# Pouring Concrete floor in existing pole barn



## kdrymer

I am planning to have a concrete floor poured in my existing 25' x 24' pole barn. Barn is about 30 years old so it doesn't have any settling occurring. Contractor plans to pour 5 inches of 4,000 PSI concrete with rebar reinforcement on top of a compacted gravel base. The current dirt floor will need to be dug down 8 - 10 inches, and then 3-5 inches of gravel brought in and compacted and then 5 inches of concrete on top of that. I have some questions/concerns that I wanted to get some feedback on. I attached a few pictures for reference.

1. Should a vapor barrier be put down between the gravel and concrete? Contractor didnt mention about doing this so I want to ask. 

2. I believe that to bring the floor to the correct height so my garage doors still close properly the concrete will come up a few inches along the perimeter skirt boards (which effectively will also be used as forms I believe). Should I brace the outside of the boards to prevent the boards from bowing out when the concrete is being poured?

3. Do I need to be concerned about concrete being poured under the skirting boards and then any heaving during the winter months (I live in upstate NY) causing the boards to heave upwards? Would the compacted gravel underneath prevent the concrete from migrating under the boards?

4. Along the posts that protrude into the inside, should I apply any type of expansion strips (felt/tar paper) along the bottom where the concrete contacts the post, to allow for movement of the concrete? 

Thanks very much for your feedback!


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## Wuzzat?

Disclaimer: I am not a civil engineer so this is merely my two cents.

You seem to be the curious type.  Have at it. . .
http://www.eng-tips.com/viewthread.cfm?qid=392549

You might also search
"coefficient of expansion" 
for concrete.

The deeper you look, the more questions pop up.
Get at least three bids.  
The things each contractor will say will all sound reasonable and they may all say different things.
You'll learn more with each bid.
No contract will say, "We guarantee to solve your problem."  They'll say, "We will furnish and install. . .".

I've heard of one contract where the HO was supposed to guarantee that the contractor would solve the HO's problem (a cracked basement floor within the 10 year warranty on the house).

Good luck.


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## nealtw

If you are using that bottom board for forms you will need to drive a stake every 3 ft around the building about 2 ft from the building and then cut a 2x4 to fit tightly between the stake and the board.


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## bud16415

He won&#8217;t be using the bottom ring as a form as the bottom of that piece is his finished floor height the way I understand it.
I&#8217;m no expert they should be around. 
I personally would use it as the form and have a little ramp outside the doors coming in. that&#8217;s how we did my nephews and we put a small grade to it so water runs out the door. If not that I would slope it slightly to the center and have a couple floor drains. I have seen guys spray the outside frame down with used oil so as to not get a bond or tack up the half inch thick tar board for the outside edge and around the poles. I would use the mesh instead of rebar but make sure they pull it up after the pour. With pouring on top you would have to adjust the door height though.   

My guess is after 30 years your bank gravel floor is pretty well compacted.

Let&#8217;s see what the pros say.


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## kdrymer

Yes the bottom of the board is approximately the level of the existing dirt floor, as you can see in the corner picture with the garage door track. So I assume they would need to bring in their own forms to be below the inner edge of the skirt board...

Should I wrap the bottom of the posts with any kind of expansion strips? In addition to allowing for movement it would prevent concrete from directly touching the posts and potentially cause moisture issues I would think?


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## nealtw

I would be putting underground treated 2x4 against the post for forms that would be left in place. The space to the outside wall can be covered with a bit of gravel or a skim coat of concrete.
If you ever have to change a post it could be done from the outside with out disturbing the floor.
I don't know enough about expansion to get into that.


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## kdrymer

Thanks all for the feedback! It turned out great!


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