How can I easily draw an accurate slope arrow in SketchUp?

How can I accurately and easily draw an accurate arrow that points “down” on a planar surface, e.g. the way that water would flow off a roof?

When drawing a line on a plane, is there a way to reliably get it to stick to the plane? I can get the first point on the plane, but the second point is sketchy sometimes. None of the arrow keys seem to get the second point to follow the plane.



Use inferencing and the down arrow key.

What version of SketchUp are you using? Please complete your profile.

You can create an Arrow component that ‘glues’ on each face;
Draw a rectangle on the ground
Draw the arrow on it
Select only the arrow
Rightclick on selection and choose make component (the properties are automatically set to ‘glue’, but you might uncheck ‘Cut opening’)
Delete the drawn rectangle and arrow component

Now, it is in your In Model Component Library
Drag it on the roofs faces


You might also try the Slope Markers extension John McClenahan and I recently published on SketchUcation. In addition to drawing and annotating the arrow, it takes care of finding the direction of maximum slope, which isn’t always easy manually.

Edit: I didn’t notice you gave this the SketchUp free tag. The web version doesn’t support extensions.

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