# What is a 'Stem Wall'?



## TimNY (May 31, 2011)

This is a follow up to another thread..

What is a stem wall? or, what do you think a stem wall is?

Examples of what I thought were stem wall would be a crawlspace wall or the walls that usually surround a garage.

Some thought of a stem wall as the part of the wall that continues vertically above the brick ledge.

I can't find a definition in the I-codes.  I can't even find a consensus with a google search.

Is it defined anywhere? ACI maybe?

Perhaps our architect or engineer members have some references in their design manuals?


----------



## Mark K (May 31, 2011)

Please provide context to the question.  How will the definition impact what you will do?


----------



## JBI (May 31, 2011)

I don't think you're going to get a definitive answer to that one Tim.

Generally, in this part of the country, it is a short concrete or masonry wall extending from the footing to a little above grade and is often backfilled on both sides to allow a concrete slab floor to be poured - a 'stem' that connects a footing, or 'root', to a building.

Doesn't have to be masonry or concrete, doesn't have to backfilled on both sides.

Opinions will vary.


----------



## mark handler (May 31, 2011)




----------



## TimNY (May 31, 2011)

Well, the IRC uses the word "stem wall" in the foundation section.  That is really the context of my question.

What Mark has provided is what I have seen on the net (thanks, Mark).

So, taking the diagram Mark Provided, could the wall be 8' tall?

Should the "stem wall" provisions of the IRC be applied to full-height basement walls?

EDIT: I just looked at the 2009 IRC; an example would be R404.1.2.2.1, R404.1.2.2.2 .. I'm on a 2006 derivitive, and I believe the wording is different, but you get the idea.  Hard to apply the stem wall provisions if I'm not clear on what a stem wall is.


----------



## peach (May 31, 2011)

not probably a code term - a trade term... used to mean something other than a basement wall, I guess.


----------



## mark handler (May 31, 2011)

peach said:
			
		

> not probably a code term - a trade term... used to mean something other than a basement wall, I guess.


It is all through the IRC

R403.1.3 Seismic reinforcing....stem wall....

R403.1.3.1 Foundations with stemwalls.....

R404.1.2.2.1 Concrete foundation stem walls supporting above-grade concrete walls.

R404.1.2.2.2 Concrete foundation stem walls supporting light-frame above-grade walls.

R40S.3 Unvented crawl space.

R602.10.7 Braced wall panel Support.

FIGURE RS02.10.7

R611.6 Above-grade wall requirements.

FIGURE R611.6(2)

FIGURE R611.6(3)

TABLE R611.6(4)

Not just a trade term


----------



## fatboy (Jun 1, 2011)

I've always taken it to mean a less than standard 8' foundation wall. No particular reason other than trade experience.


----------



## Builder Bob (Jun 1, 2011)

JBI said:
			
		

> I don't think you're going to get a definitive answer to that one Tim. Generally, in this part of the country, it is a short concrete or masonry wall extending from the footing to a little above grade and is often backfilled on both sides to allow a concrete slab floor to be poured - a 'stem' that connects a footing, or 'root', to a building.
> 
> Doesn't have to be masonry or concrete, doesn't have to backfilled on both sides.
> 
> Opinions will vary.


Best answer ---- especially the last 3 words


----------



## Pcinspector1 (Jun 1, 2011)

The ACI, (American Concrete Institute) does not list STEM WALL but does list stem bars.

We used the term STEM WALL when installing a 10" high wall for walk-out basements here in the mid-west. Some times formed with concrete panel forms, blocks or 2x material. Rebar is used extending from the frost footer into the stem wall and anchor bolts installed like a tall foundation wall would require. Sill sealer and sole plate installed over the stem wall.

As mark posted R404.2.2.2 best describes this type wall IMO.

pc1


----------



## Architect1281 (Jun 1, 2011)

A "Stem Wall" or "Knee Wall" is a segment of a foundation wall that is not of continuous height from support point to support point.

a foundation wall would be supported at the top by a floor diaphram and at the base by a slab.

the Knee / Stem wall would be of any partial height and is typically a partial haeight wood frame wall to the floor diaphram.


----------



## globe trekker (Jun 1, 2011)

Is the term "curb wall" defined anywhere in the IRC, ..IBC, ..other?

.


----------



## mark handler (Jun 1, 2011)

globe trekker said:
			
		

> Is the term "curb wall" defined anywhere in the IRC, ..IBC, ..other?.


*"curb wall"* No


----------



## Francis Vineyard (Jun 1, 2011)

A reading of 2009 IRC R404.1.2.2.14 & R404.1.2.2.2 As shown with mark handlers example above it appears stem walls are designed to carry the load above to the footing without either lateral support at the top or bottom.


----------



## TimNY (Jun 1, 2011)

It would be nice to have it defined in the I-codes for clarity.  I like Arch1281 and Francis' explanations on the matter.

To wit, if we took Mark's photo and placed a slab against the inside of the wall, it would no longer be a 'stem wall'?

What if you placed the top of the slab at the top of the footing?  I know.. I know..

Thanks for all of the great input.


----------



## Architect1281 (Jun 1, 2011)

TimNY also the picture indicating the stemwall above would also be correct because the slab or footing has no lateral support  so  also unsupported because the base does not have a slab to resist


----------



## Rio (Jun 1, 2011)

I think that stem walls can be laterally supported at the footing and also at the top of the stem wall.  The floor diaphragm would act as the lateral support at the top of a stem wall that is being used in conjunction with a crawlspace and we do short stem walls all the time in garages to keep the bottom sill plate level while having the garage slab slope 1/4:12.

In R404.1.2.2.1 and R404.1.2.2.2  addresses two concrete foundation stem wall conditions, with paragraph one addressing stem walls that are not laterally supported at the top and paragraph two addressing stem walls that are laterally supported at the top.

P.S.  Shouldn't the drawing above in the thread show the footing supporting the stem wall being in the dirt, instead of on top of it on the crawlspace side and wouldn't the dirt itself provide some lateral support when the footing is in the dirt?


----------



## peach (Jun 2, 2011)

the floor system above restrains the top of the wall.  Unless there is a rat slab of some kind at the base, it's a retaining wall (and needs to be designed as such).


----------



## Pcinspector1 (Jun 3, 2011)

peach,

I've heard the term RAT RACE but not rat slab?

pc1


----------



## Yankee (Jun 3, 2011)

Rat slab here generally means a slab that is rough-poured in a crawl space area. Not fancy.


----------



## fatboy (Jun 3, 2011)

That's what I've taken it to mean, we don't see them here.


----------



## Daddy-0- (Jun 4, 2011)

we call the short walls on either side of garage doors stem walls. They usually have bond beams and such.


----------

