Tag Archives: columns

It’s All About the Posts!

Trimming Posts, A Taller Building, and Post Treatment:

DEAR POLE BARN GURU: Trimming posts or adding Shims? My pole barn kit uses steel trusses that sit on top of the posts and bolt to their sides. If I set two or three posts lower than the rest, can I just add a shim the top (using PT plywood or similar) to match the heights of the other posts, rather than cutting the tops of the other seven or eight posts?
How much mismatch is acceptable? Would a 1/4″ difference in the tops of the posts be acceptable or noticeable? MIKE in ORLANDO

Concrete slab in a pole barnDEAR MIKE: I will give you my answers however prior to implementation of anything I advise, you need to be contacting the RDP (Registered Design Professional – architect or engineer) who designed your building and sealed the plans to get his or her approval.
In my humble opinion, using a non-compressible shim in order to make up the difference should be a non-issue.
As to the acceptable mismatch, structurally the ¼” difference will not make a difference, however there is a good chance it will be noticeable to the naked eye, especially along either the eave girt or fascia board. The closer you can get to perfect, the better the result will be and the happier you will be with it.

DEAR POLE BARN GURU: Hello guru! We have a project on the way, and were thinking that our building the way it is engineered is going to be too short for our needs. What kind of risks, be it enforcement or safety would we run into if we increased the building height 2′? BRAD

DEAR BRAD: From a practicality standpoint all of your columns will be two feet too short, as will the wall steel. From an engineering standpoint going two feet taller changes the required sizes (dimensions not just lengths) of some of the columns. If you want taller overhead doors, then you have yet another issue.

The risks – safety – you would now be putting up an un-engineered building, which would be under designed for the loads being imposed on it and could collapse, causing injury or even death. Enforcement – if they catch you, you would have to do field modifications to bring the building up to Code.

If you are serious about making it taller, we can work with you to come up with the least expensive fixes and material swaps. The sooner you decide, chances are the less expensive it is going to be, however there would be a non-refundable deposit involved as we are going to put in some serious hours on this whether you decide to go forward or not.

DEAR POLE BARN GURU: If PCP is not good for health and longevity on a pole house replacement pole. 2 each at 30’….what treatment do you recommend on a DF pole? JOE in KAILUA

DEAR JOE: If you are using Douglas Fir, then the pressure preservative of choice is ACZA. You could also use ACQ, however it is very corrosive to steel fasteners, so you would want to have products with a very high level of zinc in the galvanization process, or use stainless steel parts.

 

Roofing Before Siding

Roofing Before Siding

If I am not mistaken, somewhere in the not too distant past I have expounded upon how I know a particular builder is or was a stick frame builder. How can I tell? The giveaway is they feel compelled to build the walls before the roof. I’ve listened to many experienced post frame builders in my career, as well as having constructed a few (hundred)post frame buildings myself.
The verdict – for best results, frame the roof and install the roofing prior to any wall framing being done.

Why?

First point is, if by some odd chance the columns at the base of the building are not exactly where they ought to be, the roof can easily be squared up still. It is relatively easy to move the tops of columns which are not framed to or sided. This allows for the column tops to be placed where they should have been at grade level.

Secondly, all of the roof purlins in interior bays can be precut to exactly the same length (in most cases), or at the very least an entire bay can be done at a time. If the column spacing varied between sidewalls and columns tops were not where they should have been, it would take custom cutting to length every roof purlin all of the way across the building. Neither fun, nor time efficient.

Third, without siding installed, it is relatively easy to square up each roof plane to make installing the roofing as painless as possible. Once either the steel roofing or roof sheathing with shingles is installed, the roof planes will be affixed where they should be.

Fourth, much easier to drive a pre-mix concrete truck around the perimeter of the building and chute the concrete in for a slab on grade floor. No framing or siding to get in the way, only widely spaced columns.

Am sure there are more reasons than just these, however the factors stated should be enough to convince any builder (or DIYer) to give it a try and see if in the end, the result isn’t far happier

Are My Columns Too Short?

Are My Columns Too Small or Too Short?

We receive and answer lots of questions. Even with a Construction Guide which extends over 500 pages, covering a plethora of topics and how to’s, there is always an unanswered question (sometimes two).

One of our good clients recently sent a query to the Hansen Pole Buildings’ wizardess of all things shipping, Justine, which I share now:

“Hi Justine, I received delivery of the columns for my building on Friday. After inspection, I had 2 questions that I’m hoping you can clarify for me because I don’t know if there is an issue with them. I also want to apologize in advance, because I know these questions are pedantic and probably nothing to worry about, I just want to make sure there’s no problem here since I haven’t been involved with the kind of construction that requires inspections before. 🙂

The building plans seem to have a slightly larger dimension than what was delivered. I’m sure the engineering has allowed enough safety margin that this won’t be a problem, I just don’t know if it’s going to be an issue on an inspection. For example, the corner columns are shown on the blueprints at 5 3/8″ x 4 1/8″ but the columns that were delivered are 5 1/4″ x 4 1/8″. So, you see it’s only 1/8″ on the long dimension of the column, but I don’t know if an inspector will have a problem with that. The same 1/8″ undersize dimension is true on the corner, endwall, sidewall, and shed columns.

I was under the impression that the length of the columns was a minimum length and not a nominal length that might be slightly less than that. It could also be that I have a misunderstanding about how the columns are spec’d. What I found is that the 14′ columns are all actually 14′ 1″, which is great, however all of the 24′ columns are actually only 23′ 10 1/4″ when measured to the shortest of the three laminated boards. They are all right at 24′ when measured to the longest of the laminated boards. This is only a concern of mine because I’m in the process of getting the site leveled out, but I’m currently at about 12″, which is cutting things pretty close on some of the columns. So, I didn’t know if the manufacturer made a mistake or if I just need to correct the way I measure them. My main concern is around ensuring I have full weight bearing on the notched post, which will only happen if I notch them at least 11″ down. I’ve attached a photo to show how I’m measuring them.”
To which our Technical Support Department cheerfully responded:

Thank you very much for sending us your concerns.

#1 You are going to find the dimensional lumber (2×4 through 2×12) provided can vary as much as 1/4″ plus or minus from the anticipated “ideal” dimensions. It is part of the randomness of dealing with an organic product (wood) which has to be milled. It is also why we are only able to use 40% of Pult (the ultimate strength of a material in a wood assembly) when engineering calculations are produced. In looking at the calculations for the long columns in the center of your building, for example, they are stressed to 92% using the “call out” dimensions. Using a Sm (Section modulus – depth of lumber squared x width of lumber divided by 6) of the 1/8″ under size, reduces the actual Sm by 1.64%, which would mean the member would be stressed to 94% under maximum design load.

#2 Column lengths do vary slightly due to the material lost in finger jointing. On the 20′ eave raised center section, with the bottom of the column at 32″ below grade, the amount of column needed would be 22’8″. With a column length of 23’10-1/4″ you could have as much as 13-3/4″ of grade change and still have plenty of column.

If you do happen to have a foot of grade change, it would be my recommendation to have the site brought closer to level before setting columns. Good compactable fill is not inexpensive. Reducing the grade change from 12″ to say four inches, as an example, saves 27 yards of fill across just the footprint of your building.

Please do not hesitate to reach out to this department further with any technical questions.

Poles for Pole Barns

Some days it seems there are nearly as many possible design solutions for pole barn “poles” as there are pole barns!

Here is a brief overview of the organic (think coming from trees) ones. For the sake of brevity, I will limit this article to only applications where the columns are embedded in the ground.

Old utility poles – not a good choice for many reasons:

https://www.hansenpolebuildings.com/blog/2012/11/utility-poles/

https://www.hansenpolebuildings.com/blog/2012/11/used-utility-poles/

Solid sawn pressure preservative treated dimensional lumber or timbers.

Be wary of trying to recycle old treated wood if it has been treated with an oil based preservative:

https://www.hansenpolebuildings.com/blog/2012/11/pcp/

Structural joists and planks are lumber which is two to four inches thick and five inches and wider. These would include 2×6, 2×8, etc., as well as 4×6, 4×8, etc. Structural joists and planks are graded under a more stringent set of grading rules than either “Posts and Timbers” or “Beams and Stringers”.

Beams and Stringers are five inches and thicker, rectangular with a width more than two inches greater than their thickness. These would include dimensions such as 6×10 and 6×12.

Posts and Timbers are 5×5 and larger, where the width is not more than two inches greater than the thickness. Besides 5×5, it includes 6×6, 6×8, 8×8 and similar.

So isn’t a #2 grade a #2 grade regardless of size? Well, sort of…..larger pieces of lumber are given a #2 grade, with more defects (like larger knots). Correspondingly, the strength values are not the same. Using the measure of Fb (fiberstress in bending) and arbitrarily picking Hem-Fir as a species, a #2 6×6 has a value of 575, 6×10 is 675 and a 4×6 1105!

Regardless of the dimension of the lumber or species, proper pressure preservative treating is essential:

https://www.hansenpolebuildings.com/blog/2012/10/pressure-treated-posts-2/

Putting together individual pieces.

Multiple joists and planks can be joined to form a column, either spliced or unspliced.

In an unspliced scenario, building heights are normally limited to 16 feet, as generally it is difficult, if not impossible to purchase pressure preservative treated 2×6 or 2×8 in lengths longer than 20 foot.

I’ve discussed nail-laminated columns previously:

https://www.hansenpolebuildings.com/blog/2013/08/nail-laminated-posts/

Glu-laminated columns.

Some interesting glulam reading: https://www.hansenpolebuildings.com/blog/2014/04/titan-timbers/

Glulam PolesThese afford a Building Designer a plethora of structural options which cannot be achieved by the use of other alternatives. With a high strength to weight ratio, and typically being very straight – in markets where they are available, they can be a wonderful alternative, especially for taller buildings, or cases involving high wind and/or snow loads.

With so many options and alternatives, how is a consumer to know what poles are best?

My vote is for the overall design solution which best meets your individual needs for creation of space and access and egress. As long as the design is structurally sound and Code conforming, at the end of the day it does not matter what the individual pieces were used to build it.