I’m designing a pole barn shop for myself. It’ll actually be built on concrete piers (with 6X6 or 8X8 posts attached with Simpsom brackets bolted to pier). Posts to be 8′ O/C. Since the posts themselves won’t go into the ground, I can’t rely on them for racking strength.
Exterior will be horizontal purlins on the posts, and then rough sawn board and batten siding. I don’t think this exterior will have the same racking resistance as typical plywood sheathing. I therefore am toying with how to get the structural integrity I need while trying to maintain the low cost of pole-type construction (ie I don’t want to spend my $ on poles, only to infill with typial stud construction anyway).
I’m thinking of placing 1/2″, or even 3/4″, CDX horizontally INSIDE the structure. It would be nailed on both ends, flat against the post (each sheet of plywood would overlap the 8X8 post by about 3.5″ or so) say….8″ O/C in a staggered pattern. Bottom and top plates would be installed to give a nailing surface on the horizontal edges of ply.
Finished walls would therefore be a series of 8′ wide by 10′ high “boxes”. Open space inside would be about 8.5″ (accounting for purlins outside the posts) into which I’d blow celulose when I have the $. No vertical studwork inside at all.
The CDX would be my finished wall surface (painted), and give some good surface for hanging tools, jigs, shelves, etc…
I’ve certainly heard it before….so by all means tell me if I’m crazy! Does this sound OK?
I’m basically looking for the cheapest way to build an insulated structure on piers.
Thanks for any suggestions!
Edited 10/14/2002 4:17:16 PM ET by Stray
Replies
This doesn't sound like pole barn builing as I know it. Perhaps more like timberframe construction in which you would use diagonal braces. For instance a piece of wood from the bottom left corner of the bay to the upper right corner or vice versa.
-Peter
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Diagonal kickers is where you want to look for your racking strength.
Excellence is its own reward!
Stray, I see a problem with your cellulose. The horizontal 2xs you have your board and battens on will allow your cellulose to pass by into the next chamber. You also will have a huge chamber that you will not be able to pack. It is going to settle to the bottom, I don't see any way to get any density in this big area.
What's your local windload? Exposure?
How long are your purlins? If they break at each post there's no strength there, and you don't really have enough nailing on just the edges to get much out of the ply. :( Joe H
an engineer would be cheap insurance on this topic probably less than $600
to ensure your safety
Thanks for the great feedback everyone.
PM22, yes, your right, more like timberframing.
I agree with you and Piffin that diagonal braces might be best. perhaps I'll use 2X6 kickers, and then still sheath the inside with like 3/8" or 1/2" CDX (I still need a finished wall to hold my insulation in). The diagonals would give some more nailing surface for the ply anyway.
JoeH
It hadn't occured to me that the air space would creat a problem for blowng cellulose (never done it). I had liked the idea that the insulation would be more continuous...ie not a lot of thermal breaking like in a stud wall. Now that you mention it, I can see what you mean about not being able to pack it. Do you think I'd run into a problem filling the big bays as much as possible, then a year later blowing more in the top after it's settled? Would the final result be nearly as good as dense packing all at once? I can live with partial insualation for a while if it means I don't have to put blocking in between every purlin. It's also nice to have a wire chase ready to go instead of drilling holes to feed the NM.
My purlins would be 2X4X16, with butt joints staggered between courses of purlins. Still wouldn't be a great deal of stregnth.
1Remoldeler
I've been thinking of getting an engineer once I'm a little further along in the design process (esp for load calcs for conc. pier spec's). Designing it is 1/2 the fun though, and I'd rather get a good "gut instinct" plan together first, to minimize engineering time($).
Other thoughts?
Thanks
yes.. why don't you want to go conventional pole building?
you can still get the insulated slab... and your racking resistance comes from the poles set in the earth..
we've built several super-insulated structures with pole barn construction....it just seems to me that your system will be more work and more money for lesser results..Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
I'm battling this question in my mind. The fallback plan is to do exactly as you suggested.
At the crux of my problem is the question:
"Do I want to build a building with a 30-40yr foundation?"
My initial reaction is no, I want to do the concrete piers and build something that'll last long after I'm gone. Once I price out the pier option (with added framing costs) I'll see if I can make it a reality.
If you don't mind me asking...in those super-insulated pole structures you built, did you insulate the slab with that treated EPS or poly material you've mentioned before? I'm having trouble finding anything but regular blue poly foam board, which doesn't say it's treated. Is there a brand I can do a search for?
Thanks,
Erik
AMF R-Control. They make it all over the country too. Joe H
Thanks for the name. I got their web site and requested some info/dealer locators. Their Performgurad EPS says it resits termites (Doesn't say anything about carpenter ants though).
stray.. joeh gave it to you..
as for pole buildings... we're required to use .60 pt for our poles, as opposed to normal retention of .40 for decks and other PT .. so i anticipate that they will last for ever.... and , if one failed.. i could cut it off and scab in a repair..but with the grading and the setting of the poles.. i don't anticipate them failingMike Smith Rhode Island : Design / Build / Repair / Restore
Hi Mike,
I guess I'm leery that even .6 could last forever, even with positive drainage etc... I've seen .4 rot out in 10 years (albeit very poor conditions), so that makes me think .6 in good conditions might be a 40yr fix. I don't want to be scabbing on new posts when I'm 72
Plus, this won't start until spring, and I wasn't sure if CCA would still be available by then (When's the phase-out?).
Placing some new type of treatment in the ground (with less track record) makes me even more leery.
I've built treated pole barns before with good success. To a certain extent it might come down to economics, but I want to "build it right" whatever that might mean.
Stray,
If your gonna pour a superinsulated slab floor, why not make the floor thick enough ( 6-8 inches is plenty) and frame your building on this "floating slab?" If the building is only 1 story, this should be no problem.
The cost of a conventional framed building versus your pole type building are probably a "wash" anyway. Studs don't cost that much. Neither does sheathing.
In your pole building plan, you are planning to use a mess of 16 ft 2x4s as perlins, and cdx ply sheathing as "post stiffners" ...by the way...diagonal bracing is a much better idea than the plywood for this purpose.). You got all the ingredients for a conventionally framed shop. Subtract the cost of the 8x8 poles, plus the cost of excavation and pouring of piers, and put this toward a conventional slab/building....and there you go....cost differences are slight. It will be easier to insulate as well.
Just a thought.
Davo