Why would a poured concrete stem wall foundation be sitting on top of concrete piers?
The stem wall does not appear to have a footing.
Do you think that this is an engineered foundation?
The home was built in 2000 and the soil expansivity rating on this land is rated as moderate on the County GIS website.
Lots of undercutting with this foundation, and some of it was caused by an animal.
2 Likes
Looks like engineered grade beams from here. Not a problem if engineered.
Looks like the vapor barrier needs a little work.
2 Likes
Hello @mcyr Marcel.
Do you think that the undercutting is normal for an engineered foundation?
Yeah the vapor barrier that’s missing in areas will get called out.
Adam
Can’t tell that from just pictures. Up here grade beam designs are poured on top of pile caps and directly on the ground. With the intent that the poor soils will shrink and not affect the foundation support.
I would think the design for that area would include any amount of shrinkage of the soils which is what it looks like to me in your pictures.
Any drawings available?
3 Likes
I don’t have any drawings available.
I’m not familiar with your terminology of “grade beam designs,” and “pile caps.” Excuse my ignorance.
@mcyr has it. Drilled piers and grade beams. The gaps under the wall in picture #2 & #3 are where the void was. Typically it stays when the forms are stripped. Somebody must have removed them. Nothing to worry about. Very typical type of foundation around these parts. Here’s what they look like before backfilling:
7 Likes
Maybe this will help, cross section of pier and grade beam foundation. Around here they call the piers caissons.
4 Likes
That’s interesting. I’ve never seen those before. It’s good to know what they look like. Are those beams below the stem wall just solid wood?
1 Like
SureVoid® products are corrugated paper construction materials , commonly known as “void forms” or “carton forms”. They create space between concrete structures and expansive soils, thereby isolating the concrete from the swelling ground.
6 Likes
5 Likes
That makes sense. Thank you for explaining what they are generally, Scott.
Those look pretty strong to begin with. Over the years I would think that they would get spongy to allow the soil to expand in there. Thank you for sharing those pictures and the link, Michael.
2 Likes
That’s weird that they call the concrete stem wall a beam. It looks like a concrete stem wall without a footing, but in this case it’s called a beam. 
A stem wall will have a continuous footing. A grade “beam” sits atop of a pile or such. It’s a beam because it does not have a continuous support, in form of a footing, below it. That’s how I understand it, anyway 
4 Likes
See, now that was the articulate explanation that helped me understand why they call it a beam. BAM! Thank you, Simon!
Would it be an unnecessary assumption to say that all pier and grade beam foundation systems are engineered (requiring the stamp of a qualified structural engineer)?
Piers, piling, helical piles, etc are typically required when the surface soil is unable to support the load.
2 Likes
Compare it to a wood beam supported by wood posts or steel columns. The difference here being that the posts/columns and beam are all made of concrete.
1 Like
Exactly. In many parts of the country, it will not be very tall, crawlspace height typically. Stem walls sit on spread footing, where as grade beams sit on piles, piers caissons, or some other point load type of footing. Grade Beams are also simple connecting points between footings. Some are designed to not be in contact with the soil, others can be. just depends on soil types and conditions.
I’ve always been told that a stem wall is a short wall that branches off of the main foundation wall and is designed to be used as support for a patio, porch, or a retaining wall. Some say it’s a short wall that simply connects the footing to the load bearing walls of a home. I’ve also been told that full basement walls are not “stem walls” because they are too tall, designed differently, and serve another purpose.
If a permit has to be purchased to construct a habitable dwelling, a permit will only be issued if the applicant has plans/blueprints that are approved by a Structural Engineer, so as far as I am concerned, all foundations, now a days at least, are “engineered foundations”. Now if the home was built in, let’s say, the late 1800s to early 1900s before such laws existed, well that’s a different story…
3 Likes
BUMP.
Good thread with great knowledge being passed along!