material take off from curtain panels that use multiple materials

[brwhi]

Hi,

We are modelling curtain panels that will eventually be built as prefabricated units (2600 x 2600). Due to the large scale of the project we need to be able to swap in and out these panels easily and compare quantities (predominantly glass vs solid). This method of modelling is causing us to get incorrect material area takeoffs (each panel has layers of glass and solid elements but when scheduled each material takes on the area of the total panel size).

We have overcome this issue with use of Material : Volume and with use of a calculated value dividing this amount by a shared parameter 'glass thickness' to get the correct material areas, but it seems strange that Revit is calculating the volume correctly and not the area, its obviously collecting the data from somewhere in order to produce the volume?

We could also use parameters within each family to calculate the glass area but we have alot of different families in the conceptual phase and I was hoping to control it at a project level rather than family..

We are also using system panels so the scheduling becomes quite customized and the quality control process slow..

We have also tried to manipulate it in dynamo but come out with the same figures. Any ideas or help much appreciated!

See the attachment for some screen shots

thanks!

Bridget 

[ToanDN]

Can you copy paste a curtain wall and the schedules to a new file and share?

[barthbradley]

Hi Bridget: If I understand the issue correctly, the Material:Area calculation in incorrect, but the Material: Volume is correct. Have you considered that the Area Revit is reporting is combined total of ALL of the surfaces of the geometry - front, back, and sides? Or have I misunderstood your issue?  

I'd wouldn't mind having a look at an rvt exhibit either. I'm kind of curious here. 

[brwhi]

Thanks for your replys! ive attached a file with the family and the schedules for you to see, thats correct what you have written - volume shows correctly but material area not. I have made some tests to check the amounts coming from dividing the volume by a thickness parameter and it works, but this work flow seems strange seeing as Revit is capable of calculating the correct volume and we can only use one value for thickness per panel.. The material area is definately not a result of revit combining sides as the areas are coming out exactly alike and equal to the total width x height of the panel.

Thanks again for all help!!!!! 

Bridget 

[ToanDN]

You are right.  The curtain panel material take-off schedule reports the curtain panel area instead of the actual material areas for sub-elements.

I can understand the reason is that Revit cannot determine which areas of the geometry to calculate from: area on one side (the same as your calculated Area based on Volume/Thickness), or area on both sides, or on all exposed surfaces, or on all surfaces).  It does not have the same problem with Volume because there is only one Volume.

I think if you want to calculate the elevation area of the material, you can safely forfeit the Material: Area for the Curtain Panel Material Take-off schedules and use the Calculated Value as you already demonstrated.

If you want to calculate the total exposed (or not) surface of the materials, you need more a more complex formula, for example:  2*(Width+Thickness) * Height (Width, Thickness, Height are dimensions of the sub-element, not the curtain panel).  Another possibility (I have not tested it myself), is nesting shared families as components in your curtain panel family.  Then create material take-off schedules for those.

[ToanDN]

I have made a test for a curtain panel with nested and shared components.  The material take-off schedule (of the component category, not the curtain panel category) report the correct total surface area of each piece.  It probably does not apply to your case because you only need the one-sided elevation area for component, though.

[Anonymous]

So that's the secret to calculating each curtain wall panel components' area - they all have to be nested components/families!

[ddei]

Revit struggles a lot with material takeoffs apart from convectional elements.

I am facing the same problem. Can get Revit calculate area in red mark up. Even when I use the paint tool it combines all of the faces and gives me a total area. I just need left and right side of the fin (A & B).

I should have to use complicated formulas to get here.