BIM / Arch Roof - Gable ends + adding two Dormer windows to an existing roof shape

[iwbnwif]

I have been using Part and Part Design workbenches for a few months and starting to feel reasonably comfortable with Freecad.

Now, I would like to work on a couple of basic projects with Arch and/or BIM workbenches.

I have followed Yorik's videos, but unfortunately they do not cover the area I am struggling with - namely the Arch/BIM 'Roof' function and in particular creating firstly a gable end (https://en.wikipedia.org/wiki/Gable) and secondly adding two Dormer windows (https://en.wikipedia.org/wiki/Dormer) to an existing roof shape.

Arch Roof.png (35.04 KiB) Viewed 1521 times

The image shows the point I have reached so far. The two problems I would like to solve are:

1. There should be a wall (gable end) reaching up the side of the house to the apex of the roof.

2. I would like to remove the highlighted part of the second roof object.

OS: Ubuntu 19.04
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16117 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.18.2)
Hash: dbb4cc6415bac848a294f03b80f65e888d531742
Python version: 3.6.7
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0

[rockn]

Hi,
For the gable, you can extend the wall to be a little higher than the top of the roof. Then you can substract the roof from the wall to get the gable.
Select both the roof and the wall in this order and click the minus button Arch_Remove.

For the Dormer : you can try to make both the roof and the dormer with the same base wire and set properties for each pane. The tool can handle it.
You can also cut the dormer with the CutPlane tool Arch_CutPlane

[iwbnwif]

Thank you for your response, this is really helpful.

The Arch_Remove works perfectly.

The Arch_CutPlane generates a CutVolume, but then I have also perform a Arch_Cut operation to actually remove the back part of the dormer (the highlighted part in my original post).

Also, the 'internal' part of the main roof remains after the cut (i.e. just the dormer is cut) - which I guess is to be expected. However, if I try to repeat a similar operation to cut the internal part of the main roof, the results are quite unexpected.

Although the CutVolume looks right, but the resulting cut ends up offset. I think that maybe the way is to create my own cut object and remove the unwanted part of the roof, or create the roof and dormers from scratch.

[rockn]

Indeed, cutplane is good to cut extremity of element (usualy beam like element)...

And unfortunately Arch Roof does not handle the place where dormer and gable are at "the same position" (excuse my english). It need a little line (> 0 mm) in the wire to make the pane. If the small return does not exist, the tool fails. Look at my screenshot and the attached file.

Capture du 2019-07-25 13-18-28.png (274.26 KiB) Viewed 1437 times

RoofWithDormer.FCStd

(15.25 KiB) Downloaded 57 times

[rockn]

Hmm, that being said.
I'm able to cut the overhang with cut plane to finally have the desired result. But it's a little hacky.

RoofWithDormer.FCStd

(17.75 KiB) Downloaded 55 times

Capture du 2019-07-25 13-31-23.png (266.33 KiB) Viewed 1431 times

[iwbnwif]

And unfortunately Arch Roof does not handle the place where dormer and gable are at "the same position" (excuse my english). It need a little line (> 0 mm) in the wire to make the pane. If the small return does not exist, the tool fails. Look at my screenshot and the attached file.

Ah, yes - I noticed this before when I was trying to reproduce the layout from a YouTube video, but making the wire represent the roof outline that I am trying to create. Your English is excellent btw!

Edit: I just realised that it is your video I was following https://www.youtube.com/watch?v=4Urwru71dVk&t=3s

Hmm, that being said. I'm able to cut the overhang with cut plane to finally have the desired result. But it's a little hacky.

Great - this works! As you say, maybe not the neatest way, but at least the right result.

Now I need to try the second dormer which starts higher up the roof. I will spend some time experimenting with the cut tools for this one.

Thanks again for helping.