# Slab on grade shed.



## [email protected] (Jan 10, 2010)

12x12 you do not need control joints. Pour the whole slab 6" and be done with it. It is small enough to float on the frost. If you only dig 12 inches down what good will that do you.

Is you frost depth 12" or 48" as you have said before. If you dont dig all the way to below frost line it does nothing but waste concrete.

A footing on a mono slab for a two story house is only 15" wide and 12" deep, anything deeper (here its 24") is to get it below frost line.


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## FramingPro (Jan 31, 2010)

[email protected] said:


> 12x12 you do not need control joints. Pour the whole slab 6" and be done with it. It is small enough to float on the frost. If you only dig 12 inches down what good will that do you.
> 
> Is you frost depth 12" or 48" as you have said before. If you dont dig all the way to below frost line it does nothing but waste concrete.
> 
> A footing on a mono slab for a two story house is only 15" wide and 12" deep, anything deeper (here its 24") is to get it below frost line.


48" here


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## Chris Johnson (Apr 19, 2007)

Foundation walls are placed 4' below grade and your slab either floats if none structural or if structural is needed it needs to be designed by the engineer including the placement and compaction of materials below. Not too often we have structural slabs on grade up here, we usually do the frost walls on perimeter and if needed piles are placed to keep point load areas below frost


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## [email protected] (Jan 10, 2010)

Our concrete companies want the slabs cut no more than 12'x12'. I usually try to cut smaller around 11. If the slb is thicker your joints can be farther apart. Control joints are not for frost nick there for the expansion and contraction and dishing within the slab itself.


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## FramingPro (Jan 31, 2010)

[email protected] said:


> Our concrete companies want the slabs cut no more than 12'x12'. I usually try to cut smaller around 11. If the slb is thicker your joints can be farther apart. Control joints are not for frost nick there for the expansion and contraction and dishing within the slab itself.


yes,
so what frost just moves it and you hope it moves as one :blink:?


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## Framer53 (Feb 23, 2008)

Turn the TV on and watch the football game. I know it isn't hockey but...

Second I told you not to worry back when you first started this threAD last year. yes the frost may or may not move it. Yes the shed at different times of the year may be out of level. So what. it is only a small shed. don't obsess about it to much.

Like I told you, I live across the lake from you with the same 48" frost level, although I am 58 years old and never seen it go that far. Not important on small structures like a shed that is not attached to a house or garage.:thumbsup:

Now turn the TV on and watch the halftime show....:clap:


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## Chris Johnson (Apr 19, 2007)

Yes when I was in the US slabs are cut at 12x12, Canada is 10x10.


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## duburban (Apr 10, 2008)

so nick, its obvious you need control joints in a 10"x10" grid and you must acid stain the squares with different colors. its a decorative shed code for all of north america. tell them you'll give em a deal on water based stains since its the greener thing to do.


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## FramingPro (Jan 31, 2010)

Framer53 said:


> Turn the TV on and watch the football game. I know it isn't hockey but...
> 
> Second I told you not to worry back when you first started this threAD last year. yes the frost may or may not move it. Yes the shed at different times of the year may be out of level. So what. it is only a small shed. don't obsess about it to much.
> 
> ...


oh ok. i over analyze things alot, Chris can tell you all about it.
So i guess theres not much i can do for we live in an area prone to frost heaving. Im not gonna make frost walls :no: so just pour it and be done with it. Im just worried that it could warp it and make my roof look ****ty but.. ill trust you guys


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## dom-mas (Nov 26, 2011)

[email protected] said:


> If you only dig 12 inches down what good will that do you.
> 
> Is you frost depth 12" or 48" as you have said before. If you dont dig all the way to below frost line it does nothing but waste concrete.
> 
> A footing on a mono slab for a two story house is only 15" wide and 12" deep, anything deeper (here its 24") is to get it below frost line.


I don't think so. I'm not a concrete guy at all but I know that here frost line was 4' but recently was changed to 6' because of the hundred year rule, but slabs on grade still need that thicker area with extra rebar around the perimeter. Nothing goes even close to below the frost line. I think 2' is typical but not certain. Like i say, not a concrete guy but i know what I see. Not always sure why though hahahaha. It may just be for the load of the exterior walls, probably similar areas beneath any interior load bearing walls or posts.

Also heated concrete is totally different from non heated. Heated foundations can be poured anywhere at all. It's only unheated that need to be below the frost line.

Really not necessary for a shed tho


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## txgencon (Jan 4, 2011)

You could get by with a 4" slab. But you want the edges down in the ground enough to keep the armadillos from digging under it so you should thicken the outer edges of the slab.


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## FramingPro (Jan 31, 2010)

txgencon said:


> You could get by with a 4" slab. But you want the edges down in the ground enough to keep the armadillos from digging under it so you should thicken the outer edges of the slab.


armadillos in ontario :laughing::laughing:


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## Sar-Con (Jun 23, 2010)

It's good to ask the questions now, but check with the local bldg. dept. on what they will accept. 12x12 needs a permit. Usually they accept a floating slab up to 500-600 before they call for a frost footing (garage, shed or otherwise). 

I would frame this up with a 2 x 8, thicker slab for 1' and then the rest can be anywhere from 5-6". Put mesh in, don't bother with rebar. Solid base of 12" min gran A, and make sure all the top soil and slop is gone. Base should be at least 12" beyond the perimeter wall (in this case, 14' x 14')

Because the shed is not insulated, no need to put insulation down around the perim.

It still has the chance to float a bit with frost heave, but with a properly compacted and free draining base you will minimize that risk.


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## [email protected] (Jan 10, 2010)

dom-mas said:


> I don't think so. I'm not a concrete guy at all but I know that here frost line was 4' but recently was changed to 6' because of the hundred year rule, but slabs on grade still need that thicker area with extra rebar around the perimeter. Nothing goes even close to below the frost line. I think 2' is typical but not certain. Like i say, not a concrete guy but i know what I see. Not always sure why though hahahaha. It may just be for the load of the exterior walls, probably similar areas beneath any interior load bearing walls or posts.
> 
> Also heated concrete is totally different from non heated. Heated foundations can be poured anywhere at all. It's only unheated that need to be below the frost line.
> 
> Really not necessary for a shed tho


Im not sure what they do in your area with regards to slab on grade foundation. Here everything has to be 18" below grade period. The perimiter footing is based on both loads and frost depth here. Ive put in mono foundations that only reguired a 12" wide 6" deep footing one bar of steel in the perimeter. We still have to go 18 down and have 6 " from finished grade to wood structure. 

What do you mean by heated concrete? Radiant? There even more stringent with radiant slabs and slabs for living space. Ive never seen or heard of a heated foundation.


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## dom-mas (Nov 26, 2011)

[email protected] said:


> Im not sure what they do in your area with regards to slab on grade foundation. Here everything has to be 18" below grade period. The perimiter footing is based on both loads and frost depth here. Ive put in mono foundations that only reguired a 12" wide 6" deep footing one bar of steel in the perimeter. We still have to go 18 down and have 6 " from finished grade to wood structure.
> 
> What do you mean by heated concrete? Radiant? There even more stringent with radiant slabs and slabs for living space. Ive never seen or heard of a heated foundation.


It's not really the foundation that's heated, it's the space between the foundation walls that's heated but the foundation gets the radiant heat. Most foundations here, 99.99% I would guess, are poured walls (or block but they are becoming very rare) on top of footings (I'm talking homes not sheds). These are basements not crawl spaces and are fully heated so the concrete doesn't freeze. In these instances the footing can be down 1' or 10' , doesn't matter. When it's an unheated crawlspace that's filled with gravel and no ducting, the footing needs to extend below the frost line, which was 4' until about 5 years ago when it became 6'. So if it is a building that falls within the OBC (ontario building code) those criteria must be met. If a slab on grade is below a heated building then the footing doesn't need to be below the frost line, but I've always seen them about 2' thick (the integrated footing not the slab). Again, not sure why. Maybe because of load bearing issues or maybe just because it's what people do, no idea, but it's waht i always see. And that footing area around the perimeter always has at least 3 runs of rebar, one near the bottom and 2 towards the top. 

Like I say, not even close to necessary for a shed, but as someone else mentioned 144sqft is over the norm of what doesn't need a building permit. In my municipality and all others I've heard of it's usually 100sqft that doesn't need one.


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## FramingPro (Jan 31, 2010)

dom-mas said:


> It's not really the foundation that's heated, it's the space between the foundation walls that's heated but the foundation gets the radiant heat. Most foundations here, 99.99% I would guess, are poured walls (or block but they are becoming very rare) on top of footings (I'm talking homes not sheds). These are basements not crawl spaces and are fully heated so the concrete doesn't freeze. In these instances the footing can be down 1' or 10' , doesn't matter. When it's an unheated crawlspace that's filled with gravel and no ducting, the footing needs to extend below the frost line, which was 4' until about 5 years ago when it became 6'. So if it is a building that falls within the OBC (ontario building code) those criteria must be met. If a slab on grade is below a heated building then the footing doesn't need to be below the frost line, but I've always seen them about 2' thick (the integrated footing not the slab). Again, not sure why. Maybe because of load bearing issues or maybe just because it's what people do, no idea, but it's waht i always see. And that footing area around the perimeter always has at least 3 runs of rebar, one near the bottom and 2 towards the top.
> 
> Like I say, not even close to necessary for a shed, but as someone else mentioned 144sqft is over the norm of what doesn't need a building permit. In my municipality and all others I've heard of it's usually 100sqft that doesn't need one.



108 sqft in toronto


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## TimelessQuality (Sep 23, 2007)

Why not on skids/wood floor? Then they can take it with them when they move....


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## dom-mas (Nov 26, 2011)

FramingPro said:


> 108 sqft in toronto


Same here, but 100sqft is easier to remember and 8x12 is the basic modular shed that everyone builds


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## footballfan (Mar 6, 2011)

Hey nick if you are worried about the slab shifting and messing up your framing. What if you built it like a pole barn put your posts in 48” and frame your roof poor around your posts and fill in your walls just a possibility? Sort of like this http://www.goodblogger.net/2011/09/11/pole-barn/


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## TheItalian204 (Jun 1, 2011)

You firm on concrete slab?


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## FramingPro (Jan 31, 2010)

TheItalian204 said:


> You firm on concrete slab?


this thread was made last year and i was bored and unsure so i brought it up again i don't even know if i am still doing this shed :whistling


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## TheItalian204 (Jun 1, 2011)

FramingPro said:


> this thread was made last year and i was bored and unsure so i brought it up again i don't even know if i am still doing this shed :whistling


Well to save yourself some money and get some extra experience(just gotta be extra careful) you could probably pour footing and rise with CMU units...just dont forget to reinforce with re-bars...then you would only need to pour maybe 3" for floor or can even get away without it depending on how lavish the shed will be. 12'x12' is almost garage size though I must say.

P.s. I am notoriously bad with dates.


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## FramingPro (Jan 31, 2010)

TheItalian204 said:


> Well to save yourself some money and get some extra experience(just gotta be extra careful) you could probably pour footing and rise with CMU units...just dont forget to reinforce with re-bars...then you would only need to pour maybe 3" for floor or can even get away without it depending on how lavish the shed will be. 12'x12' is almost garage size though I must say.
> 
> P.s. I am notoriously bad with dates.


so make a frost wall out of block? :blink:


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## TheItalian204 (Jun 1, 2011)

FramingPro said:


> so make a frost wall out of block? :blink:


its not really frost wall...

You are still pouring concrete foundation for it...you just building foundation out of CMU units instead of grade,slab etc...

Thats how we build back home,I am not sure if it is CC accepted but for shed it would be up to code I would think...just suggestion out of air since you been wishful thinking anyway:laughing:


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## FramingPro (Jan 31, 2010)

TheItalian204 said:


> its not really frost wall...
> 
> You are still pouring concrete foundation for it...you just building foundation out of CMU units instead of grade,slab etc...
> 
> Thats how we build back home,I am not sure if it is CC accepted but for shed it would be up to code I would think...just suggestion out of air since you been wishful thinking anyway:laughing:


do you pour the footings on grade i don't follow.


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## TheItalian204 (Jun 1, 2011)

FramingPro said:


> do you pour the footings on grade i don't follow.


Ok so I am actually gonna describe you the process...

Now that I think about it it might be tougher to do that what you initially thought and it might not be up to canadian code,but extra info never hurt anybody.

You dig your perimeter 14" down by width of the block (whatever your preference might be).

first 6" you fill with 3/4 down and pack it...make sure you got 6" because 3/4 packs down pretty well.

Then you get your form and reinforcement.

You poor your leftover 8"inches of concrete...as poured,stick rebards into concrete in mean of the width every 12-18".

Finsih,let it cure.

Then start laying your block from up there.

Depending on what you building depth (3/4,concrete) increases.


My grandpa used to build limestone fences like that approximately 10 feet high...They still stand.pretty sure yard of sticks will stand too


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## FramingPro (Jan 31, 2010)

TheItalian204 said:


> Ok so I am actually gonna describe you the process...
> 
> Now that I think about it it might be tougher to do that what you initially thought and it might not be up to canadian code,but extra info never hurt anybody.
> 
> ...


im either dumb or tired but ill read it tommrow thanks


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## TheItalian204 (Jun 1, 2011)

FramingPro said:


> im either dumb or tired but ill read it tommrow thanks


yo,wait,its my bad I just read the frost heave LOL 

EDIT speaking of sleep,must be the flu I caught...been fevering and bed is probably better choice than giving out hallucinated advices :laughing:


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## jomama (Oct 25, 2008)

If the soil is well draining, the gravel base is adequate, and you pour at least a 8" thickened edge with a 4" floor, the floor will work absolutely fine for a shed. You've got to keep a few things in mind about frost, which apparently confuses alot of people. Most frost damage to structures comes from tying a non-frost protected structure to a frost protected structure. Frost has little effect on monolithic slabs. 

Think about this for a minute: If it's cold enough to get two feet of frost on the West side of your 12' shed, how cold do you think it will be on the East side???

If the shed slab heaves, as well as all the ground surrounding it, will anyone even notice??


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