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I, for one, would rather be building on sand rather than clay. Clay is an absolutely terrible substrate for construction. Not to mention it does not drain. Hill

I, for one, would rather be building on sand rather than clay. Clay is an absolutely terrible substrate for construction. Not to mention it does not drain. Hills don't become saturated with water... the water tends to flow to ze bottom of ze hill, where it will saturate things. I'd be curious to know what exactly you are draining into... drywells and clay are not friends. - High-end residential builder here

WalterBright 10y ago
It drains into the storm drains, and the pipes carry that off to wherever they go :-) which is the waterways. I know that because the code people had me build a grass swale to filter the runoff from the driveway before it entered the drain. Some other homes on the hill had to be built on pilings because they were in an area which was loose dirt that had eroded away from higher up. I'm not sure if 'clay' is the right word, I don't know much about geology, but the geologist definitely said compacted "glacial till" which he said was ideal. Haven't had any settling problems so far despite an earthquake and lots of rain. I passed on another lot where the geologist said the whole hill was going to slide away at some point. The seller didn't want to hear that.
astrodust 10y ago
Clay can be a total pain in the ass to work with, it's more stubborn than concrete to remove, but you'd be hard pressed to find a material more solid to build on than rock. What's your beef with clay? The kind of glacial packed clay mentioned in this article is the sort of stuff even a power shovel has trouble with. It looks like light coloured slate, dry, brittle, and dense. I'm not sure what your preference for sand is other than it's easy to work with. That stuff can shift, it bloats when wet and heaves with frost, settles like crazy under pressure. Sure, it's easy to remove, but it's so variable I have no idea how you'd get anything to stay level on top of it.
- Gibbon1 10y ago
  Not sure but my understanding is high clay soils expand and contract seasonally due to moisture changes.
  - astrodust 10y ago
    In a location with a variable water table this could be trouble, but I'm not sure it's going to be much better in the same situation with sand. I wonder what kind of foundation these homes are built on. Do they include a full basement?
- nucleardog 10y ago
  > Sure, it's easy to remove, but it's so variable I have no idea how you'd get anything to stay level on top of it. Living somewhere built on what is apparently some of the most variable types of clay and that experiences temperature swings of ~150F throughout the year: we don't. Any basement more than 30 years old is cracked and heaved. Houses require constant adjustment of the teleposts to avoid large cracks forming in the house built on top of the foundation.

WalterBright 10y ago

It drains into the storm drains, and the pipes carry that off to wherever they go :-) which is the waterways. I know that because the code people had me build a grass swale to filter the runoff from the driveway before it entered the drain. Some other homes on the hill had to be built on pilings because they were in an area which was loose dirt that had eroded away from higher up. I'm not sure if 'clay' is the right word, I don't know much about geology, but the geologist definitely said compacted "glacial till" which he said was ideal. Haven't had any settling problems so far despite an earthquake and lots of rain. I passed on another lot where the geologist said the whole hill was going to slide away at some point. The seller didn't want to hear that.

astrodust 10y ago

Clay can be a total pain in the ass to work with, it's more stubborn than concrete to remove, but you'd be hard pressed to find a material more solid to build on than rock. What's your beef with clay? The kind of glacial packed clay mentioned in this article is the sort of stuff even a power shovel has trouble with. It looks like light coloured slate, dry, brittle, and dense. I'm not sure what your preference for sand is other than it's easy to work with. That stuff can shift, it bloats when wet and heaves with frost, settles like crazy under pressure. Sure, it's easy to remove, but it's so variable I have no idea how you'd get anything to stay level on top of it.

Gibbon1 10y ago
Not sure but my understanding is high clay soils expand and contract seasonally due to moisture changes.
- astrodust 10y ago
  In a location with a variable water table this could be trouble, but I'm not sure it's going to be much better in the same situation with sand. I wonder what kind of foundation these homes are built on. Do they include a full basement?
nucleardog 10y ago
> Sure, it's easy to remove, but it's so variable I have no idea how you'd get anything to stay level on top of it. Living somewhere built on what is apparently some of the most variable types of clay and that experiences temperature swings of ~150F throughout the year: we don't. Any basement more than 30 years old is cracked and heaved. Houses require constant adjustment of the teleposts to avoid large cracks forming in the house built on top of the foundation.