# Tall Residential Concrete Foundation Wall Question



## John 1979 (Dec 10, 2016)

Not sure what forum is appropriate for asking foundation questions but here we go. 

It's my understanding most residential concrete foundation contractors typically only have forms that will pour a max 8 or 9 foot wall height. In a walkout foundation situation when you have footing steps in order to get to the frost depth what's the typical method to get to a taller overall wall height. Let's say in this scenario the wall needs to be 12 feet tall but your still only going for an 8 foot overall basement wall height so 4 feet of the wall is going below grade. 

I'm familiar with the frost wall concept but am under the impression that frost walls are typically used when wood framing will be installed above as opposed to placing a concrete wall on top of the frost wall.

Do you pour a short thicker stem wall and then pour another wall on top? 

Thanks,
John


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## fjn (Aug 17, 2011)

I have done that and also,formed with plyform,strong backs,walers with either hair pin clamps or Jahn clamps.



http://owensupply.com/Docs/formingpage_jahn.htm


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## B.Johnson (Sep 17, 2016)

Around here they pour the wall on top of the frost footing.


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## Fouthgeneration (Jan 7, 2014)

Most here fill in with a wood framing, 12' pours cost a lot more then 8-9 ft. The wood starts well above the final grade of course...:thumbsup:

Knee walls are much weaker though.

I have seen very large(5 level) split foyer with a lower basement that was over 9 ft below the finished grade.


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## shanewreckd (Oct 2, 2014)

I plywood form lots of walls as high as 14'.

Option A:
Build your formwork as panels with studs. Use long end ties and a double waler system. Fan brace at corners, lots of intermediate bracing as well. Chews through a lot of lumber but you can reuse most of it anyway.

Option B:
You can do it with just plywood and single walers as well. Nail in an extra waler at the horizontal plywood jointand then carry strongbacks through.


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## fjn (Aug 17, 2011)

Here is a great article that appeared in FHB back in 1993,unfortunately,you have to be a member to access it. You can either buy their archive cd or do it on line. I feel this article would help you a bunch.



http://www.finehomebuilding.com/1993/01/01/designing-forms-for-tall-concrete-walls


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## John 1979 (Dec 10, 2016)

Appreciate all the info. fellas. I'm leaning towards the stem/frost wall method vs. building the tall forms. 

How would you guys handle this basement design? Goes from 6 foot, to 8 foot, to 10 foot and then finally 12 foot in the rear of the house. 

The 6 foot wall section towards the front of the house supports the garage and porch. I'm going to drop that to 8 foot since I'm hearing typically forms go from 4 foot and then jump to 8 foot (6 foot is an odd form height).

So would I be putting a short 2 foot stem wall on the 10 foot section and a 4 foot stem wall on the 12 foot section and lining it up with the 8 foot wall footer height?

If this is a 10 inch wall how thick do these short stem walls need to be in order to carry the 8 foot walls?


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## jlhaslip (Dec 31, 2009)

I have poured 10 to 12 ft deep basement walls using conventional formwork by using 2 ft panels and 4ft panels sideways on top of 8 ft panels.
By panels, I mean regular 4 x 8 ft form plywood.


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## Fouthgeneration (Jan 7, 2014)

A 6 ft crawl space????? X that out and its two steps, even if you don't pour a floor, it the cheapest heated indoor space to ever come your way...:thumbsup:

Consider balloon framing the knee walls with above story walls, if you are in a high wind or seismic area(s). Don't forget the fire blocking....

The type and size of pans used or made is trivial, How one could EVER build forms for less than what renting Efcos or aluminum basement pans costs? Maybe slave/ prison labor? 

Have an engineer show why Knee walls are not stable.


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