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.

7 thoughts on “Making Revit Work For You Using Advanced Families.

  1. avatar Campbell says:

    Interesting post,
    I have been reading through your other posts and finding them very relevant as a hydraulic consultant in Sydney.
    I am only a beginner at using Revit, however am excited about the possibilities.
    We are currently only using revit for the Show off factor of 3-d and coordination, and are finding it very time consuming. My question is, in your opinion, do think that using all the capabilities of revit in calculation and pipe sizing, that the time frame would be comparable to the older style of markups, hand calcs (spreadsheets), CAD drafting, or do you think Revit is quicker once you have entered all the data into the revit families and systems, and have a decent workflow worked out



  2. avatar Ryan Lenihan says:

    I find that the pipe sizing features are not accurate enough to rely on and I often use my old excel calc sheets to confirm sizes. I find the most time consuming part of documenting in Revit is the re-work and then keeping the drawings in a presentable standard as the model continually changes. Hydraulically, there is a further time penalty connecting services on grade.

    I find it is a case of needing to work smarter, rather than work harder. Revit can produce some outstanding results in 3D and coordination, however if the process is not properly managed, it can quickly consume your time and resources. Consider alternative deliverables. Focus on difficult design/coordination areas first and issue sketches of the model with minimal presentation in the way of notes etc. Don’t re-work the annotation as you model, just create a new sketch. As the milestone issues approach, complete the annotation and sheet presentation.

    Just one of many ideas on how to approach Revit.

  3. Fascinating blog! Is your themke custom made or did you download it from somewhere?
    A theme like yours with a few simple tweeks woild really make my blog jump out.
    Please let me know where you got your design. Kudos

  4. avatar Jed says:

    Does the NCC or AS3500 even recognize KG Martin calculations?

  5. avatar Ryan Lenihan says:

    As for if AS3500 recognises it, the CSIRO/KG Martin documents are referenced in AS3500.3 under Appendix A – Referenced and Related Documents.

    I am assuming that the question is more toward “is this even useful if this design method does not comply with Australian Standards”. It’s been a long time since I’ve done any hydraulic design, but being in QLD the process that I used to go through from memory was to reference the CSIRO KG Martin document on our Form 15 (design certificate) as well as AS3500.3, the calculations were then verified by either an RPEQ or QBSA (now QBCC) Licence holder. As long as we clearly outlined that we used KG Martin design method it was accepted by our local authorities.

    Ultimately I would assume that it would vary depending on your local authority, the engineer undertaking the verification on your design and your employer.

  6. avatar Brendan says:

    Hi Ryan, thanks for this post, it’s a great workflow for a Hydraulic designer in Revit.
    I have recently been playing around with a similar one for RWO’s and calculating the design flow & required downpipe size etc. The idea i had was using space seperators to devide a roof plan up into areas with spaces. I then created a space schedule and added some calculated values to work of the area figure and the formula : (RainfallIntensity * Area) / 3600 m²
    it works quite well but the stumbling block i have come up against now is that Revit will not let me tag those calculated values…bummer!
    Anyway Just wondering,have you made this box gutter sump family available for us to download and use & test in our own workflows?

  7. avatar Ryan Lenihan says:

    Hi Brendan,
    Not being able to tag out calculated values is pretty frustrating, I’ve spoken with Autodesk in the past putting forward a feature request of the ability to use shared parameters as calculated values, I’m not sure how that would work moving forward as it would somewhat reduce the requirement to have BIMLink. I’d also think my suggestions to a single person in Autodesk probably gets overlooked when you have the might of AUGI voting in top feature requests each year.
    Mentioning BIMLink, you can use BIMLink to populate the parameters for tagging as per my post here which I’m sure you’re aware that you can do this anyway, alternatively a quick bit of c# code as a macro or addin could probably solve the problem if BIMLink licences are an issue for your clients or workflow.
    I’ve dug around a fair bit for the family file which unfortunately I can’t find it, I was intending on putting another one together though and I may post it up on my blog in the future.
    In the meantime, you’re probably best off checking if one of your clients are interested in handing over a box gutter design excel sheet, otherwise clause 3.7 and Appendix J in AS3500.3 are where the sizing is covered as well as the CSIRO KG Martin method ( there are a number of steps involved in calculating the box gutter and sump size which for me is probably another post to explain, it’s a bit long winded to cover in a comment.

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