kg martin

Making Revit Work For You Using Advanced Families.

Lately I have found that a lot of the buzz about Revit is 3rd party add-ins and software. Sure they’re great and save a lot of time in our workflow, but what about making Revit itself do some work for you?

Earlier this week I created a box gutter sump family that replaces an Excel spreadsheet that I used to use.

You simply input the data you would normally enter into a roof drainage calculation sheet into the Revit family, I also added a few more inputs to allow further control over the family. The inputs are

  • Catchment area
  • Rainfall intensity
  • Minimum box gutter depth
  • Minimum sump depth
  • Maximum sump depth

From there, all the calculations are built into shared parameters. I decided to use the KG Martin method for sizing (from the CSIRO Experimental Building Notes 1978). Hydraulic designers sizing roof drainage know all too well about h, 2h, Dg and Dmax which were easy to work into the family in a step by step process.

My original effort at creating this family I had devised excessively complicated formulas in an attempt to reduce parameters and what I originally thought to be simplifying the family as a whole. If I had taken advice from my Planning Families post though, I would have started out a little differently. When working through a family, you not only have to take into consideration the 3D elements, but parameters as well. What resulted in an excellent parametric family had absolutely nothing that I could schedule out.

With all the calculations undertaken step by step within shared parameters, I have 17 results I can include within a Revit schedule. The outputs from the family now include data such as:

  • Catchment flow rate
  • Calculated maximum flow rate achievable by sump/outlet combination
  • Depth of sump
  • h (depth of gutter flow at discharge end)
  • Dmax (depth of gutter flow at still end)
  • Dg (Dmax + freeboard)
  • Gutter high and low points
  • Td (total gutter depth)

The schedule includes conditional formatting to warn that either the outlet is too small or the sump too shallow/excessively deep. As a further step, I also included a visual warning in the family itself, displaying a text box indicating the error within plan view.





The schedule can then be added to a calculation sheet within the project for design verification purposes.

The data inputs for each sump/outlet can be controlled through the schedule, or the user can double click on the sump within the schedule which will then take them to the family within the project.

The next step is pipe sizing. You would probably know already that Revit does not include a sizing method that specifically applies to stormwater drainage, however I have had some success using the hydronic supply system type with accurate results up to 100l/s which of course uses the data calculated within the family.

For me, being a hydraulic designer and Revit modeller, this family eliminates some double handling in data entry, saving time in modelling and performing calculations. Data entry time is further reduced by creating a fixture tag that pulls the gutter size and sump size from the shared parameters with the family. All for a lazy 90mins development time.