when to ignore frost depth?
when to ignore frost depth?
(OP)
I have an equipment that is normally supported on slab on grade.
The site we are working on is located in the north near Minnesota.
what are my options for foundation in this case?
The site we are working on is located in the north near Minnesota.
what are my options for foundation in this case?






RE: when to ignore frost depth?
"Frost - free footings may not be required for a temporary structure that meets therequirements of the state building code unless required by an engineering report.Temporary electrical and plumbing installations may be allowed for any structure by thegovernmental entities governing those areas of construction or the applicable codes."
RE: when to ignore frost depth?
RE: when to ignore frost depth?
Dik
RE: when to ignore frost depth?
Dik, what other options do I have? Can I put insulation on the side and below the slab. Slab is 16'x12'x1'-6" thick, 1' below grade. I don't want this to be complicated.
Just to be clear, if a structure is by "engineering judgment" not sensitive to movement, I can ignore the frost depth of it's foundation.
RE: when to ignore frost depth?
http://liteform.com/wp-content/uploads/2017/04/FPS...
RE: when to ignore frost depth?
Similarly for electrical connections.
Mike Halloran
Pembroke Pines, FL, USA
RE: when to ignore frost depth?
RE: when to ignore frost depth?
Tell them to move it to Georgia.
No way is a slab in Minnesota not going to move, someday.
Mike Halloran
Pembroke Pines, FL, USA
<edit>
Make that _south_ Georgia, or Florida.
RE: when to ignore frost depth?
This funny common term "frost depth" gets thrown around a lot and at any specific site it may be way off. Let's say frost depth means where the temperature can go down to 32 degrees F. That doesn't necessarily mean in that zone there will be heaving. Three things needed for heaving: Cold below freezing, water and soil with fines in the silt range that tend to expand and take on water when below 32 degrees. That last part is a complicated activity that let's not try to explain here. When you have plenty of water and that frost heaving type soil you can get major heaving. But reduce those factors and the heaving is less. For that clean granular material with barely any silt no heaving takes place. An interesting fact is that if you have plenty of water, the heat of fusion released as freezing takes place, minimizes the depth of freezing. Minimum depth of freezing is in a lake while on shore it can go deeper. On the other hand take that clean granular material for deep depths and temp can go below freeing many feet deeper than for silty ground and no heaving. Also ground surface material can insulate the deeper soil to some extent and reduce the depth of freezing. As an example no frost heaving takes place in many areas of LaCrosse, WI where I have measured below freeing temps at 10 feet depth in mid December. It's all clean sand and gravel there and deep to water. So "frost depth" there is a meaningless number. Sorry, I sometimes tend to preach.
RE: when to ignore frost depth?
i will definitely add compacted granular base material below the foundation.
RE: when to ignore frost depth?
RE: when to ignore frost depth?
also I'm not sure if the insulation I will put is effective since there will be piping and electrical conduit coming up from the side of the slab penetrating the insulation.
I'm thinking of not putting insulation at all and just use aggregate below and beyond the slab.
RE: when to ignore frost depth?
But, it still seems you are way short of needed engineering info. and maybe sorta missing the point of some of the comments above. If it is an unheated, uninsulated, enclosed bldg., or an open bldg., or basically a slab on grade, the insulation really doesn’t do much good, up in that neck of the woods. You will have frost under and around the slab, and possible some movement. The point of the insul. around the found. and maybe even extending out horizontally 3-4', a foot below grade, is to retain bldg. heat and ground source heat under the found. and prevent freezing. Alternatively, if it is well draining soil (sand, gravel, etc.), and a well drained site, low local (perched?)water table, water drains away from the slab (or bldg.) a sufficient distance, etc. the frost heaving problem is likely significantly diminished. One solution is to put these slabs at a high spot on the site and have the top of the slab be above a sloping (away) grade, not at a low spot or dug a couple feet into the ground, like a bath tub.
What type of equip. is this, how does it load the slab, and can the equip. take some of this movement, work out-of-level, etc. The slab can be made strong enough so that any movement of the slab and above will be a rigid body movement, but then can the piping and its connections to the equip. tolerate this movement. That’s a pretty good sized slab so you must be talking about some sizeable equip. Is this in conjunction with a pipeline, a compressor bldg. or some such? Does it produce enough heat to heat the bldg. and found. adequately? Is the pipeline contents heated? The pipeline should be designed for these kinds of things, how is this potential movement handled at other similar locations on the line?
RE: when to ignore frost depth?
Dik
RE: when to ignore frost depth?
RE: when to ignore frost depth?
Just noticed... that should be extruded polystyrene...
https://res.cloudinary.com/engineering-com/image/upload/v1501680735/tips/Section_ocjauc.pdf
The section assumes the space is heated. For anchors I usually use headed bolts. They work better than 'J' bolts and are less costly.
Dik
RE: when to ignore frost depth?
RE: when to ignore frost depth?
Dik
RE: when to ignore frost depth?
https://res.cloudinary.com/engineering-com/image/upload/v1501690834/tips/Sections01_esix8q.pdf
RE: when to ignore frost depth?
I'm looking at a go-by and it calls out the insulation as 2" Rigid Insulation, R-10
Not sure if the go-by is calling out the insulation correctly.
In your example, you called out the insulation as Type 4, you didn't specify any R value
RE: when to ignore frost depth?
Your geotechnical engineer should be able to help you with this, and you should have them review your design prior to issuing.
RE: when to ignore frost depth?
Why do you need to specify the thickness if you already specified the R value?
http://liteform.com/wp-content/uploads/2017/04/FPS...
RE: when to ignore frost depth?
If the building is heated I have section detail that shows the insulation wrapping up the edge of the stiffener. Dow had a really good publication on insulated buildings.
Dik
RE: when to ignore frost depth?
RE: when to ignore frost depth?
RE: when to ignore frost depth?