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joe_padavano

Bank barn flooring reccomendations

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I am in the process of planning a rebuild on a bank barn on our farm, turning it into my car shop. For those not familiar with the term, a bank barn is (usually) an old dairy barn where the stone foundation is built into a bank such that the "basement" is walk out on one side and housed the cows, but the bank on the other side allowed drive-in access to the upper floor on the other side for hay storage.

In my case about the only thing left is the foundation, so I'm pretty much starting from scratch. I plan to turn the basement into the actual restoration shop and I would like to use the upper floor as storage for completed cars. Therein lies the rub. I need a flooring system that will support the weight of several cars without requiring many posts below, since that will make the shop space less useful. The original bank barns have timber floors that supported tons of hay as well as heavy tractors, but this usually involved posts below. I'm planning on using steel I-beams to provide clear span, but I'm interested in recommendations of actual flooring. By the way, I'm an aerospace engineer specializing in structures design and fab, so I'm comfortable with the analysis (and plan on having VERY large factors of safety in the design), but I'd like to hear from anyone with experience in this area. Thanks.

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Interesting post. My wife and I are in the process of planning a bank barn although we will be starting from scratch. We are very familiar with typical livestock bank barn construction and all the factors you mentioned are the same legitimate concerns we have. since we live in somewhat hilly terrain, bank barns make a lot of sense.

In our case we will have horse stalls below so can deal with more supports however if the horses go someday, the space is more useful if wide open so we are looking at more of a free span even thouigh we don't need it right now.

Based on some research we have done on 2nd floor deck construction the first thing is to determine what PSF you will require. I "think" 50psf min is a residential standard for a garage. I have a tendency to overkill minimum specs so I was considering leaning towards 80psf. Also a factor is concentrated load based on the weight of a vehicle being placed on a small area, ie the tires.

Through looking at various buildings with higher load capacity raised floors, I have found using a combination of steel beam joists and composite decking (steel corrugated) with 3-1/2" of concrete poured on top will provide a good open span underneath without supports and give you the psf you need for cars. There are various gauges and styles of steel decking which increase the psf rating based on your requirements. The combination of corrugated steel decking with concrete on top makes for a surpisingly strong span.

One concern in your case using composite decking with concrete is whether or not your existing foundation footings can support the weight of the concrete vs the wood frame floor it was designed for. You may want to find out the size of the footer. Many old old barns don't even have a footer, just large stone.

Another benefit of concrete besides durability and strength is the wide variety of coatings that can be applied making it a real show place if you think that is a priority.

Most full service home improvement places have someone who can run the numbers through a software program based on your needs and make recommendations based on that. Sometimes they only want to deal with contractors but if you tell them you are the contractor they might oblige. As well as figuring out the deck design, they can calculate the footer requirements.

I'm sure there are other options and I'll be interested to see if anyone else has experiences to share.

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joe and jason,

i am an architect and barn designer/builder in chicago area. i am verifying that jason's 50 lb/per sq ft is the minimum for a garage for passenger cars, which is really not as much as most office buildings. add in a factor of 10-20% and you are set.

have you considered using steel bar joists? they can be attractive and unobtrusive, painted to match or contras with whatever the design is. they do not restrict running ductwork, cable, conduit etc. as you can go right thru the webs, and they can be long span maybe requiring no intermediate center supports at all, depending on the width of your barn.

let me know if you want more on this.

best,

howard mock

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joe and jason,

i am an architect and barn designer/builder in chicago area. i am verifying that jason's 50 lb/per sq ft is the minimum for a garage for passenger cars, which is really not as much as most office buildings. add in a factor of 10-20% and you are set.

have you considered using steel bar joists? they can be attractive and unobtrusive, painted to match or contras with whatever the design is. they do not restrict running ductwork, cable, conduit etc. as you can go right thru the webs, and they can be long span maybe requiring no intermediate center supports at all, depending on the width of your barn.

let me know if you want more on this.

best,

howard mock

Howard,

Yes, I have considered the steel bar joists. Ultimately it will come down to price. I have found design guidelines for the poured concrete floor slabs, including the necessary structural calculations. As you have correctly noted, most office floor slabs are designed for 80 - 100 psf. Of course, this would be primarily a storage deck and not subject to regular traffic, but as a structural engineer, margin is always a good thing.

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joe,

right, cost. with joists and heavy duty decking you might end up spending a bit more on overall steel tonnage, but then they are a whole lot lighter and easier to move around and set, and the beams will most likely need heavier equipment to lift and position. and like jason said, you will need to check the footing, if any, wherever the beams are anchored to the stone wall - or underpin and add a footing. i have done that and it's a real pain. the joists would spread the load and probably not put more vertical load per joist than the original timber framing. the forming and shoring of all the concrete for the poured in place floor is labor intensive which is unecessary with joists and decking, and if you have any interior columns you'll need to check the bearing capacity of the existing soil and pour footings. any openings should be sleeved or framed in the concrete floor, and later openings are harder to install; whereas you can more easily core the deck and lightweight concrete topping, and openings are easier to frame later in the steel deck.

sloping the topping and installing floor drains, highly recommended, is also easier.

as for flooring, you can apply harderner, epoxy topping with abrasives,

dyed concrete or anything over the topping including, i guess, wood if you wanted. obviously you don't want to add a lot of weight per square foot.

this is maybe way more info than you wanted.

best,

howard

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Keeping in mind that I have no idea of size of this building I would go with a bond beam around the stucture, incorporating a support to anchor steel joists to, and pour a concrete floor on top of steel decking. You can make the bond beam taller if you need more height, The face of it could stone venner to match existing if is below where your siding would start. I like the concrete for it's economy and fire resistance. You can treat the surface any way you choose. There are unlimited options for floor covering. John

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For what it's worth,

I had looked into this with a bank barn I had here. After checking with the local codes Gastopo, I would not have been allowed car parking on the top floor unless I installed a concrete floor!

Etters, Pa

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