planning for my new shed, foundation suggestions


I live in mid wisconsin and am planning on a 40x80' shed and would like to know what i should be doing for the foundation. I am thinking of putting a 40x40 concrete slab and would like to ensure that frost heave does not dammage it.
one contractor said to put 2 inches of styrofoam insulation, but he did not even see the site, so I'd like to know what to prepare before we get to the styrofoam. the area has a bunch of trees that will be removed, stumps pulled and etc. I'm wondering if the existing soild can be used or if i have to get some gravel
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I installed a similar structure in SW PA and had no problems with the slab ... poured 8 inches thick, at ground level, reinforced with mesh.
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It depends. What will be living in the shed? Tractors, woodshop, or just light storage? The heavier the contents, the heavier the slab needs to be. What sort of shed? Pole barn, prefab metal, or stick-built? Pole barns, the poles act as the foundation, anything else and you need proper footers and stub masonry walls to catch the weight of the structure. (Building anything on a flat slab, no matter how strong, is a bad idea for a lot of reasons.) What are the local soil and water conditions? Be a damn shame if a seasonal spring popped up in the middle of the footprint. Yeah, a layer of gravel and sand under the slab is usually called for. I'm not expert enough to address the styro- I thought that was only common in heated structures. Local concrete flatwork company, maybe even the actual concrete company, could probably tell you the usual practices in your area. You definitely want to get to undisturbed soil below the removed trees, and add back from there. Settling is a bitch.
40x80 is a damn big shed, and a lot of money. IMHO, it is worth paying the few hundred extra for a site survey and actual engineering drawings. If this is from one of the big pre-fab companies, they probably have a dealer nearby that performs that service. If I was building that big, I would use real footers, and make the slab strong enough for whatever would fit in there, which is largely a function of clear headroom, overhead door size, and road access. Even if you don't need the extra weight rating, a shed strong enough for tractors or RVs would be a good selling point for next owner, while a pole barn with a thin floor to just keep the mud out may be useless to them. I would run the footer under the opening for the big door, and put a proper sloped apron in- that is a real common spot for frost heave problems to start, from water getting under an unsupported edge of a slab.
By the way- when you do the foundation, stub in conduits for utilities, even if you don't plan to install them anytime soon. Power, water, phone, etc. They are a LOT easier and cheaper to do at the start. And if this is going to be a 'guys barn', sewer stubs for a 3/4 bath are a real nice thing to have, too. SWMBO hates grease and sawdust tracked back into the house.
aem sends...
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snipped-for-privacy@att.net wrote:

hoo boy, i try to avoid answering this question, because everyone starts labeling me as a nut.
it's going to be a workshop for building rockets. big rockets. the 40x40 concrete part will be the workshop proper, plus room for training simulators and and a conference room. nominaly heated, maybe solar, maybe wind power, maybe firewood(still in the estimation stages), plus a small office. first few years it will be up it will not be insulated, but plan on doing so later.
the dirt floor 40x40 area will be indoor parking for support vehicles, trailers, and other stuff that I'd like out of the rain but doesnt need to be off the dirt.

depends. I am leaning towards pole barn, as i can just throw a little money at it and it'll get done. even at 40x80 tens of thousands of dollars is little money compared to stick built. still shopping for estimates, anyone here can feel free to change my mind.

site is at top of hill in the area. good slope, part of property orginaly had old shed, now crumbling ruins (a century does that you know) not too worried about drainage issues. current slope is like 1 foot every 20-40ft, was planning on using tractor with blade to pull stumps, then push dirt around to level off then get a dumptruck or two of fill if needed

as you can see others in the thread pointed out "frost-protected shallow foundations" appears what the one contractor was talking about.

humph! I have a real hard time around here with the local experts. first plumber i hired before i bought the land could not find the well and septic, which i found after 20 minutes looking. other experts I've had to hire to satisfy the bank have not been experts in my opinion. hence my reason for looking on the net.

ya, I can see the nightmares already. one of the reasons why i am asking about this stuff now rather when i am about to commit tens of thousands of dollars on this

I've worked with engineers before, on other projects, see above opinion about experts.

single story, maybe 10ft to the rafters, one man door, one vehicle door(still contemplating size and style, like airplane hangar door idea) nothing real big in there, not even sure that anything with a footprint heavier than my pickup truck will be in there, and that'll be on the dirt section....

moot point, I plan on dying here. i've moved too many times in my life. not again.

I was thinking to avoid such a problem would be to run a lot of drainage pipe, and maybe even run radiant heating into the slab. not for heating, but the keep frost from forming. plan on putting up a couple of windplants and maybe a solar panel or two, so energy *shouldn't* be an issue

two explanations.....(yer gonna love this)
1)power is from overhead line, pole will be nearer to shed than house. water and sewer are a real big issue as the septic is on the opposite side of the house, but the well is nearby, but not the feed from the house (major plumbing issue, might be done anyway). cordless phone will be within range, as would be wireless network.
2)and yes, this is a "guys shop" and SWMBO wont mind, even without the 3/4 bath.
why?
we bought this house together, it originally was a duplex. she has the upstairs, and the downstairs is MINE. maybe one of the more odd compromises, but it works.
Tater Wxxxx stetson ave Dungeon T
(SWMBO lives in penthouse K, guess the first letter of HER name<g>)
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Well.. What you probably OUGHT to do is bulldoze out a level spot, lay drainpipe around the perimeter and every 10' or so throughout the interior, led out to daylight, cover that with gravel, sand, and/or the dirt you took out (depending on what it's made out of), and then pour the slab on top of that.
Are you sure you want the workshop and the other occupied spaces in the same building? I'd want a fairly substantial earth berm between me and the workshop, myself.
And blow-out panels in the roof and far wall, and an explosion suppression system.
Depending on exactly how big a rocket you're talking about, you may want at least one section of the slab poured thicker than usual.. (which would be 4") possibly by as much as 24" think, else what are you planning to bolt the test cradle to?
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Goedjn wrote:

separate plant for that. how big? 1/2 the length of a redstone approx.
workshop design should be about the same as building a homebuilt airplane. which means 40x40 is too big<g> but everyone that i've talked to has always wished they had a bigger shed, so I'm planning ahead. the non-concreted 40x40 section will be to hold things like support vehicles, launch trailers for smaller test prototypes, my personal vehicle, and who knows what else.
a 40x80 shed sounds big, until you walk out the the size of it, and start saying things like "we'll put a couple of 4x8 worktables there, put a 3ft counter along that wall, park the pickup there and the camper/mission control trailer there, the projection screen for seminars there, my desk there, the computer network there, the solar/wind/inverter setup there, the wet layup composite gear there"
even with a 3ft walk area between everything, 40x40 gets used up real fast.
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Goedjn wrote:

I'll be using hybrid motor systems, which are not explosive. but some of your points are valid and testing is done at a saparate facility, with earth bermed walls ans such planned.
workshop will be for building capsule, airframe, fins, support equipment, and other such things. hybrid systems use fuels that are somewhat safer than other things usualy found in a similar workshop.
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Goedjn wrote:

I guess this is the answer I was originally looking for, and is sorta what i was hoping that i can do. I am sorta hoping that somone here can point out why i CAN'T do that....
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Well.. the chances are good that you could get away with just digging out a flat spot, pouring the slab, and putting down a perimiter drain. The trouble is, you can't be SURE that's good enough without hiring someone to come look at the actual site. And by the time you've done that, you'll have spent a good fraction of what it will cost to just lay the subfloor drainage anyway.
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Goedjn wrote:

not from my experience.
every person i've had to HIRE in regards to this property has been less experienced and less knowledgeable about their field than *I* have. after I almost paid someone to inspect the well and septic who stated that both didn't exist, i went and found them myself, tested the water and had the tank pumped. house inspector missed a lot of areas that needed immediate repair and said the electrial was good when it was not even acceptable and an immediate fire risk.
so you can see why I am looking for the knowledge i need to do this MYSELF, as every person i've given money to has not been able to do what needs to be done
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Tater wrote:

Hi, Knowledge alone is no good. Could be dangerous if you want to learn some expensive lessons. I ran across a few so caled house inspectors who does not even possess basic electrical knowledge! Knowledge has to be with experience which is gained with time. When I work on some electrical or electronics problem I can smell/feel the problem, LOL! I never lived in second hand house. Always had it built the way I wanted. I know exactly what's what and where in and around my house and cabin out in the woods.
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Tater wrote:

If you're willing to spend the money you can always find people that know a boat load more than you do about their field. Always. People use the excuse that there are no qualified people in their area...which is rarely true. Often the owner is sending off signals that they're going to be a pain in the ass to work with. Not saying you yourself are, but it happens and I'm sure you can understand that talented contractors are more prone to act like prima donnas when it comes to picking their projects.
In any event, you're building a shed. It's not, umm, rocket science. If you have very particular requirements, you shouldn't be hiring people who build sheds for a living - you should be hiring home builders and selling them on the coolness of your rocket shed project. If you get people interested you get good prices and people who like a challenge.
Then there's the possibility that you're of the type that is never satisfied with other people's work, in which case you should either just forget about hiring contractors directly and hire a construction manager to run the project for you, or just build everything yourself. Both options have their advantages and disadvantages.
R
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RicodJour wrote:

yep! thats part of the plan. I am not real fussy about the requirements, or the construction methods, but I want to know enough about what is being done to make sure that who i pay to do it is not going to foul things up

nah, just would like to have people who say they are qualified, to actually BE qualified.

guess who used to be an adminstrative assitant for a construction manager for a multimillion dollar project for a major food company<grin>. so yeah, I've gotten to see a lot of this from a lot of angles, and am almost temped to do this all myself but i can bet the insurance companies are gonna say NO, even if the quality exceeds local contractors.
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First I wood make sure the ground is compacted. Then you would need an exterior Footing. The slab should have a vapor barrier covered by gravel. I would not use wire mesh myself. a 12'' grid of #4 rebar tied into the footing, much stronger, if concrete cracks (witch it dose) it won't pull apart. You might look into Fiberglass reinforced concrete, I'm seeing a lot of that in slabs. The best bet is check with local building department.
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Tater wrote:

You need to explain that. How can you have a 40x80 shed with a 40x40 foundation?

You only need gravel to go under the foundation not the slab. Look up "insulated slab foundations" to deal with frost heaving. You don't need to excavate really deep that way.
-tg
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Depends on the soil and local regulations. You should have some footers that go below the local frost level. ALL organic topsoil should be removed and replaced with aggregate. Level the top of the floor to be above surrounding soil level so that drainage in away from the building and not into it. You may want to add some conduit and any air lines to appropriate areas in the middle of the slab. At least provide some large conduit tubes through the edge of the slab into the ground so that water, power and anything else can enter the building without having to go over the outside edge of the concrete.

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Google "shallow frost protected foundations". They have become pretty common here in Northern MN.

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Given the special nature of the shed activities, I'd also check my fire and liability insurance. I doubt a typical homeowner's insurance policy would pay off if there were a fire or someone was injured and sued. And since the shed plan includes a training area and conference room, this sounds like a serious liability issue. I'd be surprised if you could get insurance.
I'd also check zoning/building issues and make sure you have the proper permits. If word gets around as to what you're doing, I would think there is a good chance someone could make a call to code officials, etc.
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