exteriorfootingsmunicipality
Aptos, CA, United States
What service or documentation resource can I use to determine what the frost-line is for my area? I'd be inclined to ask the county building/planning office but I suspect that they'll want to charge for answering a seemingly simple (and hopefully well documented) question.
Sprinkle flour or talcum powder on the floor. Mice will leave tracks in the powder, eventually revealing entry points or nests. You don't have to blanket the entire floor, just near the walls/borders of the rooms, and "as needed" until you have the evidence you seek. Keep in mind that their typical range is 12-20 feet from their nest.
Look for mouse droppings.
Use an ultraviolet light to find urine stains.
Use light. If you can make the room dark, look for sunlight shining through cracks from outside. Or, wait until dark and shine a light through possible cracks, either from inside or outside, and have an assistant on the other side alert you to any light shining through.
Watch for drafts. If you're in a cold climate such as Minnesota, wait until it is -20 degrees Fahrenheit, so that you can feel the cold air blasting through the mouse hole. (That's how I found an entry point recently. The cold air was flowing into a basement crevice such that I could see a spider web waving in the air. Turns out there was a crack where an addition had been put on the house. This was confirmed by shining a light as described above.)
Burying the wood post will cause it to rot prematurely. Even ground-contact rated Pressure Treated lumber won't last forever.
The only benefit of burying the post (besides it being easier to do) is lateral stability. i.e. you can sometimes neglect lateral bracing this way.
Best practice for wood-post decks is to have the concrete extend above grade and use a stand-off post anchor to hold the wood post to concrete.
Here is an example of this with some knee-braces for lateral bracing.
The braces don't match so I find this somewhat ugly, but the image is clear and easy to understand.
Footings here don't need to be deep so I often form my own square ones but sometimes I use bigfoot forms and I really like those. Although Shirlock's "mushroom" method is more than adequate if you are only required 8" wide.
Best Answer
In general you can use these guidelines.
These are very good guidelines that are widely recognized. However if getting inspected I would just ask your building department for their code requirements.
**NOTE***** This is how deep your footings would be in undisturbed soil. So for example if there was a regrading of the land - as often the case in new builds - you would have to go this deep past the disturbed soil or consult an engineer that would sign off on something else. So if they regraded your land to 3 feet and you lived in Arkansas you would need to go to 54 inches or gets clearance from an engineer to put the footings shallower.