Foundation types?

[Tractor101]

Hi all, this is my first post after lurking around here for quite some time and it is also when I have come across my first question as to how I should proceed. I am sure I will be talking with all of you much more in the near and distant future.

Ok, I am in the planning stages of building an outbuilding. I went ahead and tried a search however could not find anything that would completely answer my question. The shape of the building that I plan on building will be aprox. 30*60 feet with a concrete floor. The building will be divided into two 30*30 areas at this point with one side being insulated for a workshop and the other non-insulated for storage purposes. My main concern on getting started is how to work the footing situation, at this point my question is do I have a solid footing/slab poured and begin construction on top of that? Price is a factor here as always and am a bit concerned with the cost. My 3005 with a bucket may have a hard time getting through our clay and shale based soil that occurs about 2 ft down "frost line is 4 ft". My second idea was a brick foundation with a poured slab. Lastly and the most user friendly idea to me is to create a post type system set in concrete 4 feet down. This is something that I personally could do and would leave only a slab to be hired out. My main concern with this is rot issues, although I do plan on installing gravel and a drainage system the long term lasting ability as well as the ability to have a slab poured within are two big questions for me.

I know this is one heck on an introductory post but thanks for any replies in advance.

 

[JB4310]

The post and sono-tube piers below the frost line would be pretty much standard for your type of building. The slab could extend to the outer footprint of the building to prevent the rot you're worried about.

The full footing/foundation would be nice but much more expensive. Anything with brick or block would require full foundation.

Good luck, JB.

 

[Egon]

Pile and bearing beam construction all in concrete.

You might have to get some proper design data.

The post's, beam and floor could all be poured at one time.

 

[Tractor101]

Thank you for the responses, It looks to me at this point that I am leaning towards the sono-tube piers below the frost line. This would make construction cheaper, easier and hopefully just as long lasting. I will have the slab poured to the outer edges of the parimeter as well.

 

[Duffster]

Why the sonotubes?

It really only gets you a slab on grade, why not jusy go with that to start with?

 

[Egon]

Why the sonotubes?

The sonotubes become piles supporting a grade beam when it's all poured.:thumbsup:

 

[Tractor101]

Thank you for the tips, I will look into it. . . tubes with a poured slab seem like the be route to take. . . that way if the cost of the project becomes a bit large I can alway opt to have the slab poured at a later date, to me that is important as well.

 

[biggerten]

Others with more experience will chime in, I'm sure. But a couple things stand out as questions to ask, it seems to me.

Your mention clay soil. In my neck of the woods, this causes frost heaves, where the clay holds water and freezes in the winter, expanding and thrusting. In the spring it melts and we get frost boils where the ground gets like quicksand as the water is released. There are good years and bad years for this, it all depends on conditions.

Now, it seems to me like you would have one side heated, and presumably the ground would stay unfrozen. The other side unheated and the ground would presumably freeze. If the substrate is not properly prepared and the soil held water, and heaves while the other part of the building stays put, the building will break. I have seen decks and porches pulled from buildings and busted up from this very thing, the house stays put and everything else moves.

Good luck, and do your homework.

 

[WVBill]

I live in a County that enforces the International Residential Building Code.

So when I was planning my outbuilding, I bought a copy of the IRC Code book. Somewhere around $60 as I recall.

The book contains a wealth of information that will help you decide how to design and build your building.

Specific things like foundation and slab design when the building will be partially heated inside are covered. It will tell you exactly how wide and deep to make your footers in your location with your type of soil, for example

I think the code book is a worthwhile investment whether you're going to need to get inspections or not.

 

[davo727]

On his foundation do you guys recommend any kind of cross beam dug out before the slab is poured? Should it have rebar running in the beams?

Yeah im asking for me too