Bottom of footing elevation

[Tom Weir]

Hi all,
OK I am trying to tag footings with bottom of footing elevations. In discussions with the Revit developers a few months ago I found out that the tag "Structural Foundation Tag with Elevation.rfa" is for reading the (sometimes bogus) "elevation at bottom" parameter. And if you look at the file the label is set that way.
But how do you use it? If I try "Tag" is just gives me the size of the footing. If I try the spot elevation it consistently gives me the top of footing elevation.
I'd really like to get this to work since many of my engineers like to specify bottom of footing elevations.

Thanks and have a great day...

Tom Weir
Los Angeles

[rmcelvain.103137]

Tom,

I just tried it and it seems to work fine. I got the footing size and then EL.-1'-6". Are you sure you're using the right tag?

[Tom Weir]

The tag fooled me. I did not realize that the size of the footing was included. So I adapted it to our normal annotation: BOF=.

We would never show the size of the footing on a plan notation, but instead the schedule mark for the footing.

I am wondering if that is how others would be doing this? I know that the Revit developers are trying to find a way to organize and present spot elevations that makes more sense.

Do you present your footing tags like I am indicating? Or how then?

Tom

[Scott Blouin]

At both companies I worked for, the footing would be called out using a schedule symbol where the symbol itself would describe the footing size (F8 symbol indicating 8x8 footing, F6 for 6x6, etc). The schedule would be used to further describe thickness and reinforcement. It makes it a bit easier for the crew doing the formwork.

The only time I've seen the footing size described in plan is for special conditions where the footing is not rectangular or when one footing is dimensioned and all others are "typical".

[Jos Arpink]

Tom, we would similarly tag the footing with a mark number, F1, F2, F3 etc...and describe size, thickness, and reinforcing in a footing schedule.

We would seldom, if ever, call out the bottom of footing elevation, prefering instead to specify the top of footing elevation. Typically, this would be 12" below the slab on grade...making it easy to cover with a note for the entire drawing.

For footings directly supporting steel columns (no pedestals), there's a direct relationship between the top of the footing and the underside of the base plate...helpful when you're trying to interface with different trades and detailing processes.

My 2c

[rmcelvain.103137]

Tom,

We too would like to have the B/Ftg readily available (and T/Ftg for that matter).

Our standard for footings is F40 (Pad Footing 4'-0" sq), F46 (Pad Footing 4'-6" sq), F40N (Pad Footing 4'-0" sq non-reinforced), W20 (Wall Footing 2'-0" wide), F1 would be our 1st rectangular footing, F2 the 2nd, RW1 the 1st Retaining Wall footing, etc.

Let us know if you find anything out about this,

[Tom Weir]

Hi,
We seem to have two currents of thought at my company. Like Jos some people always specify the top of footing because it helps establish the steel column lengths.

The others though like to specify the bottom of footing elevation in order to help the contractor with excavation information. They also feel that the bottom of footing provides more information of the foundation condition, i.e. where stepping might be required.

I can see that both have advantages and disadvantages.

Tom

[Scott Hammond]

Hi Tom,

I always specified "Top of Footing", for the same reasons that Jos pointed out (less room for error).

[Tom Weir]

Scott,
But for type 5 construction (Wood) where columns are a minor factor, the top of footing rule you use would not seem as useful. That's the group in my office that mostly does bottom of footings. Actually I never put that together before...hhmm. This may be starting to make sense.

Tom

[troberts]

Has Anyone come up with a Top of Footing El. Tag???

[rmcelvain.103137]

Has Anyone come up with a Top of Footing El. Tag???

We use the spot dimensions for "TOP OF" elements, ftgs, walls, ledges, steel, etc.....

[troberts]

Thanks Rick. That is what I needed.

[mwoods]

Rick,

How are you adding the box around the elevation callout?

Is this just done with detail line or have you added it to a family?


Matt Woods

[rmcelvain.103137]

.... added it to a family?

Sort of, I created a symbol as an annotation family and then created a new spot elevation type in our template (spot elevations are a system family). You have to move the text into the box after you place the spot elevation but it still works just fine.

[MXM]

I've spent the last day and half attempting to create a "Top of Footing EL" tag but to no avail. I think my premise is correct by including a parameter using the 'Elevation at Bottom' system family parameter and then subtracting out the footing thickness. That's as far as I get though. I can't seem to come up with the correct formula. Anybody have any ideas?

[kathy71046]

This (top of footing) is what I just started trying to do, and I can't figure out how to get a formula into a tag.

Anybody?

I'd rather not be forced to add spot elevation tags to foundations that are already tagged and ready to go apart from this one critical element.

I thought if I changed all my footings to be offset from ground level I could use the offset from level parameter, but this isn't showing up in the inserted label. (a bott of footing appended in the same tag does, thickness doesn't)

[Mr Greg]

I have been having one heck of a time with the Bottom Of Footing Elevation tags. In my firm we always specify type and bottom of footing on the plan. We then generate a seprate schedule(which we usually put on the foundation sheet) with size, thickness, reinforcing. Most of our jobs have so many steps to them that there is no way to have one generic elevation on the plan.
Having got that out of the way, here is my problem. I have been trying to use the 'Structural Foundation Tag with Elevation' to mark my model. Isolated footings work perfectly. Its the Wall and slab footings that pose the most problems.

Lets start with the Wall footings. Typicaly we have foundation walls and piers. Piers get an Isolated Footing. Then I would model the wall footing. Elevation tag works fine for Isolated footing. Because wall footing joins with the isolated footing, elevation displayed in tag says 'VARIES'. So I ditch this method of modeling wall footings and go to Slab footings.

Here's the problem with slab footing tags. Bottom of footing elevations show up fine. That is until I close out of the drawing. When I open it up again all the elevations are blank. Isolated footing still work fine, but the slab footings are blank. I can make them reapear if I change the size of the footing. That kind of give the tag a jolt. But I would have to do that for every single footing, and I would have to do that everytime I open the drawing.

My only fix I have found so far is to create a Tag where i manualy type in the elevation. But this is not a viable solution as far as I am concerned.
If anyone out there has had anything remotely similar happen in their models let me know. And if there is a fix for this I am all ears. I am just the CAD manager. I cant simply tell the engineers 'Switch to top of footing instead of bottom'

Please Help.