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When does a “stem wall” that is part of your foundation become a “concrete foundation wall”?

Joe.B said:
The detail I posted in post #3 was just an example, not specific. That picture does represent what I usually see, but as a monolithic pour. I've never seen what you show in post #7.
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Well I am curious as to what is commonly done in your area. Is it a separate footing with a concrete wall formed and poured on top of the footing? Or is it monolithic with the footing and wall as one? The code books always show a T shaped foundation that I see with masonry but never with poured in place.

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Sometimes the answer can be found by flipping the question. OP asked when a stem wall became part of the foundation. My immediate response was to ask "when is it NOT part of the foundation?" That might be my Code training coming into play, since Canadian Codes consider above-ground walls to be part of the foundation, in general. Height is regulated as a function of wall height, fill height, wall thickness and concrete strength.

Is there nothing like that in U.S. Codes?

[Those inclined to self-abuse can see the gloriously metric table attached, which may not be tremendously useful to those in the Excited States, but it does show quite clearly that your northern neighbours (not "neighbors", you will note) consider a "stem wall" to be part of the foundation wall.FYI, 15Mpa=2,175 psi; 20Mpa=2,900 psi}
 

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Is it a separate footing with a concrete wall formed and poured on top of the footing?

mtlogcabin said:
Always
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I spent a couple years in Colorado and every house had a footing with 8' to 12' tall concrete walls on top of the footing.... so maybe it's a mountain thing.
 
IMHO, a two-part pour is a better system. But it takes more time and requires twice the fees for a pump truck. In this part of NW Oregon, we usually see only 10-20% 2-part foundations (footings and walls formed and poured separately.
 
I would consider this to be a foundation wall because it extends from the footing to the plate for the floor joists.

I think of a stem wall as a concrete or masonry wall that stops below the floor level and has a stud wall between the top of the stem wall and the bottom of the joists. The joint where the stem wall stops and the stud wall starts creates a hinge, which is probably the reason for requiring a greater concrete strength.

I think it would be difficult to form the "stem wall" as detailed for a single pour. The extra concrete to make it 15" wide all the way up would probably cost less than the additional labor to form the footing offset on both sides.
 
Thanks everybody for providing some input. I would like some of your opinions on the second question that came up.

Given, prescriptive residential code design is seismic design category D/E. Let's say you determine it is a foundation wall and therefor requires 3000 psi, would you require them to get special inspections?
 
Paul Sweet said:
I think of a stem wall as a concrete or masonry wall that stops below the floor level and has a stud wall between the top of the stem wall and the bottom of the joists
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Interesting. In my looking for stem walk vs foundation wall, the most common distinction was a stem wall was the foundation at the edge of a slab on ground building, and a foundation wall supported a framed floor with joists. To bad the IRC doesn't make a clear distinction.
 
Joe.B said:
Thanks everybody for providing some input. I would like some of your opinions on the second question that came up.

Given, prescriptive residential code design is seismic design category D/E. Let's say you determine it is a foundation wall and therefor requires 3000 psi, would you require them to get special inspections?
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No
 
Joe.B said:
Thanks everybody for providing some input. I would like some of your opinions on the second question that came up.

Given, prescriptive residential code design is seismic design category D/E. Let's say you determine it is a foundation wall and therefor requires 3000 psi, would you require them to get special inspections?
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Only time I have demanded compression tests on concrete was when the material was placed without an approved warming plan, and two days later, stripped forms and no tarps/heater/whatever.

Which reminds me ... I should have been given those test results by now....
 
mtlogcabin said:
Nowhere does the IRC require a special inspection for concrete that exceeds 3,000 PSI np matter where it is placed.
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That's my opinion too. And I was pretty comfortable with that, until @ICE pointed out:

R109.1.5.2 Special Inspections
For special inspections, see California Building Code, Chapter 17.

ICE said:
The way that I interpret this bit of code is that Chapter 17 of the CBC has been invoked by R109.1.5 Other Inspections.
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Not too many people here weighed in on that so I thought I'd go fishing one more time.
 
Joe.B said:
That's my opinion too. And I was pretty comfortable with that, until @ICE pointed out:

R109.1.5.2 Special Inspections
For special inspections, see California Building Code, Chapter 17.



Not too many people here weighed in on that so I thought I'd go fishing one more time.
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There have been several members that went against my opinion but I haven't heard an explanation for R109.1.5.2 that would refute my take on it.
 
Joe.B said:
That's my opinion too. And I was pretty comfortable with that, until @ICE pointed out:

R109.1.5.2 Special Inspections
For special inspections, see California Building Code, Chapter 17.



Not too many people here weighed in on that so I thought I'd go fishing one more time.
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A BO can require SI for SFD (or other IRC buildings). I have invoked this requirement for a SFD where the construction is of non-conventional methods. For example, an elevated post-tensioned slab. Jurisdiction did not have the applicable experience nor could we be on site during placement and tensioning. EoR was in agreement and wanted the SI as well.

In the case presented, following the 2022 California Residential Code, fall back to the preceding section. It makes it clear that the BO has the authority to require... not that these "other inspections" are universally required.

R109.1.5 Other Inspections​

In addition to inspections in Sections R109.1.1 through R109.1.4.2, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.
 
classicT said:
In the case presented, following the 2022 California Residential Code, fall back to the preceding section. It makes it clear that the BO has the authority to require... not that these "other inspections" are universally required.

R109.1.5 Other Inspections​

In addition to inspections in Sections R109.1.1 through R109.1.4.2, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.
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Here's two "Other Inspections" that are required:

R109.1.5.1 Fire-resistance-rated construction inspection.
Where fire-resistance-rated construction is required between dwelling units or due to location on property, the building official shall require an inspection....

R109.1.5.3 Weather-exposed balcony and walking surface waterproofing.
Where balconies or other elevated walking surfaces are exposed to water from direct or blowing rain, snow, or irrigation, and the structural framing is protected by an impervious moisture barrier, all elements of the impervious moisture barrier system shall not be concealed until inspected and approved.

Exception: Where special inspections are provided in accordance with California Building Code Section 1705.1.1, Item 3.

Between those two is this:
R109.1.5.2 Special inspections.
For special inspections, see California Building Code, Chapter 17.

There are just the three found under Other Inspections. Two are explicitly mandated while the Special Inspections is not. Given that In the IBC there is no question as to whether special inspections are required, it seems wrong to assume that none of what would be inspected in an IBC building is required in an IRC building. We spend far more time in an IRC building than any other building.

Beyond that, we ask for it, we get it.... It is generally spelled out in detail on the plans. If other jurisdictions have decided to waive special inspections based on the IRC, that would be up to them. That is not the case in any AHJ that I have worked for.

R109.1.5 Other inspections.
In addition to inspections in Sections R109.1.1 through R109.1.4.2, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.

This section opens a door to requiring any other inspection. Pay attention to the word "any". I have used this section for things that only I thought of. This section is not limiting the BO to just what is listed in this code section.. In other words it does not close a door.
 
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Exception: Special inspections and tests shall not be required for:

  2. Continuous concrete footings supporting walls of buildings three stories or less above grade plane that are fully supported on earth or rock where:
    1. The footings support walls of light-frame construction.
    2. The footings are designed in accordance with Table 1809.7.
    3. The structural design of the footing is based on a specified compressive strength, f 'c, not more than 2,500 pounds per square inch (psi) (17.2 MPa), regardless of the compressive strength specified in the approved construction documents or used in the footing construction.
If the structural design of the footing does not exceed 2,500 psi then no SI is required regardless of the compressive strength of the concrete used. The foundation wall is required to use 3,000 psi concrete prescriptively within the IRC however that is not a factor if the footing is designed to a minimum 2,500 PSI.
That is what exception 3 is saying IMHO.
 
ICE said:
Here's two "Other Inspections" that are required:

R109.1.5.1 Fire-resistance-rated construction inspection.
Where fire-resistance-rated construction is required between dwelling units or due to location on property, the building official shall require an inspection....

R109.1.5.3 Weather-exposed balcony and walking surface waterproofing.
Where balconies or other elevated walking surfaces are exposed to water from direct or blowing rain, snow, or irrigation, and the structural framing is protected by an impervious moisture barrier, all elements of the impervious moisture barrier system shall not be concealed until inspected and approved.

Exception: Where special inspections are provided in accordance with California Building Code Section 1705.1.1, Item 3.

Between those two is this:
R109.1.5.2 Special inspections.
For special inspections, see California Building Code, Chapter 17.

There are just the three found under Other Inspections. Two are explicitly mandated while the Special Inspections is not. Given that In the IBC there is no question as to whether special inspections are required, it seems wrong to assume that none of what would be inspected in an IBC building is required in an IRC building. We spend far more time in an IRC building than any other building.

Beyond that, we ask for it, we get it.... It is generally spelled out in detail on the plans. If other jurisdictions have decided to waive special inspections based on the IRC, that would be up to them. That is not the case in any AHJ that I have worked for.

R109.1.5 Other inspections.
In addition to inspections in Sections R109.1.1 through R109.1.4.2, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.

This section opens a door to requiring any other inspection. Pay attention to the word "any". I have used this section for things that only I thought of. This section is not limiting the BO to just what is listed in this code section.. In other words it does not close a door.
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ICE, I can't speak to California - ya'all do your own thing there.

What I can say is that the model code does not have the same language. Here is the 2021 IRC:

R109.1.5 Other Inspections​

In addition to inspections in Sections R109.1.1 through R109.1.4, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.

R109.1.5.1 Fire-Resistance-Rated Construction Inspection​

Where fire-resistance-rated construction is required between dwelling units or due to location on property, the building official shall require an inspection of such construction after lathing or gypsum board or gypsum panel products are in place, but before any plaster is applied, or before board or panel joints and fasteners are taped and finished.​
 
mtlogcabin said:
Exception: Special inspections and tests shall not be required for:

  2. Continuous concrete footings supporting walls of buildings three stories or less above grade plane that are fully supported on earth or rock where:
    1. The footings support walls of light-frame construction.
    2. The footings are designed in accordance with Table 1809.7.
    3. The structural design of the footing is based on a specified compressive strength, f 'c, not more than 2,500 pounds per square inch (psi) (17.2 MPa), regardless of the compressive strength specified in the approved construction documents or used in the footing construction.
If the structural design of the footing does not exceed 2,500 psi then no SI is required regardless of the compressive strength of the concrete used. The foundation wall is required to use 3,000 psi concrete prescriptively within the IRC however that is not a factor if the footing is designed to a minimum 2,500 PSI.
That is what exception 3 is saying IMHO.
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Correct.

Design professional can specify 4000psi due to weathering potential or even mere preference, but so long as the f'c (design strength) is 2500psi or less, then an exemption from SI is permissible.
 
classicT said:
ICE, I can't speak to California - ya'all do your own thing there.

What I can say is that the model code does not have the same language. Here is the 2021 IRC:

R109.1.5 Other Inspections​

In addition to inspections in Sections R109.1.1 through R109.1.4, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.

R109.1.5.1 Fire-Resistance-Rated Construction Inspection​

Where fire-resistance-rated construction is required between dwelling units or due to location on property, the building official shall require an inspection of such construction after lathing or gypsum board or gypsum panel products are in place, but before any plaster is applied, or before board or panel joints and fasteners are taped and finished.​
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Alrighty then, I see where it says "shall require inspection"
 
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