I need help, 10ft of SOFT beautiful Top soil, in the way of my house 2

[misstea]

We are planning to build a house, the land really doesn't have enough slop for a good basement, so we were going to just build a 2 story house. We got everything ready and started digging last weekend and found out that at 10ft the soil was still black and soft. Is there anything we can do to build this house. what is the best way to support this house, can we build a basement and what is the best way, or do we need to just sale the soil and build a pool > LOL!!!! PLEASE HELP< I have no Idea were to go from here. Thank You

 

[DaveAtkins]

Speaking as a structural engineer, I suggest you hire a geotechnical tesing firm to drill a couple borings and give you recommendations for building on this site.

But if I were in your shoes, I would first talk to my builder and get his input. Maybe he/she has seen this type of soil profile in your area before.

DaveAtkins

 

[Slowzuki]

From what I've read about the topic researching our foundation, you may be able to use a concrete pier and grade beam design.

If you aren't really looking to stay conventional, a treated post foundation in drilled holes may be an option.

 

[cvg]

I would second daveatkins - you should let a geotech guide your decision. You can also get good advice from local homebuilders that have dealt with your situation before. You may even be able to get some help from the city of county building and safety department.

 

[GeoPaveTraffic]

Talk to a geotech and find out what the conditions are and what the future groundwater elevation is likely to be. That will tell you whether a basement is possible. If you don't want a basement, one option would be to bring in soil/rock and raise the grade of the building pad. However, there are a lot of "got ya's" so get a good local geotech and get them and your builder/arch. talking.

 

[Ron]

Ditto on getting a geotech involved. There are ways to handle it, but you need to know the extent of your issue. If you build on it, your downside might be differential settlement, or even uniform settlement, but could be a lot of it.

Pier and grade beam is not a likely solution to soft soils at the level you describe.

 

[BigH]

There is absolutely no question that a local geotechnical engineer must be involved. It appears that you are describing, perhaps, a peat soil (10 ft of black soft). This should have set off bells and whistles. First off - where are you located? Are you in the "boonies" or inside a development - rural or urban. If there are other houses around, ask the owners if they know how their houses are founded. If they don't know - take a look to see if you see any tell-tale signs of settlement (cracked driveways might be one example - even a little fill on peaty soils will lead to settlement. There are so many possibilities that only someone with the expertise locally can help you out. Remember the cost of a geotechnical engineer might be small compared to digging out more material and having to import it. Also, why did you dig down 10 ft. I would have stopped at 3 or 4 ft (normal footing depth) and then scratched my head and wonder. You've just dug out, perhaps 6x20x30 ft more soil (viz., 130 cu.yds more than you might/should have - at $5/cu.yd - that is $700 - about 2/3 or what a local experienced geotech might have charged for some preliminary advice. So . . . get someone on board who knows what they are doing and figure it out before you do anything more.

 

[misstea]

Big H,
We are building this house ourselfs, with the help of a friend that has built houses.
The land is strange, WE are in the Boonies near the water, the land had not been touched in any way for decades I am sure, we remove the trees that were in our way. We went 10ft cause we thought that forsure we would hit something solid and be able to build a basement house. But that wasn't the case. The land development isn't costing us cause our family has the equipment to do it so that is how we could play around and it not cost us a lot, but now we are stuck, not sure what to do with this soft soil. That is why I came on here the nearest Geotech in almost 3hrs from me. I checked on that today. The funny thing is right on the boundries of our land we dug a hole for bury some left over stumps and the soil was red clay and rock. It seems like there is just pockets of this soft soil, and in the areas that we have to build our house, because the lot is narrow.
I hope this info helps with some of the questions you have. Oh there are other houses across the road on a steapier slope.

 

[dicksewerrat]

It sounds like you are on an old ravine that was filled during the last glacier event. Can you keep digging? Or can you push a pipe down to get a sample of the soils and where it stops. and most important what is below the 'peat'?

 

[GeoPaveTraffic]

I'm sure that you don't want future trouble with your house. I would contact the geotech and make arangements to meet him/her at your house site when you can be there with the equipment. They may want you to dig some other pits in the area while they are there to figure out what the geologic history of the site is. At that point they should be able to give you some good recomendations as to how to proceed.

The cost should be somewhere around $100/hr., including the travel time. If you don't need/want a formal report, then all you will be out is the time of the engineer to travel to/from the site and the time spent. When compared to the cost of a house, that is money well spent.

Good Luck.

 

[boo1]

Consider moving the home location to a different part of the lot.

 

[Slowzuki]

I only mentioned the pier and grade beam as in our area where there are soft soils they tend to drill to a bearing soil say 30 feet down, install piers then grade beam.

This wouldn't work in a area where there is no suitable soil deeper.

BTW the soft soils here are silt deposits from an old flood plain. A large hotel built here had the loading calclated incorrectly and one side sank 6" before they poured the second floor!

In our area the worst problems with settlement are poured basements under multistory houses. The old houses built on mud sills have the least problems, the houses built on driven piles seem to do well as well.

 

[Riggly]

I think you have already gotten some excellent advise. I will just reaffirm that you need to get in touch with an experience geotechnical engineer, and perform further subsurface exploration. Apparently, you are dealing with very poor foundation material (possibly peat as someone suggested).

Subsurface exploration using standard penetration testing(SPT) sampling might save you some time in evaluating the extent of the poor soil.

 

[dirtguyMD]

Alitte money spent on a basic geotech exploration / evaluation ($2,500) can save alot of money in the end. How much is your total project going to cost? So if you decide to stay with this location or move to a new location, I would still get atleast 2 SPT borings done, or one day of a drill rig.