Foundation choice for daylight basement 1

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Hello. I am considering which of the different types of available foundations will be best for a new home in south-central PA. The foundation is to be 36'x52'. The soil is a silty-loam and slopes down about eight feet over the 36 foot depth of the house. We want to install a daylight basement with 10' wall height (2' of which will be above grade on the uphill side), however, cost is an issue and would like to know what foundation types are suitable in this circumstance. In particular, can cement block be used and what is necessary to counteract the unbalanced load from the daylight basement.

The site is located within 30 feet of the top of a ridge. The slope from the home to the top of the ridge is about 10 feet in 30... not as steep as the foundation site. There are not any creeks, etc, within 800 feet of the site.

Any input would be appreciated.

Thanks.

 

[SteveBausch]

Get access to the local building code book. When you say "codebook", think "cookbook".

Nothing wrong with being able to run the calculations, but the fact remains that life is easier if the construction techniques are found in the codebook. For the inspectors involved, the process becomes a no-brainer; if it's found in the book, it's alright with them.


You will be filling the block with pea gravel grout, using #5 rebar, most likely.

There are more details, best to get them from the local building code.

 

[Focht3]

Sheesh.


Designing a retaining wall - which is what a basement wall really is - doesn't come from the building code. The "code book" is not a "cookbook" - it's a set of minimum design and construction standards. Every site and structure combination is unique - hence the need for engineers.

A 3:1 (H:V) slope is pretty steep. The slope will impose significant horizontal stresses on the basement wall that are not covered by code. And someone needs to be very concerned about the stability of the slope during construction when the slope becomes closer to 1.5:1 (H:V). [30 ft/ (10 ft + 8 ft basement + 2 ft footings {minimum})]

And that's just one consideration - I can think of at least four others requiring the services of a competent licensed engineer local to your site. Get professional help - unless you like courting disaster...



Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[canner]

I appreciate your assistance on this.. We have an alternate site that has a gentler slope. I have posted a picture here:

As you can see, the slope from the top of the hill to the beginning of the house is 7.2:1 (h:v). The slope of the land over the 36' of the house depth is 4.5:1. I have been planning on using a superior wall with deadmen anchors. What I am interested in is any alternatives to and ICF foundation that will be effective and perhaps cheaper.

 

[Focht3]

There are lots of ways to make both sites work; depending on the subsurface conditions, the steeper site may not be that much more expensive. But you need a local consultant to talk to you about your options and the likely range in costs.

The site you posted above is significantly flatter, and may be a lot cheaper to develop. (Again, get local consultant.) The effect of the slope "above" the basement will will be relatively small given the dimensions you have shown. But they need to be accounted for in design. (Think 'local consultant')

I'd probably choose the second site, myself. But I'd have to see the sites before making that final determination...



Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[RDK]

I have a house with a daylight basement and live on a street where all the houses on this side have similar basements. The soil is mainly silty sand with lenses of clay and coarse sand. It is along the bank of an oxbow of a meandering river.

The houses along here have a wide variety of basements. The most common is a concrete wall in three sides with a PWF wall along the open side. Some houses are completely concrete and some are all PWF.

There does not appear to be any particular problems with any of the houses in this area, most basements were simply built using conventional basement construction techniques for residential basements.

I don’t like block walls for basements. They have a poor history because of their inability to resist lateral loads.

Get a local engineer with experience in residential basements to advise you on specifics for your location. Talk to others who have built in this type of location to get some information on costs and performance.




Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[boo1]

Your post implies cost is your primary consern.
Consult with a foundation Subcontactor on relative cost impacts for different design parameters...

Note:
CMU, ICF, and poured concrete will all work with appropiate detailing.

 

[BigH]

How did you post the picture? What software did you use to develop it. If not too difficult, this is a great way to get the point across - I've seen some pretty convoluted attempts. Please enlighten us.

 

[Focht3]

Okay, [blue]BigH[/blue]. I have an answer for you on the "post an image" issue. If you look under "Step 2 Options" (and above the "Submit Post" button) you will see a check box with the words "Process TGML" next to it - it's a web link. Click on it to get info about TGML. (This is where I found out how to bold, underline, [green]change[/green][red] text[/red][purple] colors[/purple], etc.) Near the bottom of the page you will see:

[ img

http://www.mysite.com/happy.gif

]

[red](I added extra spaces between the square brackets and in the URL so that you could see the text here.)[/red]

So members can post their (simple) graph on a personal or company web site and show it to us without giving a URL to click on. Here's our corporate logo as a .jpg file created with Adobe Photoshop. It's a 600x394 image at 72ppi. (It's a stylized "F" rotated CW 45 degrees -)

Looks pretty good, eh? And it's only 6 KB in size.

My monitor is set to 1024x768; the image may be too large for those with 800x600 monitors. I'll bet we should limit the images to a maximum width of 500 pixels.

Hey, thanks [blue]BigH[/blue] for sending me on another "rabbit hunt"!




Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.