manual roof

[Anonymous]

hello! happy new year!
can anyone tell me how does this Design->Create roof level lines work?
i have a roof polygon that archicad with magic wand doesnt give me the right solution.
thank you

[Anonymous]

Vivi,
Roof level lines are invoked by selecting the roofs
and then go to create roof level lines where you set
the height of the the lines and whether they are calculated
to the top or under side of the roofs.
Archicad calculates where a horizontal plane set to a given height
would intersect the top or bottom surface of the roofs and
draws lines in plan at that intersection point.
This is useful for showing where to draw
say 5'-0" knee walls in an attic room.

I am unclear about what you mean by
"Archicad with magic wand doesn't give me the right solution".
Could you be a little more explicit please.
Thank you,
Peter Devlin

[Anonymous]

yes sorry i dont know how to say it really.
see the image to see what i mean
thanks

[David Maudlin]

Vivi:

ArchiCAD is using the same slope for all the roofs when creating roofs using the PolyRoof geometry method. The main difference between the two examples in your image is the 3 roofs at the bottom. If all the roofs are the same slope, then the hips and valleys of these roofs will bisect the angles between the roofs (as the angles are defined by the roofs' pivot lines). This is what happens in the example on the right. In the left example, the 3 roofs must have different slopes in order for the roof intersections to be correct as shown. A 3D view of these two examples would illustrate this point.

HTH

David

[Anonymous]

Vivi,
I made a drawing of the eave edges of a hip roof and
bay roof very similar to the roofs you showed in your
image and using the magic wand created a hip roof
that came out exactly like yours with the weird bay roofs.

David's explanation for this is completely correct and
therefor to model this type of roof one has to model
the main roof using the magic wand and the geometry method
set to polyroof and then manually model the five little roofs
that make up the bay roof.

There is a problem when making these roofs because
some of them cannot be at the same pitch and thickness
as the main roof and form the plan geometry you want.
I manually made these little roofs and then in section/elevation
corrected the pitch and thickness.

I did find a way to make these roofs with
correct pitch and thickness automatically.
After manually making the little cross gable roof that
intersects the main roof, make a mesh with zero skirt
set to the elevation of the roof pivot that is shaped
in plan like the bay roof eave edges.
Create an edge node at the position of the cross gable ridge
and assign it an elevation the height of the underside
of the cross gable ridge.
Select the mesh and and go to design extras, create roof from mesh.
This creates the bay roofs with correct pitches and thicknesses.
Please see attached image
Peter Devlin

[Anonymous]

thank you very much !
i finally did it manually too.

[Steve Jepson]

how about like this? You may want to keep all three of the roofs at the bumpout the same as the main roof as shown here.
extend the ridge back to the roof where the points of the three roofs meet. Let the bastard pitch be on the roofs that make the ridge.