Digging foundations
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bebster
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That's a small question with a long answer! Here's a great book that has lots of great information. Foundations and Concrete Work
But basically, the depth of digging depends on how deep you want your basement to be. Plus you then have to make sure that your footings are below the frost line. The less stable the soil the more you have to dig out to prevent cave in.
Concrete contractors tend to like to work with 8' high forms, so that is a popular and economical basement wall height. But 10' is a nice height if you can get it, but it means larger forms and wider walls to support the height.
But basically, the depth of digging depends on how deep you want your basement to be. Plus you then have to make sure that your footings are below the frost line. The less stable the soil the more you have to dig out to prevent cave in.
Concrete contractors tend to like to work with 8' high forms, so that is a popular and economical basement wall height. But 10' is a nice height if you can get it, but it means larger forms and wider walls to support the height.
L
LarryRB
Guest
Too many invariables with your question. I suggest watching a guy doing one new house or even a large developement.. Bldg codes, geographical area, it's substance, maybe soft soils, rock or rock ledge, high tension wiring, what is underground in the area? Gas, electric, cable, water, or? After obtaining anything from dig safe, we always dig a foundation hole right to left, finished size plus a minimum of four feet extra. This allows enough room to place footing forms, wall forms, insulation/protection and perimeter drainage. You can get involved in four different approaches doing a small developement even on the same property, say and old farm or something. Best thing is, next new home/homes you see in your neighborhood, stop, get out, watch and ask questions if their willing to stop and answer them..
dltimmons
Bronze Member
As the other replies have stated, there is no one answer to this question.
Your local building department will be able to provide you with minimum standards for each of the types of foundations used in your area. However, in most areas an engineered foundation plan is required to obtain a building permit. If an engineered plan is required, then a soils test will also be required before the plans can be engineered.
Different areas of the country have different standards, based on average depth of frost line in winter, wind and snow loads, earthquake, etc.
Easiest way to get a quick/dirty answer to you question, is to look at similar buildings, close to your site. A real answer will cost some time and money, and can be different for each site, even in the same neighborhood.
These are some of the considerations you asked about, but by no means, all of them.
DT
Your local building department will be able to provide you with minimum standards for each of the types of foundations used in your area. However, in most areas an engineered foundation plan is required to obtain a building permit. If an engineered plan is required, then a soils test will also be required before the plans can be engineered.
Different areas of the country have different standards, based on average depth of frost line in winter, wind and snow loads, earthquake, etc.
Easiest way to get a quick/dirty answer to you question, is to look at similar buildings, close to your site. A real answer will cost some time and money, and can be different for each site, even in the same neighborhood.
These are some of the considerations you asked about, but by no means, all of them.
DT
Junkman
Super Member
I have a 10' foundation and there is no way that I would ever build without a 10' foundation. The cost was an additional 25% of the basic 8' foundation for the extra 2', and it is worth every penny. Mine is 12" thick poured concrete and I have wider footings to accommodate the additional weight of the walls. The nicest part of a 10' foundation is that when all the utilities are in place, you still have plenty of room above your head if you choose to use the cellar for something other than a storage place. I have planned on finishing the walls and putting in a dropped ceiling for additional living space. The extra usable square footage is well worth the small additional cost. It is even more important if you are considering using any steel beams for additional floor support. Many foundation companies don't like to do them because it takes a little longer to set the forms, but if you are persistent, you will find one that will do it. It means laying one form lengthwise at the top of the standard 8' forms. Nothing else changes from there...
