Tag Archives: knee braces

Do I Need Any Additional Vapor Barrier?

Do I Need Any Additional Vapor Barrier?

Reader TOM in NEW LONDON writes:

“Have a 40 x 60 pole barn which I have poured a 20 X 60 6″ concrete floor with radiant heat. I have installed 1 1/2″ R 7.5 rigid pink board between the 2 X 6 side boards against the steel. I will be installing R 19 kraft faced insulation in the 2 x 6 side walls and R 38 kraft faced insulation in the ceiling. The area above the ceiling insulation is completely open to the roof.  Eaves soffit is vented. Do I need any additional vapor barrier? Have I done anything wrong?
Thank you.”

Some basic commentary, from your photo, to begin with. I obviously do not have the benefit of having your building’s engineered plans or sealed truss drawings to reference, so some of my commentary will be based upon best guesses.

I would sincerely doubt your building’s roof trusses have been designed to support loads induced into them from knee braces. Please read more in regards to this subject here: https://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/. Your first step should be to contact the truss manufacturer to verify ability of your building’s trusses to withstand loads from knee braces. With an assumption trusses were not so designed, second step will be to contact the engineer who designed your building to find out if your building will still be structurally sound with knee braces removed. If, by some chance, an engineer was not engaged to produce your building plans, a competent one should be retained to do an analysis of your situation.

Any lumber in contact with concrete needs to be pressure preservative treated – this would include plates between columns and bottom plate of your framed stud wall. You really do not want to have these boards decay within finished walls.

If you do not have a well-sealed vapor barrier beneath your concrete slab-on-grade, you need to use a good sealant over top of it.

Moving forward, to your question at hand. In order to install kraft faced batts along your building’s sidewalls, you will need to add additional framing. Most folks place another set of wall girts upon column insides. If so, in your case, then R 19 batts are not going to be adequate – as they will leave an air gap between batts and pink board. My recommendation would be to use BIBs (https://www.hansenpolebuildings.com/2011/11/bibs/) in walls, with a vapor barrier to inside face of framing before adding the finished wall material. To get best thermal performance, a layer of closed cell foam insulation board can be glued to wall framing inside, then glue gypsum wallboard (sheetrock) or your choice of other products to insulation boards. This inner layer of foam board, if joints are sealed, will act as your vapor barrier. Have your building engineer confirm your building walls will be stiff enough to keep drywall joints from cracking.

Now – roof system. Before adding a ceiling, verify your building’s roof trusses will support this added weight. Most post frame building trusses will not! Trusses should have a minimum bottom chord dead load of five psf (pounds per square foot) to support framing and drywall. Your building does not have a vapor barrier between roof purlins and roof steel. Only cure for this now will be to have two or more inches of closed cell foam insulation sprayed to the underside. If you fail to do this, you will have moisture/condensation issues in your attic. You also do not want to have a vapor barrier in your ceiling line – so kraft faced batts are out. I’d recommend 15-20 inches of blown in fiberglass insulation. Make sure to not block air intake from soffits. If your ridge cap isn’t currently vented, it needs to be.

 

Tom could have avoided a great deal of pain and expense had he and his building provider been communicating in regards to climate controlling this structure. Unfortunately, most post frame building kit suppliers and contractors are focused only upon providing a low price, instead of best design solution for their clients.

 

 

Spot Problems with This Pole Barn Photo

Spot Problems With This Pole Barn Photo

One of my Facebook friends had posted this as a timeline photo as it brought back to her fond memories of a childhood spent frolicking in hay lofts. It was so bad, I just had to save it.

So, what’s wrong with this photo anyhow?

Obviously bird excrement over everything does not pose a structural problem, but one which I would have been trying to minimize, if not avoid. One thing which was leading birds into building – excellent nesting material provided by what was once a vinyl faced fiberglass condensation control blanket (aka Metal Building Insulation).

Long ago I had espoused about joys (or lack thereof) involved in installation of Metal Building Insulation (https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/). For those of you readers who did not click upon link and read it in full, suffice it to say birds love fiberglass.

Once condensation control blanket was torn apart – there was nothing left to prevent condensation from occurring below roof steel.

Moving forward, just glancing upon structure supporting hay loft, I would suspect a high degree of under design with only chance keeping it from meeting its demise.

All sorts of things are seen hanging from trusses. Amongst these are a block and tackle, which I suspect has been used to lift bales of hay into loft. Fortunately, individual small hay bales are relatively light, as I am pretty sure trusses were not designed to support added point load weights.

While not most effective structurally, trusses can be designed to be placed upon each side of a column – provided they are done correctly. Blocking should be placed between truss bottom chords, in order to prevent weak axis bending. A bare minimum would be every ten feet.

I see no web bracing, making this highly suspect. Older barns tend to have had bracing needs neglected. Single trusses (when placed not nailed directly face-to-face into a pair, they are single) require a great deal of bracing.

Knee braces are what I see as biggest structural issue. Not only are knee braces ineffective (https://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/), but when installed improperly (as in photo) they are potentially throwing a load into roof truss bottom chords trusses were not designed to withstand.

Feel free to chip in with your observations.

 

Is the Double Truss System Stable for the Midwest?

Is a Double Truss System Stable for the Midwest?

Reader SHARON in NORTH DAKOTA writes:

“Dear Pole Barn Guru,

I have attached some pictures of a 62×96 pole barn with 12ft sidewalls. I am rather ignorant about truss systems, but this one looks atypical to others I have seen. What type of truss system is this, and is it stable for the midwest? How are your truss systems different? 

Thank you for your time and knowledge.”

Mike the Pole Barn Guru responds:

What you are looking at is a “double truss” system, where two roof trusses are physically joined side-by-side with the use of mechanical connectors (most often nails). It is absolutely stable for anywhere in the world. The most common Hansen Pole Building design utilizes the double truss system, typically with sidewall columns spaced at 10, 12 or even wider column spacing depending upon applied wind and snow loads as well as door locations. In the case of the photos you have sent, the roof purlins were placed over the tops of the trusses and staggered every other bay, this precludes the ability to pre-drill the roof steel, which would have minimized (or eliminated) the possibility of a roof leak caused by a misplaced screw. The Hansen Pole Buildings’ double truss system utilizes engineered steel connectors to attach the roof purlins to the sides of the roof truss top chords, as opposed to merely attempting to adequately nail through purlins to the tops of the trusses. The superior holding power of this connection resists wind uplift forces which could otherwise tear a roof off and send it swirling off like Dorothy’s home in The Wizard of Oz.

The most popular article I have written is on truss spacing – you can read it here: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/.

A caution – in the photos you have supplied, the trusses have knee braces, which could lead to a collapse if not engineered and accounted for within the truss design. More on knee braces here: https://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/

The benefits of double truss systems vs. single truss systems include:

1- Fewer holes to dig for truss bearings – with columns every 12 feet, it reduces holes by 1/3rd.

2- Fewer columns to have to set.


3- Reduces total number of boards and trusses having to be handled and installed by as much as 50%.

4- Eliminates possibility of the one single weakest truss failing and pulling the balance of the roof down behind it.

5- Reduces the need for lateral bracing – a properly connected together double truss is twice as stiff in resisting buckling in the weak direction.

 

Missing Shear Walls

Shear in the ‘Hood

The saga of the neighbor’s pole building continues….

I have restrained myself about as long as I can. Time for me to hack away at what I have to consider to be some basic design flaws. Other than the previously discussed, ‘not designed for the correct wind exposure’.

26x40 Pole BarnThe building is 26 feet wide by 40 feet long and 14 foot eave height. It has two 10 foot wide by 12 foot tall overhead doors in the front endwall – spaced two feet from each corner and two feet between.

I’ve previously written about how post frame buildings resist lateral wind forces by utilizing the strength of the skin: https://www.hansenpolebuildings.com/2011/12/lateral-wind-loads/.

Obviously large door openings are going to pose challenges in the dimensional stability of the end of our neighbor’s building. However some good structural design and the use of appropriate shear walls can take care of these issues: https://www.hansenpolebuildings.com/2012/06/shear-walls/

Assuming the unrealistic Exposure B wind speed which has been used in previous posts about this building (I am betting it’s at least wind exposure C, if not D) – each endwall needs to resist 2368.99 pounds of shear force. In the actual testing of steel panels over pole building frames to determine shear values, we came up with 160 pounds per foot when steel is properly applied to endwalls. (Interesting reading on steel shear strength testing: https://www.hansenpolebuildings.com/2012/08/this-is-a-test-steel-strength/).

Using this test proven value would require nearly 15 feet of endwall (measured across the base of the building at the end) sided with steel to carry the imposed loads!

There is a solution, which did not happen to be incorporated into this building – reinforcing the endwall of the building with structural wood panels (oriented strand board or plywood), aka “shear walls”.

So what else could be done in order to keep this building standing?

Pole buildings can be structurally designed either as “propped cantilevers” – where the diaphragms created by the roofing and siding transfer shear loads from the roof to the ground, or as cantilevers – where the posts do all of the work. The second choice results in the application of a force FOUR TIMES GREATER than when diaphragm design is used.

Pole Barn Knee BracesSince this building does not have the ability to adequately transfer the shear loads to the ground, the cantilever design could be an option, although the columns as specified are woefully inadequate to carry loads of this magnitude.

Builder Leroy, in an attempt to mitigate the potential problem, installed knee braces from the columns to the trusses. I shudder to even think about the new problems which have now been created with trusses which are not designed to withstand the wind load forces now being thrown into them! More reading on the ineffectiveness of knee braces can be found at: https://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/.

The structural future of this building is bleak, to say the best. In the event it blows down in our direction – we have excellent insurance coverage, and we hope our neighbor has the same.

Moral of the story – if your neighbor has a non-engineered pole building, (or an engineered one which is questionably constructed) call your insurance agent to make sure you are well covered for flying buildings (or flying building pieces) and don’t allow your policy to lapse.

Changing Pole Building Plans

You Want To Add What to Your Building?

For the most part, adding random extra framing members to a new pole building kit package is not a big deal. There is at least one crucial exception – which could result in a catastrophic collapse if included.

We go to great extremes to supply original pole building plans for every client which match exactly what is to be built. Every member and connection has been checked and confirmed for its ability to carry the appropriate wind, snow and seismic loads which are to be imposed upon the structure.

To get an idea of what is encompassed by the pole building plans, read more at: https://www.hansenpolebuildings.com/blog/2011/10/pole_building_plans/

Our Construction Guide has some pretty straightforward advice in it, including this statement in bold AND red:

“Any deviation from building plans places responsibility for the building’s structural integrity squarely upon you.”

Am thinking if I was a client and read this, I’d make sure to do it as indicated.

It further carries on to add, “A professional has designed your Hansen Building. Rely upon their experience”. As well as, “The cost to purchase “additional” materials and/or engineering if building is not built according to pole building plans is your responsibility (or between you and your building contractor in the event one has been hired).”

We even give one last warning, on the following page – tagged with a big red STOP sign (can you tell we truly do not want people to make mistakes?):

“If anyone, including any building department plan checker, field inspector, other official, or a contractor, makes any changes or deviations from provided building plans our advice is to obtain a signed statement to the effect they have now become “designer of record”. In effect, they have assumed all liability for the building’s structural design. Again, any deviation from the building plans relieves Hansen Building, the building designer or engineer from all responsibility for project design.”

I teased you with the possibility of a failure in the first paragraph – in the photo with this article is a beautiful brand new roof only. There are a couple of add-ons which were not anticipated.

Roof Only Pole BarnFrom the sidewall columns is what would be termed as a “Y” brace. The client liked the looks of them, and the way they are fastened would cause them to fall off the building long before any negative structural issues would occur (other than them falling off the building and perhaps damaging something or injuring someone).

Looking closely – the interior columns on the sidewalls have a “knee brace” attached to them. Knee braces are a no-no….and I mean a truly BIG no-no. Read more about them: https://www.hansenpolebuildings.com/blog/2012/01/post-frame-construction-knee-braces/

The goal is to always create structures which will last for generations – follow the pole building plans and chances are excellent they will!

P.S. We did nicely suggest to the client he should remove the knee braces.

Can I Purchase Just Pole Barn Plans?

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: I am very interested in pursuing a Hansen Pole Building for my horse barn.  However, since I believe I’ll need to go through a permit process, I would like to buy the pole barn plans, get my permit cleared, then buy the building kit.

The reason I would like to do it this way is in case there are issues with getting the permit that force me to “rethink” my desired approach.

Is buying just the plan an option?

Thank you for your consideration. SERENE IN SEABECK

Dear Seabeck: The first thing to do is visit your Planning Department, they will give you the answers as to how large a building you can construct, and where.

Here is more information: https://www.hansenpolebuildings.com/blog/2013/01/planning-department-3/

Once you have talked with them, contact your Hansen Pole Buildings’ Designer who can work with you to determine the best design solution.

Your Building Designer can further guide you through your Building Department requirements. With your confirmed Design Requirements and engineer sealed plans, we guarantee you will be able to obtain a structural Building Permit.

Many companies, such as ours, do not sell “just pole barn plans”.

Why? Many reasons.

1. We have streamlined our process for efficiency. This means by the time you get your plans, we are far into a ton of series of steps happening concurrently – and have done much of the “work”….which has a cost. People are willing to pay an architect several thousand dollars for house plans, but they are unwilling to pay an appropriate amount for the work involved to produce truly custom pole building plans.

2. You get the plans from us, but decide to purchase your materials “elsewhere” and then are disappointed because you paid a lot more than you thought it was going to cost.

3. Worst of all, you purchase materials that don’t match the pole barn plans from someone else and your building contractor does not build to our plans and blame us when the Building Department won’t sign off on your building.

Why do we know all of this? Been there. Done that. And we do guarantee if you do your homework and communicate clearly with your Planning Department and us, you WILL get a permit.

DEAR POLE BARN GURU: My contractor wants to put knee braces on the already constructed trusses due to shallow holes due to limestone. The holes are 18 to 20in across and 1 1/2 to 2ft deep. What’s your take? Thanks. LIMESTONE IN LOGANSPORT

DEAR LIMESTONE: Friends Don’t Let Friends Have Knee Braces – JUST SAY NO.

Here is some more reading on knee braces: https://www.hansenpolebuildings.com/blog/2012/01/post-frame-construction-knee-braces/

There are solutions based upon how far along construction is. If holes have been dug only – I’d be looking at renting whatever equipment would be needed to get the holes to the depth and diameter as specified on the engineered plans.

If further along in construction (columns concreted in) a Registered Design Professional (architect or engineer) should be consulted for a design solution.

Adequate column embedment is a serious issue, taking shortcuts can result in catastrophic issues.

Dear Guru: Housewrap, Concrete Brackets & Wobbly 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 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: Can I set my poles, or posts, on concrete rather than set in holes?  And, can I attach floor joists across the pole building to create a floor?  The planned width is 12-16′   SOMEWHERE IN SEDRO-WOOLLEY

DEAR SOMEWHERE: The answer to both of your questions is yes.

 For further reading on brackets for the columns please read: https://www.hansenpolebuildings.com/blog/2012/09/concrete-brackets-2/

 We design a fair number of buildings which have elevated wood floors, over “crawl spaces”. Please keep in mind, any beams or girders which are within 12 inches of exposed soil, or joists within 18 inches of exposed soil, must be appropriately pressure preservative treated to resist decay.

DEAR POLE BARN GURU: The instruction book is very clear about how to install roofing insulation, but silent on the correct way to install the housewrap on the walls.  I’ve used housewrap on stickbuilt walls, over the sheathing and under the siding, but never with the wrap just floating out there in space flapping between the girts.  Any tips to share about how to do this right? QUESTIONING IN CONNECTICUT.

DEAR QUESTIONING: When installing housewrap over bare studs in stick frame, or wall girts in a post frame building, run the housewrap perpendicular to the framing. In the case of a pole building –run in tightly placed strips running up the wall from the pressure treated skirt board, to either the soffit support (with enclosed overhangs) or the eave girt (with open or no overhangs).

Don’t leave the housewrap exposed to any wind.  Similar to putting the insulation on the roof with immediately putting roofing over it – do the same thing with your housewrap. Only put housewrap on as far as you can immediately cover sections with steel. On a day with little wind, you may be able to put housewrap on an entire wall before covering with siding.  On a windy day, you may have to do 3’ sections at a time to keep it all “tight” and intact.

The housewrap manufacturers typically recommend fastening to the framing with plastic capped staples or plastic capped nails long enough to penetrate the stud every 32 inches(vertically and horizontally).

 Although you will rarely find this done in the real world – ALL housewrap seams are to be taped.

DEAR POLE BARN GURU: Regarding knee braces; most of the comments above appear related to sheathed structures. What about their usefulness on open pavillion pole barns? Have a lot of movement in one barn and am putting braces on poles to beams and to trusses to try to alleviate this. Comments or suggestions welcome. WOBBLY

DEAR WOBBLY: Unless the roof trusses have been designed to support the loads being induced into them from the knee braces, don’t do it….a high wind could cause a catastrophic failure. Usually excessive movement in pavilions is due to one or more of the following: Columns are undersized or column holes are not completely backfilled with concrete. If you can provide the dimensions of your building, as well as some digital photos, I may be able to make some recommendations which would improve your situation.

DEAR POLE BARN GURU: Do you also offer wooden pole barn designs? LONGINGLY IN LANGLEY

DEAR LONGINGLY: As all pole barns are wood framed, I will assume your question is in regards to buildings which would have wood siding. The answer is yes. Any type of siding which can be used on any other structural building frame can be used on a pole barn. Whether you are looking for sheet sidings, such as T1-11, boards or planks, any can be utilized.

 Keep in mind, wood sidings are not going to be maintenance free – they require frequent staining or painting, in order to keep from deteriorating.

 

DEAR POLE BARN GURU: We have a customer with an existing Hansen pole barn with a metal roof.  We would like to install solar modules on the barn, but are not sure the structure can take the additional weight and/or the wind uplift from the modules.  Where can I go for more information?  We don’t have money in the project to hire a structural engineer, so if I could find some of the original structural calculations, that would be great.  SUNNY IN SANTA CRUZ

DEAR SUNNY: Although solar panels are relatively light weight, chances are the roof structure would not be designed to adequately support any extra load over maybe a pound per square foot. If you could provide for us the information on the original purchaser of the building, we could verify the actual capacity of the roof system. Give me a call and I’d be happy to research this for you.