Why are some parts of the model paintable but not others?

Hello… I am new to Sketchup and trialling it for the Interior Design course I am doing - apologies for the rookie question!

I am creating a floor plan and have been using components - so switching between 3D and 2D. I now simply have to paint the walls black for the 2D floor plan, but my interior walls around my stairs will not let me select them and paint them. I manually created the stairs with the line tool and have noticed some have a face and some don’t - I have no idea why.

I can see my interior wall that won’t paint doesn’t have a selectable face but I don’t know why or how to fix it.

Happy to upload my model but would you want the 2D or 3D export and which format?

Thanks for any help… loving the tool so far.

The original .SKP SketchUp model file would be the most useful (rather than some exported variant of the SketchUp model).

The line tool will create faces if and only if the edges that bound the face are co-planar. The SketchUp “inference engine” makes this easy to do generally, but it is also quite possible to place end-points imprecisely, which can make a set of edges be non-co-planar. One common scenario in which unintended positioning errors occur is when length snapping is enabled (which I think may be the default, sadly). Turn it off, via the Model Info window as I recall. Without a face, a material can only be applied to the edges themselves.

To fix the geometry, you will probably have to delete and re-draw some edges. Zoom in close to the corners where you expect edges to meet, and see if there is a gap. If you find a gap, delete one of the adjacent edges. If you don’t find gaps, try drawing new edges across diagonals of where you want a face to form (form one existing end-point to another existing end-point). If adding a diagonal edge causes faces to form (two of them, one face on either side of the diagonal), that likely means that the other edges are not co-planar. You will have to decide which edges are most likely in error and delete them.

Then re-draw the edge(s), being careful to allow the inference engine to show when the start and end points are exactly on top of existing reference locations. These are shown by SketchUp as a green dot when the cursor is close to an existing end-point, a cyan dot when close to the mid-point of an existing edge, a gray dot when close to the center of a circle or arc, etc.

By the way, are you creating any Groups or Components to hold the edges and faces of the various parts? This is an extremely important aspect of using SketchUp.

Hi Tom - thanks for this comprehensive help. I will have a look and if still struggling, post my model. This all makes perfect sense though. Yes, I have been creating groups and components… need to re-read the benefits of one over the other to work out when to use which… been using them for things like doors so I can move them easily and copy them easily.

Thank you so much (will look at this at the weekend, if not before).


Good luck! :slight_smile:

Both groups and components have the property that they form a logical boundary or “context” for the edges and faces within them. This means that the edges and faces within a group or component (sometimes they are collectively referred to as an “object”) will not stick to, or merge with, edges and faces in any other object. This is the major benefit of groups and components.

The difference between a group and a component is that copies of a group are independent of each other (more-or-less, details in a moment), whereas copies of a component remain linked behind the scenes. The multiple instances of a given component all share a common definition. Editing any one instance of the component actually modifies the common definition, which causes all other instances of that component definition to instantly change as well. For example, if you have a six-panel door component and you want to change something about it, modifying any one instance of the six-panel door will automatically change all other instances of that door.

If you have made a copy of a given component and you decide that modifications to this new instance should not be propagated to the other instances, the Make Unique function will break the link to the original common definition. This component instance will become linked to a new component definition. For example, one could copy a six-panel door component, make it unique, and modify it into a four-panel door. Other instances of that new four-panel door could be placed in the model and all four-panel doors would stay “in sync” with each other. All the six-panel doors would remain synchronizing with each other as well.

In contrast to the behavior of components, modifying a group will have no effect on any other copies of that group. I wrote above that copies of groups are more-or-less independent of each other. To clarify, copies of a group do actually share a common definition initially. As soon as a given copy is opened for editing (e.g., by double-clicking on it) that copy of the group becomes truly independent right then and there (even if no changes are made while the group is opened). Generally it does not really matter whether the copies of a group become truly independent when they are created vs. when they are opened for editing. The one practical effect of deferring the “uniqueification” of a copied group is to reduce the .SKP model file size. If you make 1000 copies of a group, initially they all share a common definition (edges and faces etc.) that is stored once in the .SKP file, along with the position and rotation etc. of each of the 1000 copies. If the 1000 copies were made truly independent immediately, then the .SKP file would contain 1000 copies of the edges and faces along with the 1000 position and rotation information, generally making for a much larger file size. As you edit some of the 1000 copies of the group, the file size will gradually increase as more and more groups become truly independent.

Thanks Tom - I managed to sort out my inner walls and thanks for the info on groups and components… most useful!