Scaling down a pole building design?

[cbcansurvive]

I’m thinking of doing a small (12’ x 16’) pole building next spring to serve as a place for outdoor tools, firewood, etc… I want to go with pole construction because I want a gravel floor and it will be faster/cheaper to build. When I look for guidance on the ‘net about basic pole building construction I find plans for huge (20’ x 40’ with 10’ ceilings and massive roof trusses) buildings. It’s easy enough to scale the designs down, but I’m wondering if I can scale the materials down a bit. For example, the poles themselves. The large pole buildings call for at least 6x6 if not 8x8 posts. Since my roof will be a simple gable with a 12’ span, I’m wondering if 4x4 posts would be sufficient. 4x4x12 posts (4’ in the ground, 8’ above ground)-I was planning to dig holes 12” in diameter and 48” deep on 4’ centers for the long walls and 6’ centers for the short walls. The bottom 6” of the hole would be filled with concrete. The posts will rest on the concrete and the holes will be filled with gravel. The difference between using 4x4 posts and 6x6 posts (11 posts total) is just shy of $200. Some may say “just go with the larger posts and be done with with it-its only $200,” but if using 6x6 posts is complete overkill for a building that small, why spend the extra money? I should probably add that snow load is a variable because I am in Northwestern New Jersey at the median elevation (500’) for the area. Feet of snow is an increasingly rare phenomenon, but it’s not uncommon to get 8-10” of heavy wet stuff in late February/early March. Any ideas?

[ErinP]

Blow the $10.
You won't regret it.

Practical Pole Building Construction: With Plans for Barns, Cabins, & Outbuildings

[just_sawing]

If equipment is going to be in the shed 6x6s are best. If it is a storage shed 4X4s can be used.
12 by 16 shed with a 8 foot front 6 foor back shed design
5=10' 4X4
4=16' 2X6 for back banding
8=12' 2X6 Side Banding
2=16' 2X10 Headers for roof
9= 14' 2X6 Rafters
16=10' Pearling (THis is what the roof metals goes on)
Need 400' of 1 inch boxing
This is the no thrill open on the front shed

[texican]

Plans Schlans...

Build it whatever size you want... Set your outside corner posts, and then place some interior posts on the wall... the spacing depends on how large your posts are. In my big barn I used logs greater than 12", and for the beams, I used >10"... and the spacing between the uprights was over 10'. If I'd used small 4x4's, I'd probably only go around 4'.

There are books out there... check with your local library... interlibrary loan.

Plans, are only guidelines... build it to suit yourself, adopt whatever good you find in all the plans to get your 'own' set of plans in mind.

[tomwendy]

On the footings I would put 6" of gravel first then fill the rest with concrete the idea is to not let water wick up the end of the post and water will find its way down there if placed on concrete at the bottom it will have nowhere to go except up the post and will rot rather quickly and use treated posts or treat the below ground areas your self.
Tom

[treefrog]

any wood you put in the ground will rot. preserving it, just slows the rotting process. i have a pole barn and i did masonry foundations for it. it's simple. dig a deeeeep posthole, six feet deep if possible, and maybe eight to twelve inches in diameter. buy a column block, (single cell concrete block 12"x12"x8") position the block over the hole, and put a heavy duty 2 1/2"X2 1/2" angle iron in the central hole with a couple feet above the top of the column block and a couple feet below. wire enough rebar to the bottom of the angle iron to almost reach the bottom of the hole. two half inchers should be enough. be sure the angle is in place so that when you put the bottom of the wood post in the inside of the angle iron, your posts will line up in the right position. then pour concrete in the hole up to the top of the block (and a little more to shed water). when your concrete sets, bolt the wood posts to the inside of the angle of the angle iron. two or three 3/8 lag screws on each side will do, actual bolts with nuts on them are better.

you now have your posts sitting eight inches above grade. they will last longer than you will. if you want taller foundations, stack blocks, or use ceramic flue liner. it comes in lots of sizes, and looks nice, but is pricier than concrete.

good luck
t.f.

[cfabe]

cbcansurvive,

I just built a 12x18 pole barn and went through the same thought process as you. You can definatealy scale down the materials, there are only a few areas where sizing is critical, these are the beam along the top of the posts and the roof rafters. If you search around online, you can find calculators to calculate both of those. You will need to know what your snow load requirements are, then calculate the load each part of the building must carry to size it. For the posts themselves, the required size is determined by wind load calcs and those can get complicated. I decided I was comfortable with 4x4 posts without doing the calculations.

Here is how I did my construction. I have some photos of the construction in my blog, see link in my sig. Feel free to PM me if you have any questions.

4x4 treated posts set on a 14" precast concrete footer 3'6" underground, backfilled with soil. 6 foot post spacing. Footers only required on side walls not the middle post in the end walls. I assumed 2000psf soil, but my soil is probably much higer than this.

Single 2x12 beam at top of posts, sitting in a notch cut out of the posts. Nails/lag screws were not strong enough to carry the load alone, so I did the notch.

2x6 roof rafters spaced 12" OC for 40psf snow + 10psf dead load. 2x8 at 16OC would work too but 2x6s were a little cheaper. I had just under a 12' span on the rafters, but I left about 2' overhang either side to protect the walls. Remember to factor in the overhang for the snow load. I chose to use a shed roof so I could add another 12' side to the building later and have a gable roof. I put hurricane clips on to protect from roof uplift.

Walls got 2x4 girts at 2' spacing, sheathed with 5/8" T1-11 siding. I chose this since building was for my goats and I thought they would beat up metal siding. The plywood siding also gives greater shear strength to the building compared to metal. Considering paint it cost more though.

Roof got 7/16 OSB sheathing and asphalt shingles.

Here's a pic of the finished building, well the front of it anyway.


Here's a pic showing the framing.

[cbcansurvive]

Thanks! That's exactly what I needed!

[Farmerwilly2]

I think you're on track now. I wanted to mention that you can also get treated posts in a 4x6 size. It's handy in that it gives you a bigger nailing surface for your girts and lets you use 2x4 nominal lumber for bracing.
Happy hammering.

[willow_girl]

It has been my experience that every time I've built a building (and there have been quite a few) I've always wished later that it were larger.

[rambler]

Originally Posted by willow_girl

It has been my experience that every time I've built a building (and there have been quite a few) I've always wished later that it were larger.

Always.

Always always.

--->Paul