Forums >> General Discussion >> Revit Project Management >> REVIT 2015 material takeoff, gross area issue

serialkill

active

Joined: Tue, Mar 16, 2010
8 Posts
No Rating

Dear revit users,

recently I have experimented with revit schedules. After some time I have noticed that material takeoff does not work correctly (maybe I am doing something wrong) so I updated Revit arch 2015 to Service pack 3. Still I can not configure material take off to work correctly, please see the attachment.

The problem is that revit counts everything excluding corners, which is strange thing. I believe, that this is my lack of knowledge. Please advise me how to make it work.

After doing some manual work, that is shown in the pic. everything seems ok. It normal or is it a better way?

Thank you in advance.

Attached Images

This user is offline

serialkill

active

Joined: Tue, Mar 16, 2010
8 Posts
No Rating

Manual correction.

Attached Images

This user is offline

WWHub

site moderator|||

Joined: Tue, May 16, 2006
13079 Posts

Revit works correctly - you need to do some testing to learn how it works.

In the images below, I have two different walls with different brick both are 10' long from the outside corner. 

In the first image, I used the standard joint.  Note that the brick area and the exterior wall face area are the same for the individual walls but they are different from each other.  Why?  The thickness of the brick at the corner is subtracted from one wall.

In the second image, I changed the wall joint to a mitered joint.  Now both walls have the sam exterior face and material area.

This is the same for all layers in the wall. 

Attached Images

This user is offline

WWHub

site moderator|||

Joined: Tue, May 16, 2006
13079 Posts

Note - For area plans, you can sketch the areas instead of using the automatic sketch.

This user is offline

serialkill

active

Joined: Tue, Mar 16, 2010
8 Posts
No Rating

WWHub,

thank you for the reply. So to be clear, if I draw a building without correcting wall joined, I get different amount of materials comparing to calculating everything by hand? And if I want a correct answer I have to correct all the joints?

Am I missing something? or all the users do that? Is there a better way how to get the correct amount of materials?

This user is offline

WWHub

site moderator|||

Joined: Tue, May 16, 2006
13079 Posts

I don't understand your question.  As I showed you, Revit takes off the material correctly.  I sounds like your hand process is the one that is incorrect or do you actually specify for all materials to be mitered at their corners?

This user is offline

serialkill

active

Joined: Tue, Mar 16, 2010
8 Posts
No Rating

Probably I did not explain myself correctly. Could you please explain why it happens so (what is the logic) "In the first image, I used the standard joint.  Note that the brick area and the exterior wall face area are the same for the individual walls but they are different from each other.  Why?  The thickness of the brick at the corner is subtracted from one wall.." and how to avoid it? How to avoid substraction without correcting all joints?

The reason I am asking you is this. At the beginning I thought that if I draw a cube from walls that is 10units*10units*10units and from the 4 sides would add 0.2 units material thickness, I should get 81.6 units3 (8.16 units2 * 10 units). I made area calculations in autocad. However, by default, without changing wall connection type, in material schedule I get only 77.44 units3 of material. So I am missing 4,16 units of materials.

I have found sadly ended discusion about this topic http://forums.autodesk.com/t5/Revit-Architecture/Wall-Material-Takeoff-problem/td-p/5010618 . They ended figuring out that revit calculated material takeoff only by core center line. That is in many cases misleading. It this true?

Do you understand my concern?

This user is offline

serialkill

active

Joined: Tue, Mar 16, 2010
8 Posts
No Rating

Anybody?

How do you calculate materials correctly (in materials takeoff) without manually changing wall corners (intersections) from butt wall joins(that is default) to miter wall joins? 

Super thanks in advance.

This user is offline

WWHub

site moderator|||

Joined: Tue, May 16, 2006
13079 Posts

serialkill,

Because of your post, I tested your question and found there are errors.  I have created a project and questions that I will be submitting to Autodesk.  I'm pretty sure that this used to work correctly in versions earlier than 2012 but I don't have those installed anymore.  I tested on 2012 and 2015 and found the same errors.  Here is what I am writing to Autodesk.

----------------------------------

We have found some real inconsistencies and errors in material takeoffs in Revit.  This problem seems to be the same in 2012 through 2015.  Please explain.

Why are material areas incorrect?

Please look at the following plan and material schedule: <Image 1>

• View 1 has two walls with different materials in each wall using a butt joint
•  View 2 has same two walls but a mitered joint

Look at the following material schedule <image 2>

• ·         View 1 – The material areas for the exterior brick is correct for the two walls.  (Note material name for vertical walls are (2))  The takeoff accounts for the material thickness.

• ·         View 1 – The material areas for the sub layer is incorrect and the same as the outside material – not the interior material asked for.

• o   Plywood, Sheathing should be 100 SF

• o   Plywood, Sheathing(2) should be 95 SF

• o   Metal Stud layers should both be less than sheathing layers

• ·         View 2 – The material areas for all materials are based on the mitered joint face of each layer

• ·         View 2 – Unlike the butt joint, the thickness of the outer material is subtracted and the mitered joint face is used.

Attached Images

This user is offline

serialkill

active

Joined: Tue, Mar 16, 2010
8 Posts
No Rating

Dear WWHub,

thank you for the effort. However in one forum I have found that some people already asked autodesk about this problem. Autodesk knows about this issue. This is called known problem. And as I understood, this is made so Revit would have a better performance - it counts everything from the central line. However, nobody knows if this issue will be fixed or not. Moreover, some people already asked if they could get a possibility to chose a default wall joins. And once again - nobody knows if they even consider to make it.

The most disappointing thing is that my gf is working with archicad. And it does what it should do. Sometimes I am thinking about joining the other side. Probably it will be the resistance, the bright side, since long time ago every year revit get a bit darker interface - so it should be the dark side.

Thank you once again.

This user is offline

WWHub

site moderator|||

Joined: Tue, May 16, 2006
13079 Posts

The "counting from the centerline" comment just doesn't make sense.  If you look at what I posted, the material areas for all layers are correct corner to corner for the mitered joint.  So the only additional area is the overlap at the corner.  However, the but joint only measures the exterior area correctly but then it uses this area for all other layers.  This has nothing to do with the centerline. 

If the mitered area is close then why doesn't Revit at least use this area for all calculations and just tell us that?  That would be a closer approximation.

This user is offline

JWalinck

active

Joined: Mon, Apr 15, 2013
1 Posts
No Rating

Hi, just wanted to pitch in to say I've been having the same issue and have run tests that verify that the centre line is used for calculating the area of every layer in a given wall. In my case a ran tests on a 4m x 4m box with a 400mm thick wall - the schedule returns results based on a length of 4400mm - the wall length plus 200mm to the centre on either corner. This means that when you miter the joins, the schedule ADDS material to the external layers and SUBTRACTS it from the internal ones ie. if you don't go through the miter process, you'll have estimated too much plasterboard and not enough bricks! You can see in the attached image that the insulation value is almost the same, as it is closest to the centre of the wall. The left box (blocks) is mitered, the right box (brick) is butt joints. Have attached a diagram for clarity.

Attached Images

This user is offline

Revit 2013 Material Takeoff area calculation

2

Material Takeoff

5

Material takeoff , Cost using both area and volume

1

Material Takeoff issue

4

IFC export: Gross Area

2