Author Topic: Micropile foundations  (Read 5221 times)

Offline Joe Sr.

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Re: Micropile foundations
« Reply #15 on: December 12, 2011, 08:31:34 AM »
In the US, is it relatively common to see houses built near riverbeds? I mean, there's St Louis, for example, but I dunno on a residential scale.

Unfortunately, yes.  Typically farmland, but also whole towns are built in the flood plains.  And people hope the Army Corps keeps the damns working.

Annual flooding here in the Midwest is a BIG deal.  Last year they blew a dyke in downstate Illinois to save one town and washed away everything on the other side of the dyke, which was mostly farmland.

Construction on pilings is a common practice, though I don't know how common for a single family home but I would guess uncommon.  What it basically means is that the soil won't support what you're doing.

Get a local professional.  Someone there has dealt with this.  How to get a good reference for who to deal with is an important question.

Good luck.
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Offline punatic

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Re: Micropile foundations
« Reply #16 on: December 12, 2011, 08:32:42 AM »
Sounds like the land has two concerns; flooding and unstable subsurface conditions caused by river sediment.  Looking at the flood history, it's been over 170 since the last major flood.  Also, there are long periods between floods.  This could mean the next major flood may not happen in your lifetime, or the next major flood is way past due and could happen in the next rainy season.

How do you feel about building a basement in a flood zone?  You have to decide what your tollerance for risk is.  Will the worry cause you to lose sleep?

Building a basement over piles should not be a problem.  Building a basement in an area with a high water table could mean constant headaches.

You need to consult with a geotechnical engineer who is familiar with local conditions and construction techniques.  I am certain the engineer will request test borings on the site to determine the specific subsurface conditions.  The engineer will know who to recommend to do the foundation work and can act on your behalf to make sure the design is properly constructed.

Do your due dilligence now.  Save money later.
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Offline phillamb168

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Re: Micropile foundations
« Reply #17 on: December 12, 2011, 08:53:12 AM »
The people I've talked to today say I need to request an 'etude du sol' - soil study. They do exactly what Puna mentions, take ground penetrating radar scans of the whole lot, then take at a minimum of three core samples. It's expensive, but I'd rather pay a bit more for some place where I won't have problems later on. More cost now = less cost later, etc.

I know it's not ideal to do this, but the thing to remember is that the entire country is less than the size of Texas, but with three times the population. All of the 'really good' land already has a house on it, and demo costs are crazy crazy high because of anti-pollution and antiquity regulations. Which means to get anything with some property, you have to buy swampland or something slightly better...
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Offline morticaixavier

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Re: Micropile foundations
« Reply #18 on: December 12, 2011, 09:00:17 AM »
The people I've talked to today say I need to request an 'etude du sol' - soil study. They do exactly what Puna mentions, take ground penetrating radar scans of the whole lot, then take at a minimum of three core samples. It's expensive, but I'd rather pay a bit more for some place where I won't have problems later on. More cost now = less cost later, etc.

I know it's not ideal to do this, but the thing to remember is that the entire country is less than the size of Texas, but with three times the population. All of the 'really good' land already has a house on it, and demo costs are crazy crazy high because of anti-pollution and antiquity regulations. Which means to get anything with some property, you have to buy swampland or something slightly better...

When I was a little one I lived with a pack of wild lesbians who decided to build their own house... on a flood plane... from reclaimed timber... octagonal. It actually worked really well and is still standing 30+ years later. What they did was build pilings out of 24"x24" beams that were salvaged from an OLD factory. They tied several together and put them in 6' holes so when the river flooded (which is did every year) the pilings would float up slightly and then settle back as the water level dropped. Now this was in VT in the 70's so zoning was not much of a problem and you would probably have a hell of a time getting past zoning in france what with the antiquity rules etc. but it can be done in even the most unstable land. It just takes a lot of foresight.
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Offline bo

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Re: Micropile foundations
« Reply #19 on: December 12, 2011, 09:10:44 AM »
The people I've talked to today say I need to request an 'etude du sol' - soil study. They do exactly what Puna mentions, take ground penetrating radar scans of the whole lot, then take at a minimum of three core samples. It's expensive, but I'd rather pay a bit more for some place where I won't have problems later on. More cost now = less cost later, etc.

I know it's not ideal to do this, but the thing to remember is that the entire country is less than the size of Texas, but with three times the population. All of the 'really good' land already has a house on it, and demo costs are crazy crazy high because of anti-pollution and antiquity regulations. Which means to get anything with some property, you have to buy swampland or something slightly better...



When I was a little one I lived with a pack of wild lesbians who decided to build their own house... on a flood plane... from reclaimed timber... octagonal. It actually worked really well and is still standing 30+ years later. What they did was build pilings out of 24"x24" beams that were salvaged from an OLD factory. They tied several together and put them in 6' holes so when the river flooded (which is did every year) the pilings would float up slightly and then settle back as the water level dropped. Now this was in VT in the 70's so zoning was not much of a problem and you would probably have a hell of a time getting past zoning in france what with the antiquity rules etc. but it can be done in even the most unstable land. It just takes a lot of foresight.

Are you suggesting that he hire a pack of wild lesbians? Where would I find them in the phone book? :D

Offline dak0415

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Re: Micropile foundations
« Reply #20 on: December 12, 2011, 09:19:00 AM »
Are you suggesting that he hire a pack of wild lesbians? Where would I find them in the phone book? :D

That would be "ENGINEERS - CIVIL - WILD LESBIAN"
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Offline tschmidlin

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Re: Micropile foundations
« Reply #21 on: December 12, 2011, 11:08:49 AM »
I lived in a house on pilings in NJ on one of the barrier islands (Long Beach Island).  There you had to have break-away walls on the bottom floor in case the waves came over the dunes, but you probably don't need to worry about that.  Anyway, that's not really the point.  It will add to the cost of construction, but it's straightforward and not some new and questionable technology.

I don't think you can count on having a cellar of any sort there, but the engineer you hire should be able to give you the details on that kind of thing.  1.5 acres on a river?  Sounds good to me :)
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Offline Joe Sr.

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Re: Micropile foundations
« Reply #22 on: December 12, 2011, 11:22:49 AM »
Drive sheet piling deep enough, install the proper drainage and pump system and you can have a basement anywhere.

It may not be cost effective, though...
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Offline punatic

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Re: Micropile foundations
« Reply #23 on: December 12, 2011, 11:42:28 AM »
Phil - Do other homes in the area have basements?
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Offline tschmidlin

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Re: Micropile foundations
« Reply #24 on: December 12, 2011, 04:21:41 PM »
Drive sheet piling deep enough, install the proper drainage and pump system and you can have a basement anywhere.

It may not be cost effective, though...
Sure, you could build one at the bottom of a lake if you did it right . . . actually, that would be pretty cool :)
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Offline phillamb168

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Re: Micropile foundations
« Reply #25 on: December 13, 2011, 07:55:35 AM »
Phil - Do other homes in the area have basements?

The geology around here is nuts. Check out this image to give you an idea:



Limeston, colluvial, alluvial, calcates, granite, sand...

Some homes do, for example, my current one. But, my wife got ahold of a soil engineer last night - SO NICE on the phone, hell of a welcome change from the b*tch from the mayor's office - and he said when we go visit the property on Thursday to see where the other houses are, what they look like, etc. He said that a basement is indeed out of the question, and it's a matter of 'if' not 'when' the river will flood. But mirroring what tschmidlin and morticai said, it's doable but not with a basement.
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Offline morticaixavier

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Re: Micropile foundations
« Reply #26 on: December 13, 2011, 09:16:57 AM »
Phil - Do other homes in the area have basements?

The geology around here is nuts. Check out this image to give you an idea:



Limeston, colluvial, alluvial, calcates, granite, sand...

Some homes do, for example, my current one. But, my wife got ahold of a soil engineer last night - SO NICE on the phone, hell of a welcome change from the b*tch from the mayor's office - and he said when we go visit the property on Thursday to see where the other houses are, what they look like, etc. He said that a basement is indeed out of the question, and it's a matter of 'if' not 'when' the river will flood. But mirroring what tschmidlin and morticai said, it's doable but not with a basement.

I miss my basement. They don't have basements in california. It's nice to have a 4 hundred year history of how that river behaves though.
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Offline phillamb168

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Re: Micropile foundations
« Reply #27 on: December 13, 2011, 09:49:45 AM »
Phil - Do other homes in the area have basements?

The geology around here is nuts. Check out this image to give you an idea:



Limeston, colluvial, alluvial, calcates, granite, sand...

Some homes do, for example, my current one. But, my wife got ahold of a soil engineer last night - SO NICE on the phone, hell of a welcome change from the b*tch from the mayor's office - and he said when we go visit the property on Thursday to see where the other houses are, what they look like, etc. He said that a basement is indeed out of the question, and it's a matter of 'if' not 'when' the river will flood. But mirroring what tschmidlin and morticai said, it's doable but not with a basement.

I miss my basement. They don't have basements in california. It's nice to have a 4 hundred year history of how that river misbehaves though.

fixed that for you ;-)
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Offline tschmidlin

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Re: Micropile foundations
« Reply #28 on: December 13, 2011, 10:59:43 AM »
I wish we had a basement.  I have no idea why we don't, there's no flood risk.  They just don't seem to be done much in this area.
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Offline morticaixavier

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Re: Micropile foundations
« Reply #29 on: December 13, 2011, 12:31:34 PM »
I wish we had a basement.  I have no idea why we don't, there's no flood risk.  They just don't seem to be done much in this area.

I think what it often comes down to is expense v. necessity. I would guess that frost line where you live is only a couple feet deep at worst. it's a lot cheaper to sink some pilings (of stem wall) a couple feet than to excavate and pour a true basement foundation. I grew up in new england and the front line there is down around 5 feet. once you are digging down that deep you might as well put in a full basement. Here in southern NorCal the frost line is somewhere above grade so you get a lot of slab on grade or pilings on grade as the real concerns are seismic and termites.
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