adding onto house

>>1192479
>It'd also extend about 6' below the ground

Where do you live? 6ft should get you below the frost depth almost everywhere, but we should make sure.

walls without foundation? what is this shit?!

>>1192498

house was built '47, standards were a bit looser back then. The builder at least used 2x4s in the frame though.

>>1192479
the actual labour is the easy part
passing building inspection and proofing your design is quite the other. if you already have the plans worked out and the calculations done for your soil type, accounted for trees and temperature and all that shit then go for it, if you are pouring a slab your going to be calling up a mixer anyway, rent something to mix mortar it will take you 3x as long to mix it as it does to lay it ignoring the energy you will spend. if you enjoy boring repetitive hard labour like laying blocks then go for it what are you asking us for? sometimes there is nothing better than getting away from all the bullshit and doing something brainless for a few days to get back to reality. landscaping would be fucking therapy if i was in charge.

>>1192527

This was less a question about the hard labor involved (a thing I'm fine dealing with, I spent all last summer building a cement wall around my property) and more if an 18" foundation is (generally speaking) sufficient. I ask because, in case it's not obvious, I really don't want to do a solid slab because I've had them crack on me before.

>>1192546
Not something 4chan can tell you, call an inspector or an engineer.

Codes are different everywhere. Not a lot of people are using block for much of anything where I live. All slab and ICF.

It takes more labor and skill to run a block wall like your pic than an actual formed and poured foundation.
12"x12" footing below grade (depending on your local codes) with a double run of #4 bar, then a stem wall 6"-8" thick with single runs of bar. Stab bolts per local code. Use 2x6's or 2x8's to form your walls and then when you strip the forms those boards become your floor joists. On the inside span 18"x18" piers with a rebar grid hold up your joists. Use prepoured pier blocks at grade level and then cut posts to carry girders which run across the inside span, joists on top.

You would need to pour a continuous reinforced footing if you did a poured foundation, block wall, slab, etc anyway. You will most likely be paying a ton of fees on top of whatever concrete you buy (short load, carbon tax, fuel surcharge, etc) plus you may need to hire a pumper. When you look at it that way, it's just a couple bucks more to pour the entire stem wall.

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>>1192546
>>1193259
Yeah. You need someone to do the calculations. It depends on the soil and how your local regulations are. I'd ask the guy in charge but the basic plan would be like this.