i need to know how to build a foundation with a crawl space.?
Answers:
Wouldn't that be a slab of concrete with concrete block piers for your floor beam. You can frame above the beam or put down strong panel and pour your finished floor.
Other answers:
Which state do you live in?
In Calif, you need a structural engineer almost everywhere to properly design a foundation, plus how to tie it into your existing foundation.
In areas where the ground freezes during the winter, you need to place the footing below the deepest frost point - check with your city building dept for their requirements.
Years ago, you could just dig a 12x12 deep footing, line it 2x12's, and build an 8" wide foundation wall above that. Throw in a few lengths of rebar horizontally and vertically, and be done with it.
Now foundations have to be engineered. At a minimum, you have to add longer hold down bolts and shear wall tiedowns at the proper locations.
Check with an expert.
Which state do you live in?
In Calif, you need a structural engineer almost everywhere to properly design a foundation, plus how to tie it into your existing foundation.
In areas where the ground freezes during the winter, you need to place the footing below the deepest frost point - check with your city building dept for their requirements.
Years ago, you could just dig a 12x12 deep footing, line it 2x12's, and build an 8" wide foundation wall above that. Throw in a few lengths of rebar horizontally and vertically, and be done with it.
Now foundations have to be engineered. At a minimum, you have to add longer hold down bolts and shear wall tiedowns at the proper locations.
Check with an expert.
Without going into detail, you would need to build your foundation wall with "pockets" that would accept "beams" for support. These beams would have to be supported on "piers" (cement block columns) at prescribed intervals between opposite walls. The columns would have their own concrete footings. Lengths of beam can be joined on top of some of these piers by overlapping (a 20' length is about the longest) On top of these beams will go the floor joists. On top of the floor joists goes your sub-floor. Then the walls. Then the pre-made roof trusses. .Then some roof plywood. Etc. But just study some DIY books found at HDepot or the like. Call around to find someone to design it for you.