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Old 05-24-2016, 05:15 PM   #1
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General framing question for post building


I would like to know if I can use a span of 12 feet between 6x6 posts. The top of the posts will be fitted with double 2x10's for the exterior wall girder, notched & bolted to the 6x6. Girder is doubled on the exterior side of the wall & the interior will also have a 2x10. The top plate will be a double
2x8 sitting on top of the girders & the posts. The building is 18 feet x 24 feet. Eighteen being the width so there is a center wall post on either side at 12 feet splitting the 24' building length.
The center post will also have a double 2x10 x18' each side of the 6x6 post. Ceiling joists will run from the gable end wall to the center 2x10. So the joists will be 2x8's x 12 feet. running from the gable wall to the center span girder.

I don't know if I've explained this correctly. This will be a storage building, un occupied. We never get any snow or ice buildup here in South Carolina. If it snows an inch or two overnight, it's gone by morning sunrise, so there is no snow load danger. So what I'm really asking here is can I span 12 feet between 6x6 posts. I can't find anything specific on the subject from the engineering point of view on small building construction. I do have a permit for the construction. So far I'm approved for my post holes, but the inspector said nothing to me about my post hole locations. All he asked me was if I was using 6x6 for the posts. He said all I would need was an inspection when the framing was done. He also asked what the building was for. I told him tool & tractor storage only-no barn animals. He said ok.

Thanks for your opinions.
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Old 05-24-2016, 06:27 PM   #2
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Re: General framing question for post building


I had a difficult time visualizing your project from the description. Certainly you can span any distance you want, you just need to size the beam correctly, which is based on the load the beam will carry. The design load includes dead load of the framing, plus live load of storage material, snow, wind, that sort of thing. I doubt you will find explicit code material for sizing a beam, usually the beam size is customized based on the actual applied load. Code will typically tell you the load in pounds per square foot for live and dead load, you run the calculations.
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Old 05-24-2016, 11:04 PM   #3
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Re: General framing question for post building


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I had a difficult time visualizing your project from the description. Certainly you can span any distance you want, you just need to size the beam correctly, which is based on the load the beam will carry. The design load includes dead load of the framing, plus live load of storage material, snow, wind, that sort of thing. I doubt you will find explicit code material for sizing a beam, usually the beam size is customized based on the actual applied load. Code will typically tell you the load in pounds per square foot for live and dead load, you run the calculations.
Yes, I had a difficult time trying to ask my question. Since posting here, I located the IRC 2012 which in general terms requires that the maximum span between 6x6 posts be no greater than eight feet between posts. This is somewhat of a general guideline because it would require more details on the construction in general. I've been told I can span 12 feet between my posts. However, if I get the one code enforcement official who bothers to look at the 2012 IRC & is guided by the 8 foot general guideline, I could face a losing battle to convince him otherwise. I can live with the 8 foot spacing between posts. Twelve would be great for my equipment storage, but not worth getting into a brew Ha Ha with the code official. Thanks!
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Old 05-25-2016, 04:12 AM   #4
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I had a difficult time visualizing your project from the description. Certainly you can span any distance you want, you just need to size the beam correctly, which is based on the load the beam will carry. The design load includes dead load of the framing, plus live load of storage material, snow, wind, that sort of thing. I doubt you will find explicit code material for sizing a beam, usually the beam size is customized based on the actual applied load. Code will typically tell you the load in pounds per square foot for live and dead load, you run the calculations.
Yes, I had a difficult time trying to ask my question. Since posting here, I located the IRC 2012 which in general terms requires that the maximum span between 6x6 posts be no greater than eight feet between posts. This is somewhat of a general guideline because it would require more details on the construction in general. I've been told I can span 12 feet between my posts. However, if I get the one code enforcement official who bothers to look at the 2012 IRC & is guided by the 8 foot general guideline, I could face a losing battle to convince him otherwise. I can live with the 8 foot spacing between posts. Twelve would be great for my equipment storage, but not worth getting into a brew Ha Ha with the code official. Thanks!
The distance between posts does not determine how much load the post can carry, the distance would only cause a problem with the beam that sits on top of the posts; meaning the further apart your posts are the larger the beam that sits on top of them would need to be.The size of posts determine how much weight it can carry not how far apart they are. Hope this made sense!
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Old 05-25-2016, 11:01 AM   #5
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Re: General framing question for post building


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The distance between posts does not determine how much load the post can carry, the distance would only cause a problem with the beam that sits on top of the posts; meaning the further apart your posts are the larger the beam that sits on top of them would need to be.The size of posts determine how much weight it can carry not how far apart they are. Hope this made sense!
Yes! it makes sense to me. But here is the problem. the 2012 IRC code for pole barns- Post & frame structure calls distance between posts not to exceed eight feet. Beyond eight feet-the code calls for documents & calculations (R106 & R301) to be submitted to the building official. In other words, the code allows you to space posts at 8 feet. After that, complete details & calculations of the design criteria must be submitted. At that point you would be asked to show the load bearing criteria of the girder/top plate mounted to the posts. The code also states that the official can waive any or all the documents as they see fit.

In other words- The code is allowing you to build a post & beam building with reasonable distance between posts (8 feet), after that you may have to present engineering calculations to determine the size of girder/top plate lumber you are specifying, along with all other details, like roofing, etc.
So once again, we have a code that is complex to understand, expensive to provide, & then left in the hands of an inspector who may or may not have the skills or engineering background required to come to the correct decisions. No wonder Trump is gaining in the poles.
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Old 05-25-2016, 11:49 AM   #6
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Re: General framing question for post building


You submit plans with calculations which specify a certain beam or cross member - material and geometry. Office approves and gives permit. You install. Inspector ensures it is installed as specified on the permit.

Why the dig at inspectors?
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Old 05-25-2016, 12:47 PM   #7
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Re: General framing question for post building


I too am puzzled why you are so mad at the code. This is pretty typical in code, they give you a prescriptive solution to a framing issue. In this case, apparently you can go up to 8 feet between posts with no calculations. Presumably the code specifies the size of the structural members. If you want to go bigger, you need a design with calculations.

This is really no different than building a deck or a house. If the code specifies a method of construction, you typically can avoid the need to hire an engineer or architect. If you want or need to deviate from the prescriptive design, you submit the calcs and plans to show that your design is safe.
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Old 05-25-2016, 04:14 PM   #8
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Re: General framing question for post building


What size would a window header be for a 12 foot window opening?
If your code has tables for window headers, would that apply here?
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Old 05-25-2016, 04:29 PM   #9
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Re: General framing question for post building


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Originally Posted by 1acre View Post
You submit plans with calculations which specify a certain beam or cross member - material and geometry. Office approves and gives permit. You install. Inspector ensures it is installed as specified on the permit.

Why the dig at inspectors?
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Originally Posted by Daniel Holzman View Post
I too am puzzled why you are so mad at the code. This is pretty typical in code, they give you a prescriptive solution to a framing issue. In this case, apparently you can go up to 8 feet between posts with no calculations. Presumably the code specifies the size of the structural members. If you want to go bigger, you need a design with calculations.

This is really no different than building a deck or a house. If the code specifies a method of construction, you typically can avoid the need to hire an engineer or architect. If you want or need to deviate from the prescriptive design, you submit the calcs and plans to show that your design is safe.
You both are reading me the wrong way. I am neither mad at inspectors or the code .I'm frustrated with the code. If you take time to look it up you will see why. Mr. 1 acre-your correct! Just submit plans with calculations. Do you know how to do that? It requires dead & live load calculations, lumber sizes & verifying load carry capabilities. It also requires detailed drawings.

I'm doing nothing more than a storage building 24'x42' to house a tractor on a 5 acre field. If you look up the codes, they are really not specific other than covering the situation by stating the inspector has the last word.

I just finished building a home two years ago, & I ran into the same stupid stuff with crawl space ventilation requirements & LVL beams. The inspector could not grasp what he was reading & seeing on my house plans. He finally said OK after several calls to the architect. My architect said he just did not understand the engineering (math) nor could he properly read the plans.

So rather than get on me saying I'm on the inspectors back, why don't you consider my situation. Yes, I can build this barn with 8' post spacing, but 12' would be better for my needs. How do I get an inspector to roll with me.
My foundation/footings have been approved. There will be only one more inspection which is after the building is framed & in the dry. At that point, its a done deal. There will NEVER be a CO issued, as it's a storage building. So if he fails it, who really cares? His disapproval in this case would be meaningless to me, except for the fact, I take pride in doing things right. But in this case doing it right means I have to spend at least $1,000 plus with an engineer to give me calculations & plans? I'm not going to spend 10 grand to house a 2 grand tractor & a bunch of hand tools shovels that are fifty years old.

Hopefully now you will understand the situation a little better. Maybe you can offer a solution rather than a personal criticism. Maybe you can show me how to do those needed calculations & drawings. I'm NOT a stupid person. I just don't have the engineering math needed. Maybe you can help me out & do the math for me. Why are you so down on this DIY'er.
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Old 05-25-2016, 04:41 PM   #10
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Re: General framing question for post building


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What size would a window header be for a 12 foot window opening?
If your code has tables for window headers, would that apply here?
I can't compare it to a window opening-However the code states for a barn door 12 foot wide opening the header must be 2x10 doubled. You bring up a very good point here. But does it apply in this case. Don't know. A barn door is usually hung on the gable end of the structure. I'm really not sure, but you bring up a really good point on spans between posts. THANK YOU! Maybe that could convince an inspector if I present it to him for consideration.
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Old 05-25-2016, 05:00 PM   #11
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Re: General framing question for post building


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Mr. 1 acre-your correct! Just submit plans with calculations. Do you know how to do that? It requires dead & live load calculations, lumber sizes & verifying load carry capabilities. It also requires detailed drawings.
To answer the question, yes. Building structures aren't directly in my wheel house, but I could figure it out. Depending on how complicated it is, I would even stamp it with my PE stamp.

Have you tried calling your regulating agency and asking them? I've found actually going down to the office and asking questions gets some results. My county even has a guy who sits there full time and answers any questions you may have, along with all the code books. Have you tried doing that?

BTW, almost every modern house has a 2 car garage. And those openings are how big? Since it is done routinely, your regulating agency may already know what you need if your building and span isn't too crazy. If that is the case and you need an engineer, I'm sure it wouldn't cost too much if what you are trying to do is pretty straight forward.

No reason to be frustrated at the code and your regulating agency, especially if you haven't asked them any questions. Sure, if they're not helpful, that's one thing, but just ranting online probably won't get you very far. It certainly won't build your shed for you.
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Old 05-27-2016, 07:57 AM   #12
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Re: General framing question for post building


The risk from assumptions should be yours only. If you don't need permit, why go ask the town inspector? Verbal or written it becomes official for the town. Saving $500 is not worth engineering on your own.
8' span is known and practiced standard for double 2x10 beams/girders. That is for one floor and roof, however. Whoever suggested 8' is trying to make life easier for you. 2x8 spans 12' but it is about at its limit. For unused ceiling it is more than enough.
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Old 05-27-2016, 11:25 AM   #13
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Re: General framing question for post building


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To answer the question, yes. Building structures aren't directly in my wheel house, but I could figure it out. Depending on how complicated it is, I would even stamp it with my PE stamp.

Have you tried calling your regulating agency and asking them? I've found actually going down to the office and asking questions gets some results. My county even has a guy who sits there full time and answers any questions you may have, along with all the code books. Have you tried doing that?

BTW, almost every modern house has a 2 car garage. And those openings are how big? Since it is done routinely, your regulating agency may already know what you need if your building and span isn't too crazy. If that is the case and you need an engineer, I'm sure it wouldn't cost too much if what you are trying to do is pretty straight forward.

No reason to be frustrated at the code and your regulating agency, especially if you haven't asked them any questions. Sure, if they're not helpful, that's one thing, but just ranting online probably won't get you very far. It certainly won't build your shed for you.
Thanks for your advice. Actually I was going to call the code inspector's office, but then I felt that they would not be in a position to answer engineering questions because that now puts them in the position of giving building advice which is something they may not do for legal reasons.

Great minds work alike! You mentioned 2 car garage construction. My garage was an issue when my architect drew up my plans. The garage is around 24'x28' foot clear span. In order to meet code we had to use pre fabricated wood ceiling joists placed 12" on center. This was because above the garage was a Bonus Room & in order to meet codes for a clear span garage with no
supporting columns & meet the load requirements of the bonus room we had to use engineered joists.

There are answers to all of these problem. But as a homeowner & DIY'er it sometimes is a problem to get to the correct information. I'm going to do some more asking at the code office & see what I get. If that fails, I'm going to ask my home architect to take a look at my storage barn plans & the code & if necessary, I will ask her for the calculations needed.

I pulled a permit for this building project. The inspector has already been out here & green lighted my Post footing holes. He asked no questions other than to ask me what size lumber I was using for the posts.

I am not trying to get anything past an inspector. I'm trying to do the job right. I have the building skills necessary to do the work. What brings hesitation to the job is the one engineering question on trying to understand code requirements the way they are written & what actually is "Real World". I see a lot of people who are DIY who put up structures That should be condemned from the get go. I pride myself on the work I can do & the knowledge I have with which to do it. Thanks for you suggestions & advice.
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Old 05-27-2016, 12:07 PM   #14
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Re: General framing question for post building


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The risk from assumptions should be yours only. If you don't need permit, why go ask the town inspector? Verbal or written it becomes official for the town. Saving $500 is not worth engineering on your own.
8' span is known and practiced standard for double 2x10 beams/girders. That is for one floor and roof, however. Whoever suggested 8' is trying to make life easier for you. 2x8 spans 12' but it is about at its limit. For unused ceiling it is more than enough.
Yes- I fully understand that risks & assumptions belong to the project originator. That's why I'm SEEKING advice & not winging it as they say. It's not a case of saving $500. I'm not sure where that came from as I don't recall mentioning $500, but maybe I gave you that impression somewhere.

I am not "Engineering" on my own. I'm not an engineer by profession. I don't diagnosis & self medicate either.

The plans I have for this barn come from a Professional architect. The plan is designed to cover codes & situations in just about every state. Original plan calls for 6x6 posts space at SIX feet apart on the 24' dimension. The girders called for are double 2x10's notched & bolted to the posts. Really overkill here in the South, but in the North in some states, local code requires it.

The 2012 IRC uniform code calls for a span of no greater than 8 feet between posts for AUX. residential buildings with double 2x10' girders.

I want to build with posts 12' on centers. Here is where the code becomes difficult to interpret. Code R106 references to code R301 which essentially requires you to show your theory & calculations & engineering when you span over 8 feet. The code also states that the local building authority can either enforce the code (IRC) or modify it in any way they want to modify it along with any submissions or arguments the owner builder may submit. This is more ore less on how the IRC works for ANY building requirements. AS a DIY'er who is trying to build a quality structure & to also build within the code requirements, it becomes difficult to understand what is legal & what satisfies local authorities.

Have you ever built anything that requires permitting? I've built a total of three homes in the past thirty years & all built & occupied by me & family.
I'm not exactly a stranger to this code stuff. Over the years it has become better with the adaptation of IRC 2012 by many of the states & local code officials. However it still leaves a lot of room regarding things like Barns, Pole buildings, outbuildings or special use residential buildings.

I agree with you regarding 8' spans with 2x10. My plan is/was to set 6x6 posts 12' feet apart & run double 2x10's on the exterior wall side & on the inside another 2x10 directly opposite the exterior double 2x10's. All notched & bolted to the posts. The top plate of the wall would be 2x8 doubled.

Based on the code of 8' between spans- I could be asked by an inspector to prove out to him/her that I can safely use 2x10's as described to carry the additional weight between 12' posts. I assume to do that I would need calculations on weight load of roof-dead & live. I would need to know raw lumber deflections for 2x10 spanning 12'. I would then need to show the math that proves out that the building design will work & not collapse under its own weight. I am not an engineer. Can you do the necessary engineering & calculation that an inspector may ask for? And keep in mind the inspector is under no obligation to grant an approval no matter what I present to the inspector. What happens then? Thanks for your interest in my problem. I'm trying to do it right.
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Old 05-27-2016, 12:15 PM   #15
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Re: General framing question for post building


I build a lot of pole buildings.We have a lumber yard in the area that specializes in custom pole framing and has an engineer on staff.I tell them what I want .They engineer it and sell me the package.Cheaper and better quality than the big box stores and no engineering cost.
Your location may help find a better answer.
Do a search for places like this http://www.graberpost.com/ in your area.
A lot of these buildings have 16' doors so the posts are obviously over 8' OC.The difference at these spans are the headers
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