Help with creating curved face on model (Bay Window)

Hello, this is my first time posting on this forum even though I’ve been lurking here for a long time. Im modeling a curved roof for a bay window, I’ve got the framing all complete, but im struggling with creating a surface on the curved surfaces, more specifically the hip part of the roof. If anyone can help me out id very much appreciate it. Thanks

Curved Roof.1.skp (109.4 KB)

Something like this?

I used a cross section of the roofing skin and a Follow Me path. Due to the way your framing was laid out I found that starting on the centerline of the roof structure and modeling the left half, then making a flipped copy of the the geometry for the right half was best. The back was trimmed off flat with the “wall” after extruding.

I thinkn if I were modeling this from scratch I would model the sheathing first and them trim the framing with the sheathing. Sort of reverse engineering it.


Wow that looks perfect, thanks! What exactly do you mean by “used a cross section of the roofing skin”?

If you think about the rafters being slinned over with OSB or thin plywood and then imagine running your circular saw straight up next to the center rafter. The face in the kerf of the cut is the cross section of the roofing skin. The edge of the sheathing, basically.

I went back and redid the profile of the sheathing. That’s the cross section of the roofing skin. Down at the bottom, shown selected is the edges for the Follow Me path.


Ohh okay, I understand now. Thats very helpful. Thank you for taking the time to help me, I very much appreciate it!

You’re quite welcome.

I had a bit of a play. I remade the rafters and cleaned up the base framing some. I found some odd dimensions with some of the straight pieces. The only one I edited for length is the top horizontal. I don’t claim this is perfect or exactly the way the rafters should be made but it should give you an idea.
Curved Roof.1.skp (108.5 KB)
Have a good holiday.

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Okay cool, is there something I did incorrectly as far as creating unusual dimensions? Maybe something I can look to avoid in future projects, I’m still relatively new to sketchup.

I like what you did with the rafters, adjusting the angle so that the sheathing sits flush is a good idea. Im curious as to how you did that. Ill give it a go on my own to try and figure it out. But if its something easily explainable I’d appreciate it.

One last thing, how do you have your settings set up so that when you select an individual component it auto-hides the rest of the drawing? That much more convenient that how I’ve been doing it, I go in and manually hide everything if need to make adjustments.

Thanks again, and a happy holiday to you and yours as well.

I expect there’s a couple of things going on. First you had Length Snapping enabled in Window>Model Info>Units. That often leads to incorrect dimensions. Turning that off is always recommended. The other thing you may have been doing is just dragging out some of the dimensions and trying to hit them without actually entering precise values. You’ll notice I also set the Display Precision as high as it will go so that small discrepancies can be seen. My recommendation is to leave Display Precision set higher than you would actually work in the shop or on site so that you can see if there are dimensions that might cause problems.

I modeled the rafters as the rectangular solids they would be to start with and then used the roof sheathing to trim them. I used an extension called BoolTools 2 for that because it respects the component-ness of components and reduces the amount of work one needs to do. Eneroth Solid Tools would also work. Check the Extension Warehouse.

I don’t know if you’d really cut the rafters that way. Having built a couple of boats I can imagine applying some of the methods from that to building this thing.

There’s a setting in Window>Model Info>Components for Hide Rest of Model. That makes the rest of the model disappear when you edit a component. You’re right. It’s really handy. Some times though you’ll want the neighboring components to be present while editing. I set up a keyboard shortcut for that option so I don’t have to open the Model Info window to change it. I’ll often go back and forth between showing and hiding the rest of the model several times while editing a component.

One other thing I should mention. I set the component axes for the frame parts so they align with the geometry. This can make working with them easier but it also means you can pry out a decent cutlist from the model if you want it.

Spend some time going through the Fundamentals at If you build this thing you might share some photos of it in the Gallery here.


Okay I’ll make those adjustments in my settings. I also hot keyed the Hide Rest of Model like you said. Thats was a great recommendation.

That BoolTool extension is incredible, I downloaded it and started using it. And wow, it saves a crazy amount of time vs double-clicking and intersecting faces. Then going in and cutting out all the excess, which sometimes left hole in my solid objects. This is a game changer lol.

And yeah, I’ll see how it works out cutting the rafters. I’ll use a jig saw to get the general shape, then to get the angle on the curve correct it’ll have to be done with a spokeshave and some elbow grease. It won’t come out perfect, but now i have a more precise idea of how the angle should look and measure out making it easier to do it.

Thanks for all the help again, that was above and beyond what i expected when initially posting on this forum. And yes, if and when i build this. I will take pictures and post them on here and ill make sure to tag you in it. Thanks again my dude!

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Bool Tools2 is indeed a fantastic extension but you have Pro and thus you allready had the native solid tools which do basicly the same…

Old-fashioned blood, sweat and tears stuff. I like that!


Except that Bool Tools 2 respects the component-ness of components. The native Solid Tools do not.

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Well, depending on what you mean by basically the same. The native solid tools have the nasty habit of producing a group as the result regardless of what the original solids were, and renaming that group something like Difference. BoolTools 2 does neither of these things (neither does Eneroth’s solid tools). In my experience, BoolTools 2 also has fewer issues with small faces. From a few crashes I got in the past that left the operation incomplete, I got the impression (which I can’t prove) that BoolTools may temporarily scale the solids up before operating on them and then scale them back down.


Completely agree with that, that’s why I said “basicly”
I use BoolTools2 because I have no access to the native Solid Tools but even if I had access
I would spend the money on BoolTools, no questions asked!
Worth every penny!

I have both solid tools and BoolTools2 and use BT2 all the time for all of those reasons. I do find that it crashes my SU occasionally when I do something it doesn’t like. However, I find my 2023 SU Pro crashes when I make too many move ops in quick succession. I think I need a bigger computer…

Not necessarily, according to your profile, you’re using Sonoma which isn’t supported by sketchup 2023, that may be the cause of some crashes, on the other hand in my experience SU 2023 has been the one with more bugs that I can remember, hopefully SU 2024 will correct most or some of them to have less crashes.

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