"Tater" wrote in message
ups.com...
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

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...