https://community.graphisoft.com/t5/Collaboration-with-other/Create-an-expression-using-a-value-defined-in-the-materials/m-p/279709#M36686 You are right, no Density of Building Material is available.<BR /> There is only Building Material name you can use defining property expression.<BR /> <BR /> You probably wanted to get weight of element?<BR /> <BR /> Maybe you need to solve it this way: to write very long expression, that will check Building Materials names and match with density, that you need to write manually in this expression code.<BR /> <BR /> Something like (IF Building Material = "name" THEN Density = "...") OR (IF Building Material = "name" THEN Density = "...") - I'm not following exact punctuation of expression, just as an example.<BR /> <BR /> Long expressions are working too. I once wrote this (it detects building material and calculates bricks or blocks quantity): Mon, 24 May 2021 21:42:12 GMT Podolsky 2021-05-24T21:42:12Z https://community.graphisoft.com/t5/Collaboration-with-other/Create-an-expression-using-a-value-defined-in-the-materials/m-p/279708#M36685 <DIV class="actalk-migrated-content"><T>Hi.<BR /> <BR /> I'm trying to create a property defined as an expression, using the value of density stored in a material described in building materials dialog box. But I can't find any property of a material in the list of parameters and properties.<BR /> <BR /> ¿any solution?</T></DIV> Mon, 28 Jan 2019 11:11:21 GMT https://community.graphisoft.com/t5/Collaboration-with-other/Create-an-expression-using-a-value-defined-in-the-materials/m-p/279708#M36685 Roger C 2019-01-28T11:11:21Z https://community.graphisoft.com/t5/Collaboration-with-other/Create-an-expression-using-a-value-defined-in-the-materials/m-p/279709#M36686 You are right, no Density of Building Material is available.<BR /> There is only Building Material name you can use defining property expression.<BR /> <BR /> You probably wanted to get weight of element?<BR /> <BR /> Maybe you need to solve it this way: to write very long expression, that will check Building Materials names and match with density, that you need to write manually in this expression code.<BR /> <BR /> Something like (IF Building Material = "name" THEN Density = "...") OR (IF Building Material = "name" THEN Density = "...") - I'm not following exact punctuation of expression, just as an example.<BR /> <BR /> Long expressions are working too. I once wrote this (it detects building material and calculates bricks or blocks quantity): Mon, 24 May 2021 21:42:12 GMT https://community.graphisoft.com/t5/Collaboration-with-other/Create-an-expression-using-a-value-defined-in-the-materials/m-p/279709#M36686 Podolsky 2021-05-24T21:42:12Z