A rectangular domed roof

Hi, All

The current project I’m working on has a rectangular roof approx. 27m x 40m It is domed by 153mm at its centre.

Is there a way of modelling this so it is curved, rather than angled?

As ever, your knowledge is greatly appreciated.



You need to give us more info and check the measurements. 153 mm is a bump over that size.

So what do you want to curve? The shape to the top or the corners?

p.s. I started with the wrong bulge, 715mm instead of 765m. But the idea is the same.

edit: I also missed to mention that after ‘Explode all’ you need to select all of the rough dome geometry > use ́Intersect faces with Selection’


Not sure If I’m missing a process or if the arc is too shallow, but I don’t get the option to explode when I pull the arcs…


As you can see in the screenshot, both arcs have a base edge drawn to optain the faces to then Push/Pull.

  • draw the arc
  • draw the base edge to optain the face
  • group face+arc+base edge together
  • do the next arc etc.

It is the groups that you explode later, not the arcs,


Sorry if I’m being dense here… At what stage do you do the push/pull? When I group the arc, line & fill it won’t let me PP.

I’ve done it via ‘edit group’ but when I do the intersect faces it still shows the arc on each of the edges of the slab rather than merging into a dome…

I’ve been doing so well at this, too…

You haven’t answered me so I have used an arbitrary height.
Intersect roof


I’m so sorry! Totally missed your question…

Yeah, it’s just a slight dome of 153mm above flat at it’s highest point…

Thanks for the above…that’s clearer!


I’m still struggling with that 27m x 40m x153mm


Tell me about it…

It’s a very specific design element.

I’ve followed your technique above, but the model comes out striped and angular…

I’m missing something…

Attach your model.

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Due to the nature of the project I can’t, sorry.

Just the bits you are trying to use. Copy and paste into another model and post that.

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Don’t worry about the bit that sticks out…

I wanted to see the parts you were using to make the dome. Not the flat slab and all the other stuff you left in the model.
You need to Purge your model when you delete things for them to be gone.
You also appear to be using Tags incorrectly.
You should only assign Tags to groups/components/dimensions etc and never raw geometry.

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I didn’t build the model - it was a colleague.

For the dome I am using the arc function then adding a line to create a surface.

This is a dome with 153mm at the center, whats the point.
GIF 10-03-2022 11-30-55 PM


It’s to shed water apparently…

we all think it’s stupid too…


A 153 mm arc/dome at 40 m span will look flat. A human must use a measuring instrument to notice the curvature. Old concrete floor slabs often warp downwards at the middle to the same degree or more and the naked eye cannot see this either. To counteract this, prestressed slabs are curved upward. The standard is not to model it.

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If you really must model it, do it with larger curves like in my gif, then use the scale tool to scale down using the middle handle, and type in 153mm and hit enter.

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