Modelling a complex Parisian style roof

Good morning/evening.

I have been really struggling to figure out a method to model a rather complex (At least to me) zinc Parisian style roof on a central London property.

I have built a model of the property using scale drawings which I pulled from planning records but I have hit a dead end when it comes to modelling the roof. The geometry is quite complex and Im at a loss as to how to model it.

The records which I pulled from the council don’t include accurate roof drawings as it was changed at some point during the build so I would have to go off it by eye.

Any ideas very much welcome!

I cant seem to post multiple photos so here is the model I have created so far.

I’m struggling to understand the shape of the building from your image.
It should be a rectangle but it looks like a hexagon.

That’s a pretty interesting type of mansard roof!

I’m by no means an expert but on first impression I think I’d model the dormer windows first with what I’d assume is a parapet gutter configuration (although I can’t see a rainwater hopper) as you probably have an idea of sizes from an elevation/section for the windows.

If there is zero information on the different pitches of the roof, I’d guestimate the first angle of the lower part of the roof based on what you can see on the cheek of the dormer. Then do the same for the upper portion of the roof based on what looks right in relation to the lower part.

The standing seems are laid out in a regular grid so you could probably use these as the frame working out from the dormers to then put faces on.

I’m not sure if I’ve articulated my POV across, I hope it makes some sense. Probably best just to play around with it to try and get something that looks right with the scale and angles before going into more detail.

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It is indeed a strange shape! Its on a corner of two intersecting streets and Is wider at the back then the front. Its not quite flatiron extreme however.

Thank you for the fast response. Mansard roof you say. Good to know the official terminology. I actually did some further digging and found this which I must have missed?

The lantern on the plans was never constructed but the rest of it looks fairly plausible.

Now, Im guessing that I sketch it out and extrude… I’m not sure how I will set the pitch I suppose I would experiment.

I would start with the basic shape of the roof in cross section. Use that with ‘Follow Me’ plus the building perimeter to get the basic roof shape.
Add slanted edges on the roof face at the appropriate locations and pull out the created vertices from the top perimeter.
Add the dormers as a component, four times, as I see in the image.

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That seems like a workable method Dan. I shall try that from the plans I have and report back

Block out the roof structure, I you look at it its pretty modular. So an intermediate section and a dormer are the modules.

You have to guess at the top but id assume a flat roof.
Personally, I’d start with the Dormer, the intersection with the mansard on the dormer cheek is a clue to the pitch which will allow you build the connection panels - there is your component.
Then the bottom path of the mansard section - the path is then just offset back and scaled at each vertical stage.
you’ll have to judge the offsets but you should be able to get close.
When you build your panels make sure that you model in the joint details and offsets at the time its easier to do it at that point than try and add later…


oops, forgot to add skp

Mansard.skp (212.6 KB)

Bloody hell bifterx. That looks excellent. I hope you did not put too much time into it on my behalf.

Yes the roof is a flat fiberglass type and has a deck ontop so I have access to all of the measurements.

No, it was actually very very quick.
Started with a box for the dormer and a line segment to guesstimate the pitch from the photo.
Then draw out the ‘ground-line’ - a four segment line, then copy em up and scale and just draw in the connection lines. The only plugin I used was Thicken for the intermediate joint and the crown joint.

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I love stuff like that. the geometry and angles are pretty simple but those zinc roofs look amazing in real life!

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Pretty much what I was trying to get at, thanks for doing a far superior job at explaining! Very interesting detail indeed!

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Added some quick standing seam detail & parapet.

Mansard.skp (659.6 KB)


Looks really good thanks allot Bifterx. I actually started to scale everything yesterday and build out the corner section but admittedly Im still figuring Sketchup out so quite slow.

If it interests you at all I have uploaded my model. It should all be to scale. The proposed roof plan is not accurate as changes had been made during the build so theres not much to go on other the photos. Mews.skp (2.6 MB)

Hey, those renders look super realistic! :wink: