topic Re: Zone Area Reduction for Low Ceilings Not Applying in Modeling

Zone Area Reduction for Low Ceilings Not Applying

Heftor — Wed, 15 Oct 2025 06:48:08 GMT

Hi,

I'm having trouble getting the automatic area reduction for low ceilings to work and would appreciate some guidance.

This is my ceiling:

Here is what I have done:

In Project Preferences > Calculation Units & Rules, I went to the Zone Area Calculation section and defined a Reduction for Low Ceilings (e.g., reduce areas with a height below 2m by 50%).
I then created a zone in a room with a ceiling height lower than my defined limit.

The Problem:
Despite these settings, the "Reduced Area" in the Zone Stamp shows the same value as the "Gross Area." No reduction is being applied.

and there is only the reduction of the walls but nothing else.

Even on the 3D i can see the zones not being right.

Is there a specific way the ceiling height is measured for this rule to work (e.g., from the active story level, from the floor)?

Are there any common pitfalls that would prevent this rule from triggering?

Do I need to use the "Calculate Zones" command for this to update?

Thanks in advance,

Hector

Operating system used: Windows

Re: Zone Area Reduction for Low Ceilings Not Applying

Barry Kelly — Wed, 15 Oct 2025 06:52:21 GMT

I believe you need to trim the zone to the roof (ceiling) for this to be calculated.

Barry.

Re: Zone Area Reduction for Low Ceilings Not Applying

Olivier-IDAO — Wed, 15 Oct 2025 07:49:36 GMT

After you trim the zones, don't forget to update them for re calculation...

Re: Zone Area Reduction for Low Ceilings Not Applying

Heftor — Wed, 15 Oct 2025 16:24:32 GMT

Hi @Barry Kelly and @Olivier-IDAO ,

OK, I have done what you advised:

Trimmed to the roof:

before update:

After update:

but the definitions from the zone doesn´t match:

still there is no reduction in the lower part and the crop is almost 1m more deep that the 2m height

Thanks in advance,

Regards,

Hector

Re: Zone Area Reduction for Low Ceilings Not Applying

Olivier-IDAO — Wed, 15 Oct 2025 13:28:34 GMT

Hi Heftor,

Wouldn't you have drawn lines as Zone Boundaries where the zone stops?

Or an other idea, you have walls in your ceiling defined by default as Zone Boundaries...

Otherwise I don't see what redefined the zone in this way?

Let me know

Olivier

Re: Zone Area Reduction for Low Ceilings Not Applying

runxel — Wed, 15 Oct 2025 16:11:35 GMT

Trimming (or SEO) would not modify the floor plan display of your zone.

What you see is what you maximally get.

Looks like there is something (probably a line with the attribute of zone boundary) in the way, and when you updated the Zone it shrinked to it's current size.

Another reason could be due to Reno: The Zone can only react to what it sees. E.g. if the Zone is set to new, it won't "see" Walls that are set to TBD.

Re: Zone Area Reduction for Low Ceilings Not Applying

Laszlo Nagy — Wed, 15 Oct 2025 16:34:50 GMT

@Heftor,

Can you select this trimmed Zone (R 5.13) in the Floor Plan and display it in the 3D Viewpoint so that we can see exactly how it looks after trimming?

Re: Zone Area Reduction for Low Ceilings Not Applying

Heftor — Tue, 21 Oct 2025 09:45:49 GMT

Hello all,

I have to isolate the room to find that there is an error. Unfortunately, I cannot find which is the "line" that´s messing with the room calculation.

So far, this is what I have done:

Subtract the ceiling from the room:

Recalculate the room:

and it works

on the real model, I have to find why when i do this steps something is wrong and it was wood structure on the floor plan, I have to hide that layer.

because when i recalculated

it goes from this:

to:

Because of the wood structure on the floor plan, was cutting the zone, hiding that layer it working fine:

Thanks again for all the help, we are still fairly new to the archicad workflow 🙏

Regards,

Hector

Re: Zone Area Reduction for Low Ceilings Not Applying

Laszlo Nagy — Tue, 21 Oct 2025 09:49:15 GMT

If you set the "Relation to Zones" setting of any element (e.g., a Wall) to "No Effect on Zones", then it will not influence the Zone's geometry.

Re: Zone Area Reduction for Low Ceilings Not Applying

Heftor — Thu, 23 Oct 2025 15:31:31 GMT

Hi @Laszlo Nagy ,

Thanks for the insight, I will be aware of that next time that i start modelling.

I see that works also for columns, that I used to make the over structure.

Thanks for the support,

Hector