Monday, August 15, 2011

Demo Is Not a Phase

At least in Revit's "world".

This is a common point of confusion when people start using Revit phasing tools, real versus virtual, Revit's "reality" versus real "reality".

Demo is not a phase in "Revit land". It's a phase in "People land" because people do demolition things before some other construction things. Revit however considers demolition to occur during the new work. You have an existing building and then do new work...demolition is no different from erecting a new wall to Revit. The phasing tool is focused on showing things graphically not how we "people" think of managing our construction tasks. I can do demolition in one room while someone is painting a wall in another.

[Edited 8/16/2011] After a couple of emails I decided to alter this post a bit. To restate my initial premise:
    Revit does not require a separate phase for demolition in order for the phase filters and graphic overrides to work.
It is possible to add a demolition phase and keep things in order. It can be confusing though to be sure the elements are modeled in the correct views, using the correct phase and phase filter settings. The more complex the requirements are for showing the contrasting phases of work are the more peculiar things can get.


Brian Payne said...

I have always found it helpful in training others to have them think of phasing in terms of deliverables and/or years.

Phase 1 = 1970 = Original Building
Phase 2 = 1983 = Addition 1
Phase 3 = 2011 = Addition 2

Demolition activity of original building that occurred in 1983 is not a phase.

Jason Bailly said...

I've always said that demolition is 'An action' not a phase. That is why you have that nice little sledgehammer tool! You can use it to perform the action of demolition on objects in your model. Phases are not explicit actions, they are windows of time where change occurs. Managing windows of time is something that is not done by a tool like the hammer rather is is done in a sequential list like the one that is provided to you in 'Manage Phases'

Ree said...

AWESOME WAY TO PUT IT. I remember in revit 2009 doing a Demo phase 1st revit project and learned the hard way. Yikes Thanks for sharing. Cheers

Dean said...

Interesting post and how to look at phases.

The issue we are having is related to cost specifications and using the phases to determine what is being demolished and what is replacing or being added in schedules. In this regard demo is a "phase" as we need to split the costs. So far we haven't found a better way to determine the costs, any idea's?


Steve said...

If putting elements on their own demo phase is helping you do cost estimating then you've got a good reason to "break the rule". Revit does not "need" a separate phase to show the graphically difference between them.

Estimating inside Revit is not a one-button exercise regardless because schedules are focused on specific categories. It take many schedules to tell the story and even with those there is no way to compile their tales into a single summary.

That's why exporting to other tools (Autodesk's QTO is one example) is the current "best scenario". Estimators all have their own ideas about how to assemble their information into a coherent story, so no single tool (apart from Excel) seems to stand-out for this yet.

Rob Valenti said...

So in Revitworld, is it correct to say that things are only "demolished" insofar as they are absent in the current phase? If so, I can see the confusion, since we all know that demolition is dirty, hard work - an "action" for sure.

Right now I am trying to figure out how I might configure things if I want a Demolition sheet with depictions of demolition related objects such as a waste chute, dumpsters, or dust suppression systems.

I'm not a demolition contractor, just a guy trying to understand phasing. But I have to say that this conversation reminds me a little bit of the marijuana scene in "Animal House." I guess this is why I fell in love with Revit...

Steve said...

Items that are used for demolition like you describe would be generally be considered temporary, used during the new construction work for demolition activities.

You place them in a view assigned to the New Construction phase and demolished in the same New Construction phase.

Revit regards elements that are demolished in the same phase they are created in as temporary. Elements created in an earlier phase and demolished in a later phase fit Revit's demolished criteria.

The phase filters define how each state appears (New, Existing, Temporary, and Demolished). The stock template will show temporary elements a little differently than demolished.

David Koch said...

The problem with creating a separate demolition phase (eg, three phases: existing, demolition and new construction) is that when you add a new door in the "new construction" phase to a wall created in the existing phase, the "demolition" infill created for the opening in the existing wall will not show up as "demolition" in the demolition phase (where, presumably, the demolition of entire objects has been done), and any demolition done in the demolition phase will not show as demolition when viewing Previous + Demo in the new constructio phase.

You could manually demolish the opening, and then draw in a new wall to host the new door, but that is too much work, in my opinion (especially if you are only going to demolish the actual opening, and not the entire partition to structure above). I would imagine the effort would multiply on a project with multiple new construction phases.

Using the same names for both the actual phases and the phase filters also contributes to the confusion that many users experience.