Tag Archives: lumber allowable defects

When Size (or Lack Thereof) Matters- 4×6 Columns

Prior to Hansen Pole Buildings’ client’s plans being sealed by our third-party engineers, their preliminary plans are uploaded for client review through a login. While review goal is to make certain everyone is working from a same left and ensure doors and windows are properly located, it does trigger some interesting discussions at times.

Here is a recent email received from one of our clients in Ohio:

“Just had the chance to look through the plans. Was surprised to see 4x6s on the corners of the main building. What is the rationale for that? If it’s simply cost savings, can I pay extra to have 6x6s in those 4 places?”

Here is my Pole Barn Guru response:

Prior to verifying the larger dimension (albeit weaker) member might work, this may prove valuable reading:

From the Hansen Pole Buildings Construction Manual:

Why might corner columns be smaller sized? Each building column carries a load equal to ½ distance to next column on each side!  This means corner columns are carrying about ½ other column’s loads. Further, on an enclosed building, corner columns are braced in two directions by girts and wall steel (or other sidings).

Why might a building have 4×6 columns, rather than 6×6? As mentioned in lumber defects section (Page 37), 4×6 lumber and 6×6 lumber are graded under different “allowable defect” categories. 4×6 material is held to much more stringent guidelines. As an example, if allowable defects from a 4×6 #2 grade, were applied to a 6×6, 6×6 would have to be graded as Select Structural. Conversely, if allowable defects from a 6×6 #2 grade were applied to a 4×6, 4×6 would be less than “utility” grade.

These allowable defect characteristics follow through to design values used for structural calculations. Without getting overly technical, 4×6 #2 Fb (fiberstress in bending) value is nearly double 6×6 #2 value.

As well as: https://www.hansenpolebuildings.com/2014/08/lumber-bending/

In the event you still wish a material change, please contact Materials@HansenPoleBuildings.com.

Post frame efficiency is achieved by every member and connection being checked and verified for ability to carry imposed loads. Software utilized by Hansen Pole Buildings and our third-party engineers verifies complete structural adequacy in all cases.

Termites and Pole Barns

A Buggy Situation

A client writes to Justine (the Hansen Pole Buildings’ Order Fulfillment goddess) this week:

termites“I was hoping to get some advice.  I’m still working on the building having just completed rafter placement and was starting to pull apart the two bundles of lumber for the purlins.  When I started pulling boards out of the bundle I noticed some surface damage that just kept getting worse as I sent through the stack of lumber.  Toward the center there was a large amount of termites, see pictures.  The odd thing was it only affected the stack of 2X6X10′ boards, the other bundle of lumber, sitting right next to it was untouched.  This is really unusual for our area where summers are hot 90-100° with very low humidity <15-20% making termites a very rare issue.  The lumber was stored as instructed in your manual but now we have a probably 1/2 of the 2X6X10′ boards that are damaged significantly.  Since termites are not a large problem in this area and all of the infestation was in the center of a stack of very wet wood (not from any rain or external water) and there was no damage to the stack sitting next to it, I suspect it came with termites but of course I can’t prove that so as disappointed as I am let me get on to the request for advice.  These boards are primarily used for the purlins and horizontal siding support around the outside of the building.  I know the purlins are structural and need to be 100% clean wood, but is some level of damage acceptable for the horizontal boards between the posts?  If so, how much, or is any penetration by the termites into the wood render it unusable? “ 

Personally, I feel bad for the client, however he did take delivery of the materials back in April and on May 3 he wrote to Justine:

“I have all of the material and all is in good shape.  Thank you for all of your support”

On one hand client has received everything in good order, on the other hand nearly four months later there are some challenges. It is possible the lumber was shipped buggy – wildly random things do happen. It is also possible the material got wet in the spring and the heat from the 90-100 degree summer days caused the relative humidity in the center of the unit to increase as the unit was likely paper wrapped. In either case, it ended up as the perfect breeding ground for pesky little critters.

The lumber grading rules are fairly generous about allowable defects, so some of the damaged materials may be able to be used.

Here was Justine’s response (spot on by the way):

lumber damage“We would happy to provide some advice for this situation. Let me first say this is why we stress so much to inspect and inventory wood as they arrive up front. You are probably correct in your conclusion they came with the mites in the bundle. If the bundle would have been opened then we could have probably avoided your current situation.

To answer your question, yes there are some level of acceptable defects in lumber. Keep in mind the wall girts are just as crucial as the roof purlins in supporting the loads of your building.

You can read about these allowable lumber defects on our blog: https://www.hansenpolebuildings.com/2013/12/lumber-defects/

I would generally apply some common sense on how I use certain boards and which ones I decide not to use. I would say first take the boards you deem usable but in the worst shape in locations which don’t provide as much structural value like in blocking locations. For girts and purlins they don’t need to be perfect but anything meeting the allowable defect rules it will work for those locations but I would try to keep the better boards for those two locations. Anything which does not meet the minimum requirements will have to be replaced.”

Moral of the story – regardless of whom you buy your building from, or where the lumber came from, inspect it thoroughly at time of delivery for defects as well as surprises. This allows for anything out of the ordinary to be taken care of promptly, before feelings get hurt. And, always try to use materials as expediently as possible, the sooner they become part of your new post frame building, the happier they will be.