Tag Archives: pressure preservative treated splash plank

Why Not a 2×6 Bookshelf Girt on a 4×6 Column?

Why Not a 2×6 Bookshelf Girt on a 4×6 Column?

Client TROY in MONROE COUNTY writes:

It was my understanding that 4×6 posts were used, so a 2×6 girt could be mounted flush on the inside of the building and extend 1.5” beyond the post at the outside of the building. Why can’t exterior and interior sheeting be applied to the 2×6 girt?  What is the advantage of the 2×8 girt?

Are the rafters spaced at 12’, is that the need for 2x10s?

If they’re set on the same post as the truss, is there room?  5.5” post minus 3” for double truss leaves 2.5”.  Do you take away 1.5” for the rafter leaving 1” of post?

Feel free to call if it’s too much to type


Mike the Pole Barn Guru says;

Thank you for being an inquiring client, those who ask lots of questions are those who get results they are happiest with!

On a 14′ sidewall, truss bearing columns are unlikely to work as 4×6 due to failure in weak axis bending (they want to buckle due to compressive loads from dead loads and snow). So now we are into either 6×6 (or in some cases larger) solid sawn columns, or glu-laminated columns for truss bearings.

Couldn’t 2×6 bookshelf girts be used and be flush to both sides of these?

With 6×6 columns, they do tend to vary in dimension – sometimes as great as 1/2″. This would potentially result in columns sticking outside of plane of a 2×6 bookshelf wall girt, making finish on one side problematic.

More importantly (and less recognized by most providers) is pressure preservative treated splash plank at base of enclosed walls must be attached adequately to transfer wind shear loads from roof, down through wall sheathing (steel siding), to splash plank, then to columns and into ground. Greatest forces are at the top and bottom of walls. When splash planks are applied to the exterior face of columns, it allows for appropriate connectors to be placed from splash plank to column to provide a continuous load path. 

Other members (such as overhead door headers and window supports) are also best installed on exteriors of columns (they transfer shear loads as well).

To hide columns and provide for space occupied by exterior fastened members, 2×8 bookshelf girts work nicely in combination with either a 6×6 solid sawn or multi-ply 2×6 glu-laminated column.

This also allows for a deeper wall cavity, hence greater thicknesses of insulation may be utilized. I would consider using two layers of 3-1/2″ Rockwool batts with a well-sealed interior vapor barrier.

While main clearspan interior double trusses will notch three inches into sidewall columns, rafters for your attached shed will be applied to column faces, rather than further notching of columns. With your roof loads, it actually takes two 2×10 rafters on each side of columns spaced every 12 feet.

Provided your site has adequate space, I would recommend you consider a 40′ x 48′ x 14′ clearspan building, rather than 28′ x 48′ x 14′ with a 10′ x 24′ attached shed on one side. It will be easiest to assemble, takes away a pitch break between main building and shed, eliminates an interior column and provides full headroom from eave-to-eave. This would also allow for those 8′ wide by 9′ tall overhead doors to be increased in width to 9 or 10 feet wide, keeping mirrors on vehicles. You will also find this to have far greater value for resale (multiple times more than any added investment).

Please feel free to reach out to me at any time with structural questions.

Rust, Washington State, and Sleeves or Protectors

This Wednesday the Pole Barn Guru answers reader questions about potential for rust on a welded oil field pipe framed building, if Hansen has structures in the state of Washington, and if sleeves or post protectors are needed for post frame construction.

DEAR POLE BARN GURU: My barn is a welded oil field pipe frame with what we call red iron purlins, basically a metal c channel. I had concrete poured yesterday and they didn’t use any wood framing. They just used the bottom purlin as the frame. Is this going to be an issue? Thank you, sir. PJ in MADISONVILLE

DEAR PJ: I personally remain a skeptic about performance of buildings done by welding up oil field pipe. This could be a partial reason one does not find welded up oil field pipe buildings anywhere structural building permits and inspections are required. I would imagine your non-galvanized bottom girt will slowly rust away, however not much you can do about it at this point. I hope it works out better for you than I suspect it will.


DEAR POLE BARN GURU: What areas in Washington State do you service?

DEAR DANIEL: Hansen Pole Buildings has many buildings in all 50 states – including Alaska and Hawaii. We have provided roughly a thousand fully engineered post frame buildings to our clients in Washington State, and I would venture to guess there are multiple buildings of ours in every county.


DEAR POLE BARN GURU: My main question is regarding the skirt board and posts. I know it’s pressure treated but what about long term exposure to ground contact? Obviously when pouring a monolith slab for a stick frame house the wooden forms are removed afterwards. And I’m thinking that just maybe even though we are blessed with a low humidity climate, the building inspector with Yavapai County (seat- Prescott, Arizona) will question such exposure and certainly may want the posts in sleeves and skirt board removed or placed at finished concrete grade for attachment purposes ( like a bottom plate with a stick house) where there’s any chance of water or earth contact. Also with the YC Building Safety Department there’s no mention of the IBC only the IRC. I would appreciate any thoughts. STEVE in CAMP VERDE

DEAR STEVE: We have provided several fully engineered post frame buildings to our clients in Yavapai County without undue challenges.

Pressure preservative columns are all rated UC-4B and skirt boards (splash planks) UC-4A. This meets with AWPA described uses: (www.awpa.com/images/standards/U1excerpt.pdf Page 4). From peer reviewed research, it would appear UC-4B treated wood columns will likely outlive your grandchildren’s grandchildren. Should you have concerns, we can provide plasti-skirts to cover splash planks (https://www.hansenpolebuildings.com/2017/08/plasti-skirt/) and Plasti-Sleeves for columns (https://www.hansenpolebuildings.com/2012/04/plasti-sleeves/).

While barndominiums would fall under IRC requirements, IRC defaults to IBC when it comes to non-prescriptive structural systems (https://www.hansenpolebuildings.com/2018/10/what-building-code-applies-to-post-frame-construction/).



Avoiding Being Driven Crazy With Barndominium Questions Part II

Part II of a two part series. If you didn’t see Part I, go back one day.

Mike’s answers are in italics.

 In each house at ends of the “L” layout, I plan to have 1/3 open plan at two stories, for our great room, with nice windows for great views.

The other 2/3 areas will have 2 bedrooms and maybe a sitting area on the second floor.

  • Do  really need 6” * 6” poles in this area for the 2nd floor?
  • I was planning on building the upstairs like you do in a stick built house which would be use the 1st floor wall as load supporting, use 12” floor joists and  add a beam where needed and then use steel adjustable poles. (Cover poles later)
  • Is this OK to do?
  • Would the steel poles need to be on thicker concrete?
  • Would the 1st floor walls that will load support the 2nd floor need to be on thicker concrete?
  • You are free to say, “Greg if you had a decent floor plan, we should add a few poles, as it would be so much stronger, better, and other”.
  • Thoughts? Mike: Personally I would clearspan your second floor using prefabrciated wood floor trusses. There would be supported by LVL beams attached to your perimeter columns. This allows for walls to be placed anywhere without having to create bearing walls or have interior columns. All mechanicals can then be run through this floor truss system. If you were to approach your second floor as if it was traditional stick frame – you would then be faced with how to support it at exterior walls, since they are horizontally girted. Any bearing walls would have to have thicker concrete below and adjustable steel pole locations would probably require some sort of concrete pier (or at least slab being thicker and perhaps requiring some extra rebar). If using adjustable steel poles, I would want them to at least be wrapped with two layers of 5/8″ Type X sheetrock so in event of a fire they would not lose their temper, deform and collapse. 

Wall Girt System questions:

  • If the posts are 6” * 6” what width are the horizontal girt boards?  Are they 2” * 6” *  X’ or 2” * 8 “ * X’? Mike: For glulams of 2×6 you would have 2×8 girts, for 2×8 columns, 2×10 girts. These will project 1-1/2″ outside of your perimeter building columns.
  • If they are the 2 * 8’s, is there a little board you would put on the post, between the post and the outside metal? (This little stuff drives me crazy too!) Mike: Blocking would be placed on column exterior faces, aligned with wall girts to provide a continuous line for attaching steel siding with screws.
  • Are the vertical spacer boards nailed to the side of the post as shown on the attachment, so horizontal bookshelf girts can be nailed vertically into the spacer to avoid toe-nailing all of the girt boards? Mike: Bookshelf girts will be supported at each end with solid blocking against columns – no toe-nailing of girts to columns.

Does the lowest board on the posts, (Grade Board?), does it actually contact the dirt floor before pouring the floor? Mike: Bottom of pressure preservative treated grade board/splash plank is set at grade, so it is in contact with ground.

So the board will have 4” – 5” of cement contact? Mike: Top of your concrete slab would be 3-1/2 inches above bottom of splash plank.

How far does the siding cover the lowest board? Mike: Bottom edge of steel base trim drip leg will be at four inches above bottom of splash plank. This allows for any exterior concrete (walkways, approaches, door landings) to be poured against treated splash plank rather than against steel siding or trims.

Do you ever use a composite board for the grade board? Mike: Splash planks are used to transfer wind shear loads from siding to columns and into the ground. Composites are not structural and do not have an ability to transfer these loads.

Sorry for all the dumb questions. Mike: Only a question not asked would be considered as being dumb.

I appreciate all the effort from Hansen Pole Buildings.