topic Re: Roof with varying slope in Modeling

Roof with varying slope

arg617 — Tue, 23 May 2023 12:18:38 GMT

I'm hoping someone can help me with a roof I'm trying to create. It's basically a shed roof where I would like the ridge fixed at a certain height (35') and the exterior wall fixed at 25'.

The problem I'm having is that the exterior wall is not parallel with the ridge. Here is the plan:

I first tried making a zoning envelope using the morph tool just to get an idea of the envelope I can work within for this project:

I end up with a flat portion at the ridge, where if I try to move the node the morph ends up creating a ridge line. So I tried a mesh, since I thought I can then use that in order to eventually use the "mesh to roof" tool, but the mesh also ends up creating an extra ridge - like this:

In section this ends up looking like this:

I feel like there must be a simple solution to both creating a morph with varying slope and creating a mesh with varying slope. Heck.....even a roof with varying slope should be easier.

Any pointers would be appreciated. I've spent hours at this and feel like I'm getting nowhere.

Thank you.

Re: Roof with varying slope

Eduardo Rolon — Mon, 27 Feb 2017 20:21:44 GMT

Instead of a Morph use a Rule Surface Shell to see if it works

Re: Roof with varying slope

Richard Morrison — Tue, 28 Feb 2017 03:49:15 GMT

Based on what you're describing, either the ridge is going to slope or the wall is going to slope. Which do you want?

Re: Roof with varying slope

Steve Jepson — Tue, 28 Feb 2017 09:07:42 GMT

I am only guessing at what you want it to look like. I think what your asking for might be 3 roofs. ?? Like this? The one at the top is flat. ?

http://www.youtube.com/watch?v=6Lr6buAy6_g

Re: Roof with varying slope

arg617 — Tue, 28 Feb 2017 15:41:12 GMT

ejrolon: The shell worked for getting the shape right, but it doesn't seem like it can be edited as a roof (although this may just be me not really knowing how to work with shells, I can't seem to stretch the length once the shape is created). I also lose out on using "trim to roof".

Richard: I want neither the ridge nor the wall to slope. I just want the rafters to change their slope to account for the varying length they need to be in order to take on the shape of the plan. Using the shell command I can now see that the slope of the rafters at the wider end is 31.75 and the slope at the narrower end is 28.24.

Steve: The flat roof portion is what I need to avoid.

Thanks for your input everyone!

Re: Roof with varying slope

Eduardo Rolon — Tue, 28 Feb 2017 16:13:11 GMT

For the Shell you will not use "Trim to Roof" you will use "Solid Element Operations" where the Shell is the Operator and the Walls are the Targets with the "Subtract Upwards" Option.
---
If I understood correctly…
The Shell will not work in the same way as a Roof, that is why it is a different tool. So you will need to keep playing with it.

Re: Roof with varying slope

Steve Jepson — Tue, 28 Feb 2017 19:52:46 GMT

arg617 wrote:
...

Steve: The flat roof portion is what I need to avoid.

Just give it a different pitch/slope. If the surface is flat, no matter what the angel, the roof tool is the best thing to model it with because of the Ctrl-Click feature. I use roofs for all kinds of things even if slope is 0.

Soffit, ceilings, vaulted ceilings, concrete flat work, floors, roof rake edge/drip edge, continuous ridge vent, stair rail cap...I wish all of the modeling tools had that sort of Ctrl-Click feature.

http://www.youtube.com/watch?v=ZLwi4_Q29og

You could use a slanted wall if you don't want to use 3 roofs. ?

Tip about posting image that is too big: I make this mistake too often.
If the image size is larger than the screen of the viewer they will have to pan with the bottom/side scroll bars to see the entire image you have posted. This can mean that you made it impossible to see the whole thing at once.

Also, on the Forum every post made before or after your too wide picture will be that same width that was necessary to view the too wide post; so we have to pan using the bottom/side scroll bars to view every post, even if it does not have a too wide image in it. For this reason, it is best to keep your images to a smaller initial viewing size. If they want to see it bigger they can click on it, download it, what ever.

The resolution of my laptop screen is 1920x1080, however, people do complain sometimes that the image is too large for efficient viewing on this Forum.

Re: Roof with varying slope

arg617 — Tue, 28 Feb 2017 22:26:43 GMT

Thanks for the tip Steve. The slanted wall might come in handy.

Regarding not wanting the flat portion - it's not about not wanting to use three roofs. It's that I just want a gable (for lack of a better word) roof. One side with a consistent roof pitch, the other with a varying pitch to account for the angled wall.

The reason for this is that I'm battling with a tight zoning envelope on this project. While I seem to have figured out how to represent the maximum zoning envelope using the Shell command, I have a what seems to be a steep learning curve in using a Shell to create the various layers of the roof in the exact locations they need to be in.

(I'll be sure to test out the image sizes before posting next time!)

Re: Roof with varying slope

Eduardo Rolon — Tue, 28 Feb 2017 22:48:59 GMT

The Shell can be a Composite, so you only need one and define the composites.

Re: Roof with varying slope

Richard Morrison — Tue, 28 Feb 2017 23:44:13 GMT

The geometry you are requiring does not work with straight rigid members. You are essentially asking for a hyperbolic paraboloid. If you are okay with a tent structure, or other warped plane, fine. Just let us know.

Re: Roof with varying slope

Steve Jepson — Wed, 01 Mar 2017 03:09:52 GMT

arg617 wrote:
... One side with a consistent roof pitch, the other with a varying pitch to account for the angled wall.

Is this not the shape of the roof you are after?

Post a free-hand sketch of what you need. Cell phone picture or something. Any shape roof can be modeled with ArchiCAD.

Re: Roof with varying slope

Barry Kelly — Wed, 01 Mar 2017 03:39:48 GMT

If you want to keep the top of both walls level then at a minimum you will need two sloping roofs.

Barry.

Re: Roof with varying slope

Barry Kelly — Wed, 01 Mar 2017 03:41:35 GMT

Or a twisted shell.

The 2 flat roof is basically just a very simple version of this twisted shell.

Barry.

Re: Roof with varying slope

arg617 — Wed, 01 Mar 2017 19:25:37 GMT

Thanks for all the feedback!

A twisted shell is probably the best way to explain it. I'm thinking that we can use straight rafters (16" o.c.) since we would know the high point, low point, and length that each member would need to be.

From there we should be able to add the roof sheathing with a slight bend to it. It's nothing dramatic, and I don't think it would be more difficult than a curved roof eave or eyebrow roof I seem to see a lot of. The bend we would have is more gentle than that, but it does basically extend through the entire roof.

Here are a couple of quick sketch models:

Re: Roof with varying slope

Steve Jepson — Wed, 01 Mar 2017 20:06:08 GMT

Very good! Yes, the twisted shell roof is perfect for that roof shape.

Tip: use a similar but flat plane roof to automatically generate the rafters with Roof Maker, then delete that roof and adjust the rafters individually to fit the curve of the twisted shell.

I am not sure it is worth using the twisted shell because it may not be detectable from the street anyway. You could let the plate line of the angled wall follow the slope of a regular smooth plage roof. ?