Footers at different heights. Possible? Practical?

[Matthew S. Whiting]

I'm designing a house that will set on a slope (10-15%) and have a
walk-out basement. The soil is quite rocky and hard to dig (the backhoe
struggled digging 4' deep holes for the septic system soil tests. I'd
like to have the footer on the downslope wall below the frost level
which is around 36" where I live. However, if I make the footer the
same level all the way around, this would require about 9' of excavation
on the uphill wall. Is it possible to have the footer on the downslope
wall 3' or so lower than the footer on the other three walls? If this
is practical, should the two footers be left separate or connected with
a vertical "post" of concrete? Or is it better to just pay the extra
excavation cost and put everything lower and raise the slab 3' above the
footer to bring it to grade on the downslope wall?

Matt

[J Pagona]

The downslope footer can be lower than the upslope footer. The footers on the
sides will have to be stepped, so that they are below the frost level at all
points.

J. Pagona

[Nnails456]

>I'm designing a house that will set on a slope (10-15%) and have a
>walk-out basement. The soil is quite rocky and hard to dig (the backhoe
>struggled digging 4' deep holes for the septic system soil tests. I'd
>like to have the footer on the downslope wall below the frost level
>which is around 36" where I live. However, if I make the footer the
>same level all the way around, this would require about 9' of excavation
>on the uphill wall. Is it possible to have the footer on the downslope
>wall 3' or so lower than the footer on the other three walls? If this
>is practical, should the two footers be left separate or connected with
>a vertical "post" of concrete? Or is it better to just pay the extra
>excavation cost and put everything lower and raise the slab 3' above the
>footer to bring it to grade on the downslope wall?
>
>Matt
>
>

where we build (MN) top of footing needs to be at least 42 inches below grade.
You can have as many elevations as you want, as long as you maintain the 42
inches at all times. This is easiest accomplished by building a form out of
plywood for the face of your "drop". The footings remain continuos, they just
go verticle at the point of change in elevation. Hope this helps.

[prlau...@my-dejanews.com]

In article <368D67...@epix.net>,

whi...@epix.net wrote:
> I'm designing a house that will set on a slope (10-15%) and have a
> walk-out basement. The soil is quite rocky and hard to dig (the backhoe
> struggled digging 4' deep holes for the septic system soil tests. I'd
> like to have the footer on the downslope wall below the frost level
> which is around 36" where I live. However, if I make the footer the
> same level all the way around, this would require about 9' of excavation
> on the uphill wall. Is it possible to have the footer on the downslope
> wall 3' or so lower than the footer on the other three walls? If this
> is practical, should the two footers be left separate or connected with
> a vertical "post" of concrete? Or is it better to just pay the extra
> excavation cost and put everything lower and raise the slab 3' above the
> footer to bring it to grade on the downslope wall?
>
> Matt

Hi Matt, Putting footings at different elevations is a common practice.
One way to connect the stepped footings is to use the foundation wall as the
connector. Proper rebar placement and the foundation concrete will marry the
upper and lower footings.

ron

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[Ken Holmes]

It is entirely possible to have different sections of the footer at
different elevations -- depending, of course, upon soil conditions. But if
you have questions about matters such as these, it's probably best to
consult a pro for some guidance.

Good luck,
Ken Holmes
http://www.oldhouseweb.com

Matthew S. Whiting wrote in message <368D67...@epix.net>...

[Rick Smith]

Matthew S. Whiting wrote:

> I'm designing a house that will set on a slope (10-15%) and have a
> walk-out basement. The soil is quite rocky and hard to dig (the backhoe
> struggled digging 4' deep holes for the septic system soil tests. I'd
> like to have the footer on the downslope wall below the frost level
> which is around 36" where I live. However, if I make the footer the
> same level all the way around, this would require about 9' of excavation
> on the uphill wall. Is it possible to have the footer on the downslope
> wall 3' or so lower than the footer on the other three walls? If this
> is practical, should the two footers be left separate or connected with
> a vertical "post" of concrete? Or is it better to just pay the extra
> excavation cost and put everything lower and raise the slab 3' above the
> footer to bring it to grade on the downslope wall?
>
> Matt

this is a very common step footer situation, the footer needs to be stepped
down on the walk-out end. Check with local building code officials for
details as to the placement and cross section of the steps, which in my
experience should be a one piece pour to prevent shifting. Your mason can
help with this also. I have not done one of these in years but if memory
serves me correctly, for my location, we formed off a step that ran 1 and
1/2 times the drop in length. Bend rebar in a Z shape to reinforce the
step. Also keep block spacing in mind; masons can cut block to fit your
step lengthwise but the height needs to be accurate. Sometimes if the drop
was a large one I did it in two steps.

as for the rock problem... my wrost experience with this was finding a
single rock, I have a photo of it with my wife's car parked next to it for
scale (you can only see part of the front fender of her subaru wagon) that
had to be blasted and removed in sections. When you play in the dirt you
run into rocks. If your on a solid rock outcrop, only a geologist can tell
you for sure, you can peg your foundation into it, otherwise, keep digging
and hope all the rocks are small enough that your excavator's equipment can
handle them.

hope that helps

rick

[prlau...@my-dejanews.com]

In article <76mlkv$3pf$1...@winter.news.rcn.net>,

"Ken Holmes" <kjho...@ix.netcom.com> wrote:
> It is entirely possible to have different sections of the footer at
> different elevations -- depending, of course, upon soil conditions. But if
> you have questions about matters such as these, it's probably best to
> consult a pro for some guidance.
>
> Good luck,
> Ken Holmes
> http://www.oldhouseweb.com
>
> Matthew S. Whiting wrote in message <368D67...@epix.net>...

> >I'm designing a house that will set on a slope (10-15%) and have a
> >walk-out basement. The soil is quite rocky and hard to dig (the backhoe
> >struggled digging 4' deep holes for the septic system soil tests. I'd
> >like to have the footer on the downslope wall below the frost level
> >which is around 36" where I live. However, if I make the footer the
> >same level all the way around, this would require about 9' of excavation
> >on the uphill wall. Is it possible to have the footer on the downslope
> >wall 3' or so lower than the footer on the other three walls? If this
> >is practical, should the two footers be left separate or connected with
> >a vertical "post" of concrete? Or is it better to just pay the extra
> >excavation cost and put everything lower and raise the slab 3' above the
> >footer to bring it to grade on the downslope wall?
> >
> >Matt
>

Stepping footings is a trivial problem as long as they sit on good base and
are tied together