Thank you. I appreciate the link and enjoyed reading what they had to say.
One of my personal observations when digging and filling in trenches is that even years later when everything appears to be solid, the fill dirt is always different then the undisturbed dirt. I doubt it will ever be the same, but until it is, it will always absorb more water then the undisturbed soil. Grass grows better there for this very reason. What I'm seeing and my thinking is that in traditional basements, they have to back fill around the basement wall with something. It does not matter what you use because whatever it is, it will hold more water then the surrounding, undisturbed soil. Since this is going to happen, getting rid of the water that is now being allowed into the surrounding area outside the walls becomes the challenge. Gravity says water will go down as far as it can, then fill up the hole. Since the bottom of the soil under the basement is also undisturbed soil, what you have done is create a pond with a room inside of it. The challenge in all basements is how to get rid of the water that you have created a place for it to travel to.
I also feel that basements are just bigger french drains. Dig the hole, fill it with gravel and it fills up with water. What to do with the water is the next step in the process, but if you had never dug the hole, water would never be in the ground to any significant level, and you would never have to deal with what to do with it once it fills up that hole.
If anybody has done any significant digging with a backhoe or excavator, you will learn real fast how much water is in the ground at different depths. I have places where I can dig down four feet and have it fill up with water during the middle of summer. Where my house is, I can dig down 12 feet, and have, without any sign of water or even moisture on the sides of the hole.
My thinking is that with the rubber liner up against the sides of the hole I dig for the basement, when I pour concrete, it will force the rubber liner solid against the undisturbed soil. The only path for water to get down into the ground there is going to be along that seam, or outside edge of the rubber liner, which is going to be very tight because of the weight of the concrete, and it's ability to form to the shape of the wall. Cost of this much concrete is insignificant compared to building with block, sealing the block, buying drainage gravel and creating a drain line to where it comes out on it's own, or installing a pump to remove the water that I'm inviting into the sides of the basement walls and storing under the basement.
Swimming pools that are done in concrete do not float out of the ground. Fiberglass pools do because of the fill material that goes in around them after they are placed in the ground. This fill material becomes a storage location for water to build up until it floats an empty pool upwards. This is why they fill fiberglass pools as they back fill them.
I do not believe there is any chance of my basement floating if done the way I propose. The floor alone will be a very thick slab poured before the walls. Then the walls will be poured at the same time as the slab for the addition, with one wall of the basement being part of the footing of the addition.
I'm enjoying the research into this, and appreciate everyone's thoughts, suggestions and concerns. They make me think harder about this, and force me to look into what is done and why it's done. For me, this is a lot of fun!!!
