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Avoid Being Driven Crazy With Barndominium Questions Part I

Avoiding Being Driven Crazy With Barndominium Questions Part I

Loyal reader and client GREG in KENTWOOD is planning his new post frame barndominium home and has questions no one else will answer. Mike’s answers are in italics.

Mike,

Good morning, I hope all is well with you.

I have some questions that I would like to understand and it is driving me crazy, because no one other than Hansen Pole Building, it seems will answer my questions and return my calls. Most the crazy part is about the slab. I find cement workers are not great communicators. I am 56, a mechanical engineer, have renovated several houses from the studs up, I can do plumbing without butt crack showing, I raced stock cars for 10 years, I tell you this, because I know how to build stuff and am not afraid of hard work. My job requires a detailed list of Bill of Materials, precision drills and reamers and very detailed processes to make fuel injection parts, ABS brake parts and other. I hope you can help out, as I am ignorant about some simple facts that are driving me crazy.

Mike: We believe good communication is essential to successful completion of most any building. You will find we strive towards written communications in order to minimize (or eliminate) possible miscommunication of important facts and details).

I also would like to say Brenner is doing a fine job.

Mike: Brenner has a passion for post frame buildings and he is not at all afraid to reach out to higher authorities for answers to complex structural questions.

Due to your great level of communication, you so far are my #1 choice to partner with on my new house. I also would be willing to visit you in MN if you have/think I could see examples of my questions first hand.

Statements from details I learned at Code Meeting:

In Michigan, in my county I need to have a 2’ foam, below grade, with R10 barrier, around the full foundation or slab perimeter.
So my building code staff recommends a Rat Wall 2’ below grade, or a crawl space with footers, or a slab with a wooden wall built to hold the 2’ foam below grade.
I don’t really have a problem with the Rat Wall, but it certainly will add more cost to cement.

My questions on this topic are:

- If using a Rat Wall, it seems like the 6” * 6” poles will then be encapsulated in cement for about 2.5’ at minimum. I thought the poles were not supposed to be in cement as it causes probably more decay than dirt.
  Mike: Concrete does not cause premature decay of properly pressure preservative treated columns.
- What are your thoughts?
  Mike: Personally I would build over a crawl space because my knees are far happier living on wood than concrete.
- What would you recommend for the 2’ below grade issue regarding the slab foundation? Mike: With a slab on grade, you can use rigid perimeter insulation without a need for a ‘rat wall’ or wood foundation wall. It can be held in place by backfill on each side. It can be placed running from below base trim on exterior of splash plank, or on inside of splash plank. If on inside of splash plank, it eliminates having to protect it from possible UV degradation.

On attachment pictures in the middle pages show where the 6” X 6” poles go and spacing, listed are my questions:

I am concerned with spacing of 12’ and 14’ of the 6” X 6” posts. (I’m sure the loading is OK, within code, but see below)
Mike: Actually with your 21 foot eave height and Exposure C for wind 6×6 columns will not engineer out. Your building will have glulaminated columns manufactured out of high strength 2×6 or 2×8 depending upon location.

- One concern is getting wood in today’s supply chain that are straight enough for the girt boards and purlins at 12’ and 14’, should I be concerned? ( I can’t get straight 2” X 4” at 8’ for the walls I have built in last year alone.) Mike: Lumber is obviously organic and we can no longer cut down those old growth trees where one might be able to get straight grained, narrow growth ringed lumber with few or no defects and very little warp, twist or cup. One beauty of steel roofing and siding is it hides a plethora of framing imperfections (like warp), due to high ribs of steel siding.

When using double trusses, at all locations, why not just go to 8’ centers on the poles? I know it is more 6” X 6” poles, but really is not anymore trusses and may help get straighter girt and purlin boards.
Mike: Wider spaced columns allow for more flexibility in location of doors and windows and an added advantage of not having to dig as many holes. If you were thinking of using a single truss every eight feet, rather than a double truss every 12, I would discourage it. Double trusses allow for true load sharing and eliminate any possibility of a single truss having a weak point, where under extreme loads (beyond design loads) it may fail and bring down your entire roof.

Come back tomorrow for Part II in Barndominium Questions!

This entry was posted in Uncategorized and tagged rat wall, pressure preservative treated columns, Exposure, crawl space, rigid perimeter insulation, Wind Exposure Category on October 7, 2020 by admin.

Door Facing North, Optimizing Space, and Remodel?

DEAR POLE BARN GURU: I have a (about) 40×24 pole building that faces north. I have a regular door that faces west. The wind and any accompanying rain typically blows directly against that west facing door. The building was built in 1996 by the original owner of the house. I’ve only lived in the house for 3 years and when we bought the house the moulding and threshold were starting to deteriorate. I would like to add an awning over the door to stop the rain from pounding against it. Is it as simple as attaching a ledger board, building off it, and adding a roof? CHRIS in SEAFORD

DEAR CHRIS: You sadly have a very common problem – people all too often end up with exterior people doors which are sadly inadequate for long term use. Most often they have wood jambs which have been left exposed to the weather and not kept painted or otherwise protected.

As to your solution – just adding a roof off the existing building may very well be problematic, as the footings of the existing building are probably inadequate to support the added weight from the added roof (awning).
What I would do – I would replace the troubled entry door with an insulated commercial steel door with steel jambs which is factory finish painted (I actually have recently done this with three of my own doors).
If you do want to build a permanent roof over the door, you should hire a competent registered design professional (architect or engineer) to inspect your present building and design a solution for you which will not compromise the integrity of your existing structure. It will be money well invested.

DEAR POLE BARN GURU: Hello I am wanting to build a 40x104x18 pole barn, my dad will have his living quarters and a wood shop on the main level, the second level will be my living quarters and an exercise room. The top level will be 40’—40 feet. What kind of beam or footing do you recommend? Also if you would like to quote me for this building package that would be great. Thank you, SHAWN in WRIGHT CITY

DEAR SHAWN: Lots of ways you can go with supporting your second floor, and how you design the floor will determine the size (diameter) of the concrete footings needed beneath the individual columns.

Least expensive will place a literal forest of columns below the floor – on 40 foot square, most probably every 10 feet in both directions. Whilst this might be dandy for the pocket book, it could cause challenges with the use of the space below.

As columns become spaced further apart, the beams necessary to support the floor joists and possibly the floor joists themselves are going to become larger in dimension and their cost will not be offset by the savings of a few columns.

I recently designed a floor for a 40 foot by 40 foot residence which had only a single column dead in the center. The LVLs (https://www.hansenpolebuildings.com/2013/01/lvl/) necessary to carry the floor joists were 20 inches in depth! The floor joists were 2×12 at 12 inches on center. Not a low budget investment, but it did provide far greater flexibility downstairs.

Another option is to go to prefabricated wood floor trusses. In our own home we have a 48 foot wide clearspan floor – it is also four feet deep! A floor this thick requires a taller eave height to allow adequate headroom. And yes, it is expensive!

Regardless of which of these options works best for your internal layout it will behoove you to look at the ultimate stiffness of the floor in regards to deflection. Some extended reading on floor deflection and vibration can be found at: https://www.hansenpolebuildings.com/2015/12/wood-floors-deflection-and-vibration/.

DEAR POLE BARN GURU: I currently have a 30×40 pole barn. I want to install a post lift and would need to remove one bottom chord on a truss. The trusses are 4ft on center. Is this possible and how would I do such a thing? The pole barn is also insulated and closed in with 5/8 osb. Except for the one 8 ft span. DUSTIN in NESCOPECK

DUSTIN: Given enough time and money, anything is possible, although probably not practical. Your situation is one of my “case in points” as to why post frame buildings with trusses placed every four feet on top of truss carriers is not the most flexible design solution when it comes to having to remodel.

Should you pursue a remodel, it should ultimately involve a registered design professional (architect or engineer) as what you are looking at doing is not going to be a simple task.

I’d probably follow a path such as this – adding a new extra truss to the single truss at each side of the eight foot area. Temporarily supporting the flat purlins over the middle truss whilst removing it, then adding purlins on edge between the two new trusses (and either under or next to the existing purlins). Keep in mind, this is a highly simplistic outline and the actual fix will be far more complicated.

A less expensive solution – add a 12 foot bay onto one end of the building with a truss on each side of the 12 feet and purlins spanning from truss to truss.