Footings for Shed

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Hello,
I'm about to build a 12' x 12' shed. I've drawn the plans, elevations and sections in AutoCAD and have every detail hammered out. I'm going to dig 4 holes for the footings and am planning on pouring concrete in the holes to make a base for CMUs. The question I have is how do I make sure that once I've stacked and mortared the CMUs that the top of them are all at the same elevation height so the floor joists that rest on them are nice and level? Do I use some sort of stake and water level or laser level to make sure that each poured base is at the same elevation? Do I just fudge it in the thickness of the mortar between the CMUs so that the last one on top of the stack is level with the others? What's the process that the pros use?
Thanks in advance!
Jason
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On Apr 15, 10:17 am, snipped-for-privacy@gmail.com wrote:

Either a water level or a laser level will work. You only have to make sure the top of each is level - "close enough" is okay for the bottom.
Since you're planning on using concrete to fill the cells, I'd use Sonotube and forget about the block. Excavate, pour the spread footings, insert and plumb Sonotube, backfill, laser level to mark the outside of the Sonotube for the top of the pour, poke a nail through the side of the tube, pour concrete and install anchor bolts.
I'd also use more than four points of support to better distribute the load and minimize differential settlement. People often underestimate the amount of load they'll put in a shed, and yours is a substantial size.
R
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I've seen those before and they look much easier. Originally I wanted to use CMUs because they're square. I see on the sonotube's website that they make square ones. I didn't want to use circular forms because I don't want the footing to extend out beyond the wall but a square form wouuld work great. I've never seen them in Lowe's or Home Depot. I will find a distributor and see if I can't snatch some.
I will definitely consider using more than just one in each corner since forms would be quicker and easier.
If I use these forms, do I still need to pour a base for them? Should I be putting gravel in these holes?
Thanks again!
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The "pro's" would probably use a transit, but a laser level would work fine if you have one. I personally use a simple water level made from an old wine bottle and a length of 3/8" clear tubing. It's accurate, and can work around corners or other obstructions a laser or transit would have difficulty with. A home built water level is also cheap. :)

I didn't realize square sonotubes were available, all I've ever seen is round. In any case, you could also build some simple square forms out of plywood and 2x4 reinforcements. Remember to add some rebar to your posts and footings.

Have you considered pouring a concrete slab? It would be faster, easier, and cheaper than pouring support columns and building a floor. You could build a simple perimeter form with 2x8's or 2x10's, and dig down on the edges for perimeter footings. If you're in an area with deep frost lines, you could dig holes for "posts" and pour the slab and footing posts at the same time.
Anthony
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*Getting off topic, but have you considered the property tax ramifications of building a shed with permanent footings. In my area of NJ that is considered an improvement and contributes to the tax base of the property. Everyone around here just lays out a gravel base and puts a shed with skids on top.
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In addition to that good advice, the OP should verify the zoning requirements. Some areas don't require a permit for a shed that's under some arbitrary size (10' square in my area). Over that, and you do, which opens up many cans of worms. Others have posted about digging a hole and just filling it with concrete. That's not "legal" according to some codes. In my area the permit and foundation trigger required and separate inspections for excavation, footing, framing, etc.
R
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I checked with the county and as long as I stay under 150 sq. ft I don't have to get a permit. Otherwise, I would build it bigger ;)
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wrote:

In addition to that good advice, the OP should verify the zoning requirements. Some areas don't require a permit for a shed that's under some arbitrary size (10' square in my area). Over that, and you do, which opens up many cans of worms. Others have posted about digging a hole and just filling it with concrete. That's not "legal" according to some codes. In my area the permit and foundation trigger required and separate inspections for excavation, footing, framing, etc.
R
Ditto for Maine as well...My shed is 10'X10' on 6"X6" PT skids and is sitting on concrete blocks in gravel...No permits , code or setback BS and no TAX increase...LOL...Hasn't moved much in 2 years and if it does I will just jack it back up with my floor jack that I use to jack up the car and truck in my garage and re-level it...I see no reason to have a foundation for a shed...Seems like ALOT of work and expense for nothing...IMHO....
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With my shed I put in the biggest I could and not get taxed or need a permit. I just considered if I ever need more space I would add another one. Where I am in Midwest footings are only done with small sheds if shed is in open high wind area and needs to be bolted down.
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It has been a few years since I built my shed, but at that time a concrete slab was a lot cheaper and faster to build than a wood floor and support blocks.
A slab usually sits closer to the ground, which makes it easier to wheel in the mower, and other equipment.
A slab lets me wheel in a muddy tiller or a wet snow blower without worrying about the floor getting wet and rotting. Once the mud dries, I just sweep it out.
A slab can support a lot of weight if I want to stack lumber, bricks, a heavy tablesaw, or whatever inside. I don't have to worry about joist spacing or spans.
A slab gives some mass to the building, allowing you to bolt the shed down to resist wind and seismic forces.
I built a shed on skids a few years ago and greatly prefer the slab floor. The only advantage the skids had was allowing the shed to be dragged to a different location if needed. On the other hand, my current shed used to be on a slab on the other side of the house. I unbolted it from the slab, braced it inside, jacked it up, and placed skids underneath. Then I drug it around to the back of the house with a bobcat. I jacked it up, poured a new slab underneath, and bolted it down to the new slab. A bit more work, but it just shows a shed can still be moved even if it's built on a slab.
Just my two cents...
Anthony
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If you were really good you would have moved the slab at the same time. ;)
R
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How you get a slab being cheaper or faster beats me. It only takes a hour or two to level some blocks for a shed. And costs a few dollars. Even a 4" slab costs several hundred. And ok, you moved a shed that was on a slab. Tell us about how you jack hammered up the slab or do you just have a orphan slab in the middle of your yard now?
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On Apr 22, 11:16 am, snipped-for-privacy@gmail.com wrote:

Hmmm, it seems that you forgot to factor in the cost of the pressure treated floor platform for your shed slab/platform comparison. Probably threw off your analysis just a wee bit.
12' x 12' x 4" slab is roughly two CY of concrete - figure $200 to $300 for the material cost. Add in some anchor bolts and some 2xs for the perimeter formwork and the slab materials cost is roughly three or four hundred bucks.
The same size framed platform would require five sheets of 3/4" treated plywood ($150), either all 2x12 construction as per the OP's initial post or three beams with 2x6 or 2x8 joists ($250 for 13 PT 2x12s at 12'), plus nails, pier blocks, etc.
I'm ignoring labor cost as we're talking about DIY stuff, but the end result is the same. The wood platform would take longer to build and cost more than a simple slab on grade. If you want to figure in labor costs and/or contractor speed construction, concrete guys would knock out the slab in a couple of hours with a few breaks in the middle.
As far as the old slab that Anthony has (or has not), that has nothing to do with the comparison of the relative costs between a slab and a framed platform. A friend had one of those "orphan" slabs in his backyard and we built a new shed on it. You could also use the orphan slab as a patio, outdoor work area or sell it on eBay.
R
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wrote:

Hmmm, it seems that you forgot to factor in the cost of the pressure treated floor platform for your shed slab/platform comparison. Probably threw off your analysis just a wee bit.
12' x 12' x 4" slab is roughly two CY of concrete - figure $200 to $300 for the material cost. Add in some anchor bolts and some 2xs for the perimeter formwork and the slab materials cost is roughly three or four hundred bucks.
The same size framed platform would require five sheets of 3/4" treated plywood ($150), either all 2x12 construction as per the OP's initial post or three beams with 2x6 or 2x8 joists ($250 for 13 PT 2x12s at 12'), plus nails, pier blocks, etc.
I'm ignoring labor cost as we're talking about DIY stuff, but the end result is the same. The wood platform would take longer to build and cost more than a simple slab on grade. If you want to figure in labor costs and/or contractor speed construction, concrete guys would knock out the slab in a couple of hours with a few breaks in the middle.
As far as the old slab that Anthony has (or has not), that has nothing to do with the comparison of the relative costs between a slab and a framed platform. A friend had one of those "orphan" slabs in his backyard and we built a new shed on it. You could also use the orphan slab as a patio, outdoor work area or sell it on eBay.
R
The only PT I used is the 6X6 PT skids..The floor is KD 2X6s and pine boards sitting on blocks...Why would you need 2X12s and 3/4 inch PT plywood for a small storage shed??? What are you gonna do , store a ton of bagged concrete in it ???LOL... Plenty of air circulation under it and NO rot after 5 years in Maine...And you're forgetting the TAXES , PERMITS and SETBACK BS for a PERMANATE shed on a slab verses one with NO tax increase or permits ect for one on skids and blocks........
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There are many ways to build a shed. The OP wrote this: "I really don't want to build a slab because I am planning on storing stuff under the shed and hiding it with lattice all the way around. It will be a good place to put certain types of things."
Maybe you should set the OP straight and tell him why his ideas for his design are BS and he should build your shed. Or not. Go with the "or not".
A few observations: - I did not recommend a slab. I replied to someone who thought the slab would be a lot more money than a framed wood platform. Since I won't be building the shed, and it's not my money or effort, I don't really care which way the OP goes with the construction. I am simply supplying advice and experience so the OP can evaluate the alternatives. - I did not forget the taxes and that stuff. John G. touched on the topic and I added to it in a subsequent post. - I do not know what the OP wants to store under the shed, or how high off of the ground he wants to go, but I'll give the guy the benefit of the doubt that after he's settled on a solution that it will work for him. - If you've followed this thread, you have seen how the OP started with the 2x12s to (no doubt) minimize the number of piers. He has shown flexibility on this. An admirable trait. - Maine is not exactly rot central. You have that thing called winter that slows it down a lot. Forgoing the PT joists would doom your shed in short order in many parts of the country. In two years in New Orleans, or other termite haven, your design would be infested. - I am pleased that you built your design that you like. That process is not unusual.
I do not mind criticism of my posts - I even had one that deserved it - but it does no one any good when the criticism loses track of who said what, and gives contrary advice that is specific only to a certain situation or location.
R
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wrote:

There are many ways to build a shed. The OP wrote this: "I really don't want to build a slab because I am planning on storing stuff under the shed and hiding it with lattice all the way around. It will be a good place to put certain types of things."
Maybe you should set the OP straight and tell him why his ideas for his design are BS and he should build your shed. Or not. Go with the "or not".
A few observations: - I did not recommend a slab. I replied to someone who thought the slab would be a lot more money than a framed wood platform. Since I won't be building the shed, and it's not my money or effort, I don't really care which way the OP goes with the construction. I am simply supplying advice and experience so the OP can evaluate the alternatives. - I did not forget the taxes and that stuff. John G. touched on the topic and I added to it in a subsequent post. - I do not know what the OP wants to store under the shed, or how high off of the ground he wants to go, but I'll give the guy the benefit of the doubt that after he's settled on a solution that it will work for him. - If you've followed this thread, you have seen how the OP started with the 2x12s to (no doubt) minimize the number of piers. He has shown flexibility on this. An admirable trait. - Maine is not exactly rot central. You have that thing called winter that slows it down a lot. Forgoing the PT joists would doom your shed in short order in many parts of the country. In two years in New Orleans, or other termite haven, your design would be infested. - I am pleased that you built your design that you like. That process is not unusual.
I do not mind criticism of my posts - I even had one that deserved it - but it does no one any good when the criticism loses track of who said what, and gives contrary advice that is specific only to a certain situation or location.
R
Fair enough....
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I decided to do footings instead of a slab. I have got the four corner footings done. I don't know if it's going to be cheaper or not but I already know that this is a lot slower than pouring a slab. It takes me about 45 minutes to dig a 20" deep (frost line here is 18") by 20" diameter hole and haul half the dirt away to another spot on my property where I need dirt. Then I pour concrete in the hole until it's 20" below my line that I have strung between my batter boards. I've got a piece of rebar in the middle that will stick up into the hole in the center of the 8x8x8 CMUs. I will fill the CMUs with concrete once the mortar between the blocks set. The tops of all four foundations are level. This has worked pretty good but it does take a bit of time to lay the block and make sure they're square and level. It would have been much quicker if I would have just made a square form but at least I'm doing something I've never done and am enjoying being outside.
My foundations may be overkill for a shed but this bank is man made and probably isn't as compact as I'd like so I'm hoping that these footings are adequate and that the shed doesn't settle much.
I've posted pictures of the process to a public section on my flickr site and I'll continue to post pictures until the shed's complete. Feel free to watch what I'm doing and make any suggestions. Even if it's too late to correct my mistake, a posting could help the next person that wants to build a shed.
Here are the pictures: http://www.flickr.com/photos/jcarwile/sets/72157617110532689 /
Thank you everyone for all the valuable input!
Jason
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My shed is 8x12, and it has been a few years since I've bought construction lumber, but here are some rough estimates for a wood floor structure using approximate prices at the time:
$16 - (2) 2x6x12' joists (for rim joists) - $8 each $50 - (10) 2x6x8' joists @16" OC - $5 each $75 - (3) 4x8x3/4" CDX plywood sheets - $25 each
That's $141 just for the floor structure, probably more at todays prices, and even more if you choose pressure treated lumber (good idea for a shed close to the ground.
Then you have to support the floor somehow (again, just guessing on the prices, as I haven't purchased lumber in a few years).
1. I used two 4x6x12 pressure treated "skids" sitting right on the ground. These cost me about $15 each, or $30 total. It works, but definitely not a long lasting option.
2. You could also use six "deck blocks". These cost about $5 each at the time, or $30 total.
3. You could pour concrete footings ($4 a bag x 6 footings = $24), install post bases ($5 each x 6 = $30), and install wood posts (one ten foot post, about $10, could be cut into six small posts). Total, roughly $64.
3. Even if you cheap out and just set the wood floor on concrete "cinder" blocks, you're talking a couple of bucks each, or $12 for the six blocks.
So, total cost for the floor and support structure would be between $150 and $200 or so, depending on local prices at the time. I didn't factor nails or other needed fasteners, or the time and gas it takes to drive to the store, pick up the supplies you need, and hopefully have some way to haul them home.
My 4" thick 8x12 slab, on the other hand used 1.25 yards of concrete for $150. About equal to the cheapest wood floor structure, but notably less if you build a quality support for the shed. I already had boards to build the forms, but even if you didn't you could reuse the form boards in the shed construction. So no additional cost there.
As far as time, I erected the slab forms in less than an hour, and poured the concrete in 30 minutes or so. Yes, you have to schedule and wait for the concrete delivery, but that's no worse than having to go get the materials for a wood floor.
Regardless, even if the slab ended up costing a bit more or took more time to complete, it offers many advantages I listed in my previous message.

Most people don't move a shed once it is built, I was just pointing out it was possible even with a slab.
In my case, I was renting a Bobcat anyway to do some landscaping work, which made it easy to drag the shed to it's new location. I then broke up the old slab by lifting it up from below with the Bobcat. I used the broken slab pieces and many native rocks to fill in a low area that I backfilled over for a parking area.
Anthony
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Excellent point. An additional consideration are your local zoning ordinances. A friend of mine who is building a large shed for a workshop decided to pour a slab foundation. Because of the size, the zoning regulations mandated drain tile be installed, along with a gutter system for the roof. Hopefully your project won't be affected like this, however it's worth checking out. If you get the chance, check out my other tips on my <a href="http:// www.storageshedplansblog.com">Storage Shed Plans</a> blog.
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I have another way also. build your frame out of 12' x 12' joist. Temporarily stake it level. Prior to that dig your holes and place the frame over them. Level the frame, and stake it, fill the holes with concrete and use a post or whatever to the frame. Use post bracket attachment and imbed the post in the concrete and attach to the frame.......Let it set, and then take out the temporary stakes...... voila. just one way to do it. Most just pour the concrete, and set pier blocks in the concrete. then after the concrete is set, cut small posts to support the floor system so that it is level. the posts are cut level, the piers are pored without worrying about level.
Easier is pour a pad, 12 x 12 x4" thick/with footing, put anchor bolts in it, and build the shed on that! Oh, there are other ways too.... jloomis

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