rfcomm2k

Foundation spec

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Here is a picture of the foundation I need for this building. 16x12 footing 48" below grade. 4" slab on grade. Stem wall 8" wide at the top and 12" above grade (excluding sill plate). And an extension of the stem wall to support the slab.

 

How do I achieve this in HD Pro 14?

 

And why does the program insist on having a foundation room underneath a slab on top of stem wall?

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16x12 footing 48" below grade.

 

That setting is in the Terrain Specification Dialog after creating a terrain plane (building pad setting).

 

 

 

 4" slab on grade.

 

Set in Foundation Defaults dialog

 

 

 

Stem wall 8" wide at the top and 12" above grade (excluding sill plate). And an extension of the stem wall to support the slab.

Set  in Foundation Defaults, Terrain Specifications Dialog and by you.

 

 

 

And why does the program insist on having a foundation room underneath a slab on top of stem wall?

Respectfully, a mechanical device (the software) does not - is not capable of "insisting" on anything, it does only what it is "told" by end user settings only. Your job is to learn how it was programmed to work and to then control its results by study and practice of what you learned by study.

 

DJP

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Thank you for reply DJP. I did not know the terrain spec had info regarding the foundation.

 

Question now. The building is built on a slab on grade, no basement or crawl space. The garage will have a curb wall on 3 sides that is to be 8" above the top of the slab. But the rooms adjoining the garage will have the slab at the same height as the top of this curb wall. I thought I saw a spec somewhere about the curb wall (where else would I have come up with the term curb wall), but I cannot find it now.

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This can be set in Foundation Defaults but also for finer adjustments,one can directly adjust such heights manually in the Foundation wall poly-line per foundation wall. I rarely invade the province of the Structural Engineer, adjusting from specifics given by the Engineer and not in the absence of one ($5,000.00 fine in Texas for acting like an Engineer without having one on a retainer).

 

DJP

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rfc ......would you mind adding your name to your Profile please ,it's easier to "talk" to someone if there is a name behind the face.....

 

your Pic didnt attach again ..... so you need a ledge for the Slab to sit on? .....this could be done with a pony wall as a foundation , top part 8 " and bottom Part 10" to get the 2 inch ledge.

 

 

"And why does the program insist on having a foundation room underneath a slab on top of stem wall?"

 

***Don't use "Floor Under this Room" in foundation defaults use the next setting ,"Floor supplied by Foundation Room Below"

 

 

The Terrain Building Pad height setting only raises or lowers the Terrain in regard to the Main floor height , it doesn't effect the foundation in anyway....

 

 

here is a quick plan showing the settings I think you want , the cross section shows the use of the Basement Wall as a Pony Wall idea on the RH side.  

 

61-inch Basement.plan

 

*** you just posted above me as I am typing this post up , you didn't say it was a garage in your 1st post so my plan doesn't show that but should help

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Sorry Mick, I tend to look at something and assume everyone sees what I am seeing, even if they are not in the same room I am in!

 

The specifics (for the moment) are a 3 bay garage on left end of structure with 16' ceilings (for RV and for servicing plow trucks). The rest of building, also resting on a slab, is a house. It is my understanding that there must be a curb wall between house and garage (in this case curb wall wraps all the way around, with openings cut for the garage doors). The house slab will rest even with the top of curb wall or will rest ON TOP of curb wall. But there are no floors or rooms beneath the house slab.

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Hi Rob, Thx....

 

I believe they call it a Gas Curb in some Locales , but regardless there is usually a curb as the siding must be 6-8" inches AGL for Rot protection,(Code) and the garage slab is usually only about 2" AGL with a slight Ramp to drive in.

 

Its always better to work with your Plan and measurements , what works in a test plan (above) may not work in your plan , but most of those settings should be configurable in the Foundation Defaults or the Build Foundation DBX in Pro.

 

Post your new plan if you need more help...

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Is this what you want the foundation to look like?

post-63-0-48678800-1436898253_thumb.jpg

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The Curb and Step upto the House yes , but he needs a 16x20 footing and a 48" stem wall (frost wall) + 12" AGL (60")  with a ledge to sit the slab on.

 

if the wall AGL needs to be 8" that would mean the lower Stem wall would need to be say 10" to form the slab support ledge , you can get the ledge using ponywalls , but I am not sure I full understand what he needs , so wanted to see his Plan.

 

M.

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The ledge to support the slab is (IMO) needed because the slab rests on top of 2" of foam insulation, under which is a base of compacted gravel. The slab will have numerous zones of radiant heat.

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Is this what you want the foundation to look like?

 

Yes Jo_Ann, that is exactly it. The terrain is flat, and will be referenced as 0". The stem wall is 60" high. Top of stem is 12", So there is 48" of stem below grade, resting on top of a 12" high x 16" wide footer.

The location is Willow Alaska, which is why the foundation needs to go so deep.

 

The garage floor rests 4" above grade, leaving an 8" curb.

 

The top of the house slab rests even with the top of the stem wall, thus there is a step up from the garage to the rest of the building.

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This can be set in Foundation Defaults but also for finer adjustments,one can directly adjust such heights manually in the Foundation wall poly-line per foundation wall. I rarely invade the province of the Structural Engineer, adjusting from specifics given by the Engineer and not in the absence of one ($5,000.00 fine in Texas for acting like an Engineer without having one on a retainer).

 

DJP

I thought I remember seeing a post from you some time ago giving tips on the typical chain of events to creating a plan. i.e. choose a template, then modify the default settings, then draw the first floor, then check/modify the terrain, etc. Not sure I have them all or in the proper order, but could you identify for me the post I am speaking of? I cannot find it in my search for "default"

Also, if I am correct in my understanding, if I want the top of a 4" garage slab to be 4" above grade, with a gas curb (stem wall) protruding 8" above the top of the slab and 48" below grade, then I should set the foundation defaults to walls with footings, minimum sem height 49 1/2, garage floor to SWT 8", and garage stem height 49 1/2. And set the floor defaults to a 4" concrete floor structure, and  leave the floor finish @ 7/8.

Is all this correct?

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OK, I am ALMOST understanding this, after reading the manual, testing theories, etc. I thought I had it all right till I took a closer look. I have attached a test plan and an elevation from it.

 

Elevation is taken standing in the garage looking toward the house. On the right I see the stem wall for garage and the sill plate on top of it, just as expected. But I see some strange things in this pict also.

 

1. To the left of door the stem wall steps down at the top exactly 1.5", the thickness of the sill plate. And the sill plate is not represented along the back wall (under door). This step down appears to coincide with where the outside wall for the living space meets the wall for the garage.

2. What's up with the stem wall and footing on the left? Why is it white instead of gray?

 

It was my intention (once again) for the garage slab to sit 4" above grade, stem wall (excluding sill plate) to terminate 8" above top of garage slab. The house stem wall (excluding sill plate) should terminate at same height and the top of the house slab should be even with the top of the stem wall. Thus, the sill plates for entire structure are at the same height.

 

So what did I miss this time?

 

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Did you get things sorted  Rob ?  sorry I haven't been online in a week as I had an unexpected stay in the Hospital....

 

Foundations are tough ,always have been and I don't think the newer versions are much better , lots of Talk on Chieftalk about it too. 

 

M.

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took a quick look at your test plan , if you build your foundation with the Sill plate turned off  and the Footing set at 16x20 as you 1st mentioned it looks ok to me although I don't know how you got your minimum Stemwall Height of 49 1/2" ? 

 

your frost depth is 48" and you also need to be 12" AGL (above ground level)  which would mean your min. stemwall height is 60" + 1 1/2" for the Plate =61 1/2"  I believe.

 

***EDIT Having played some more to try getting the 8" step to the garage floor, and then looking at the Garage Heights KB Article again, as it didn't seem to work as I assumed , I noticed that They  stressed this point

 

Note: You may want to change the Stem Wall (I) height to meet your frost depth needs, however, before making any changes to the Structure settings in the Room Specification, you must first turn off Auto Rebuild Foundation

 

 

This is probably something I missed earlier too as it seems to work per the KB once I disable Auto Build and changed the default floor structure to 4" concrete not the 12 5/8" framing and subfloor and adjusted the settings in the Room DBX's as needed ie garage floor -8" and Stemwall Top 0".  With Autobuild still on 1/2 the settings are grayed out or immediately turn back to something else (default?) if autobuild is still on...

 

 

Mick.

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