Pole barn plan - sanity check

[ejb]

Hi guys...well after much debate, (pole barn versus morton building etc) I *think* I am going to go the pole barn route w/me providing most of the labor; I may hire out a few pieces like the roof to get it covered fast...

Anyway, I need to put together a materials list to get a decent estimate/plan together for my building permit, so I am hoping to detail what I'd have in mind here and have you guys shoot holes thru it:

- barn is to be used for haystorage, equipment storage and animals (sheep and goats now, who knows what else down the road), No heated areas. Dirt floor throughout.
- barn dimensions 36x60 with 6x6 PT posts 12' oc using pre-engineered wooden trusses 4/12 or 6/12 pitch so no internal posts will be necessary.
- 16 posts total. Posts will be set by digging/augering in 4ft, dumping 80lbs of concrete. Setting posts on dried footer and leveling/tamping .
- Posts will be 16' tall, so with 4ft in the ground I will end up with 12' clearance inside.
-Along the top of the posts I will attached 2 - 2x12 boards, one on the inside, one out the outside to support the trusses; sandwiching the 6x6 posts and blocking as necessary.
- trusses will be 2'oc with 1' overhang. Hurricane clips as neccessary to attach to frame.
- 2x4 purlins will run horizontally at 2'oc on top of the trusses for attaching the metal roof. (Is insulation necessary to prevent condensation?)
- metal roof will be installed with a ridge vent along the entire top.
- on the outside of the posts, I will first install a 2x10 PT "skirt" at grade level, and then go up ever 2' with 2x4 nailers for the outside boards.
- outside boards will be vertical 1x8 or 1x10 with 1x2 battens. I am considering wrapping the entire building with tyvek before putting on the boards to cut down on drafts, good idea? necessary?
- some of the bays will either be left open entirely on one side, or have big homemade wooden slider barn doors.
- thinking that after the posts are installed, and the PT skirt is on, that I should bring in a good 12-18inches of good draining sand/gravel to keep the area dry.
- might install gutters along both sides just to keep excess water away from the building.

All lumber (except trusses) will be roughcut pine/hemlock from the local mill; cheaper and better looking imo.

Total cost of materials, not including nails and miscellaneous hardware is just about $10K (4.60/sf). This compares with about $34K for a similar sized morton building.

Anyone see any big flaws in my plan? Things that I should add or take away?

 

[bczoom]

ejb,

You're list seems pretty complete.
A couple things I see:
80# of concrete/hole may not be enough. Not sure how deep you're going but with as 12" hole, 80# of concrete won't give you much for each post.
Are you going to put anything on the inside of the walls? You mentioned a Tyvek wrap but you'll need to keep the animals away from it.
Gutters are a good idea.
Are you including any electric?

How detailed do you need for the building permit and will the assessment be based off of the cost or value of the building?
Around here, they ask the cost but an assessor comes out when completed and uses some algorythm for computing its assessed value. So... nobody includes any materials in the initial list for doing anything inside the building (walls, electric, whatever's going on the floor...). The assessor can only look at the outside of the building.

 

[bontai_Joe]

I'd be concerned about snow load calculations. My opinion is you are a little light structurally for snow loads in your area, both on your post footings and post spacing. Please have someone familiar with your local codes check this out for you. Nothing worse than spending $10K on a building and having it squashed flat under a foot of snow.

 

[SPIKER]

looks OK to me, few things I might consider

1- go with 8' OC for the 6x6 posts, this works out beter for the 2x12 and the 2x4s and makes for a bit better stiffness on the high walls.

2- i would go T & G treated sills 3 high ~18" better for rain and manure splash on side walls. manure eats metal pretty quick.

3. make sure it meets local codes as here it requires a 24" hole now per post with better biscuts or larger pad poured in bottom. needs to be SOLID not the gravel only base. mine used 24" holes with 12" thick x ~18" dia waffer dropped in bottom. holes were 5' deep with 4' of post burried at the LOWEST POINT of the barn so that means upper side posts were deeper by almost 1 foot across corner to corner. (barn is on slite grade.)

4. make sure the trusses meet snow loads and center spacing is good, (some use 4', 24" or 16" and they are engineered to the spec required by you & local codes & snow loads.) I kept mine all at 16" on the 2nd floor for easy internal work...

Mark M /forums/images/graemlins/smile.gif

 

[bontai_Joe]

Spiker's 8' spacing and larger/deeper footings sound better to me for increased strength structurally, especially for snow loads. Again, check out what local code requires.

 

[bczoom]

I was also thinking/recommending what Spiker said about 8' OC for the posts but deleted my thought before I did all the math.
You may find that going 8' OC may actually cost about the same or even less. If you change the (3) 2x12x12 and all the 2x4's to 8', the change in price down to 8' material would probably pay for the extra 6x6's and concrete. Not sure nowadays, but it used to work that way.

 

[plumboy]

I'm going to tackle a pole barn this winter as soon as the material shows some sort of releif,Maybe a spring job.But as far as the post and putting the crete around you might want to think about getting the posts in thier holes and using your purlins as braces(need some 2x4's as stakes) to level them up and have a front loader come and pour them all at once.Thanks for sharing,I'll be reading your thread.

 

[cowboydoc]

I wouldn't wait for materials to go down at all. Every report I have seen says it is just going to get worse. I put off our house addition for a year and it cost me ALOT thinking it was going to go down. I finally bit the bullet and we're about done now. Everytime I've been back to the store I have seen the prices continue to jump on everything.

 

[cowboydoc]

All the pole barns that we have built have been on 8' centers with the same for trusses. I have often seen putting the trusses every 2' but why?? The purpose of a pole barn is save costs. The only reason I can see is if you are going to put plywood on the roof and shingle it. If you're going to put metal on the roof just go every 8' for trusses, put your purlins on and save yourself thousands of extra cost in materails. The trusses are your most expensive piece and then if you put plywood on top of that you've just added 30-40% to the cost of your building.

 

[shvl73]

12' O.C. is real common around here for posts, especially for 12' box stalls. Rough 2x10 face nailed or let in to the post w/ 2x10 top plate (if face nailed). It handles the snow load just fine. The 2x12 plan is one better. Face nailing the header allows 2x6 diagonals between header to post for lateral bracing. I also see 2x6 sidewall gurts flat between posts w/ another 2x6 face nailed on exterior of posts, 24" - 36" O.C. w/ 2x10 rough pt mudsill. I've thought of the housewrap idea for our eventual barn as well. I think a larger & thicker pad for the posts would be good. I've seen a 16" x 16" pre-cast block sold for that purpose, I think it was 12" thick. I have a neighbor that designs barns & I could check if you want.