Post hole depth and spacing?

[Cuda416]

I'm getting ready to build a pole building (shop) and at the stage of getting quotes for having the holes dug. I don't have and tractor and I'm having trouble finding some place to rent an auger with something to mount it to around here. btw, "here" is Castroville TX, of that helps.

If I could rent the equipment, I'd give it a go, but barring that, I have an estimate for 16" holes, 48" deep for $100/hole, or 36" deep for $80. One guy says his is 24" deep, in concrete, 17 feet high and been there for 12 years without problems.

My question, then since there is really no "frost" problem here that I am aware of, city says so too, how deep do I need to go?

Also, the shop will probably end up being 32x40 (or 32x48) with a 14' foot ceiling (min 12') as i want to also build a loft for storage inside, and either a 4/12 or 6/12 pitch. I was thinking of having all of the posts placed 8'-OC. Seems like overkill but I'd rather be safe then standing next to a toppled building. Ok, I know that's not likely but what's a reasonable alternative?

The posts will be embedded in concrete, at least that's the plan.


Thanks!

 

[larry_g]

Your not giving any information on soils condition, wind load, and other details that may influence the decision. Your going to find all sorts of answers come flying at you here as pole buildings vary widely in their design. Our county requires a 2' dia and 4' deep with concrete fill. Posts are on 12' centers. This is an 8x8 post. You have to consider the posts as only part of the whole. Without all the details what your asking cannot be answered.

This sounds like a dream you have and are making it up as you go. I'd suggest that you have a completed design and go with it.

lg
no neat sig line

 

[Cuda416]

Your not giving any information on soils condition, wind load, and other details that may influence the decision. Your going to find all sorts of answers come flying at you here as pole buildings vary widely in their design. Our county requires a 2' dia and 4' deep with concrete fill. Posts are on 12' centers. This is an 8x8 post. You have to consider the posts as only part of the whole. Without all the details what your asking cannot be answered.

This sounds like a dream you have and are making it up as you go. I'd suggest that you have a completed design and go with it.

lg
no neat sig line

Yes it is a dream, that I am trying to turn into reality without killing my bank account. So that said, I am trying to learn as much as I can about the things. You raise excellent points though and that's why I am hear asking these questions. I've seen a whole slew of folks "making it up as they go" and things seem to work out, but they also seem to know a heckuvalot more than I do about building these. I'v also seen quite a few people hire contractors who didn't seem to have the customers best interest in mind. I'd rather know when I'm being snowed then not and so I learn everything I can about projects in which I might have to rely on someone else to get done.

I'll call the local building dept. and ask what they normally require. I did that for the wind load and some other details but didn't think about the hole depth/diameter. 2+2 I guess. . Although I am outside city limits and don't require a permit, I DO want to follow local guidelines for the basic safety aspect of it.

Any other items other that wind load (90 Mph sustained) I should ask about?

Thanks for the response.

 

[theoldwizard1]

I'll call the local building dept. and ask what they normally require. I did that for the wind load and some other details but didn't think about the hole depth/diameter. 2+2 I guess. . Although I am outside city limits and don't require a permit, I DO want to follow local guidelines for the basic safety aspect of it.

Best place to start !

They may give you options. Post in ground, with/without concrete. Concrete footing with post on top, etc.

 

[bbirder]

Call a couple of contractors and get a free quote on a turn key job. You can then query them on depth, distance and post size they are quoting. Get your answers from the guys that do this every day, then you can put a pencil to it and decide if it is worth tackling on your own. I built my first one and contacted my second. I'll never attempt to build another myself.
PS.. Sounds like the guy quoting you on digging for your posts is pretty expensive.

Sent from my LG-D850 using Tapatalk

 

[Cuda416]

Call a couple of contractors and get a free quote on a turn key job. You can then query them on depth, distance and post size they are quoting. Get your answers from the guys that do this every day, then you can put a pencil to it and decide if it is worth tackling on your own. I built my first one and contacted my second. I'll never attempt to build another myself.
PS.. Sounds like the guy quoting you on digging for your posts is pretty expensive.

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Thanks for the idea. I thought it was a bit high too, but the next guy quoted me 3200 for 20 holes (just getting ballparks). Ouch

 

[Cuda416]

Spoke to the city building permit department today. Although they are more than willing for help me find the info from the 2012 code books they are using, they seem to have nothing on file. Kind of surprising since everywhere I look, I see pole buildings, many within the city limits.

They kind lady said she'd call me back and/or email me the information. So, barring any real information, I have to think doing anything better than the 2012 code minimums would be a good idea. i'm very interested to see what they come up with.

That said, anyone here from the San Antonio area who knows if their town actually does list minimums that I can maybe use for a basis?

 

[buddyboy]

stop into 84 lumber, talk to someone behind the desk.

they should be very familiar with your local requirements and what and how the contractors in the area are building pole barns.

also they should have the software to draw up plans for you along with a materials list.

they'll know how deep your holes need to be and how and what to backfill them.

have them print out a basic set of plans for you so you can take it home and study them.

good luck

 

[ard]

There is no "code" on "how deep and far apart do poles need to be"

You have no firm specs on height, dimensions, construction details. NOBODY can give you an answer.

Now, you can look at other plans, talk to people about what they did, or get advice- all great ideas...BUT...at the end of the day, unless you have a set of plans AND you give it to a structural engineer, you wont get an 'answer'.

Id do 48inches. Only $20 a post more, thats nothing- in the scheme of things.

 

[John in OH]

As someone already mentioned, your question can't really be answered until you finalize the building overall dimensions and general details (ie., quantity & size of doors, windows, roof pitch, etc) of what you want.

Then, I'd recommend that you take this "design" to a couple of local lumber yards and get them to quote you a pole barn "package". Basically, a pole barn package is a kit of all the material for the barn that includes poles, girts, trusses, siding, roofing, doors, windows, etc. (sometimes even fasteners and hardware accessories). Everything that you would need to build you pole barn .... all properly engineered and sized for your geographic location and typical soils. Also included will be the design details for the pole foundations. This is also typically the most "economical" way to buy the material.

Once you have the material, you and a couple of buddies can erect the barn at your leisure with confidence that everything is properly designed. No more guess work.

 

[Cuda416]

There is no "code" on "how deep and far apart do poles need to be"

You have no firm specs on height, dimensions, construction details. NOBODY can give you an answer.

Now, you can look at other plans, talk to people about what they did, or get advice- all great ideas...BUT...at the end of the day, unless you have a set of plans AND you give it to a structural engineer, you wont get an 'answer'.

Id do 48inches. Only $20 a post more, thats nothing- in the scheme of things.

If a town has requirements that must be adhered to, isn't that "code"? Otherwise what is the point of having inspectors check for certain things being done. I've read many times here about people having to have the holes planted in 24" holes, 48" deep and concrete filled to the brim. Others say they required 8x8" poles.. Other things like snow loads, wind ratings etc also come into play. Structural engineers take all of those things into consideration, they dont just make things up, eyeball them and say "yup, looks great!" How is that not following code?

Honestly not trying to argue, just trying to understand all of this and not build something that will kill me or someone else.

I'm on a pretty strict budget and will do as much as I can myself.

So my questions are really about finding what guidelines are appropriate for my area. Those requirements are what i refer to as "code"

You make some interesting points, no doubt. If it helps, I want to build a shop that's 36x48x14 ideally but may have to reduce the width a bit.

Thanks for your response

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[Cuda416]

As someone already mentioned, your question can't really be answered until you finalize the building overall dimensions and general details (ie., quantity & size of doors, windows, roof pitch, etc) of what you want.

Then, I'd recommend that you take this "design" to a couple of local lumber yards and get them to quote you a pole barn "package". Basically, a pole barn package is a kit of all the material for the barn that includes poles, girts, trusses, siding, roofing, doors, windows, etc. (sometimes even fasteners and hardware accessories). Everything that you would need to build you pole barn .... all properly engineered and sized for your geographic location and typical soils. Also included will be the design details for the pole foundations. This is also typically the most "economical" way to buy the material.

Once you have the material, you and a couple of buddies can erect the barn at your leisure with confidence that everything is properly designed. No more guess work.

Yup, a few have pointed out the flaw in my logic and it's sinking in. I keep equating local requirements to "code" which seems to be misnomer.


Im planning on going to 84lumber in the east side of San Antonio after i get the dimensions locked down. Then I'll get things spec'd appropriately. Hopefully the next thread I start will be my build thread

Thanks

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[gungatim]

I was on a budget when I built mine, and did a lot of the same "dreaming" the OP did before I actually had a plan, so I can sympathize.

what helped me was buying the install manual from Menards, was like $3, that helped a lot. then I went to their free design kiosk and spent a half hour or so creating different size plans. you then print out the material list and you will be able to see how many poles, spacing, depth, etc. that various designs require.

if you have a Menards, the service is Free, if not, check around the other lumber places, I bet more than one of them has one of those kiosks where you design decks barns garages, etc...

 

[Cuda416]

I was on a budget when I built mine, and did a lot of the same "dreaming" the OP did before I actually had a plan, so I can sympathize.

what helped me was buying the install manual from Menards, was like $3, that helped a lot. then I went to their free design kiosk and spent a half hour or so creating different size plans. you then print out the material list and you will be able to see how many poles, spacing, depth, etc. that various designs require.

if you have a Menards, the service is Free, if not, check around the other lumber places, I bet more than one of them has one of those kiosks where you design decks barns garages, etc...

Thanks, I'm planning on doing that very thing at 84lumber as has been suggested. Solid idea that i wish I'd have known waa possible weeks ago.

Thanks!

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[blair683]

I did a lot of research in this before building my pole barn. I'm in Ohio so our frost level is 36". I made my holes 18" diameter by 40" deep. But in my research I found people in states with no frost concerns were putting posts only a foot in the ground. If I were you I would use 6"x6" posts 24" deep 8' on center. If you're concerned about uplift just run a piece of rebar through the bottom of the post (horizontally). Then incase in concrete. You will find that a lot of people in this forum will critize anything that you do. But most are just keyboard warriors. I to live in an area with no permit requirements. If you feel comfortable with the integrity, then I say go with it. I built mine on my own and never built a structure before in my life. I was lucky to have an excavating company three blocks from my house. They brought a mini excavater down and did my 16 holes for 170 bucks.

 

[lakeroadster]

Cuda... have you seen this site? APB Pole Barns: How to Build a Pole Barn

"Hole depth is determined based upon the frost heave in your area, wind speeds, wall size, building dead load and other factors."

Lots of good data. Spend some time there, you'll learn a lot.

 

[Cuda416]

Cuda... have you seen this site? APB Pole Barns: How to Build a Pole Barn

"Hole depth is determined based upon the frost heave in your area, wind speeds, wall size, building dead load and other factors."

Lots of good data. Spend some time there, you'll learn a lot.

No, I have not, holy cow! That's exactly what i need, the crash course in pole barns. I will definitely plow through that one, thanks!

 

[Cuda416]

I did a lot of research in this before building my pole barn. I'm in Ohio so our frost level is 36". I made my holes 18" diameter by 40" deep. But in my research I found people in states with no frost concerns were putting posts only a foot in the ground. If I were you I would use 6"x6" posts 24" deep 8' on center. If you're concerned about uplift just run a piece of rebar through the bottom of the post (horizontally). Then incase in concrete. You will find that a lot of people in this forum will critize anything that you do. But most are just keyboard warriors. I to live in an area with no permit requirements. If you feel comfortable with the integrity, then I say go with it. I built mine on my own and never built a structure before in my life. I was lucky to have an excavating company three blocks from my house. They brought a mini excavater down and did my 16 holes for 170 bucks.

Thanks, I don't mind the criticism, I think people generally mean well and what they say often comes from 'somewhere' and they may have valid points. i always welcome and and all comments and information, opinions etc. You never know when someone will tell you something that just "clicks".

There is a house being built in the neighborhood. next time i see the guys out there digging stuff up, I'm going to go have a chat with them.

Thanks for the input.

 

[Cuda416]

stop into 84 lumber, talk to someone behind the desk.

they should be very familiar with your local requirements and what and how the contractors in the area are building pole barns.

also they should have the software to draw up plans for you along with a materials list.

they'll know how deep your holes need to be and how and what to backfill them.

have them print out a basic set of plans for you so you can take it home and study them.

good luck

I'll be taking this advice for sure. Thanks!

 

[6768rogues]

Don't put them in concrete. Put a concrete pad in the bottom of the hole and after it cures put the pole one it. If you put concrete around the pole, the pole will shrink and a pocket for water will form. Then over time the pole will deteriorate. I have replaced poles where that happened.

 

[Cuda416]

Don't put them in concrete. Put a concrete pad in the bottom of the hole and after it cures put the pole one it. If you put concrete around the pole, the pole will shrink and a pocket for water will form. Then over time the pole will deteriorate. I have replaced poles where that happened.

Good to know, thanks!

I have been leaning towards using the anti lift method of adding short lengths of 2x6 around the bottom of the poles before tamping the back-fill. Any thoughts on that?

 

[lakeroadster]

I have been leaning towards using the anti lift method of adding short lengths of 2x6 around the bottom of the poles before tamping the back-fill. Any thoughts on that?

My "Lester" built barn has the anti lift boards... check out my build thread link in the signature line below for more information. Just 2x6's nailed and glued to the bottom of each side of each post.

 

[blair683]

I put my posts on premade concrete "cookies" in the bottom of the hole. Then dumped an 80lb bag of concrete in dry. Then backfilled with the dirt I removed from the holes.

 

[Cuda416]

My "Lester" built barn has the anti lift boards... check out my build thread link in the signature line below for more information. Just 2x6's nailed and glued to the bottom of each side of each post.

Thanks I'll check it out.

 

[Cuda416]

I put my posts on premade concrete "cookies" in the bottom of the hole. Then dumped an 80lb bag of concrete in dry. Then backfilled with the dirt I removed from the holes.

I've read about the "debate" of using dry vs wet, but never looked into it. Why dry?

 

[ard]

If a town has requirements that must be adhered to, isn't that "code"? Otherwise what is the point of having inspectors check for certain things being done. I've read many times here about people having to have the holes planted in 24" holes, 48" deep and concrete filled to the brim. Others say they required 8x8" poles.. Other things like snow loads, wind ratings etc also come into play. Structural engineers take all of those things into consideration, they dont just make things up, eyeball them and say "yup, looks great!" How is that not following code?

Honestly not trying to argue, just trying to understand all of this and not build something that will kill me or someone else.

I'm on a pretty strict budget and will do as much as I can myself.

So my questions are really about finding what guidelines are appropriate for my area. Those requirements are what i refer to as "code"

You make some interesting points, no doubt. If it helps, I want to build a shop that's 36x48x14 ideally but may have to reduce the width a bit.

Thanks for your response

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"Code" may say "the building shall withstand a 90MPH wind.

That code does NOT translate that into beam sizes, shear panels, uplift values, ground compaction and footer depths. The code may provide data and methods around those things, but one national code cannot have a table of 'pole barn footing depths for any size pole barn built anywhere in the USA"

Your best path will be the one you seem to be on- what works in the area, what other kits are requiring, word of mouth, etc

My sole point is that focusing on 'code' for an unengineered pole barn will likely be frustrating.


GL

 

[Cuda416]

"Code" may say "the building shall withstand a 90MPH wind.

That code does NOT translate that into beam sizes, shear panels, uplift values, ground compaction and footer depths. The code may provide data and methods around those things, but one national code cannot have a table of 'pole barn footing depths for any size pole barn built anywhere in the USA"

Your best path will be the one you seem to be on- what works in the area, what other kits are requiring, word of mouth, etc

My sole point is that focusing on 'code' for an unengineered pole barn will likely be frustrating.


GL

Very good points and I appreciate you pointing them out. it has been frustrating trying to get info from the local building department.

What I am starting to understand is that these things are engineered around specifications/requirements and built to suit rather then what one normally refers to as code. I suppose what i am looking for in reality are localized "best practices".

Little by little, I'll make enough course corrections to get on a solid path forward. That's what is great about forums like this. I'd hope that at some point I'll be able to help someone out and avoid mistakes I may make.

 

[D94R]

My "Lester" built barn has the anti lift boards... check out my build thread link in the signature line below for more information. Just 2x6's nailed and glued to the bottom of each side of each post.

Menards spec's their barns this way as well. I thought "Ok", but then reasoned with myself that if the wind or frost is enough to lift the weight of the 6x6, plus wall, plus roof, plus whatever.... that 4" of extra width isn't going to stop it.

My posts are down 48", on 4" concrete pads, with those anti-lifts attached per plan.

 

[Cuda416]

Menards spec's their barns this way as well. I thought "Ok", but then reasoned with myself that if the wind or frost is enough to lift the weight of the 6x6, plus wall, plus roof, plus whatever.... that 4" of extra width isn't going to stop it.

My posts are down 48", on 4" concrete pads, with those anti-lifts attached per plan.

I got the impression the anti lift boards were more about wind than anything and they acted like a "barb" against the settled/tamped soil. I haden't considered they might be for frost.

 

[6768rogues]

If the supports are below the frost level in your area, frost will not lift it and lift boards will not have to do anything for frost. If the supports are not below the frost depth, it could lift without regard to what else you do to try to prevent it.

 

[John in OH]

Don't put them in concrete. Put a concrete pad in the bottom of the hole and after it cures put the pole one it. If you put concrete around the pole, the pole will shrink and a pocket for water will form. Then over time the pole will deteriorate. I have replaced poles where that happened.

Above info from 6768rogues is correct.

 

[ptgarcia]

Anyone try foam yet?

 

[Cuda416]

Above info from 6768rogues is correct.

Thanks for info John, I appreciate your addition to the discussion.

When I was in Somalia in 92/93, we planted a sat dish in the dirt. Used smallish rocks as fill and it locked that thing in tight. What's the consensus on using an alternate fill, rather then the original soil?

 

[buddyboy]

the last thing you want to do is to create a 'well'

think about it, you are digging a hole, if you fill it with porous material then any surface water will collect in it.

some people think that rocks keep water away from the posts. rocks do lock in the post nicely but consider the following:

take a glass, pretend that is your hole; drop a chopstick in the glass, pretend that is your post; backfill your hole with marbles. that holds the chopstick pretty darn good... now pour water in the glass

concrete is porous and will shrink, leaving a gap for water as well.

if your soil is clay, I would say to use that to fill in your holes.

a concrete pad is needed in the bottom of your hole, this is to keep the post from sinking into the ground.

depth of hole takes into account many things, frost is one, but shear force is another important one. I am sure there is a ratio of pole in groundole above ground dependent on pole thickness

another important aspect of pole buildings is proper site work. the ideal spot is where water will drain away from the building in all directions.

overhangs are important too, as this will keep the ground around the building dry

it's not a mistake that a wooden bridge that will last 100's of years is covered with a roof.

 

[ptgarcia]

Soils, soils, soils. You need to know what you're building on before you can begin to figure out depths and spacing.

 

[Cuda416]

the last thing you want to do is to create a 'well'

think about it, you are digging a hole, if you fill it with porous material then any surface water will collect in it.

some people think that rocks keep water away from the posts. rocks do lock in the post nicely but consider the following:

take a glass, pretend that is your hole; drop a chopstick in the glass, pretend that is your post; backfill your hole with marbles. that holds the chopstick pretty darn good... now pour water in the glass

concrete is porous and will shrink, leaving a gap for water as well.

if your soil is clay, I would say to use that to fill in your holes.

a concrete pad is needed in the bottom of your hole, this is to keep the post from sinking into the ground.

depth of hole takes into account many things, frost is one, but shear force is another important one. I am sure there is a ratio of pole in groundole above ground dependent on pole thickness

another important aspect of pole buildings is proper site work. the ideal spot is where water will drain away from the building in all directions.

overhangs are important too, as this will keep the ground around the building dry

it's not a mistake that a wooden bridge that will last 100's of years is covered with a roof.

Thanks buddyboy, that's a great explanation and makes total sense.

Site prep is another topic I'm researching. It seems like such a simple thing and might be, but there seem to be 1000 different preferences how how to achieve the right height to set the skirt/rat boards at etc. I get the premise, but not how to determine the various heights etc.

 

[rburke65]

Rocks are not shaped like marbles! Cuda....you think having posts 8' OC is excessive? I just put up a shop and used a 'pole barn' foundation and I used 4"x6" posts, 4' deep holes, with a concrete cookie in the bottom and my holes were every 4 feet apart.

 

[lakeroadster]

My "Lester" built barn has the anti lift boards... Just 2x6's nailed and glued to the bottom of each side of each post.

Menards spec's their barns this way as well. I thought "Ok", but then reasoned with myself that if the wind or frost is enough to lift the weight of the 6x6, plus wall, plus roof, plus whatever.... that 4" of extra width isn't going to stop it.

Here's the logic behind the anti lift.

The dirt, concrete, whatever around a regular post will set up and get hard, almost like a casting surrounding the post. Pulling a post out of the ground that is smooth sided all the way to the bottom is a piece of cake, relatively speaking.

Contrast that to a post with 2 x 6's nailed to the sides at the bottom. Now when you go to pull the post out the 2x6 is trying to plow thru the dirt as the post lifts up... that makes a huge difference.

So whether you are talking frost heaving, or lift due to wind forces, those additional 2x6's make a huge difference.

 

[Cuda416]

So whether you are talking frost heaving, or lift due to wind forces, those additional 2x6's make a huge difference.

I figure it cannot hurt and for such a cheap thing to do, it's almost dumb NOT to do it.

 

[hangfirew8]

When we built a large deck, we poured the concrete around large bolts with metal plates nutted on the bottom and the threads sticking up. Put a nut and tape over the top threads to stop from concreting them.

Then after it cured we bolted the metal post holders to the bolts. If the posts rot we just replace them. Sold the place 20 years later and posts still fine, in wet humid Maryland.

Posts never touched dirt. All wood that touches dirt will wick moisture and rot, whether it's pressure treated posts or T-111.