Loft Surface in Revit
The loft command is a useful tool for creating 3D geometries. But does Revit have a loft command? The answer is yes. Revit provides the "Loft" command through Dynamo. This article explains the process of creating a loft surface and the concept of using three parameters in design instead of specific numbers. To illustrate this approach, we refer to the elegant Bosjes Chapel project. This article outlines a simplified model and overall approach to designing a loft surface.
Bosjes Chapel
What is more tranquil than a unique surface extended symmetrically over a pond of water? The smooth, undulating edges of the surface rise and fall playfully, bringing satisfaction to the eyes. It is all just one continuous surface, no more, no less. This simplicity is a hidden reason why the surface is so appealing. This building is Bosjes Chapel, designed by Steyn Studio in 2016 and is located in South Africa.
![hodaganji_1-1733264054657.png Figure 1. Bosjes Chapel, Steyn Studio, South Africa, 2016[1]](https://forums.autodesk.com/t5/image/serverpage/image-id/1441660i3DA80C4E33D211BE/image-size/medium?v=v2&px=400)
Inspired by Psalm 36:7, the structure has a hint of floating/gliding. The hyperbolic paraboloid surface creates a self-supporting structure, free of columns, leading to an open space. The chapel aims to be welcoming through its open space design.[2]
What makes this chapel minimal in some way is that the roof surface is a continuous loft surface, which can be created with no more than three profile curves. Each curve needs a minimum of five points. Here are the steps on how the geometry of this chapel works:
- Create Points: Create five points for each curve.
- Form Curves: Create a curve out of the five points.
- Repeat: Repeat the process to create two more curves.
- Create Loft Surface: Create a loft surface out of the three curves.
- Import Graphics: Import graphics and visualization.

Figure 2. Bosjes Chapel, Step-by-Step Creation in Dynamo, Revit. Model by Author
Points and Parameters
Let us create the first five points for the first curve. If we consider the distance between points 1 and 2 as “Width” or “W,” the “X” coordinates of points 2, 3, 4, and 5 would be W, 2W, 3W, and 4W due to the symmetric design. Points 2 and 4 are located on the ground, while points 1, 3, and 5 have the same value for height, which we call “Height” or “H.” Hence, the coordinates of points 1 to 5 would be as shown in Table 1.
Table 1. Bosjes Chapel, Coordinates of Points
Points,
Curve 1
|
X
|
Y
|
Z
|
Points,
Curve 2
|
X
|
Y
|
Z
|
Points,
Curve 3
|
X
|
Y
|
Z
|
1
|
0
|
0
|
H
|
1
|
0
|
D
|
H/2
|
1
|
0
|
2D
|
H
|
2
|
W
|
0
|
0
|
2
|
W
|
D
|
H
|
2
|
W
|
2D
|
0
|
3
|
2W
|
0
|
H
|
3
|
2W
|
D
|
H/2
|
3
|
2W
|
2D
|
H
|
4
|
3W
|
0
|
0
|
4
|
3W
|
D
|
H
|
4
|
3W
|
2D
|
0
|
5
|
4W
|
0
|
H
|
5
|
4W
|
D
|
H/2
|
5
|
4W
|
2D
|
H
|
For the third curve, the “X” and “Z” coordinates remain the same. The only difference is that the points are moved along the “Y” axis by the whole depth of the building, which is 2D if we consider “D” as the “Depth” module.
Regarding the second curve, the “X” coordinates remain the same, but the points are moved by an amount of D along the “Y” axis. The heights of the points are reversed, meaning that points 2 and 4, which had a height of zero in curve 1, now have a height of “H.” Points 1, 3, and 5, which had a height of “H,” are now lowered to about half of “H.”
Using parameters “W,” “D,” and “H” instead of actual values is beneficial because if we change our mind about a dimension, we do not need to update the values one by one. We only need to update the parameters “W,” “D,” and/or “H” for the whole surface to be updated automatically.

Import Geometry
The model should be imported into a Mass Family first so that the surface is recognized by Revit as a roof. The roof will be created as a Roof by Face from the Mass Family. Next, the Curtain Walls can be attached to the roof to follow the roof curve automatically.
Skills
Table 2. Skills Required to follow this article.
|
Beginner
|
Intermediate
|
Advanced
|
Not Applicable
|
Revit
|
|
x
|
|
|
Revit Family
|
|
x
|
|
|
Dynamo
|
|
x
|
|
|
Geometry
|
|
x
|
|
|
Mathematics
|
|
x
|
|
|
Tutorial Videos:
Loft Surface, Dynamo, Revit:
Bosjes Chapel modeling, Dynamo in Mass Family, Revit:
Your Ideas:
Now, what building do you have in mind to model using this approach? Please feel free to let me know how it works!
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References
[1] https://www.archdaily.com/867369/bosjes-chapel-steyn-studio
[2] http://www.steynstudio.com/projects/bosjes_chapel/