Planning Families. Lessons Learnt as Families Develop.

In Australia we call it hydraulics. USA call it plumbing engineering. UK, health care engineering. Whatever it may be called in your region, you would be well aware that out of the box, content is severely lacking in Revit content.

I started using Revit MEP in 2008, Revit MEP 2009 was released the same week. The company I work for had won a project, a 7 storey plus basement, 5 star Greenstar rated office building built for the State Government. Myself and another drafter were sent off for some ‘intense’ two day training in Revit MEP so that we could learn the software to model this project. After 2 days we were supposed to be revit gurus.

Well. 3 years later and I still would not consider myself a Revit guru. A somewhat wise man once told me to never ever believe that you are the best at what you do. There is always bound to be someone out there better than you. Basically, it is a slightly self deprecating way of saying “you never stop learning”

Once we started modelling this project, with no prior experience other than our somewhat lacking education, we realised we had embarked on a long an arduous journey, this is where we come back to content.

For those that don’t know, the humble floor waste gully (FWG), or floor drain as some may know it, is a rather important piece of kit in hydraulics. In Australia, floor wastes are mandatory in some areas and optional in others. Generally you will see floor wastes in public bathrooms, where they are required beside urinals, or they may be collecting water from a nearby basin, shower or tundish. The concept is simple. Lets stick a grated drain in the floor in case anything floods, there is a way for the water to escape without damaging the building.

When I created my first floor waste family (based off the Iplex Palazzi style trap), I had no formal training in family creation, as such, there were no parametrics involved, the floor waste was simply a modeled based on my AutoCAD 3D experience and attached to a floor (floor based). This was my first lesson learnt.

In Revit, you can not host to walls, ceilings or floors in a linked model. Not immediately understanding what I had done wrong, I started to draw floors in the amenity blocks where floor waste gullies were required. I also had trouble creating a floor not bound by walls, so I had to create architectural walls as well. Quite a frustrating process, especially when rooms changed.

The other problem with this floor waste, I was convinced, was lack of parametrics. Because I didn’t even know where to begin, with no help to be found, no Revit site I could find had any useful information on creating parametric families, I had to live with a fixed position family.

I chose an arbitrary height of 300mm from the top of slab. This was great for some areas, not for others. 500mm thick slab. No worries, floor waste can sit in the slab. I have to admit, even though the family looked great, it also looked somewhat unprofessional.

The next development in my floor waste family was to change it so that it was hosted to a face, rather than a floor. Already a great improvement over the last. Problems were still apparent though. At the same time that we are still developing our Revit capabilities, so are many architects. Many people will tell you, especially people from a Revit MEP background, that deleting walls, floors and ceilings from your Revit Architecture model is a big no no! Rather you should move them where possible. The reason behind this is that any objects hosted to your now deleted elements, like FWG v2.0, will cause dramas for the MEP modeller.

Thanks to some formal training in family creation, I though I would solve my fixed position floor waste problem once and for all. As you can see, this new and improved version had an integrated riser which is attached to a face, which when inserted in the MEP model would be the floor. Brilliant! Well it just wasn’t meant to be. On the next project, were were dealing with an inexperienced architect, floors were being deleted left right and centre, even after we very clearly communicated with them to stop deleting things and to move them instead.

Most of the time this resulted in the either the floor waste family being completely deleted, or to cause headaches with pipework connections downstream.

The other issue was the integrated riser. If you needed to change the height of the floor waste to cater for a thicker slab, or to make an easier connect to a drain, you had to change a parameter, which is fantastic until you change it too far and all the pipework disconnects.

So in essence I had created a brand spanking new revision of the family which essentially had all the same problems, just for different reasons. Second lesson learnt.

The next, and at this point final revision which we will call FWG v3.0, has what I think are two great leaps forward in development. The first, and probably the most important, is that the family is no longer hosted to anything. Floating around with no host association was the solution to the majority of our problems.

The floor waste now has a pipe connection at the top of the four-way riser. The idea is that you draw a pipe vertical from the family to the floor or reference level. You can lock the top of the pipe to the floor or reference level if you wish. As long as you do not try to raise the level of the FWG above the slab, you no longer have troubles with pipework disconnecting when the height is changed.

Not content with simply fixing the riser issue, I decided to make some changes to the four way riser which was actually the request of one of our modellers. Previously, the four-way riser was fixed, only allowing connections in 45 degree increments to the outlet. With a lot of hair pulling and the odd desire to throw my computer out the window, I finally figured it out. We now have a rotating four-way riser.

I spent what is no doubt too many hours trying to get the riser to rotate properly. The reason why I was failing was because I was trying to rotate multiple extrustions which I had attempted to lock together with reference planes and fixed dimensions. Lesson 3 learnt.

The secret to making it work is quite simple. I re-created the four-way riser as a seperate family. Once the riser section was nested into the trap family, I was able to apply an angular parameter, linking it to a reference plane within the nested riser family.

Now that I have somewhat perfect floor waste family, I have created a few more based on the same concept. In Queensland, we more often use 100 dia floor waste rather than the 80×65 floor waste I has originally modelled. But there is still a requirement for both.

I have now applied my lessons learnt from my original 80×65 FWG to the 100 dia FWG, shower traps, clear outs, overflow relief gullies and many other core hydraulics components that do not come with Revit out of the box.

8 thoughts on “Planning Families. Lessons Learnt as Families Develop.

  1. avatar Adam says:

    Hi Ryan,

    I have just completed my formal training in Revit MEP and have also noticed the lack of hydraulic equipement for Queensland designers. I was hoping you could share your FWG and IOS families with us?
    As you can understand, I’m not keen on starting from scratch.



  2. avatar andy varga says:

    is there anyway to create a floorwaste family (ie FW, riser and Ptrap) that will change in height (without moving off the floor height) when you move the connected outlet pipe up or down?

    Many Thanks,


  3. avatar Ryan Lenihan says:


    You can either do what I had originally done, with the built in riser and parameter to adjust the height, however I found I had a lot of issues when moving downstream pipework or the floorwaste itself with drainage disconnecting when there was no real reason for it to do so.

    The other option which I do now, is I have a pipe connector at the top of the 4 way riser and I draw the riser in as a pipe, and the pipe can be aligned/locked to either the floor or reference plane. That way when you move the floorwaste up or down, the riser pipe will remain connected to both the floor and the floor waste.

  4. avatar Matthew Bray says:

    Hi Ryan,
    I am in the same Boat as Adam,
    Have undertaken basic training and noticed a lack of information for Queenslanders, ecspecially with Floor Waste Gullies!
    I found this post after searching for “Revit floor waste trap” or something along those lines and this is the most comprehensive article on the topic.
    I would be most appreciative if you could share your FW and IO families as well.

  5. avatar Ryan Lenihan says:

    Hi Matt,

    In all honesty I was hoping people could take something from what was posted and create something that suits them. I will collate some families that will be made available for download shortly.

  6. avatar james pettit says:

    Hi Ryan,

    Just wondering if you have had any experience with graded pipes to 4 way risers etc? the four way riser I have created works if I use flat pipework but on a 1/60 fall (1.6667%) it spits the connection as REVIT doesnt seem to like connections less than 3 degrees?

  7. avatar Ryan Lenihan says:

    Hi James,

    In the family, check out the pipe connector properties, check to see if the pipe connector has ‘Allow Slope Adjustments’ checked. If you don’t have this checked, the fitting will not allow a sloped pipe.

    Slope Adjustment Check Box

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