topic Re: How to calculate in a schedule the external wall surface (for painting)? in Project data & BIM

How to calculate in a schedule the external wall surface (for painting)?

LucaLeo — Mon, 29 Sep 2025 10:22:50 GMT

Hi everyone,

I’m new to Archicad and I can’t find a simple and correct way to get, in a wall schedule, the total external wall surface of the building in square meters.

My goal is to create a schedule that tells me how many external surfaces will need to be painted.

I have already tried several schedule fields (such as Wall Surface Area, External Face Surface Area Gross/Net), but the values I get don’t match:

• even in simple models (e.g. a 4×4 m room with a height of 2.70 m) the calculated surfaces don’t correspond to the expected mathematical value;

• in some cases the external surfaces are smaller, because Archicad subtracts the wall thickness at the intersections of corner walls;

Question:

👉 What is the correct method to make Archicad calculate the net external wall surface, with openings subtracted and internal parts excluded, so that the schedule gives me the real value of the surfaces to be painted?

Should I set up Zones, use a particular property, or is there a specific schedule field I am missing?

Sorry if this sounds like a basic question, but since I’m new to Archicad I can’t figure it out and it’s driving me crazy.

For clarity, I’m also attaching a simplified model (not my actual project, which is larger): I’m using it just for testing and to manually check the surface calculations.

Thanks a lot to anyone who can help!

Operating system used: Windows 11

Re: How to calculate in a schedule the external wall surface (for painting)?

alemanda — Sun, 05 Oct 2025 15:27:58 GMT

Hello,

you have to use the surface schedule in order to know the exact area of a surface.

If you try with the element schedule you can get the value "surface area on ouside face" or "inside face" but this value does not take into account penetrations due to PBM and SEOs ...

Here's a sketch. 4 walls; 2m long, 2m high and one opening 1 m x 1 m; wall thickness 20cm. Expected yellow surface 4x4 - 1 + 4x1x0,20 = 15.80

Then you can setup a schedule of surface (not of elements; in archicad there are 3 types of schedules) and you get the correct surface area, filtering by surface name

I sent a private message to you. I'm Italian too. Check your inbox in the forum platform (top-right corner).

Re: How to calculate in a schedule the external wall surface (for painting)?

LucaLeo — Mon, 29 Sep 2025 07:20:04 GMT

I have already tried with an abacus created for surfaces but I get wrong values, for example for a simple room I get different values (including or not the thickness of the wall in the intersection areas) depending on the fields and I don't understand what I have to do to get the right result (I attach an image). I apologize again if my request seems triviale, and thank you

Re: How to calculate in a schedule the external wall surface (for painting)?

mthd — Mon, 29 Sep 2025 07:53:10 GMT

No need to be driven crazy just yet 😆. @JaredBanks who is an Archimaster of residential design shows an accurate method using zones & schedules to extract accurate wall surface quantities.

I like his method very much and it is simple and easy to follow. He tests it, to show us how when a door is removed from the model and you update the schedule the quantity adjusts correctly.

Please see his method on his excellent tutorial video below.

https://www.youtube.com/watch?v=tWyUnDTBtG4

Re: How to calculate in a schedule the external wall surface (for painting)?

LucaLeo — Mon, 29 Sep 2025 08:37:34 GMT

Thank you very much, but in this video I seem to understand that it shows how to calculate and find the surface areas of the walls of the internal rooms, I would need a solution/method to find the area of the external surfaces

Re: How to calculate in a schedule the external wall surface (for painting)?

mthd — Mon, 29 Sep 2025 10:18:31 GMT

Yes he has zones set up for external areas from what I saw on the video. You can private message him to ask for more information on how he extracts that external painting area from the model.

This older post also may help with calculating external wall area ?

https://community.graphisoft.com/t5/Project-data-BIM/Calculation-Surface-Area-of-the-Wall-Outside-Face-Net/td-p/576279

Re: How to calculate in a schedule the external wall surface (for painting)?

JaredBanks — Mon, 29 Sep 2025 15:14:10 GMT

This other video I did should cover exactly what you want: wall surface area.

https://youtu.be/_OcTE242CfU?si=ZHqVmKHQZt7k26KL

In the video I do tests with fills and different scheduled fields to confirm I have the right information.

Re: How to calculate in a schedule the external wall surface (for painting)?

Jihoon — Wed, 01 Oct 2025 00:11:55 GMT

We developed an Archicad add-on for intuitive area takeoffs. Search “AvroForm” on Google for details.

Re: How to calculate in a schedule the external wall surface (for painting)?

mthd — Wed, 01 Oct 2025 02:11:19 GMT

Hi @Jihoon, Do you have a direct link for this add-on ? I have searched it with that spelling and I can’t seem to find it.

Re: How to calculate in a schedule the external wall surface (for painting)?

LucaLeo — Wed, 01 Oct 2025 11:23:51 GMT

Thanks for the reply.
I've already seen this video, but I need to take a closer look. In my case, if I use the same fields and verify their accuracy, even just to test on a simple shape, I get incorrect results for one reason or another (the surface area totals take into account the wall thicknesses on some walls and not others; if the wall is recessed, the entire calculation is calculated, not just the portion remaining outside, etc.). I'll try to take a closer look anyway.

Re: How to calculate in a schedule the external wall surface (for painting)?

mthd — Thu, 02 Oct 2025 01:35:44 GMT

A very basic simple calculation like this shouldn’t be so difficult just to obtain the total external wall area painting surface of a building.

If zones are used to obtain this information why not create an external perimeter zone plane that touches the external face that can extract this information from the model ? Of course you would need it to calculate the external reveals of openings too for painting area.

QTO (Quantity Take Off) is very weak inside Archicad and needs much attention and development for real world applications.

We shouldn’t need endless ad-ons !

Thats why I am happy to send a DWG file right into Chief Architect and rebuild a basic model for QTO. That will also auto build framing for me and create an XL spread sheets, cut lists and schedules. For residential construction and QTO this tool is absolutely awesome.

Re: How to calculate in a schedule the external wall surface (for painting)?

LucaLeo — Tue, 07 Oct 2025 19:38:40 GMT

Thanks, I'll check now,