Provision For Void

News in latest release

- Current Project is no longer limited to being the MEP Model.
This allows all disciplines to work with voids or provisions as such.

- Now creates the actual voids if "Building Model" is the current project.
If "Building Model" is not the current project then ProvisionsForVoid are created.

- Use Scopeboxes to limit selection
- Use SectionBox to limit selection if current view has one enabled.
- Non-Intersecting CableTrays
Generate voids/provisions even if CableTrays do not intersect building elements.

- Fixed an issue where Roofs did not generate void/provision.


Description of functionality

This function can be used by all disciplines to create provisions for voids, or actual voids.

A "provision for void" is typically made by Electrical or HVAC engineers.
It is a solid object representing a void in a building element.
This provision is created as a family which can be communicated back to the structural engineer through an IFC file or Revit model.
When exported to IFC these familys become IfcProvisionForVoids.
They can be imported into software such as Tekla Hole Reservation Manager.

A void is the actual opening typically made by the structural engineer.

More about workflows here:





User Interface



- Select a Revit or IFC link containing building element categories for which you need to check for void requirements.
- Select a Revit or IFC link containing service element categories for which you need to create voids or provisions for void.
- Select the service and building element categories for which to make provisions for void.
(Fittings are currently not supported.)


If you have scopeboxes in your project select those in "Volume of interest".
However if you have a sectionbox active this will get first priority.

You can also preselect elements before you run the function.

- For rectangular profiles you will get a rectangular provision.

- For circular profiles you will get a circular provision.
However there are some considerations regarding this.

When a circular profile hits a face at an angle the resulting crossection will be elliptical.
Where the largest elliptical diameter increases the more slope you have.
To avoid a very large circular provision we have set a 1:10 ratio limit.
Lets say you have a Pipe going through a wall and the slope of the pipe is more than 1:10.
Or if a vertical pipe hits a floor where the floor is sloped more than 1:10.
This will generate a rectangular boundingbox family.

So more than 1:10 and you will get a rectangular provision even though the profile of the serviceelement is circular.
Sometimes that is what you want and sometimes not.
If not you will have to place that void provision manually or use shapemode  "Direct Shape".

Note that you at any time can override a circular profile to generate a rectangular provision.
This is done with the parameter "PFV Rectangular Override" found on Pipes, Ducts and Conduits.


- Shape Modes

Will attempt to place a facebased family where needed.
If your service element pass through a sloped element/surface it needs to be placed by face to align itself to the slope.
If for some reason we are unable to get the face for which to place the family a rectangular unhosted boundingbox family will be placed.
When the family is placed it has parameters for oversize both on Type and Instance Properties.

When the building element project is the current file this mode will create actual voids.
If not then provisions are created.

This mode requires a usable 3D view in the selected document where the selected categories as visible.
If we cant find a suitable 3D view you will need to create one.
- If you have a linked RVT-file (either from Open RVT og Open IFC) just open the file a create a 3D view.
- If you have a linked IFC file (Link IFC) use an IFC import template that contains a 3D view.
The IFC import/link template is set in Open->IFC Options -> "Default Template for IFC Import".

"Direct Shape"
This creates a exact shape for the intersecting volume between the service run and building element.
No oversize option is available here so its up to you and the structural engineer to work out rules for oversize.
We do expect (though have not seen) in some rare cases an exact shape is not possible to create due to extreme or unusual geometry.
If that happens this shapemode will fall back to shapemode "Normal".
(Which in turn has a fallback to shapemode "BoundingBox" as described above.)

This mode will always create provisions not the actual voids.

This will create a rectangular unhosted boundingbox family for the intersecting volume.
For most buildings with no sloped walls, ceilings or floors this will be sufficient.

When the building element project is the current file this mode will create actual voids.
If not then provisions are created.


"Non-Intersecting CableTrays"

You can create Void Provisions for CableTrays even if they don physically intersect the building elements.
If the distance from the CableTray endpoint to the wall is inside the specified range you will get a void provision.






Properties of provisions

(Except shapemode "DirectShape")

You can set the provision oversize in the properties of the family.
In Type Properties you will find a "pfv_Oversize" parameter.
This will set oversize for all instances of that type.

You can further override this per instance.
In Instance Properties theres "pfv_Override Oversize".

Theres also a "pfv_Actual Oversize" parameter.
"pfv_Actual Oversize" will display the actual overrsize in current use, type or instance.
If overridden pr instance it will display the override value.
Giving you an clear schedulable oversize from one single parameter overridden or not.

Service Run Properties

Cable Trays, Conduits, Ducts and Pipes has these parameters to allow you more control.

"PFV Group ID"
If you have a number of smaller runs close you migth want to create just one void covering them all.
To do this just assign them to the same PFV Group.

In the example below we have assigned 6 pipes to PFV GROUP "CN01".
Doing so will create one Void (or provision for such)  covering all 6 pipes.





"PFV Exclude"
Use this to exclude the service or building element from provisional void calculation.


"PFV Rectangular Override"
 Use this to force a rectangular shaped void provision for circular service runs.

If you want to examine in detail what the function does theres a logfile created in %TEMP%.
The log file is named "ProvisionForVoid_FileName.log".


Known issues:
PFV Group ID
If a collection of serviceruns are in the same "PFV Group" and pass through more than one wall,
the resulting void provision will extend to cover all walls.
If this becomes an issue split the service runs between the walls.

Linked IFC files
In a wall consisting of multiple layers only one of the layers might be detectable.
The issue affects both Revit's builtin "Interference Check" and API methods.
So if your service element doesnt pass though the entire wall thickness, this clash migth not be detected.
(For example if a a cable tray runs paralell to a wall with is stringer inside just some of the wall layers.)
This has been reported to Autodesk.

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