mission is to protect the safety of those who will be utilizing the structures built under the auspices of the Code. For practical purposes, every word, of every section of the Building Code has been scrutinized, analyzed, hashed over and rehashed to produce what can only be considered as a magnificent work. Even at this, amendments, additions and subtractions are proposed and made or rejected, providing an updated version every three years, which reflects changes which have come about from better science and research.

The Code also allows individual jurisdictions, to make local amendments to the Building Code. Oftentimes this is done without a sound engineering basis, or research to confirm the reasoning behind the amendment(s).

I am going to now pick upon a single permit issuing jurisdiction. This unnamed county has, as is their right, adopted the following:

15.16.060 Post Frame Structures (pole buildings).

A. Post frame structures over twelve hundred (1200) square feet in area shall be designed by a professional, licensed by the State of (Name Withheld) to design such buildings. The licensed professional shall affix his/her certification and signature to the design, including design drawings and details, specifications, and calculations. Any changes to the design, drawings, details, specifications, and calculations during review or construction shall be prepared and certified by the licensed professional designer of record and submitted for approval of the building official prior to incorporating such changes into the work. The minimum design criteria for post frame structures are as follows:

1. Minimum snow load is thirty-five (35) pounds per square foot (PSF). Reductions in live load/snow load are not permitted.

2. The minimum roof purlin dead load is 5 PSF.

3. The maximum total load deflection is:                       

 a. With ceiling: L/240

 b. Without ceiling: L/180

4. The maximum wall wind load deflection is L/120.

We recently had a plan review done, in this county, and the Plans Examiner/Building Inspector threw in this curve:

“Our standard design for accepting engineered plans for pole buildings over 1200 square feet, require that purlins/girts are spaced no more than 24” O.C.  Your plans call for girts spaced at 31 5/8” and purlins at 29 ¼”. “ 

After some discussion with the Plans Examiner the resultant was (as relayed from one of our owners):

They don’t have a 24” oc girt and purlin requirement – just the change to deflection that we looked at. His (building officials) reasoning was ‘experience’ – that engineers use code to under design buildings.

I will only address issues which I feel are either contrary to the Building Code, do not make sense from an engineering standpoint, or do not have a rationale under the Laws of Physics.

Minimum snow load. The Code addresses how to calculate Pf (flat roof snow load) and Ps (sloped roof snow load) based upon Pg (ground snow load) as well as factors such as Is (building importance), Ct (temperature factor – is building heated or not), Cs (sloped roof factor), and Ce (roof wind exposure factor).

Picking an arbitrary roof snow load, leads to the possibility of either gross over design (causing more cost to the building owner) or gross under design (leading to a possible failure).

As espoused by this jurisdiction, a roof for an Essential Facility (think fire station), which is unheated, has a 4/12 slope shingled roof, and is protected from the wind, would have the very same load as a heated storage building with an 8/12 pitch metal roof, which is exposed to the wind. Common sense says this is just not the case.

Minimum roof purlin dead load of 5 psf. The dead load should be set by the RDP (Registered Design Professional – architect or engineer) who designs the building to reflect the actual imposed loads. As 60% of the dead load is used to calculate the wind uplift forces on the building, an arbitrarily high dead load could result in the under design of the connections between purlins and trusses, as well as trusses and columns.  Potentially this could result in a design, by statute, which results in an overstress of these connections.

In reality 2×6 roof purlins at 24 inches on center, supporting a 29 gauge steel roof induce an actual dead load of about 1.5 psf (pounds per square foot). The 5 psf requirement is 333% higher than reality.

The Building Code allows for purlins supporting a light gauge steel roof to have a deflection of L/150, rather than the stiffer L/180. Deflection criteria have nothing to do with the structural integrity of the roof, merely esthetics under high loads.

The Code allows for wall girts supporting light gauge steel siding to have a deflection of L/90, rather than the stiffer L/120, as long as brittle finishes (such as plaster or drywall) are not being supported. Again deflection criteria have nothing to do with the structural integrity of the siding, merely esthetics under high loads.

Creating criteria which are counter to the majority of the jurisdictions in the country only creates confusion for RDPs, building providers and contractors, as well as increasing costs (without reciprocal benefits) to building owners. These criteria appear to be arbitrary and capricious in penalizing post frame construction against other forms of building construction.

If the feeling is the Building Code allows RDPs to under design buildings, then the jurisdiction should move the International Code Committee (along with providing rational proof as to why) to change the IBC. If snow load is their concern, the utilization of higher Pg values than have ever been historically seen (while not a reality), would allow for a uniformity of calculations by registered engineers.