27 Jun

Revit Room Computation Height – What is it good for?

In Revit, computation height is the distance above the room level where room perimeter is measured.

By default, computation height is 0 units above base level of room. To place rooms, they first must be enclosed with room bounding elements.

For example, the drawing below shows a section of 2 rooms which are on different heights. The dashed red line is computation height. Note that in Revit, computation height line shows only when we select a room. It’s shown here for easier preview.

By the default, computation height is 0 units above base level of a room. This option is in most times accepted, unless we have room bounding elements which are above the computation height like on the left room in the drawing above.

To change the computation height, we need to go to any section or elevation, select the base level in properties palette, and change the computation height value.

In the example below, we can see that room with sloped floor is not created since the computation height is too low and room is not enclosed (see drawing below: computation height line can’t reach the right room bounding element / wall).

By rising computation height, we can see that room is now created.

The computation height can be useful in most cases, but sometimes a better solution is required.

In the drawings below, we can see that, if we rise the computation height to reach the right room, the room on the left will be out of reach.

The solution is to assign the rightmost room to another level. The point is to use one level with one computation height, if possible, for all the rooms belonging to that level.


Rooms with sloped boundary objects

There is one more example of using computation height. The drawing below shows a section of a room with sloped walls/roof.

If we rise the computation height to appropriate height, the area and the volume will change the values. This can be useful for showing usable space.

Notes and issues

  • Changing the computation height can affect the performance of Revit (many rooms = many calculations during changes = more time needed to calculate all volumes).
  • Room bottom or – Room Base Offset (Room Property) from the level must be below or equal to the computation height of the level, otherwise you will get the error message “Room’s lower offset is above the Computation Height”.
  • Room top or – Room Upper Limit (Room Property) from the level must be above or equal to the computation height of the level, otherwise you will get the warning message “Room Volume is being calculated above the Upper Limit of this Room. Change the Upper Limit and Offset or change the height of volume calculations.”
  • Sometimes if we have structural slab under the base level and non-structural floor (layers) above, the room will be created in the tight space of 0 height, which can cause issues, so the non-structural floor should have “Room bounding” option turned off.
  • If you are getting rooms like these:

Change Volume Computations setting under „Area and Volume Computations“ (Architecture tab > Room & Area) to “Areas and Volumes”.


02 May

How to create PDF with layers, from Revit

Creating (producing) PDF with layers from Revit, using Print to PDF option is, unfortunately, not possible.

The solution, however, is simple. If you have AutoCAD.

Let’s say you have Revit view or sheet that you want to have in PDF with layers so they can be turned on/off appropriately. The procedure to achieve this is simple:

1. Export your Revit view or sheet to DWG file format (make sure you have appropriate Layer key assigned so Revit categories are put into valid DWG layers).

2. Use AutoCAD to open exported DWG.

3. Choose print option in AutoCAD to print model or layout view (Ctrl+P), select “DWG To PDF.pc3” printer from printer Name dropdown menu.

4. Click on “PDF Options…” button and make sure “Include layer information” checkbox is checked (it should be checked by default).

5. Set other options appropriately (sheet size, scale, plot style etc.)

6. Click “Preview” button and choose print if preview is correct.

That’s it.

12 Nov

Modeling Structure in Revit: 3. Practical guidelines for modeling vertical structural elements

Practical guidelines for modeling structural elements in Revit include:

Guidelines for vertical structural elements:

  1. Modeling structural bearing walls
  2. Modeling structural non-bearing walls
  3. Modeling other (non-structural) walls (in case they are needed for some reason).
  4. Modeling structural columns

guidelines for horizontal structural elements:

  1. Modeling structural floors
  2. Modeling structural framing
  3. Modeling structural foundations

General rule is to model everything the same way as Read More

12 Nov

Modeling Structure in Revit: 2. Set Levels and Grids

“Set levels and grids? Just throw a few of them in the model and let’s do some real modellin’!”

Level as the most important element

Levels are the most important elements of a Revit model. Grids are important, but not so much as levels (you know, if you delete a grid, nothing will get deleted with it like when you delete a level).

Your whole future (re)modeling work  depends on how you plan and set your levels in the beginning. Levels and grids are “the structure” of your Revit model. You don’t need to be a structural engineer to know the importance of a good structure. Here are some important tips about how to properly Read More

02 Oct

Modeling Structure in Revit: 1. Tweaking template for IFC

IFC Revit model building story preview in BIMvision

Let start our structural modeling with some tweaks to the Revit template for successful later IFC export. To align with IFC file organization, in Revit project or template file we need to add additional parameters and enter values to the correct existing ones.

General IFC file organization:

  • Project
    • Site
      • Building
        • Building Storey
        • Building Storey
        • Building Storey

Project Information

To set IFC parameters “Project”, “Site” and “Building”, first we need to set Project Number, Read More

14 Jan

Custom Revision Numbers in Revit

Do you hate when you must use custom revision numbers in your Revit project? How many hacks do you think you need?

For example, you must use combination of letters and sequencing numbers at the same time. There is prefix and suffix options. Both of these features are useless if project rule is to use, for example, the following sequence:

A1, B2, C3, C4, C5, C6 …


P1P2P3P4R1, R2, R3 …

or something like that.

Well, solution for this „problem“ is very simple. Maybe you didn’t notice, but, in Revisions dialog (ribbon tab View > Revisions), on the bottom-right there is an option Read More

10 Nov

Display fire rating symbol with doors in Revit

In your Revit project documentation, sometimes you want to display parameters or values that are not available in Tag’s Label dialog.

Let’s take an example:

Door fire rating is a system parameter that you can use (and tag) with a door family. But, you do not want to display parameter value but rather a symbol representing value (or a range). There is no way that Revit will allow this to happen using regular Tags, that is, Tag familiy cannot “read” a value and then “decide” what graphic symbol to use. You must do this manually by using “correct” tag or tag type.

There is, however, an alternative solution. It is not coolest solution because it is off Revit’s logic (where model elements and annotations are separated) but it works.

What you need to do is: Read More

30 Aug

Cannot select multiple elements in the Plan View

Common “problem” I see my coworkers stumble upon is the problem with selection of multiple elements in the Floor Plan (and other Plan Views in Revit).

What’s the problem: “Look, I have no problem with selection of elements one-by-one, but when I try to select few of them at the same time, nothing happens! What’s going on?”

So, point is you CAN select something. That eliminates element selection controls as potential problem (you know, those little switches in the lower right corner of the Revit).

Solution: Check if elements you are trying to select are not in the Read More