Have you ever tried to move something in SketchUp and accidentally pulled half your wall along with it? Or applied a paint colour and watched it continue into the next room?
I see these things all the time when I’m teaching interior designers how to use SketchUp. Usually, there’s a pretty simple explanation. But when you don’t know what’s causing the problem, you can spend a lot of time trying to fix it.
Here are 10 mistakes I regularly see in my students’ models, along with the habits that will help you avoid them.
Want to see what these look like? Watch the video below, where I demonstrate each mistake and how to fix it.
1. Forgetting to group before drawing the next thing
SketchUp has something called “sticky geometry.” Raw edges and faces that touch each other in the same editing context connect.
So if you build your walls and immediately start drawing your floor without grouping those walls first, things can get messy. You try to move one element, and something else comes along with it.
The habit I teach my students is simple: Build. Group. Build. Group.
Build your walls, then group them. Build your floor, then group it. Before you move on to the next element, ask yourself, “Did I group this?”
It feels repetitive at first, but eventually it becomes automatic.
2. Not selecting everything before grouping
Sometimes you remember to create a group, but a few edges or faces get left behind.
This often happens when you double-click a face instead of triple-clicking to select all the connected geometry. From your current view, it might look like everything is selected, even though the underside or some of the sides aren’t.
Before creating your group, orbit around and check your selection.
Then try this quick check: right-click your new group and hide it. If you still see edges or faces that should have disappeared with it, you missed something.
Fixing it now is much easier than discovering it after you’ve built three more things on top.
3. Ignoring unusually bold lines
A slightly heavier line can be a clue that two neighbouring faces aren’t aligned.
For example, you might build your walls from a series of rectangles. If one rectangle is slightly out of alignment, that small difference can cause problems once you start adding height and creating openings.
If an edge looks unusually bold where you expected a flat, continuous wall, zoom in before erasing it.
Check that the faces are actually flush. Otherwise, deleting the edge might also remove a face you wanted to keep.
The line is a clue to investigate, rather than something to immediately clean up.
4. Adding extra geometry when you only need to divide a face
Let’s say one wall continues through two rooms, but you want a different paint colour in each.
If it’s one continuous face, applying a material colours the whole thing. You might be tempted to draw another surface on top for the second colour.
You don’t need to.
Open your wall group and use the Line tool to divide the existing face where the colour should change. Make sure the line connects all the way between the bottom and top edges.
You can then apply a different material to each section.
The same idea works for flooring. If you want tile in a powder room and wood everywhere else, divide the existing floor face along the room’s perimeter.
5. Leaving objects paper-thin
Have you ever added a rug and noticed it flickering as you orbit?
If you’ve drawn a flat rectangle directly on your floor, you now have two faces occupying the same space. That flickering is called z-fighting.
Give the rug a little thickness so its top surface sits above the floor. Even a small amount can resolve that overlap.
Think about the object you’re modelling. A rug, countertop or shelf has thickness in real life, and giving it thickness in your model helps avoid these issues too.
6. Using groups for repeated objects
Groups and components both keep geometry contained. But components are especially useful when the same object appears more than once.
Think of four identical table legs or a series of matching shelves.
Make one component, then create copies of it. When you edit the geometry inside one instance, the other instances update too.
If your client decides those shelves should be thicker, you’ll be glad you only have to make that change once.
When you’re building, think beyond what you need right now. What might you need to change later?
7. Bringing in 3D Warehouse models without cleaning up
A downloaded chair can bring more than a chair into your file. It can also introduce tags, materials and other content you don’t need.
I’ll be honest: I usually download directly into my working model. But I clean up afterwards.
Check the tags that came in, fit the object into your own organization, and give it a useful name so you can recognize it in the Outliner.
Also, purge unused content periodically. Deleting a bed you decided against doesn’t necessarily remove its component definition and materials from the file.
After trying several furniture options, that unused content can add up.
8. Leaving stray edges behind
Temporary lines and leftover Follow Me paths are easy to forget about.
If you’ve organized your model with tags assigned to groups and components, turn those tags off and see what remains visible. You may discover loose edges you no longer need.
Check them before deleting anything, especially if you’ve intentionally kept reference geometry.
In the video, I also show how I use CleanUp³ by ThomThom to remove stray edges.
9. Leaving section planes visible in scenes
If you return to a saved scene and notice a strange grey haze, check your section planes.
The section cut doesn’t have to be active for the plane itself to remain visible.
Turn off View → Section Planes, then update your scene so it remembers the setting.
It’s a quick fix, but it can be surprisingly confusing when you don’t know what you’re looking at.
10. Creating walkthrough animations that give you whiplash
A walkthrough should help your client understand the space. Sudden camera turns and jumps in height can make that harder.
If two consecutive scenes face almost opposite directions, try adding an intermediate scene so the camera turns more gradually.
Then check your eye height. Moving from a view near the floor to one near the ceiling can feel like you’re flying through the room. Use the Walk tool to help maintain a consistent height.
Finally, give the transitions time to happen. Try setting the scene transition time to four or five seconds, then watch the animation and adjust as needed.
These considerations matter when your scenes play as an animation. Individual views exported for a presentation don’t need to flow from one to the next.
A few small habits make a big difference
You don’t have to remember all of this the next time you open SketchUp.
Start with grouping as you build, checking that your geometry is aligned, and cleaning up as you go. Those habits make it much easier to keep working when the design changes.
And if you’d like me to walk you through building a model from the beginning, that’s what we do in SketchUp for Beginners. We work through the process step by step, using examples that relate to your work as an interior designer.
Prefer learning on your own schedule? The on-demand course lets you work through the lessons at your own pace and revisit them whenever you need a refresher.
Prefer learning together? Join the live course for scheduled classes, real-time feedback, and the chance to ask questions as we go.
