Clarifying stem walls for basements in Chief

[BnCKelley]

Can someone please help me understand what's controlling this stem wall? I can't set my ceiling height like I want in the basement. Ideally, I want a stem wall poured on top of my footers 104" plus sill. Why is there such a gap that I can't adjust? This screws me everytime on a basement.

[Michael_Gia]

A few important things to keep in mind. 
 

The stemwall height includes the thickness of the sill plate, so do the math for that. 
 

When you enter a rough ceiling height this value will push the footings and floor down, as in away from your absolute “0” level. So regardless of the value you specified for stemwall, it is the ceiling height that will take precedence.  
 

Your “Rough Ceiling Height” plus your “Floor Structure” will give you the proper stemwall height, PROVIDED the already entered stemwall height is less than that total value. That’s because even if the stemwall height is less the action of entering a ceiling height which is greater will have the effect of “pushing” down your footings and elongating your stemwall. 

In your screenshot you have a floor structure of 18-3/4” which I’m assuming  is not what you want but I know for a fact that you got that by messing around with the stemwall height value. Don’t do that.  If anything, just enter 0” for stemwall to reset the foundation height and then go back and re-enter the rough ceiling height which will then correct your stemwall height. 
 

Example:

If you want a stemwall height of 104” with a floor structure of 4” then enter 100” for Rough Ceiling height and that will give you a stemwall of 104” including that pesky 1-1/2” sill.

(providing your existing stemwall height is LESS than 104”). Crazy, I know. 

 

About that stupid sill plate;
If you want 104” of concrete then enter 105.5”for rough ceiling height. This will give 1.5” sill plate slapped on top of a 104” stemwall.  
 

Afterwards, IF YOU PLAY AROUND with the stemwall height and enter 110” then you’ll see a gap of 6” between your floor and the top of your footing. 
Because your larger stemwall height value is pushing your footings down and leaving your floor “floating”. 
-> to correct that then just enter a stemwall height ridiculously lower than your ceiling height and then go back and re-enter the ceiling height to correct it. 
 

Experiment on a simple structure by splitting the screen with floor plan and cross section so you can see both. 
Add some visible cad lines at the proper heights in your cross-section so you can see the effect of this system in real-time as you experiment with different values. 
 

This explanation might have been convoluted but I wanted you to understand the quirks of this very convoluted system Chief has devised. 
However convoluted though, I can’t see any better solution which gives so much control over every aspect of the relative heights of a foundation.  
So I guess we’re lucky?  

[joey_martin]

All the info is right there in the box.

[Michael_Gia]

I think the only confusing item is the behaviour of the stemwall value. 

The fact that depending on which order you enter values in the “Relative Heights” section of the Dbx you get different results. 
 

Other than that, the newly introduced highlighting of the graphic when you hover your mouse over the input boxes pretty much demystifies the whole process. 
 

Still feels clunky though. 

[ricatic]

Michael

Thanks for your description of how the stem wall/floor height/ceiling height relationships actually work...I wish you had posted this a year ago as I tore my hair out chasing the ceiling heights in my early days...I finally figured most of it out but the initial learning curve is a bit steep...you made it much clearer but I think newbies will still flounder a bit due to the convoluted complexity of the DBX choices and the proper order of inputs needed to accomplish the goal...

 

Regards

[GeneDavis]

A half hour spent with a simple test plan will teach you everything you need to know about this.  If you won't do that important self-teaching, you'll probably still be getting confused no matter how much you read or watch.

[Michael_Gia]

The image below is what I would prefer.

 

Because that space between the top of the footing and the floor structure is actually buried in the floor structure and not obvious to everyone.

Why not make it obvious?  Right now you have to go back and forth to set your stemwall or do arithmetic before hand.

I think the litmus test of any DBX is, "if the user has to do even the simplest arithmetic then the DBX has failed".

 

I know seasoned Chiefers can snicker at newbies, but remember when you were in that position?

 

[ricatic]

2 hours ago, Michael_Gia said:

The image below is what I would prefer.

 

Because that space between the top of the footing and the floor structure is actually buried in the floor structure and not obvious to everyone.

Why not make it obvious?  Right now you have to go back and forth to set your stemwall or do arithmetic before hand.

I think the litmus test of any DBX is, "if the user has to do even the simplest arithmetic then the DBX has failed".

 

I know seasoned Chiefers can snicker at newbies, but remember when you were in that position?

 

 

Agree with all you wrote...I have worked through most of the tripups included in this particular CA logic...and while practice is certainly the answer, there are some issues

that are far from real world construction practices...my  experience comes from 50 plus years working in the field as a tradesman and eventually working up to Senior Project Manager....this caused a lot of head scratching at first as trying to understand the computer logic used by CA was polar extreme to real world experience...then I read a quote from David J Potter about the people writing code at CA...paraphrased it went something like "very smart people who know nothing about construction practices"...this viewpoint makes it easier to understand the problems we often encounter...

 

Regards