14 x 20 Pole Barn using 4x4 posts

[Dougryan]

Hi,
I've built a few sheds over the years using stick built methods with framed wooden floors. A couple of 12x16, and one 12x12 on a cement slab, so I'm familiar with 2x4 based shed building.

Now I'm looking to build something a bit bigger... 14 x 20... and really interested in a small pole barn style structure.

My first major question, since I'm not familiar with this building style, is about the poles. I would prefer to use 4x4s since they are easier to work with. I'll need 12 footers so that I can bury 4' and have 8' walls. A 12 foot 4x6 or 6x6 would be really heavy and hard to plumb etc. While I could use larger lumber and 10 foot spacing, I was thinking that I could use 4x4 posts and 5 foot spacing.

So five 4x4 posts along each 20 foot wall, plus two more posts along the 14 foot walls. Evenly spaced on one wall, but a bit wider on the other to allow for a 6 foot wide door.



What do you think? Some folks really frown upon 4x4 posts even in the smallest pole barns. Some promote 6x6 or even 8x8 posts.
I should also mention that I plan to use 2x4 girts and T1-11 siding. So the siding itself will add to the rigidity and support of the walls.

Thanks,
Doug

 

[newbury]

Several things immediately come to mind:

What is the source/quality of your 4x4's? I've seen a lot of HD, lowes, and similar twist horribly as they age.
Another option would be using 3 2x4's sandwiched together such that the "grain" tends to go opposite, still the weight of a 2x6 but if done right should hold together well.

Why T1-11? Do you like to paint and replace? I built a 10x15 shed back about 1985 in Virginia. Used T1-11, primed and painted (and painted, and painted, about every 3 years). After about 8 or 10 years the bottom edges were starting to delaminate.

Tore off the T1-11, put on 4x8 sheets of Hardieboard. Painted once.
Still looks like the day I put it up.

Another good choice for siding would be metal.

 

[Dougryan]

4x4s would be from my local HD. I could see using three 2x4s together. A bit heavier than a 4x4 but stronger than a single 4x6. Something to think about.

T1-11 is just popular around here. I did a quick search for the HardiePanel (4x8 siding) and it's just not available around here (western NY). The only way I could find it is: Get an In Home quote from HD and it requires HD Installation. That's crazy. I did use HardieBacker board for a recent fireplace project and I really liked working with it. I can see the benefit of using cement board as siding. I'll keep my eyes open and see if I can find it from other sources.

 

[KennyG]

From a strength standpoint, the 4x4s are probably ok, even with 8 foot spacing for a 14 foot span if you are using a metal roof. However, I would recommend going to 4 x 6 because of the lumber quality. Around here, it would take some sorting to find 4 x 4s that are straight and clear enough to make me comfortable. I also wouldn't go with the T-11. You will need girts anyway to span the poles and metal is much more durable. If you need T-11 to match other buildings, I would say forget the poles and go with stud walls.

 

[dmccarty]

To add to what Newbury said, I would also be concerned with a five foot spacing of 4x4 posts where I live but if there was any chance of a decent snow low... I can't remember the load numbers for a 4x4 but they would on the Internet somewhere along with the roof load requirements for your area.

I was looking at a Morton built barn years ago and I was impressed with the 2x6 boards laminated together to form 6x6 posts. The posts were strait and with a 2" thickness the wood treatment really should get to the inner part of the lumber.

When I have bought treated lumber for projects that need to be done right, I go to a somewhat local wood treatment plant that has been in business for generations.

Using 4x4s makes me nervous but running the numbers should make things clearer.

Later,
Dan

 

[wawajake]

In my younger years , I installed a few clothesline poles using 4 x 4 pressure treated posts , for myself and friends........big mistake, they all warped over time . Unless you have a very good source of wood , I suspect yours will be the same result. Laminating a few 2 x4 or 2 x6 together would help alleviate the warp potential.

 

[CalG]

I've built a car park just a bit larger. It's a salt box metal roof with open gables and no walls. It's just standing on 7 4X4 posts. I did "double up" on the bottom 8 feet with a sandwich of the 4X4 between a pair of 2X6 pt.

The location is in the woods, so wind loads are tempered. We get the snow however. That seems to slide nicely but it sometimes takes a day of warmer weather.

The car park is 5 years old, and still standing. I do have a little trouble with one corner where I could not get down into the earth as deeply as I would like. Ledge is like that. ;-) Frost lifts the post some springs. I need to dig it out to gravel and sleeve that post. Not a big issue, the structure is pretty flexible, I call it "earthquake proof". ;-)

 

[Deere Dude]

If you are ever going to cement the floor I would cement it now and just put 2x4 walls up and forget the pole barn structure style.

 

[Dougryan]

Well, my first intention was to do a cement slab and stick frame it. Then I thought about the need for a monolithic slab.


I didn't do this kind of slab for my 12x12 shed since it was so small. But I figured the 14x20 would need some type of reinforced footings etc.
That got me thinking about the pole barn idea. Let the poles do the support work and at a later time, pour a 4" slab inside. I really don't want to do a wooden floor again. It will be either cement on day 1 or gravel followed by cement in the future.

So, I guess I'm still up in the air about stick vs pole. By the time I do laminated posts (2x4s plus glue and bolts) or larger 4x6 or 6x6 posts, the cost appeal of the pole barn becomes less of an issue. Plus, I can sling 2x4s around by myself all day. I could manage 12 foot 4x4s too... but when we start talking about larger dimension posts, it's no longer a solo project.

Back to the drawing board...

 

[CalG]

No tractor to help set the posts?

Oh.. craftsman... I understand your concern ;-)

 

[Sawyer Rob]

I would NOT use 4x4's, I'd use 4x6's...

I would NOT use flat lumber nailed together... Most flat lumber is not treated for in ground use, the companies that lam up flat lumber spec out to have their flat lumber treated better.

Make sure any nails/screws that go into treated lumber are meant for treated lumber or they WILL fail by rusting out...

SR

 

[buckeyefarmer]

You need .6 cca wood in the ground, Probably won't find that at HD.
For the building size, 4x4 is ok, but twisting is a major problem. For your size building I'd frame walls with footers and 2x4 walls.

 

[boggen]

dig your holes with a PHD (post hole digger), fill them up with concrete to a couple inches above ground. set your lumber on top of that. set an anchor before the concrete dries. so you do not need to fuss with drilling and setting an anchor later on. (no lumber in ground) and doing this way, you can pre set the tops of all the posts with a "water level" and be ready set go.

if you digging holes and dropping lumber down into the holes. you generally need to have a little "ley way" as far as how long the posts are. so once you get them all set in the ground, and have them supported with say two 2x4's angled up for bracing. you can go back around and cut all the tops off evenly with the trusses.

being your in NY, i would imagine frost depth atleast 3.5 feet deep, here in illinois it varies between 3 to 3.5 feet depth, you being further north imagine frost depth is deeper.

if you dug holes and filled with concrete, you could buy some bags of ready mix cement. squirt some water into the holes with garden hose, dump dry bags of concrete down into hole. squirt some more water in. use a larger "coffee can" or like doing for a make shift sono tube above ground level. and finishing topping off with some concrete above ground level. set in your anchor for your lumber.

stick building does have advantages, as far as spacing out the studs. so you can easily match up what ever you use for sides (metal, to plywood, to other)

 

[skipmarcy]

Definitely a minimum of 4x6 to get the better quality and strength, they're barely heavier than a 4x4. How are you going to get a 4' deep post hole ? My hand posthole diggers will only get me down about 30" before you can no longer get a bite of dirt. Using my digger on the tractor with standard augers can only get me down a touch over 3' before the pto shaft gets too close to the ground. I pour some concrete in the holes about 3"-4" deep and let it set a day or two for a footer, then drill a hole thru the lower end of my post a put a piece of 1/2" rebar thru it and build my framing for the building before going back and pouring concrete around the posts and then filling with dirt and tamping with a rock bar real well as you go.

 

[Sawyer Rob]

Cementing a post in where I live, will guarantee it will have a much shorter life!

SR

 

[Tomtint]

I built a small barn / large shed last year. Had the same concerns you are asking about now. I wanted a post and beam look, and a concrete floor. I had thought about using 4x4s for the posts and nailing a 2x4 to the outside of it to help mitigate warping. After a bunch of thought, I ended up going with 6x6s and a PT wood deck on concrete footings, and the frame as well as the siding is all rough sawn pine. As it ages I'm expecting to have ongoing maintence to keep it looking good, but I'm ok with that.

 

[buckeyefarmer]

I have used 4x4 posts for a small 10x16 shed roof and it worked out ok. Depends on the quality of your lumber.

 

[Kenneth in Texas]

4x4's are fine, I used them on a 24x36 building that I built 25 years ago, just as straight and solid as they were then, just make sure drainage is good around them.

 

[JeremyL]

The posts you got 25 years ago were treated differently. Nothing you can get today will be of the same quality.

 

[Sawyer Rob]

The posts you got 25 years ago were treated differently. Nothing you can get today will be of the same quality.

And, that's a fact!

At least nothing a home owner can get....

SR