Complex Roof Lines on First Project

[elliekate]

Hello, I'm a student just learning BIM and trying to model my house. Unfortunately, there are lot of roof lines and I'm confused on the approach I should have.

I was able to draw this in sketchup. It's complicated. The key is to have the roof interacting from multiple floors. I know the walls need to form a closed loop, but should that loop include multiple floors?

I'm also confused about the roof section at the rear of the house. That roof goes from the back to close to halfway up the back wall of the house.

I was able to draw the house in sketchup (wow that was hard) and the roof lines should look like this?

This _isn't_ homework. It is just me learning and I would love any tips on how to join complex roofs across multiple floors.

[ToanDN]

- Don't worry too much about Level.  If a roof covers multiple Levels then pick the lowest level to sketch the footprint and you can always move it up or down later.

- If it can't be done using one roof then you can model multiple roofs and join them.

- Roof by Extrusion is a great tool to draw sash roofs, where you want to control the low and high points instead of slope

https://revitpure.com/blog/9-tips-to-understand-revit-roofs

[elliekate]

I will definitely try the roof by extrusion and am reading your link now. I have two blockers now:

* for the roof on the back -- what would you call this roof section. I'm not sure how to approach a "half roof" since I'll need a complete loop to make a roof. Is this a good use case for an extrusion. Once I extrude it, I'm not sure how to combine things.

* second, I can't get my parameters to load in properties. For example, I want to have a "my_overhang" parameter that I would use here:

this approach doesn't work:

I also tried to load it as a formula.

I've defined it as a global parameter:

[ToanDN · Accepted solution]

Overhang is only available when you use model roof by footprint and use Pick Walls.

If you use Pick Lines the you need offset the lines manually to create the Overhang.  Pick Lines and Pick Walls should not be mixed within a single roof sketch because Pick Lines define the eaves and Pick Walls define the plates.  There are of course exceptions where you can mix, for example the red roof in your picture.

That red roof can model as a roof by foot print with 3 sides using either Pick Lines or Pick Walls (with 0 overhang) and the front lines using Pick Walls with an positive overhang.