An old house in a new program

What could be a better subject for a first Revit project than my childhood home? In may not be a particularly old house, but given that the plans predate CAD itself, it seems appropriate to bring it into the 21st century with a touch of BIM.


I’ll start by laying out a grid of reference planes, which should come in handy later on when aligning objects. If I had a perfect scan of the original plans I could do this with an underlay image and just trace over the lines, but in this case it’s a matter of copying dimensions and spacing the reference planes accordingly.RefPlanes

Now that there’s a grid logic, it’s time to start laying the foundations. I choose ‘Structural Floor’ from the home menu, and trace over the slab areas in plan view.

FootingWith the foundation laid, I can start to add walls. The house has 240mm brick veneer exterior walls and 70mm interior partitions , so I create a new structural wall types for each. Since the ceiling height is 2400, I also set the ‘Unconnected Height’ in the properties tab to 2400. This can be adjusted later depending on the depth of the floor topping.



Now that the walls are in place, I add a surface to the floor for each room. In the house there are three types of floor topping: Ceramic tiles for the kitchen and dining room, carpet for the bedrooms, and timber for the lounge room. This requires three new floor surfaces, offset above the footing slab and locked to the edges of the walls.

FloorSurfacesBy placing a few standard windows and doors, and giving some textures to the materials of the floors and walls, the house now begins to resemble the real thing. But there’s still a lot of work to do – on my next post I’ll focus on creating custom parametric windows, and special elements like columns and beams.



A 3D modeller learns Revit

RevitInterior3As a 3D modeller, learning a BIM package means becoming accustomed to a very unfamiliar way of creating spaces. 3D animation suites, such as 3dsmax or Blender, primarily use meshes, arbitrary surfaces of polygons that enclose volumes without actually occupying the volume inside – it’s as if everything is hollow.

Revit is quite different. Here, every object has a volume, and some objects even have negative volumes – they’re effectively holes cut into walls or floors. For example, in the above image, the archway is an object, but one that occupies negative volume, cutting a hole through the brick wall.

Approaching Revit from a background in Blender, one of things I had to wrap my head around was the method of using reference planes and parametric relations to define the dimensions of a component. Revit may not be the most efficient tool if you need to model a hundred unique windows, but what if you can make just one window that is dynamically adjustable? Suddenly all this talk of parametric objects is much more appealing!