Transparent planes/surfaces

Hi all.
Apologies first. I am a complete novice and learning as I go along.
I am using SketchUp Make 2017, newly downloaded.
I am attempting to render a house in 3D in order to visualise different expension designs.
My problem is I have ended up with several planes or surfaces, particularly on the roof which are ‘transparent’. That is, I have complete lines around them but they have not made a ‘surface’. So I can see through them into the interior of the house and whatever I do I cannot make them solid.
Does anyone have any idea what I have done wrong, or how to make these planes/surfaces useable?
I do hope this makes some sense. I am unfamiliar with the jargon.

There are a number of possibilities. One common one is that the edges don’t all lie on the same plane. Try drawing a diagonal line between corners. Do you get triangular faces?

Uploading the SketchUp file is the best thing. It eliminates the need to guess what the problem is.

Thanks DaveR.
What a useful, swift and informative reply!
I tried drawing diagonals on the faces which is very useful for narrowing down the problem area.
I think I have attached a copy of one of my files.
I wouldn’t want you to waste any time on this. But a pointer as to whether it is worth trying to sort it out, considering the numerous problems or, I am thinking more likely, ditching it, watching more tutorials and starting again.
I am probably starting in the wrong place, using incorrect practices or a combination of all.
Thanks again.
30 Kent Road-try2-ext1.skp (312.6 KB)

The first roof part I looked at was the back open area. I copied the edges over and you can see that drawing in a diagonal completed the faces. Also adding guidelines to the top and bottom edges extends the lines so you can see they are’t parallel.

I would expect more of the same in the other problem areas.

Get to looking for the on-axis indications when you are drawing. With a little practice you’ll find it gets easier.

Is this a model of an existing house or is this for new construction?

There are many improvements you can make in your modeling. One thing that makes it easier to manage the model is to use groups and components to isolate parts of it. Also, I would suggest waiting until the geometry is complete and correct before adding textures. Seeing the textures is fun but they can mask issues that should be taken care of before moving on.

Added: As I’m going around your model trying to fix the roof surfaces, I see there’s a place where the ridge comes down to the wrong corner. There’s no edge joining the front and back ridges…
Screenshot - 11_26_2017 , 6_21_22 AM

In addition, the windows you’ve drawn under the eave here aren’t on the wall. The front one isn’t even flat. I turned on shadows and enabled shadows from edges to show those edges are floating in space.

The edges in blue had to be added to get the faces to fill. This obviously doesn’t make the model right but it fills the holes.
Screenshot - 11_26_2017 , 6_25_50 AM

If I was your teacher, I would suggest starting over with a better foundation. It would make the model easier to work with as you go.

Thanks for your time and interest.
The main lump is our existing house and the smaller, single storey ‘L’ shaped piece on the right of your first pic is the potential extension that I am trying to visualise before going ahead and shelling out much time and money to build.
Hence my dabbling in things I do not understand. It is quite fun though.
I have found out that the house is a lot more complicated than I had realised. The roof alone, and I haven’t even started on the back and lower side!
You are spot on about the axes. I am sure that is at the root of many of my problems. Slapdash work, too late at night.
Thanks to your suggestion of building triangles I did just spot the line at the back of the roof in the wrong position (between our communications) and moved it. Didn’t make the surface flat though so there is obviously another problem somewhere.
I need to learn about groups and components. I was certainly feeling that, as the model grew, it was getting too much to deal with and found myself flitting to one sie and then the other. But that probably says more about my character than ability. Splitting the model up may simplify the work, but I am sure I need to watch more tutorials before I start again. I would worry that I was making a group with the wrong dimensions to ‘stitch’ on to the main group.
And I agree that starting again, although daunting, would be a better proposition that trying to fix all the inconsistencies that I have built into this model.
One of my major headaches when building the roof was measurements, as I cannot get up there with a tape measure. Too much guessing doesn’t work for me.
Sorry, the windows on the side are an embarrassment (another one…). I knew that as I was hurriedly stitching them on. I just needed them in approximately the right position to make the relevant view from the ‘extension side’ of the house look familiar in order to show it to the relevant authorities (wife).
PS The shadows are very useful. Thanks. There is a lot going on in this software.
I think it’s back to YouTube to watch more tutorials. Is this the best way to assimilate info on this?

:smiley: :smiley:

Kind of gives you an appreciation for those who build such things in reality, doesn’t it?

Even if you did get up there an measure it, you might find some of the roof dimensions don’t add up quite right. Of course in reality things have sagged with time. You also get gentle curves as things twist out of shape. Those things can be drawn into SketchUp but it’s usually not worth the time. Drawing things neatly makes more sense.

Since the addition is really the “thing” here, I would probably first draw the entire house as a simple (yeah, right, he says) mass and make it a group or component. Then you can add more detail in the addition without it being stuck to the house. If you are doing the work of building it, you might find it useful to draw some of the construction details to help you think through the real building process.

Video tutorials on You Tube can be good although there are some that aren’t that good and might teach poor methods. Practice is number one. Practicing drawing on axis, for example, builds muscle memory. With a little bit of that, you’ll find it difficult to accidentally get off axis. Getting really familiar with the tools helps, too. All those things that come with working with real tools.

Feel free to ask questions as they come up. Send a PM if you’d rather.


This house was built in 1926 so, without doubt, you are right and there
will be bending and sagging. It is indeed an age related thing and, as I
am afraid I am finding out at my age, not restricted to buildings…

The building is distinctly straighter and with closer angles than either
of my two previous homes, which were both of the late Victorian era.
Luckily I don’t need to worry about the real world minor discrepancies
so, as you say, neatness is best.

I won’t be doing the work myself, my talents lying more in the realms of
motor repair. There are bits I can do, but nothing that would be ‘on
show’ when finished. Some things are arts acquired, partly, by years of
practise. Building walls and plastering definitely fall into that category.

I will start this again from scratch and see how it goes. It should be a
bit quicker than last time as I am beginning to learn how to use some of
the tools as I go on. And if I don’t have to sit for hours getting
frustrated that it doesn’t seem to work, because I am building on top of
a mistake I made earlier, it will be quicker still.

Thanks for the offer of further advice and I will almost certainly have
to rattle your cage again at some point.

Meanwhile I will load this onto the laptop and take it down to the pub
to annoy my structural engineer friend this evening.



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