https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259346#M33959 For your shown example you could have the zone boundary just be a polyline and you can automatically update the zone.<BR /> <BR /> It should work exactly the same for volume as area in terms of reducing the zone by column. Mon, 30 Sep 2019 12:59:20 GMT Erwin Edel 2019-09-30T12:59:20Z https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259343#M33956 <DIV class="actalk-migrated-content"><T>Hi,<BR /> <BR /> Is there a way to have a Zone and in an expression, create a calculation that deducts every Column from the Zone that is inside/partly inside of that zone ?<BR /> I have tried to achieve that but not succeeded<BR /> <BR /> Any one out there good on calculations?<BR /> <BR /> Thanks,<BR /> <BR /> Dominicus</T></DIV> Mon, 30 Sep 2019 11:24:31 GMT https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259343#M33956 dominicus 2019-09-30T11:24:31Z https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259344#M33957 If you set a column as a zone boundary or substract from zones (based on project preferences) and have the zone set as automatic updated, the area of the columns should be deducted automatically.<BR /> <BR /> If you select Reduce Zone Area only, you can schedule Column Substraction and the shown area in plan will not be affected. Mon, 30 Sep 2019 11:55:44 GMT https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259344#M33957 Erwin Edel 2019-09-30T11:55:44Z https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259345#M33958 Thanks for the fast reply<BR /> BUT<BR /> I also need the subtracted area of that zone<BR /> AND<BR /> The zones I use for this purpose are drawn by hand (not automatically updated)<BR /> <BR /> So the suggested does not work in my case - I think?<BR /> <BR /> In the attached pics I will try to outline the way I want it to work.<BR /> <BR /> <BR /> Dominicus Mon, 30 Sep 2019 12:32:05 GMT https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259345#M33958 dominicus 2019-09-30T12:32:05Z https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259346#M33959 For your shown example you could have the zone boundary just be a polyline and you can automatically update the zone.<BR /> <BR /> It should work exactly the same for volume as area in terms of reducing the zone by column. Mon, 30 Sep 2019 12:59:20 GMT https://community.graphisoft.com/t5/Collaboration-with-other/ArchiCAD-and-calculations/m-p/259346#M33959 Erwin Edel 2019-09-30T12:59:20Z