topic Re: Cut to roof issue in Modeling

Cut to roof issue

Durval — Fri, 13 Mar 2026 00:12:38 GMT

Below we see the plan view and the 3D view of two walls cut by a roof (Modeling > Connect > Trim to Roof/Shell – menu names may be a bit different as I use a localized version). Notice the walls extend beyond the roof projection. I expected the portions of the walls outside the roof projection either to appear uncut (which I believe was the behavior in previous Archicad versions) or to be cut by the sloped plane of the roof, but the portions below that plane would remain visible. However, these segments disappear completely in the 3D view (even though they are still present in the plan view). Why does this happen, and how can it be avoided?

Operating system used: Mac Apple Silicon Sequoia 15.6.1

Re: Cut to roof issue

Lingwisyer — Fri, 13 Mar 2026 01:19:54 GMT

Trim featue has worked like this since I first used it in AC17. I rarely use the option due to this... Use a SEO

Re: Cut to roof issue

Barry Kelly — Fri, 13 Mar 2026 02:16:43 GMT

Same problem with SEO.

The operations don't show in plan so you will still see the wall to their full extent.

Barry.

Re: Cut to roof issue

Lingwisyer — Fri, 13 Mar 2026 04:21:43 GMT

It was more about the portions outside the trim disappearing in 3D.

Re: Cut to roof issue

Barry Kelly — Thu, 19 Mar 2026 21:19:01 GMT

Sorry, I read it as the problem was with the walls showing in that plan view when they are not they in 3D.

If Durval does want them to be there in 3D, then SEO is the way to trim.

Connect > Trim uses the roof trimming body and will either cut away what is inside the body or outside the body, leaving only the other portion.

SEO only cuts away the roof and what is above or below it, leaving anything outside the roof area untouched.

Either way, the floor plan will not show what is happening in 3D.

Barry.

Re: Cut to roof issue

Durval — Thu, 19 Mar 2026 21:17:26 GMT

Actually, what I was looking for was in the right-click menu: "Trim by Single-Plane Roof" (or something similar).

I think that was the only way to trim walls to a roof in the really old versions (I’ve been using Archicad since v4.5 — last century!)

Re: Cut to roof issue

Barry Kelly — Thu, 19 Mar 2026 21:22:39 GMT

Crop to Single-plane Roof is an old command and you will find the association is not live.

If you delete the roof, the walls will remain cropped.

SEO and Connect > Trim are associated, so as you adjust the roof the walls will re-trim automatically.

Barry.

Re: Cut to roof issue

Patrick M — Thu, 19 Mar 2026 21:23:41 GMT

I think you hit the nail on the head with the Crop to Single-plane Roof being a really old method... was the only method when I started as well. Solid element operations are much more reliable, flexible, and easy.
just beware of the pitfalls; they can cause a lot of file performance issues if abused:
https://wwabim.wordpress.com/2016/03/22/solid-element-operator-errors/