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

 

[CurlyDave]

...guess I'll get a marine port-a-potty...

Dig a dry well (hole about the size of a 55 gallon drum, full of gravel) and drain the sink into that. Mount a funnel on the wall and drain that into the same dry well.

 

[markrahn]

for the drain, gray water only, you could build out a 20 foot long by 3 foot wide french drain, just put it about 3 feet deep and line the bottom with about 16 18 inches of septic rock. For those times when you may have a BM experience, you could get a composting toilet.

 

[davygp38]

...guess I'll get a marine port-a-potty...

Dig a dry well (hole about the size of a 55 gallon drum, full of gravel) and drain the sink into that. Mount a funnel on the wall and drain that into the same dry well.

I was thinking of doing this for my new Garage. The problem is, in the peoples republic of New York, everything has to be inspected several times throughout the build. I was thinking of hiding the pipes under the slab, then cutting them out when the build was done but who knows. If anyone has any tricks I could use to sneak the plumbing in it would be appreciated.

 

[Boeing]

"Once upon a time.....there was a new concrete floor to be poured. There was a toilet line (4") with flange set in place. A piece of waxed paper was placed over this toilet flange and concrete was poured for the entire floor. As everything looked like a normal barren floor an inspection was made successfully. After said inspection was finished the waxed paper was gently chipped out and VIOLA....a toilet flange appeared....
But we all know how fairy tales are ficticious...

 

[Boeing]

Dave....or somebody else, should I put in a large conduit from the outside, under/thru the pad and up the inside wall for electricity? or plan on new 'lectricity to go THRU the thin steel wall? I guess a meter would be mounted on the wall, huh? these steel buildings are just so thin....I guess if I...planted a small light pole they could attach to that and go underground to the building.

 

[tommu56]

If the meter is to be on the out side of the building so the reader can read it I would poke through to the panel.

If the meter and disconnect is some were else (in the house or other building) bring it in through the slab don't forget to put a ground rod in too. while you are at it before the pour.

Again you can can rough it in with a female coupling with a flush plug just below the surface (so no one can see it) and chip it out later and run the stub out past the side of the building under ground out of site. just grease the plug and pipe up so the concrete won't stick to it

 

[CurlyDave]

"Once upon a time.....there was a new concrete floor to be poured. There was a toilet line (4") with flange set in place. A piece of waxed paper was placed over this toilet flange and concrete was poured for the entire floor. As everything looked like a normal barren floor an inspection was made successfully. After said inspection was finished the waxed paper was gently chipped out and VIOLA....a toilet flange appeared....
But we all know how fairy tales are ficticious...

I don't think I would put an illegal toilet in an outbuilding. Too much water with each flush, too much sewage, and in most places a big fine if you are caught.

OTOH, every time I am out in the woods and need to go #1, I don't run off looking for a men's room. A dry well, or even a French drain is good for handling small amounts of water.

* * * * * * *

You need more than an electric meter -- you need an electric panel also. And, you need a plan for electrical distribution inside the building. Conduit? Armored cable?

If your plan involves a piece of plywood, or even dimensional lumber to hold the meter and panel that you are going to mount outside the building, mount it on the North side if possible. Sunlight really tears up paint on wood, and facing North minimizes this.;

 

[tommu56]

Don't mount meter socket on any wood put some extra 2X4 wood on the back of the metal and use 4 1 1/2' short lengths of 1" pvc conduit and long lag screws to space the meter socket out from the metal. this will give you about 3/4" from the ribs and 1 1/2" to the flat so no debris collects or it can be cleaned out. Coat the pipe ends with clear silicon caulk and re caulk after its all together.

tom

 

[Boeing]

That's a great idea Tommy....I HATE crushing the steel ribs. And Dave, Thanks, I plan on running romax in the interior, I don't think that requires conduit. If it does then #12 wire thru plastic conduit.
Thanks guys.

 

[CurlyDave]

In CA, where I am re-building my burned down house, exposed romex can not be run less than either 7' or 8' above the floor. I don't remember which but my inspector reminds me.