Cut Behavior of Low Walls

A long time ago in a galaxy far far away…

Queue the music... 

There is a feature called “low walls” in Revit.  “Low walls” are walls that have a unconnected height of less than 6 feet. 

Low walls are important to know about because they display differently than other walls in a floor plan view.  “Low walls” will display as projected lines even if they are tall enough to be cut by the Cut plane for the view.    

The wall on the left is a “Low wall” with a unconnected height of 5’, the wall on the right has a unconnected height of 6’. 

It seems like “Low Wall” behavior has been around in Revit forever.  The  question is though, what can you do make a low wall show up as a cut wall in a view?

There are two options. 

Option 1:

Change the offsets in the View Range for the View Depth and the Primary Range’s Bottom to negative one foot (-1’-0”).  By moving the Bottom and View Depth down one foot for each foot that the the wall is offset from the 4’ cut plane in the view and adding one foot to start you can get Revit to ignore the “low wall” behavior". 

For example, if you have a wall that it 4’ high and want to show it being cut, change the cut plane to 3’-0” (to make sure you cut the wall) and then set the View Depth and Bottom to –2’-0”.  Basically, make sure that the if you add the cut plane and the bottom offset (with no negative sign) that it equals 5’ (3’ + 2’).

Option 2: 

I think option two is easier and more flexible.  For this option, instead of modifying the view range, you change the wall.  Instead of using the unconnected height option to define the height of the wall, set the wall so that it is constrained to the level above (using Top Constraint) and then set the Top Offset Parameter to a negative value so that the value that displays for Unconnected Height (it will be grayed out, but will update) with the height of the wall.  Making this change will overwrite the “low wall” behavior, but still give you the same height wall. 

I’d be curious to hear about any “Low walls” that you’ve needed to show as a cut wall so please comment away.

Comments

[Daniel Stine]

We run into this on upper floor plans, where some of the walls occur below a sloped roof near the perimeter of the building.

[Harlan Brumm]

Probably you could use the first option and adjust the cut plane and the bottom offset for the primary view range for this one . This should help to get the look you need for those walls. However, you don't need to do this if the walls are attached to the roof. This Low wall behavior does not apply if the walls are attached to something.

[Dennis Nelson]

I personal think that this is a problem that should be corrected. Walls should follow the easy, self explanatory rule, it they are cut by the cut plane then will show as cut. If you want to still have the "low wall" function put it in as a instance property check box.

I assume this also why slabs that fall with in 4'-0" of the cut plane will show no matter what the bottom plane or view depth is set to.

[Ron Palma]

Similar to your option 2, If I know that the wall must be a specific height measured from teh floor, then I set both the Base and Top Constraint to the same level, then for the Base Offset set it to 0", and the Top Offset to the positive height value above the level specified in the Top Constraint.

[Paul Hildebrandt]

I've been using Revit since version 8 and have never noticed this behavior before. Probably because we are usually adjusting the cut plane and view depth settings for other reason.

It's be nice if this behavior was more visible in settings or the help files.