Tag Archives: Uplift

One End of My Pole Shed is Moving Up

One End of My Pole Shed is Moving Up

Pole Building Storage ShedReader JOEL in GULLY writes:
“I have a question for you, I built a 24 x 30 foot pole shed with ten foot side walls about 30 years ago, I dug the poles down 60 inches and the building sat perfect for 25 years, then a few years ago the one end started coming up out of the ground about 4 inches and that end has been moving up every year, as of now the south corner has lifted about 8 inches, I dug down in the corner post thinking a rock may have moved up under the post but there was nothing there, so what do you suppose has happened under the ground to start this ground shift? Water? I live in northwest Minnesota about 80 miles from Canada, and where the shed sits we never drive there, just curious.”

My best guess is underground water. Here’s a look at some options:

1. Dry Creeks
This is a subtle and creative solution for drainage issues and offers a bonus: it’s pretty.
A shallow trough is lined with stones or rocks, offering excess water a place to flow and runoff.

2. Trench Drains
This is a great choice for heavily paved areas such as driveways and parking lots. Trench drains are concrete-lined channels helping direct water flow while filtering out debris using grates or filters to reduce clogging.

3. French Drains
A more intricate method of controlling water flow around a building or property is by using French drains. This, and proper site grading, will probably achieve your best results.
French drains are typically perforated pipes channeling water in a specific direction. These pipes are usually covered with rocks and gravel to help with filtration, water flow and ensure pipes stay in place.

4. Site Grading
Site grading involves changing landscape to encourage water to flow in a desired direction — away from your building.
Many drainage issues stem from improper grading techniques during a building’s construction. At a minimum you want to grade at least 10 feet from your building with a 5% or greater down slope (this is also a Building Code requirement).

5. Dry Wells & Reservoirs
When surface water has no place to go, it pools and floods. Building a dry well underground, or a surface reservoir gives excess water a home. Swales fit into this category: https://www.hansenpolebuildings.com/2013/01/swale/

Foundation Requirements, Stem Walls, and Building on Slab

This week the Pole Barn Guru answers reader questions about the type of foundation and uplift requirements there is for and RV cover and “what not,” building a home on a stem wall or with crawl space, and pluming for a building built on slab.

DEAR POLE BARN GURU: For a 24 x40 x12 pole barn residential use as an RV cover and what not what type of foundation and uplift requirements are there other than the post being set around 4 feet in the ground? STEVE in FORT MCCOY

DEAR STEVE: Column embedments and encasements need to be engineered to adequately resist uplift, overturning and gravity and will be determined based upon design wind speed and wind exposure, roof dead loads (plus snow in more northern climates), whether building is enclosed, open or partially enclosed, etc., as well as soil bearing capacity. When columns are effectively constrained by a concrete slab on grade, it helps to potentially reduce depth, diameter and required amount of concrete needed for hole. Due to complexity of these factors, embedment and encasement, as well as any added uplift plates or cleats should only be determined by whatever engineer will be sealing your plans. He or she should also provide verifying sealed calculations to certify adequacy. A consideration – if this will be a roof only structure, Moment (bending) loads on columns are four times as great than on a fully enclosed structure – this results in more concrete being needed for holes.

 

DEAR POLE BARN GURU: I’m building a post frame building/house. I want to use stem wall or pillars, wet set brackets. Is there a huge cost difference or benefit over the other? Does stem wall, if used, have to be on a footer or does it act as it’s own footer? I want floor to be 1.5′ above grade if that makes a difference. Thank you for your time and input. LONZY in CONWAY

DEAR LONZY: Post frame buildings make for excellent homes! Great choice. My educated guess is your floor is going to be over a crawl space. If so, your top of floor will probably end up being more like two feet above grade, rather than 18 inches. This allows for better access to utilities as well as not requiring all supporting beams and joists to be pressure preservative treated. Concrete stem walls will need to be at least six inches thick and on top of a six inch deep by 12 inch wide concrete footing (for a single story), resulting in a far greater investment in forming and pour (both in materials and labor). Concrete piers are pretty low tech and then sides of your crawl space will consist of (usually) steel siding.

 

DEAR POLE BARN GURU: What is the best way to plumb a pole barn home. I would like to keep the concrete floors, but I need a way to plumb it without having to jackhammer concrete when there is an issue. NICHOLAS in LOUISVILLE

DEAR NICHOLAS: In all reality, chances of a modern plumbing failure under a concrete slab are very, very small. Tens of thousands of homes and apartments are built every year in our country with plumbing under concrete floors, attesting to how rare a failure occurs. Older slab on grade buildings have had challenges from deterioration or perforation of copper pipes or joint issues. Your best prevention is a well-prepared site, as shifting soils are your most likely cause of a plumbing challenge. Remove any expansive soils and compact fill in no greater than six inch lifts. Keep water from being able to run under your home – by grading away from building perimeter at least 10 feet at a 5% slope. Build pad for building up above surrounding property. Use French drains if underground water is suspected. Drain gutters sufficiently away from home. Use PEX for all under slab water lines. All pipes need to be extensively tested for drainage and air pressure in supply lines multiple times during rough-in process prior to slab being poured. Testing should take place once after rough-in is completed and before backfill when dirt is pushed back into trenches to cover pipes. It should be tested once again after backfill has taken place to ensure no damage to pipes, then once again after concrete slab prep has been finished. I have heard of people running their under slab PEX through larger diameter sleeves, however this seems to be an unnecessary expense.

Blown-In Insulation, Uplift Plates, and Truss Spacing

This week the Pole Barn Guru answers reader questions about better blown-in insulation on 3/12 pitch ceiling, a reader with uplift issues and how to prevent them, and some concerns about truss spacing at 8′ oc.

DEAR POLE BARN GURU: Hello, I have a 30×48 pole barn with scissor trusses 6/12 outer pitch 3/12 inside pitch. It has metal roof with dripstop. Trusses are 4’ on center and I was going to place metal on inside ceiling 3/12 pitch then place blown in insulation on top of that. Would it be best to use fiberglass blown in insulation instead of cellulose? I will be sure to place baffles on eaves for proper ventilation. Do I need any vapor barrier between the metal and insulation seeing as I have dripstop on roof metal? Thank You! DON

DEAR DON: Yes, use blown fiberglass rather than cellulose. Cellulose has fire retardant chemicals in it, when combined with excess moisture, it will prematurely decay steel liner panels (and cellulose is much heavier than fiberglass). Unless you are located where there are over 8000 annual heating degree days, you should not have a ceiling vapor barrier.

 

DEAR POLE BARN GURU: The wind lifted my pole barn up about a foot on one end last spring and hasn’t settled back down. Wondering how to get it back down to earth? STEVE

DEAR STEVE: Your building has sadly become an experiment to show what happens when adequate uplift provisions have not been made during construction. Hopefully your building has been insured for replacement costs – so you can have this work hired out.

In order to successfully get a ‘return to earth’ your building should be disassembled back to at least a point where no column uplift is detectable – including removing uplifted columns from ground.

Re-dig all offending post holes.

Add an uplift plate on on side of each column at bottom. https://www.hansenpolebuildings.com/2018/12/uplift-plate/
Stand columns in holes, so bottom of column “floats” roughly 8″ from bottom of hole. https://www.hansenpolebuildings.com/2015/04/floating-poles/
Pour bottom 18″ or more of each hole with readi-mix concrete.

Re-frame building, replacing any damaged lumber or trusses.

Before putting steel panels back on building, confirm no slots have been created in panels due to tearing around screw shanks when building lifted. Replace any damaged panels.

 

DEAR POLE BARN GURU: We are having a 30 x 50 barn built, and our builder just put up the trusses. It is a stick frame barn on a slab and the trusses are spaced 8′ apart. The concern is that there are not enough trusses. It looks like a “pole barn” but is on a traditional slab identical to our house and the “poles” are not buried. Trying to find information on truss spacing has been difficult. Both dad and uncle think it is not enough and have traditional construction backgrounds. Please help. ASHLEY in ANDERSON

DEAR ASHLEY: Provided your building’s trusses have been engineered to adequately support loads when spaced every eight feet, there is nothing wrong with them. https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/
What is wrong is it appears this building is being constructed without site specific engineer sealed structural plans. Chances are better than most you will have some future challenges due to this. Roof purlins should be attached to trusses using Simpson or USP brand joist hangers. Truss bottom chord bracing is missing and truss heels should be attached to walls with an uplift connector adequate to resist your roof flying away during a high wind event.

Hi, I Should be an Engineer

Hi, I Should Be an Engineer. Can You Tell Me What I Left Out?

Seemingly every Spring I receive an email similar to this one from JOHN in UNION DALE, who it sadly appears has not done much (if any) homework in reading my articles.

JOHN writes:

“ Hi, I have been doing a couple of months homework on making my pole barn, my plan is a 30×50. Right now my plan is using (16) 6x6x16 pole about 52 inches in the ground, the spacing between posts will be 10 ft, now I have not decided on a concrete cookie before the setting the post or gravel first has a drainage layer the set the pole and then use about 5 bags of concrete for uplift protection and the normal back fill, for the posts I got post protectors, so the wood is separated from the soil, my plan is to use double  2×12 for the top strapping with the posts notched at the top for added snow load, has far has the roof it will either be a 4/12 or 5/12 pitch my plan is using 2×6 rafters that I’m making on the ground and hoisting up by myself and they will be on 48 inch on center, my purlins are going to be 2x4s about 2ft apart and standard metal to finish it off, if you can can you please let me know if I left anything out, thanks ps I forgot to say the door opening on a non-load bearing wall will be a 12ft wide and 10ft tall, I’m thinking about putting a door  on a load bearing wall a 10ft, all doors are going to be sliding barn doors.”

Mike the Pole Barn Guru Responds:

Well John, you have left out a crucial part. One no proper pole barn should be without. Plans designed and sealed by a Registered Professional Engineer specific to your building at your site. To build without them is, in my humble opinion, fool hardy and I cannot endorse your plan of attack or methods of construction without them. Outside of this – attempting to field construct your own roof trusses is not a good choice. Prefabricated trusses are truly a bargain, especially when considering risks involved should your home made trusses collapse injuring or worse killing you or a loved one. 

For last year’s related article, please read: https://www.hansenpolebuildings.com/2019/05/self-designed-pole-buildings/

For extended reading on the misadventures of site built roof trusses: https://www.hansenpolebuildings.com/2018/12/site-built-roof-trusses/

There is a Right Way and This Way

There is a Right Way and This Way

When it comes to building construction, there are a plethora of both right and wrong ways to do assembly. Pictured below is a wrong way (does not happen to be post frame construction).

Roughly 20,000 post frame buildings of experience has taught us virtually anyone who can and will read instructions composed in plain English, and is physically able, can construct for themselves a beautiful new building.

There does exist a certain subset of humanity who are incompetent. Not only just incompetent, they will fail to recognize their own lack of skill, fail to recognize genuine skill in others and fail to recognize how extreme their inadequacy is!

For extended reading on this subject, please see: https://www.hansenpolebuildings.com/2015/01/dunning-kruger-effect/

Now we do make every effort to attempt to prevent even those who are incompetent from creating situations similar to what is pictured in this photo. For those without prior construction experience and have never really looked at a building under construction (or photos of one), this photo shows sloped rafters supported by engineered steel brackets (joist hangers). Properly designed and installed, joist hangers will support members from blowing away (uplift) as well as what I refer to as, “The Denny Lee Effect”.

As a college sophomore, at Bozeman’s Montana State University, I took Professor Denny Lee’s Physics class. Now Denny was quite a showman. First day of class – in a huge lecture hall filled with hundreds of eager students, he offered a semester’s A to anyone who could explain how gravity works.

Hands popped up everywhere, answers and theories were flowing like hot air balloons in Albuquerque in summer – and Denny shot them all down.

After we all gave up, Denny gave us his answer, “The Earth sucks”.

As pictured (installed upside down), gravity might not be a factor, however uplift would be.

Every Hansen Pole Buildings’ blueprint is fully engineered and detailed showing every component, where they are installed as well as how – down to each joist hanger, nail and screw!

If this is not enough, 66,000 plus words of step-by-step assembly instructions in the Hansen
Buildings Construction Manual walk either a DIYer or builder through every step.

But wait – there’s more!

(No, not a ginsu)

Lost, dazed, confused or just needing moral support?

Included in each and every Hansen pole building purchase also is unlimited free Technical Support from people who have actually built post frame buildings!

Uplift Concerns, Retro-fitting Insulation, and High Water Tables

This week the Pole Barn Guru answers questions about uplift concerns, retro-fitting insulation, and setting posts in high water tables.

DEAR POLE BARN GURU: I am adding an open overhang to the gable end of my 40×80 pole barn. I bought 36’ trusses and will lower them to fit under the existing gable going out 16’. Since the underside is unfinished should I worry about wind uplift? SCOTT in SHERIDAN

DEAR SCOTT: Regardless of whether your addition will be open, enclosed, or somewhere in between uplift should always be a consideration. Ideally the original EOR (Engineer of Record) who designed your 40′ x 80′ building would be consulted, not only because of a potential uplift issue, but also due to what affect open carport will have upon existing building. You may be placing wind shear issues upon endwall closest to addition and these will need to be addressed, as well as if endwall column footings will be adequate to support added weight (not just dead load, but also potential weight of a snowfall). An issue of drifting needs to be reviewed also, as snow could build up upon carport roof against existing endwall.

If original EOR proves unavailable (or nonexistent), you should enlist services of a competent RDP (Registered Engineer or Architect) qualified to review your existing building, as well as your intended work.

DEAR POLE BARN GURU: Need your suggestions on any improvements I can make. Below is a sketch of my current building roof insulation. Basically I tried to seal off the cathedral ceiling using the bottom of the purlins to hang 4” Dow board sealed with aluminum tape. I did purchase the radiant reflective barrier that was installed per instructions between the roof purlins and the steel roof panels. I live in Michigan.

I love my two pole buildings I purchased from you guys. Just need some help on insulating the roof on my last building. Nothing is wrong. Just concerned about the un-vented dead air space. JOHN in SAGINAW

 

DEAR JOHN: Always glad to hear back from happy building owners! As long as the cavity was dry when it was sealed up, and the Dow board is sufficiently well sealed there is a chance you will not have problems. The only guaranteed solutions involve having to take down the insulation board and make provision for airflow from eave intake to ridge exhaust by drilling holes through all of the purlins.

 

 

DEAR POLE BARN GURU: Mike can you please tell me what is the proper way to set posts in holes that have water. High water table. Thanks much I enjoy your blog. PATRICK

DEAR PATRICK: Back when I was a contractor we would run into this situation occasionally. Our solution then was to stand columns in holes, brace them and then backfill with pre-mix concrete with very little water in it. Concrete weight would displace water in hole. It did take a significant amount of concrete, however it was only about $30 a yard then.

How I would do it now – I would use sonotubes equal to or larger in diameter than what was specified by engineer. Cut tubes to depth of hole length, then cover one end of tube with six ml black visqueen (read about visqueen history here: https://www.hansenpolebuildings.com/2013/07/moisture-barrier/ ) sealed tightly around sides of tube. Place tube in hole with covered end down (this will take some work, as tube will want to float like a boat). Once sonotube has been placed, backfill around outside with compactable material – compacting no more than every six inches. Then stand column in tube, brace it and backfill with pre-mix concrete as engineer specified.

 

What Size Posts Should I Use?

What Size Posts Does My Building Need and How Deep Should They Be?

Reader ANONYMOUS in BENTON writes:

“1. If my building has 16 posts and posts are 12 feet apart do I need 4×6’s or 6×6’s?
2. If the plan shows 16 feet above grade how much do I need underground?
3. If the posts are set 12 feet apart will two 2x12s glued together support a truss system with a total length of 36 feet?”

Mike the Pole Barn Guru responds:

While I appreciate your questions, we as a company and me as an individual do not provide free engineering services. In answer to your questions:

1) Without knowing the full dimensions of your building, including roof slope and overhangs (if any), if the columns will be adequately tied into a concrete floor, as well as your site’s snow load, design wind speed and exposure, seismic zone as well as the dead loads which will be carried by your building there is no possible way for me or any RDP (Registered Design Professional – engineer or architect) to be able to answer this.

2) The depth of the columns into the ground should be shown on your engineered building plans (you do mention you have plans). At a minimum the holes should be no less than 40″ deep and must extend below the frost line. Ultimately the depth and diameter will need to be determined by the RDP in consideration of the factors listed in (1) above, as well as designing for the ability to adequately prevent uplift.

3) Since I would use double trusses which bear directly upon the columns, there would be no need to use any other type of dimensional lumber to provide headers for a truss system. Again, this is where your RDP can design to adequately provide an engineered system to support the trusses.

My best advice, since I am guessing you are somewhat floundering in this, is to invest in a fully engineered post frame building kit package which includes plans sealed by a RDP and designed specifically for your building, at your site. It just isn’t worth trying to avoid the small expense into a proper design – especially when the lives of the occupants depend upon it.

Here are some other articles which pertain directly to this subject and should be read: https://www.hansenpolebuildings.com/2014/12/free-pole-barn-plans/ and https://www.hansenpolebuildings.com/2017/11/dont-engineering-fool/

 

 

 

 

Soil Bearing Pressures Challenge

Soil Bearing Pressures Challenge

Fast and Loose With Numbers and Terms
DAN from MOUNDS VIEW is the first reader who admits they are an addict to my blogs – for this, I love you man!! Luckily there is no 12 step program to cure you, so you are just going to have to keep feeding the addiction.
Dan called me on the carpet, so I will bring out the Roomba® to clean things up.
Dan writes:
“This message is about an answer you gave to a guy 1-25-18, who asked for an analysis of the post load of his building. And I agree with your answer that he should get a pro to review the design but, why are you playing fast and loose with the numbers to scare him??

From the data given you came up with 8860 lbs/post, which is OK, but then you didn’t tell him that it results in just 292.9 PSI at the bottom of each center post, which is well under the 2100 psi given soil load. Instead you converted the 292 psi to 42,177 lbs/ft, which technically is correct, just to scare him. However, the post is only 0.21 ft^2, so the max load is still the 8860 lbs.

The real concern is ”is the 2100 psi” soil rating correct and what is he going to do about the uplift forces? And I agree he needs a footer, but your ”raise the post and pour” can easily do that.

I sent this message this way to keep it off line.

You have so much good stuff in the blog that you don’t need ”tricks” to get the message across.

Dan who’s addicted to reading your blog.”

Mike the Pole Barn Guru responds:
Dan, Dan, Dan – I’ll post just about anything which isn’t profane online, so no problems, we are still friends!

Here is the challenge – soil bearing pressures are to be expressed as pounds per square FOOT (psf), not pounds per square inch (psi) the difference being a factor of 144.
As an example – from the 2015 IBC (International Building Code)

https://codes.iccsafe.org/public/document/IBC2015/chapter-18-soils-and-foundations TABLE 1806.2 the vertical bearing pressure (capacity) of Crystalline bedrock is 12,000 psf or 83.33 psi. The probability of anyone having 2100 psi (302,400 psf) soils would be just below the chances of the Cleveland Browns winning the Super Bowl this year.

Fall Up, Go Boom

Fall Up, Go Boom

What? Sir Isaac Newton pretty much confirmed things do not fall up.

Well, this building did not actually “fall” up – it was sucked out of the ground. How would I know this? Look at the ends of the columns which are lying on the ground. There is no concrete attached to the bottom of the columns, nor is any method for preventing uplift even obvious to the more than casual observer.

 

In review of the NFBA (National Frame Building Association) Post-Frame Building Design Manual (January 2015) the issue of column uplift is all but ignored. Beginning with the end of Page 5-37, it is concluded two pages later. Options for preventing uplift are really not addressed.

For decades we, if not many other post frame designers and builders, have relied upon the bond strength between concrete and wood in designing column embedment to prevent uplift issues. More can be read about concrete to wood bond strength here: https://www.hansenpolebuildings.com/2013/04/pole-barn-post-in-concrete/.

I’ve expounded previously upon the use of nail on truss plates for assisting in uplift construction (https://www.hansenpolebuildings.com/2013/04/truss-plates-for-column-uplift/).

There truly is very little information available. Of all places, I did find some relevant information on the City of Hendersonville, Tennessee website (www.hvilletn.org):

Column uplift protection: Columns shall have uplift protection by one of the following methods:

1. Two 2x6x12 inch column uplift protection blocks attached to each side of the base of the column. The column uplift protection blocks must be placed horizontally, attached per Table 5 and comply with Section R317.

2. 12 inch high, concrete collar poured on top of footing around the post, with 2- #5×9 inch rebar placed through the post at 3 inches and 9 inches from bottom of post in opposite directions. The rebar ends shall be installed in accordance with ACI 332 for the specified distance in inches from contact with the soil.”

Table 5 mentioned above happens to be five 16d hot dipped galvanized nails into each block.

While I was researching for this article, I happened upon an example for preventing uplift in an all steel building. The building in this case was a 60 foot span and steel frames every 25 feet. In this case the design footing was eight feet square by 3’8” in depth!!

The all steel building is going to have footings which take nearly nine yards of concrete per bearing location!! This is near the capacity of a pre-mix concrete truck, per one end of each frame!

Getting back to the post frame building design solution, our engineers have determined reliance upon the concrete to wood bond strength only is not quite as conservative as they might like.

The solution – Hansen Pole Buildings, LLC engineered post frame buildings now have added the nail on uplift plate tot the roof supporting columns to tie into the concrete column encasement.

The investment is minimal and it does afford some added insurance of success in preventing uplift.