Hello All new to Board (Soil Questions)

TRE329 · May 27, 2010, 07:33:36 PM

Hi all I am new to the board,other than lurking. This is a really great site. I am very interested in building my own home. I have been playing around with a few plans ,trying to find the right one.
I was reading some of the posts and figured first off I had better find out what my soil was like as that might shape some of my decisions.

Can anyone help me determine how this info affects my foundation ,plans etc.

diyfrank · May 27, 2010, 08:02:03 PM

On that same site find the section that looks like this.

Use this chart to see the soil characteristics.
http://countryplans.com/smf/index.php?topic=8861.0

May 27, 2010, 08:58:16 PM

Ok I found the page you were refering to ,and it does not look to good. The table in the article is refering to basement foundations ,so how does this relate to the other foundation types?

n74tg · May 27, 2010, 10:04:29 PM

Hello Tre - I'm over in Hot Springs, so welcome to the forum.

In answer to your question, why don't you just see what others in your area have used for foundation designs. You will probably see several different designs and can compare how it looks like they did over the long run. There might be a county extension agent you could call up. And I'm sure University of Arkansas has some information on the subject.

My project is on clay over shale. If memory serves for the type soil I had my footers needed to be I think 8" thick by 16" wide. I think I averaged 17-17.5" width so the load is spread out a little more.

My foundation has been working fine for about 3 yrs now.

Good luck with whatever you choose to build.

TRE329 · May 27, 2010, 10:29:23 PM

Quote from: n74tg on May 27, 2010, 10:04:29 PM
Hello Tre - I'm over in Hot Springs, so welcome to the forum.

In answer to your question, why don't you just see what others in your area have used for foundation designs. You will probably see several different designs and can compare how it looks like they did over the long run. There might be a county extension agent you could call up. And I'm sure University of Arkansas has some information on the subject.

My project is on clay over shale. If memory serves for the type soil I had my footers needed to be I think 8" thick by 16" wide. I think I averaged 17-17.5" width so the load is spread out a little more.

My foundation has been working fine for about 3 yrs now.

Hi Tony Thanks for the reply
I spent about 3 hours the other night reading and looking through your whole blog. Really nice home project you have there. I was interested in yours because I am thinking about 28 x 50 for mine. I get over to HS from time to time ,would love to come by and see yours in person sometime.

Good luck with whatever you choose to build.

May 27, 2010, 10:41:22 PM

Hi Tony
Thanks for the reply. I have seen a lot of foundations ,having worked for Terminix for about six years, before I realized I would not be able to walk in a few years after crawling so many houses and left. IMO alot of them did not look strong enough so I will probably go overboard when I do it. Going with a larger plan like yours,did you find that you had to change anything as far as load bearing walls ,etc.

I actually spent about 3 hours the other night reading and looking through your whole blog. I am thinking about 28 x 50 or close to that so your 30 x 60 was very intriguing. I get to HS from time to time ,would love to see yours in person sometime.

diyfrank · May 27, 2010, 10:44:03 PM

Your soil is list as group 2 with medium to high frost heave potential medium to low expansion. I wouldn't say it's bad soil. Quite average really. The article on the other link is for backfill on basement foundations. The soil characteristic is what you wanted. If your down below the frost line, which you should be anyway you should be all right. Clay is the one that raises a red flag to many because it can be unstable and the heave potential is high.

TRE329 · May 27, 2010, 10:52:57 PM

Thanks Frank

One thing I had noticed on other examples was that after about 30-72 inches they hit some harder substrate. Mine is pretty much the same all the way to 6 foot (silt loam ,silty clay) is that a problem that it runs so deep. Could I be making this harder than it needs to be , just over do it per my tendencies and let it ride?

diyfrank · May 27, 2010, 11:27:14 PM

If your ground is wet it may not be the best but if it's dry you may be fine. I always probe when in doubt. If you can take a piece of re bar and stick it in the ground more than a few inches with a fair amount of effort you may want to have your sub grade looked at by a pro. You can always over excavate and bring it up with rock to take care of soft areas. Talking to people in your area is a good way to get a feel for what is needed.

You haven't said yet what type of foundation your thinking on.

May 27, 2010, 11:31:10 PM

Well since you asked ( just kidding I figured I better give ya'll some idea of what I was thinking) I
worked up a quick plot of what I have been thinking about.

n74tg · May 29, 2010, 05:27:28 PM

Tre:

PM me a couple of days before you next plan to come to Hot Springs and I'll give you directions.

Your foundation plan drawing above is actually more robust than mine was. I have only two longitudinal beams where you have three and I spaced my piers on 10 ft centers, where you went with 8'. Unless you live on extremely poor load bearing soil I expect you have achieved your goal of overbuilding your foundation.

I also used three 2x10 sandwiched for my floor beams and 2x10's for floor joists, mostly set on 24" centers, but everywhere there would be ceramic tile I went with 16" spacing. If memory serves, it gives me basically an L/700 deflection limit, where L/360 is often considered acceptable. With your beams being on 7' centers you might be able to get away with 2x8 floor joists.

Other than increasing the width of the footers by on average an inch, I didn't do anything else to beef up the footers. Getting a good concrete cure to yield maximum strength by keeping the concrete wet and covered for a whole WEEK before uncovering, I didn't do anything else. Good curing practices really do pay off even though it adds a little time on the front end of the project.

Now, get busy and start building. Pictures, we want to see pictures. Just kidding, do them when you're ready.

Good luck with it.