Wednesday, June 22, 2011

Some Little Tips about Foundations

So, sometimes your wall foundations will extend past the edge of the wall foundation its joining into. This typically happens when dealing with wall foundations where the eccentricity is set to something other than zero, but I've also seen it at walls where a curve is made up of a bunch of straight segments.

In the example below you can see that the foundations on the left have their eccentricity set for an offset. This works rather well when you do not want to use a retaining foundation when dealing with the same footing width regardless of wall thickness. On the right is the example of the curve made up of straight portions of walls. And we can see the wall foundations have gone CUH-RAAZZZY!!!
So to fix this is simple. Whereas, I had been putting voids in there, or some disallow join on the wall but then when changes happen, those voids and disallowed joins never seem to follow no matter how intelligently you try to constrain them... and then one day I just.. dragged it out.. and dragged it back in.. and magic happened.

See…
It’s a bit deceiving because the circle drag handle is at the wall join where it should be, so at this point you don’t think that’s actually controlling the end of the footing that’s sticking way out there. But.. hello, duh.. it is!

I usually just drag mine to snap to the edge of the other wall footing, or at the curved situation where I’m not sure where it needs to end I begin by typing in a small distance just a bit more than zero. Then it takes a bit of shimmy-ing at the curved situation but totally do-able. (Helps to turn off your snaps when shimmy-ing)

Next up is something new with Revit Structure 2012. With the cut solids enhancements you can get a better display of your isolated foundations when working with additions to existing buildings where the existing footings and new footings join regardless that one footing was actually poured 50 years ago. *sigh* I’m not sure why Revit lets one phase join with other phases or why the material from the phase graphic overrides does not really affect it (maybe if all my elements were set to by category? Yuck!) Anyone Anyone? Bueller? Autodesk?

Anyways, back to the point here… In previous versions you had to unjoin your isolated foundations and then use the linework tool to hide any of the overlapping lines. This would also throw off you concrete material takeoffs.

In Revit 2012 you can unjoin your isolated foundation and then Cut them. First picking the foundation that will have the volume taken away from it (i.e. your new foundation being poured) and then pick the foundation that will do the cutting (i.e. your existing foundation) and your takeoff is now correctly showing which foundation is really full volume vs. which is having the portion removed.
There may still be some lineweight/type issues depending on the order you placed your foundations to begin with, however this, in my opinion, is a great improvement.. Now if it only worked with wall footings… :(

There are a couple of workarounds for that. You could model your existing wall foundations with a different material than your new foundations, however all those different types would drive me nuts, so I typically model just a small portion of new wall without a new wall foundation simply overtop of the existing wall foundation disallowing join at the wall and unjoining the footings.

Thanks for reading! If you have any additional foundation tips put them in the comments!

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