Steel Building Foundation options

[quazz209]

Hey guys, been lurking for awhile checking out projects and trying to get ideas and recommendations for my shop I am about to put up. This is located in upstate NY. Around the Albany area. I am looking at a 50x80 building with 14' eaves. I have a construction background and have a good grasp on the budget and everything else involved. However when it comes to the foundation on this project i severely underestimated based on what I am currently being told. Every engineer I talk to wants to do a footing, minimum of a 4' frost wall winch enlarges to 36"x36" under the piers and a separate floor. I was anticipating something similar to a frost protected shallow foundation and piers poured for support. It seems to me that all the local guys want to go very conservative, or is this the only way to do it? Just looking for alternatives you guys may have seen done or other options as my initial estimates were in excess of 100yards low considering the size of this building.

Any experiences or options you might know about or have seen please let me know. I am trying to save my budget on this one...

 

[nehog]

1. Talk to the building manufacturer about what they recommend.

2. My building is sitting on a floating 'Alaskan' slab, and has been fault free and crack free. I have rebar in my 4-6" slab, the perimeter is about 30 inches wide, and about 18" deep. Nothing special where the building's red iron is bolted down to the slab other than some extra rebar.

 

[dlenkewich]

Perhaps its the size of the building that requires a large footing?

 

[joe_padavano]

1. Talk to the building manufacturer about what they recommend.

^^^^^ This.
I'm an aerospace structures engineer and put up a metal shop building last year. My impression (OK, based on a single sample) is that these buildings are engineered to use the minimum amount of material possible. The siding is a structural member and the bottom edge of the siding must be fastened to the slab to provide the proper resistance against racking due to wind. The frame itself is pretty minimal and the structural analysis of the building counts on the moment carrying capabilities of the footings, foundation, and slab. My building was analyzed for the D.C. area and still has 16" wide footings with a 3 ft deep cinderblock foundation and a 6" slab on top of that.

 

[quazz209]

Hmm, the plot thickens. It seems as if there is a little bit of everything out there. I would prefer a monolithic pour if possible. It just simplifies so many things but I certainly want my building to put up properly. I have talked to a few different engineers and one says we could design to monolithic and another says maybe it can be done but should be done with the "traditional" design.

Keep the input coming as to what has been done in the northern frost prone regions under your buildings.

 

[readhead]

I sell and erect metal buildings. The siding and roofing are not included in the diaphrams. The primary and secondary structure are stand alone. The slab is not included in the reactions. You don't say which is the length or the width but at 50' minimum depending on soil condition you may need to tie the footings at each end of the ridgid frames together. That is usually accomplished by several large pieces of rebar in a thickened part of the slab. And no the slab is not structural. I would definitly have a structural engineer design the foundation. We have done mono pours lots of times. At lower elevations we have used frost protected turndowns between the piers but we put a bunch of bars in them and treat them as grade beams.

 

[jimp]

Mine was a monolithic pour, 72X60.

It included 36" sq. column footings for the load bearing column and 24" for the end wall columns to 36" deep. It also has 36" deep 10" reinforced perimeter wall (just like a stem wall but no footing, #4 - 12 on center each way)and all the support columns footing are tied to the oposite with extra rebar. The slab is 6" with #4 - 12" on center each way.

I have a few hair line cracks but none are openning.

I also believe that your snow loading and frost line are much higher than in Kansas.

My builder did say that he would pour the floor without the perimeter wall but would not recommend it.

 

[OldbutNew]

30' x 48' monolith pour, 30" square x 48" deep footers under each structural element with 30" deep x 12" wide ratwalls (full of rebar) around the perimeter. Welded re-bar cross-ties connecting the main trusses through 6-7" deep hat sections through the floor. 6x6 8 ga. mesh welded to the rebar. 1500 ft. of 1/2" Pex tied to the rebar. 36 yards of 6 bag mix.

ONE hairline crack the day after we poured. Has been stable for 8 years.

SPEND THE EXTRA BUCKS ON THE FOUNDATION!
If you get it wrong... you are truly screwed.

 

[Engineer61]

I think jimp has a good point here, 4000 sqft building and 30-40 1b/sqft snow load is a lot of weight (60-80 tons) and you will need a good foundation with a wide continuous footer to help hold it up. I don't think that piers is really the way to go; a lot also depends on your soil conditions; clay, sand etc of your subsoil under that footer.
Also think about the sail factor of those 14 ft eves in a high wind, a good deep foundation will help to keep a building from flexing and flying away.

 

[cyamaha2007]

Our red iron 50x100x building sits on a 4ft deep 3ft wide foundation.

 

[coxodoina]

It seems as if there is a little bit of everything out there.

 

[coxodoina]

I have a few hair line cracks but none are openning.

 

[joe_padavano]

I sell and erect metal buildings. The siding and roofing are not included in the diaphrams. The primary and secondary structure are stand alone. The slab is not included in the reactions.

That may be the case for YOUR company's buildings, but it certainly is NOT the case for the one I put up. The reaction calculations are included in the plans. In my case, the siding reaction is definitely required to satisfy the wind load calculations, and that calculation includes the reaction into the slab at the base of the siding. This is why it is MANDATORY to contact the building's manufacturer and find out how the building was designed. Apparently each manufacturer does it differently. The information provided in this thread is anecdotal and may or may not apply to the O.P.'s specific building.

 

[readhead]

It would be interesting to know what you bought. We rep two of the oldest companies in the business and have erected probably a dozen others and the story is the same. Obviously the sheeting provides a certain amount of shear but none of the buildings we have erected calculate that value into the reactions. The structure is braced to stand alone and the covering is just that, a cover. It was explained to me once that the company cannot depend on the erector to install the sheeting correctly so it is not included in the calcs. The reactions are provided for the EOR to design the foundation. In our experiance the slab design is independant of the pier and foundation design and is not structural.

 

[OldbutNew]

I'm in Michigan, so my snow and wind loads should be similar to upstate NY, UNLESS you are in the lake effect belt.
My building (Miracle Steel) came with a full set of foundation prints.
If your building supplier is leaving you on your own...

 

[nehog]

...
My building (Miracle Steel) came with a full set of foundation prints.
If your building supplier is leaving you on your own...

Yep, mine was the same: they told the buyer exactly what was required, how to do the anchors etc., and that is the best way to fly. That way there is no question about meeting building code requirements, or liability if something terrible goes wrong.

 

[quazz209]

I have looked at a number of suppliers...Northland, American, Olympia and some others a little further away and none have indicated a willingness to do the foundation design. I recently spoke with my building inspector and he commented that he frequently sees buildings in the area use piers under the loaded areas only and then a slab poured simply as a floor for the shop. He referred me to a few local builders he thought would be willing to pass on some knowledge so I need to see what they have to say. I will look into the Miracle steel brand if they include foundation designs.

 

[T-Mac]

There are so many variables that go into foundation planning that whats ok in one location may be wrong 1 mile down the road.soil type-bearing strength-drainage is number one concern IMHO

 

[T-Mac]

Mine-Peirs under bearing members,concrete slab for floor only