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Discussion Starter #1
Okay, so we're building our house next year. We're on a slope (not huge, but enough to matter) and our soil is the worst possible scenario, clay.

I've been looking at alternatives to standard footings to try to make construction easier and less expensive.

Anyway, I came across this system that uses three poles, driven into the ground at angles, that then connect to the upright. No digging, no concrete.

Sounds simple and cheap, which worries me.

Please take a second to look at it and give me your thoughts...

CV Substructure Systems
 

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I'm not a civil engineer, but IMO in most cases you get what you pay for. Building a home is not a time when you want to cheap out on things. If you want to save money you can do certain things yourself like painting, etc. Just my :2cents:
 

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Discussion Starter #3
spicersh said:
...Building a home is not a time when you want to cheap out on things...
Yeah, that's my line of thought too.

Do you think it's a sound construction method though, cost savings aside?
 

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My thoughts on it:

A traditional foundation gets a significant portion of its strength from sheer mass. Moving to a system like this puts the stress that was previously suported by all that mass into much smaller members. Your asking for a lot more from a lot less.

It would seem to me that a system like this would be much more susceptible to small movements of the earth (seismic, settling, mudslide). A traditional foundation would be able to slide a small amount to compensate for movements. Small movements would add stress to this system in a direction where the structural members are weak.

Finally, steel buried in the ground will corrode, galvanized or not (just a matter or time). I'd be concerned about the longevity of the system.


Building on pilings is not a new concept, but I've never seen it done on pilings this small.
 

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Discussion Starter #5
Thanks for your input. You put forward a very strong argument against it.

I think our best bet is going to be to stick with a standard construction: square steel posts set in concrete.

To combat any movement, we'll just go deeper than standard. It'll mean extra costs for longer posts and concrete but, by getting down a couple of metres, we can get into an area that won't have much movement, if any.

We can get posts with a turnbuckle system built into them. That way, if the house does move at all in any given area, I can go under the house and adjust the necessary post(s).


Thanks again for your thoughts. :thumb:
 

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Sounds like you have got it figured out. I am very glad to see that you are not goin with the pre-fab posts. Go deep enough, you will have a very nice solid feeling structure with the concrete columns. I like to go up out of the ground with the concrete and set a steel bracket into the piller. Then bolt on post, with notches for your outside bandboards. If you join everything together with mortice and tennon you can raise any corner of the house with a bottle jack, and shim under that post and rebolt it. I used to build barn homes and restore colonial farm houses, we would restore old barns like this all the time. Cut off the bottom of a post. Pour concret pillars under it and set it back down. -- Good luck on your project. Keep any roof run off water away from the house and you will be set.
 

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Discussion Starter #7
I won't be building the house. As handy as I am with wood, this is waaaaay beyond my skills. We're currently getting quotes from builders. Looks like it's going to come in around AUD$300k (US$220k). With the cost of the land thrown in, that'll make it a AUD$450k (US$330k) house and land package. Being that this is our first home, it's scaring the crap out of me! :eek:

The posts will be galvanised and set directly into the concrete. The concrete will sit just above ground level, enough to stop it from pooling in that spot. The top of the posts then have a steel saddle that the joists sit into and are bolted to. It's generally how things are done in Australia, unless you go for a concrete slab on the ground.

Being on acreage, we don't have town water, so all rain water will be harvested into water tanks. At this stage, we're looking at using two 23,000L (6,000 gallon) tanks. The house is about 39 squares (363sq.metres : 3,900sq.ft.), including deck area.

We'll also be putting down a bore, as the underground water in the area is quite good. That water will be used for gardening, etc.

Finally, we'll be installing a grey water recycling system, that will reuse the water from the showers, baths and hand basins in the toilets. It's amazing just how much fresh water is wasted just flushing a dunny!


Thanks for your input. :thumb:
 

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Outside the US, if a civil engineer has approved it, you're good. Everywhere in the modern world that I'm aware of, CE's are required to pass what is, in effect in the US, a Professional Engineer's licensing. They deal with all sorts of the details like impact of quake zones, expansion of clay, and the like and are certified (and often insured) to be correct.

So look for its use in any modern commercial building. And at the liability coverage for those installing such work. And the CEs that have made statements about it.
 
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