Need some concrete footing help

[Boeing]

Question for RIMSHOT. (you must be a drummer)
It does freeze in Virginia....you mentioned "frost"?? I am on the top of a hill with no accumulating water
What's a rat board? The metal building builders put a 2X8 board across the bottom of the metal walls. The dirt floor goes TO this board in most places and in some cases there is an inch or two of daylight under the board. I figured that after gravel then poured 'crete it would close any gaps under the walls.....
This is new for me so please direct me.
Thanks, Rob:confused2:

 

[rimshot]

Question for RIMSHOT. (you must be a drummer)
It does freeze in Virginia....you mentioned "frost"?? I am on the top of a hill with no accumulating water
What's a rat board? The metal building builders put a 2X8 board across the bottom of the metal walls. The dirt floor goes TO this board in most places and in some cases there is an inch or two of daylight under the board. I figured that after gravel then poured 'crete it would close any gaps under the walls.....
This is new for me so please direct me.
Thanks, Rob:confused2:

==========
(Chuckle)

Well Rob, I'm surely not a basketball player and you are right but I just think I'm a drummer.

As far as garage slabs and pole barn floors go There are many variations. In my home state of Michigan the effects of frost have caused building codes to require footings for buildings to be 42" deep.
This obviously does not apply to a pole barn and there are exceptions for a slab for a garage which can be on a slab. Building inspectors can also make some field calls.

Some building inspectors around here require what is known as a rat wall for pole barn and garage slabs. The reason is due to the fact that animals like chipmunks and wood chucks can be very destructive when they choose to dig beneath a garage floor. A rat wall is nothing more than a narrow ditch around the perimeter of a slab or pole barn floor that extends perhaps 16" straight down to keep critters from doing what they do worst when they dig around and under a garage slab.

I once had to get around a garage built on a sandy hill and jack it up to repair the slab it was built on. Believe it or not, itty bitty chipmunks had a field day over the years digging their tunnels beneath that floor. That dry worn old blow sand the garage was sitting on continued to slide out beneath the concrete slab it was sitting on until the concrete cracked and seperated right down the middle. That caused the building to settle front to back.

I repaired it by jacking the walls up and supporting the building on beams, Then I dug down and poured a footing seperate from the floor 42" below grade I laid 5 courses of concrete block up and set the walls back down on the foundation. I then poured a floor. Now that was 20 years ago and no chipmunks have found there way back. Even though pole barns are different if the conditions are similar the same damage could be done to a pole barn concrete floor. Now this was a set of conditions that caused a failure that won't occur to every concrete floor that gets poured. Some sites have different soil make up and conditions but explains the reason for requiring a rat wall. Chipmunks are not necessarily rats either but for doing what they did to that building I just told about they are close enough to a dirty rat that they deserve to be called one. If it looks like a rat, talks and walks like a rat (yadda yadda) it is a rat and the floor in my pole barn gets a rat wall none the less.

By the way, I built my pole barn with two couses of 2 X 6 t&g ground contact skirt board. The bottom course served as a screed point to screed the floor off. In order to do that I obviously held back on installing sheet steel on sidewalls.

Sorry for long post.

rimshot

 

[Boeing]

I missed one thing.....this 16" narrow ditch, is it also poured full of concrete? wonder if some kind of wire...don't know what they call the stuff, about 3/8" squares wire....much finer and stouter than chicken wire...I've seen it used to sift stream dirt for nuggets in N.C. were placed in this ditch and the ditch filled with gravel??? There are mice and I'm sure groundhogs around.....
Thanks for the info.

 

[rimshot]

Soil types of soils and it's bearing qualities has a lot to do with designing a foundation for a building. I'm sure that a well compacted mix of granular particles and small stone makes for a better surface then truck load of loose clay brought in to level a site. Especially if you are expecting to pour a foundation that is going to support the weight of a building anytime soon.

Many pole barns take up lots of real estate and are built on sites that require much fill for the sake of leveling up the grade or you have recently dug several stumps requiring more fill. Despite compaction techniques it's to be expected setting will occur and it obviously occurs more in the areas that receive the most fill. The rat wall can also be thickened and reinforced with rerod to add strength to a floor perimeter. It can be formed or not and it can be poured seperately if it is easier as well as omitted if not required.

I believe for most of us a 4-5 1/2" floor (3500# test concrete) is more than adequate. Everybody given their situation will know best if they need a rat wall or are required to have one. No question that it's more work and I'm willing to bet the majority of garage slabs and pole barn floors are poured without one. I might skip the chicken wire and throw in some rerod however.

Time for me to shut up.

rimshot

 

[Western]

With rebar. A small expense for the return on reinforcement.

Yep, going to use 2 runs of #4 (1/2") and 1 run #3 (3/8) in the footings, mat will be all #3

 

[mojoinco]

In my area (front range/east side of Colorado), most pole barns are put up, then the flat work done. So, deep treated posts, whatever pad work (proud of the surrounding area), compacting the interior, etc. My shop was ~10 years old when we did the flat work. The contractor used some sort of spacer material around the edges (looked like the old black stuff they used to use on stud walls), then laid ~3 1/2" concrete. The doorways were thicker more because of the overlap of the exterior pad and the floor than by any design requirements. The rim wood (I am sure there is a better term, but it escapes me) is the exterior form for the pad.

No cracks 8 years later. I have the TN55, 16' flatbeds, and 1 ton trucks. No issues.

I would consider a couple of features: Cut seams (you will never regret this) on areas you will use a creeper on or roll things across (including an outside pad area where you might leave a large trailer or implement to work on to work as you have time). Any area that will have plumbing (water, drain, electrical) put an access area around it and back fill it with gravel (or whatever) so that you don't have to put a hole in the sidewall, or in the case of fluids, you can access the pipe. I did this for a freeze proof faucet, but wished I had done this for my electrical panel (I would like to pull power to a shed and will now have to put a hole the wall, versus pull a piece of conduit under ground, direct burial from there). Same goes for leaving a penetration point to pull a line for gas or even air to somewhere else (I did put a line in for that -- under ground section is sch 40). Every hole in a wall/ceiling is a point that can leak.

For the walls, consider using 'closures', especially over the tops of your doors and on the prevailing storm walls (it will help with keeping mice & bugs out too). See page 20/21: http://www.metalsales.us.com/files/installation-guides/PostFrameInstallGuide.pdf

Other interesting pages there: Metal Roofing, Siding, Wall Panels and Steel Building Materials - Technical Center Metal Sales Manufacturing -

My shop was built with a proprietary panel by Lester. Good stuff, but I needed new roof cap closures (same as external closures). Had to go to them. No big deal, but anything that is special, means you might be stuck if they are no longer around (or conveniently available). Like adding on or building a matching barn later.

Just my thoughts.

 

[tommu56]

I missed one thing.....this 16" narrow ditch, is it also poured full of concrete? wonder if some kind of wire...don't know what they call the stuff, about 3/8" squares wire....much finer and stouter than chicken wire...I've seen it used to sift stream dirt for nuggets in N.C. were placed in this ditch and the ditch filled with gravel??? There are mice and I'm sure groundhogs around.....
Thanks for the info.

here is a sample plan of a haunched slab (thickened on edges)

see detail 1/1

http://justcad.com/samp1.pdf

 

[toy]

At that rate labor on my slab would have been $15,000. That is a raping. You should expect to pay between $1.25 to $1.75/sf for turn key labor excluding site and pad prep. That means they set up the batters, form it, dig the beams, set the rebar, and pour it. You provide all materials and mini X.

I was referring to cubic yard not square yard. In our area the concrete guys figure up the square footage and the depth and then figure out the cubic yard it would take to pour that amount.

 

[Boeing]

Thank you very much for the good input. I plan on getting this done this summer. Haven't decided if I want to 'crete the whole 24X40 building or...just a 24X10 "shop" area and use crush & run for the 2 car/1 car areas for the tractor and equipment. Seems mud and tire rubber might be better on gravel???? Guess I could epoxy and hose down 'crete periodically...

 

[Boeing]

May I shift gears slightly and ask about "piping" thru this pad before I have it poured?
I'm planning on water into the building and a couple of faucets thru the walls and a deep sink(will need drain). No toilet as there is no septic nearby. (guess I'll get a marine port-a-potty). I figured that the deep sink could drain into the woods somewhere.:ashamed:
Also, I will eventually have electricity.....A meter hung on the outside wall, I guess. Would you suggest that this electricity come STRAIGHT thru the wall....or put a large gray conduit down the outside wall, UNDER the wall and up thru the concrete for elec. cable?
Anything else I might be missing before I have 'crete poured? Thought about a grilled drain line in the middle of the shop floor? the building is 24X40 with the right hand 10' being shop.
Any input is appreciated. Rob