I’m using SketchUp Pro 2020 (and Layout) and I’ve been asked to provide a measured survey of an existing house in Autocad format.
Does anyone have any advice, or warnings, before I agree please? (It being a normal terraced UK house there will be very few curves (except the door swings in plan!). I don’t have Autocad so won’t be able to check if the export has worked ok…
Can i feel confident, or is this dangerous ground??!?
You ought to be quite confident, but test your export workflow (2D or 3D?,etc.) before you agree to anything. Download and install the free DWG TrueView 2021 application from Autodesk to view your files.
You can always just import your dwg back into sketchup if you want to check that the geometry is fine, or use a free viewer to check the file.
Dwg export works, you will get your geometry in ok, and dimensions and text from Layout, and your layout pages will be layouts in autocad, but you do not get a very good dwg file ( layers are gone, and your flattened dwg will have lines split into separate segments after each line meets another line.
In sketchup you can export 3d model and retain both tags and groups, and proper geometry, but then of course you lose your viewports that you get from exporting from Layout. The sketchup scenes will not export.
You could export section cuts made in Sketchup, (create group from slice), those will retain groups and components but not tags/layers.
Or you could use export via Scalp, that will have the opposite result, retaining tags, but not groups.
I have heard of a method of stacking viewports in Layout, one for each tag, and get all your geometry into autocad through that. You can search the forum for that.
so it depends, I guess, of what requirements your client has, and whether your workflow testing will take too much time vs what you get paid 
If they are ok with just getting the geometry correct and having that dimensioned in layout, you should be fine
so if you explode your viewports in layout, you have effectively made a Layout geometry version of your viewport. If you put the geometry on a Layout Layer then that layer will transfer to Autocad Layers. Groups stay grouped, but not the group name it seems. The resulting import in autocad will be geometry put in paper space, and scaled down according to the scale the Layout viewport had. so there’s that Obviously, through this process there is no preserving of origo. That you will only get if you export from sketchup itself.
i didn’t mention that the principal reason that i don’t have autocad is because i’m on a Mac (and therefore none of Autodesk’s other offerings are of any use to me either! If anyone can recommend a Mac dwg viewer (or indeed a dgn viewer) that would be great.
lots of good suggestions here and if i get more work of this kind i’ll look into them all, but in the short term, i’m thinking i just want to model it in 3d, in Sketchup, and then since the autocad user has specified nothing about what he wants (in auto cad layering, tags, grouping, blocks etc) i just want to give him what is most likely to be relatively useful to him. If that means taking it into Layout and exporting from there, that’s fine, or just 2d projections from sketchup, that’s fine too.
I am assuming that he wants to be able to use the info in autocad, not just receive autocad drawings with title blocks etc. to pin on a wall(!)
I would ask him beforehand what he needs, so you get a happy customer. Happy customers are more likely to pay.