Help for beginner: how to design a roof for a mansard

Hi, … I am a super-beginner.

I am trying to design a roof (as I have highlighted here in the pic) by extruding a plane. I have designed the plane by 4 lines but I can’t select the plane to extrude. Did I do something wrong ?

Start learning the basics: SketchUp Fundamentals -Part 1

There are many ways you can create that roof, this can be one of them

You have NOT drawn 4 edges forming a coplanar rectangle.
If you had the face would auto-form.
There’s no edge against the orange wall - trying adding that and you should see a face form…

@TIG is right, and I’ll go somewhat further. The top edges of the short wall at the left and the wall in the middle aren’t flush with the top of the orange wall. But your highlighting of where you want the roof spans all three. It is impossible for a flat rectangle to do that. Note also how the sloping edge seems to cut through the post in the middle. This says that the one or the other is askew.

Draw a flat plane on the ground. Extrude it. Group it. Then move and rotate it into place. That’s a half decent way to think about how to do this.

Thanks All.

I forgot that geometry tells us that 3 points are required to define a plane…while i was trying to define a plane through 4 points, which can be only if they are planar !

Thanks also the link for the training !

May i ask one more question ?

Once i have eventually my 2 rooms apartment designed, it would be great if i can perform some kind of rendering…but i need something really easy.
I have tried to install Luxrender but i could not even understand how to install properly. I do not want even to look at sophisticated products like Vray.

Can you suggest some easy free plug-in with some.decent output ? At the end, I just need to make my rendering to select right pavement and walls colours :slight_smile:

Thanks !


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I recommend Twilight Render. You should have no problem finding it and installing it.

Thanks ! It works! It is nor really photo realistic rendering, but i think it is enough for my tasks. I just need to get some youtube training on how to set up the lights and sun light and then i should be able to get what i want.


Great news. And for the record, you can get some really great renders out of twilight. If you have great materials and maps, lighting and models, they can be amazing.

But let’s face it. You asked for simple plug in, and this is one. If you want photorealistic you have to put time into it, regardless of software. Even Vray takes a ridiculous amount of time and energy to get anything remotely realistic. Out of the box Twilight is the same as the best on the market.

Hi, do you have any idea why Twilight is not rendering the pavement of my new bathroom ? :slight_smile:
Furthermore… what is the right setting to have more bright room ?
I have selected : Render Preset: 02.SunSkyMed.

Could you show that part of the model in SketchUp, while you have View/Face Style, set to Monochrome.

It might be that you have a jpeg of the floor plan also in the same plane as the floor. Remove that and try again.

The brightness of your room is not about a setting. It’s about lighting. You have the whole room in shadow. You have to add light and adjust exposure in the rendering settings, like post processing.

I usually use high or high+ for quality. There is a learning curve too but also a decent set of presets for materials so you can quickly add mirrors, metals, textiles, paint and stone that feel more real.

Thanks Colin. I have followed your instructions.Here below the Monochrom version:

and also the original file in sketchup (very rudimental model…)

Thanks Monospaced,
there is a jpeg map underlying… I have used it to build the 2D map.
Futhemore to get the right pavement, I have created a new material and loaded a jpg file of the nice tiles I am thinking to buy. Is this the worng way to do it ?

One more question (I shame myself… I am aware that I am trying to find a shortcut rather then studying a little bit more the Sketchup tutorials… but in few days I have to finalize the purchase of my new apartment and select all the pavement, sanitary, furniture… I am in panic mode :sweat_smile: :sweat_smile: :sweat_smile). Here it is my basic question: How should I add lights? Is it a tool in Sketchup or in Twilight. ? Thanks !

Lights are a tool in Twilight. It won’t take too long to check out their videos. Very helpful.

Reverse the floor face so that the white (front) face is out. All the objects visible in your render should have the white face visible. Apply your textures to the front faces. Twilight has trouble in most cases displaying textures on the back (blue) sides. An exception is you should apply transparent textures to the back sides as well as the front.

Assign the floor plan image to its own tag and hide it for the scenes you wish to render.

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Yes, what pbacot said. By showing Monochrome it quickly showed up any reversed faces. Reverse the face so that it’s the whiter color, then go back to Shaded with Textures, and reapply the material that you want on the floor.

Thanks… not sure what you mean to “reverse” the surface.

All faces have a front and a back face. White is the default front and blue/gray is the back.
You should only see front (white) faces on a correctly built model. Unless for some reason you need to look at the back of a single face.
Back faces are ignored in many render programs, so although a model may look right when textured it can be wrong when viewed in Monochrome.
Right click to reverse faces.

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Thanks All. I reversed the face as per above, reapplyed the same material (floor tiles created from a jpg) , but still I do not see any pavement in the apartment when i do the rendering with Twilight (i still see the underlying jpg map). Any idea ?
Thanks !

Remove the jpeg or put it on a tag and make it non visible.

Thanks … it works !

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