Foundations
Whether it's a pole barn or a house, your project needs a good foundation. What are your options? Why dig down to pour a foundation? What about pole barns or posts?
What are you options?
--A monolithic (meaning "poured in one pour" so there are no cold joints) slab is a floating, concrete slab foundation that is 3 foot thicker around the edges. Thus, the slab and foundation happens in one pour. --A traditional foundation consists of two parts: a footer below frost line (this varies with the altitude or local climate), a stem wall (poured either with the footer, or commonly after the footer). This creates a foundation and then a slab may be poured on top or framing may begin on the stem wall. Slabs may be poured on top of the stem wall or level with the stem walls --again, the options and applications vary. See Foundations and Footers below for more details.
So which foundation is best? It depends on your site conditions and overall costs. Read an excellent article here about the Pros and Cons of Different types of foundations .
What's a cold joint?
When concrete is poured and allowed to dry and then more concrete is poured connected to that, a "cold joint" is created. This cold joint is weak point in the concrete as well as a place where moister may enter. Properly installed footers and stem walls should not have cold joints. Of course, circumstances at times may make cold joints unavoidable.
Why dig down?
The ground moves as it thaws and freezes. If a footing is below the frost line, then the "movement" of the ground does not interfere/move the structure. House foundations usually consist of a footer and then foundation walls, beginning below the frost line.
Foundations and Footers: The "footer" consists of concrete usually about 16-24" wide and about 6-8" thick. This measurement depends on the structure built upon it; obviously, the larger the structure, the more intense this thickness. The walls (usually much more narrow, sit on this footer). Theoretically, this 'footer" never moves, --even though the ground around it may move up or down. Do foundations settle? Yes, occasionally. However, the overall mass usually keeps the settling to a minimum so it does not make structures unsafe. One part of inspecting a house before you buy would be to look for settling or movement of basement walls. Cracking is usually normal, though the cracks should not be large or make the entire wall appear crumbly.
What about pole barns and posts? Posts for pole barns or any permanent structure should be setting on footers, the same as the foundation for a house. Often people install what is known as a "bigfoot" (large tube that fills with concrete, looks like a "big" foot on the end). Another option is to dig a 2" x 2" (or bigger) hole and fill it with concrete. Sometimes the posts set down in that concrete and sometimes they sit on top. The principal is the same: get below frost level to minimize movement and create a solid foundation for the rest of your structure to sit on.
