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Framing a load bearing wall on post frame slab

nefarmboy

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Feb 21, 2010
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I have a post frame building that I am getting ready to pour a 6” slab in. I am going to be framing 3 rooms with a second story above it in one corner. I was planning on sinking posts 4’ down like the side walls 8’ apart, running a beam across and then using floor joists between the side wall and my new wall. It is only going to be a 10’ span for the joists. I really didn’t want to pour a footer under the walls if I could get away with it. The second story would be for storage, but nothing crazy heavy. Is this the proper way to do it, or would I be ok with just framing on the 6” slab?
 
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rponfick

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Not sure I understand your construction detail, but do you live in an area of expansive soil? I know in our area, you cannot directly frame on slab, and have to leave a 3" expansion area in the stud walls. Maybe your design accounts for this, or you have no expansive soil issues.
 

David C

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It is contrary to most, if not all, structural building codes in the US to place building loads on a slab on grade. If I am reading your question correctly you are proposing to place second level floor and wall loads on a 6” slab and this would require a minimum footing, 12” below undisturbed soil 12” wide, and 18 “ in height. Most jurisdictions would interpret your design as a two story structure and you would need to design for two story footing which would be larger than that described above.

You can easily search the internet for a site that publishes the current code for your area and determine the min. required footing design.

It is permissible to put partition wall loads on a slab on grade but if the partition wall included ceiling loads, (ceiling framing supported by the partition wall), you would also need a foundation under the wall.
 

sberry

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Yes, call it something else,,,, its now a set of big shelves.
Like most codes there are good reasons. As a true mechanical concern really not much a load bearing wall and the concrete is substantial, in fact would pour it thinner in this area for cost and if a guy wanted to reroute plumbing.
Not much true structural load, not much structure, no roof and no snow load.
 
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sberry

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For a farm boy frame it up and toss junk up there. Forget the posts, its just more stuff you dont need and cant be moved a few inches.
 

Los_Control

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In my area I am encouraged to talk to local building inspectors for advice.
They actually advertise this on the local radio station.
They stress they would rather stop by and offer free advice and have a safe community.
Would be very helpful to know what is required for your location.

Location makes a huge difference on building requirement because of weather.
Frost line, wind, rain, soil conditions ... your local inspector or building codes would be very helpful for this.
Telling us where you live would help with answers from here.

4' deep poles sounds wrong .... 6" slab is not enough to support a bearing column for a 2nd story, and over kill where not needed. Building living quarters in a pole barn ... sketchy.
I know all of this has been done before and worked.

I live in a very dry/warm climate, West TX. Because of oil industry, there is a abundance of used 3" metal pipe. Everybody uses it for building structures, carports, sheds, pole barns etc.
My house has a carport and probably 30+ years old. At ground level I have one post 50% rotted out. I have to replace it. It is a carport and I can do that.
Metal or wood post in a dry climate will rot out.

Building a pole building, 6" slab, 2nd story, living quarters etc... you wont be able to replace the poles ... your building eventually will need to be torn down.
A proper foundation and it could last forever with maintenance.
 
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Jeepster04

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If you put posts in the ground like youre saying and you run a beam between them for the joists, you'll be fine putting the wall on the 6" slab.

I would consider putting something in the bottom of the hole for the posts to sit on.
 

ConCretin

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So some of you think a 6x6 post bearing on dirt in the bottom of a hole is better than the same 6x6 bearing on a 6" concrete slab? It it not uncommon at all to frame interior load bearing walls on a slab on grade. The slab is usually thickened at these locations but it would work just fine without. What's going to happen? The wall isn't going to punch through. OP, place your slab and build your mezzanine.
 

sberry

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I agree and a wall without posts is even better. Stick built wall with a few joist and some plywood to toss **** up on is all that it is here.
 

Los_Control

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So some of you think a 6x6 post bearing on dirt in the bottom of a hole is better than the same 6x6 bearing on a 6" concrete slab? It it not uncommon at all to frame interior load bearing walls on a slab on grade. The slab is usually thickened at these locations but it would work just fine without. What's going to happen? The wall isn't going to punch through. OP, place your slab and build your mezzanine.

That was my point, the 6x6 post will rot out no matter what you do to it.
Eventually it will rot out at ground level.
We may not care if it takes 50 years to do so, we may be dead and gone by then. If someone needed to get a loan and inspection on the place, the poor foundation will not help.

It sounds like the guy is planning on $15k-$20k building, and doing it pole barn style.
The 2 story height, the 6" slab, the 3 rooms upstairs in a corner of building .... They really need to be more accurate with plans and location.
 

kbs2244

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How are the posts going to "rot out" if they are inside the building?

But I agree on the stick built wall directly on the slab

There are whole subdivisions of homes built on slabs around me
(Plumbers hate them)
 

csp

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Not sure I understand your construction detail, but do you live in an area of expansive soil? I know in our area, you cannot directly frame on slab, and have to leave a 3" expansion area in the stud walls.

This is true where there is a free floating slab which is separate from the load bearing exterior foundation of the building.

If the OPs entire interior framing rests on the slab it will move as the slab moves.
 

Tduby

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If I understand correctly you might get a little bit of change in height between the exterior frame and the floating slab inside with proper drainage and and insulation it will be minimal and since it is a pole barn not really noticeable. But this is a perfect example of why for not much if any more money on a finished shop you are better off with a typical foundation and leave pole barns for cheap sheltered storage.
 

rayra

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So much conflicting BS, at least half is irrelevant depending on soils, conditions, regional weather etc. And the OP poses the bait with no clue given about where in the USA this is happening.

If the shell of the building is holding up the roof and we're talking about framing a 2nd story within that shell and NOT connecting the roof loads, don't see why a stick frame on a 6" (reinforced?) slab won't work.

And with no info on where this is happening and no clue what codes obtain, it may be legal, it may not. And it seems most are commenting on their own circumstances or concerns.

OP didn't give us enough info and most of the comments ***-u-me too much.
 

manwithtools

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So much conflicting BS, at least half is irrelevant depending on soils, conditions, regional weather etc. And the OP poses the bait with no clue given about where in the USA this is happening.

If the shell of the building is holding up the roof and we're talking about framing a 2nd story within that shell and NOT connecting the roof loads, don't see why a stick frame on a 6" (reinforced?) slab won't work.

And with no info on where this is happening and no clue what codes obtain, it may be legal, it may not. And it seems most are commenting on their own circumstances or concerns.

OP didn't give us enough info and most of the comments ***-u-me too much.

Agreed, so much conjecture, it's almost a sin.
 
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