BIM Modelling Guidelines - Revit

In this tutorial we will take you through the BIM modelling guidelines for Revit. You can then begin exploring the benefits of our BIM Publishing Service.

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1. Type – IFC types

Every object should be marked as an appropriate IFC element type i.e. the doors should be marked as IFC Door element, floors should be marked as IFC Floor element etc.

2. Levels

Multi-level buildings should be separated level by level; each level must contain a ceiling, floor and everything between them. Objects should be assigned to correct levels.

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3. Continuous structures by level

Structures like curtain walls usually continue from bottom to top. These continuous structures need to be cut and placed according to each correct level.

 

Incorrect: curtain wall is continuous throughout two levels, while it belongs to level 1.

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Correct: Sections of curtain wall are on corresponding levels.

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How to fix continuous curtain wall: Split element by level using split element tool, accessible through S+L hotkey. Then correct base offsets (e.g. second floor section should have base offset 0.0 use base constraint of level 2)

4. Structure or object placement

All objects and structures should be placed on the correct level. Items should be in the level they belong.

 

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5. Wall connections – corners

Walls should be joined in the corners, clean joins are to ensure consistent wrapping of wall finishes.

 

Incorrect:

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Correct:

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To join walls you must intersect them, and use Geometry > Join. When walls intersect, Revit creates a butt join by default and cleans up the display in plan view, removing visible edges between the joined walls and their corresponding component layers.

To allow the walls to join in the current configuration, on the Options Bar, select Allow Join, and for Display, select one of the following options: Clean Join. Displays a smooth join. While the join is selected for editing, temporary solid lines indicate where the wall layers actually end; these lines disappear when you exit the Wall Joins tool and do not print.

Make sure layers of compound walls are aligned as intended by using Wall Join tool.

6. Wall connections – T-shaped walls

Perpendicular separator walls should not cut perimeter (e.g. exterior) walls. T-connections should be modelled so that the perpendicular wall ends on the surface of the base wall. If perpendicular wall cuts base wall (or external wall) through, and ends are visible on the other side of base wall (or external wall), it will create flickering surfaces and might expose the raw cut of the wall, or break wrapping.

 

Incorrect:

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Correct:

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How to fix wall connections:

  • Click Modify tab – Geometry panel (Wall Joins).
  • Move the cursor over the wall join, and click within the square that displays.
    To select multiple intersected wall joins for clean up, draw a selection box around the joins, or while pressing Ctrl, select each of the joins.
    Note: If you are not a student or an AUTODESK Maintenance and Desktop Subscription customer, you cannot select multiple joins and then specify the Display option. Use this procedure to select each join individually and specify the Display option, as required.
  • You can select to allow or disallow joins:
    • To allow the walls to join in the current configuration, on the Options Bar, select Allow Join, and for Display, select Clean Join. Displays a smooth join. While the join is selected for editing, temporary solid lines indicate where the wall layers actually end, as shown above; these lines disappear when you exit the Wall Joins tool and do not print.
    • To restore the join at this intersection, draw a selection box around the join location to select all of the wall ends (single-clicking the location only selects one wall end), then select Allow Join. The wall ends will clean up and join properly.
  • Click Modify to exit the tool.

7. Wall endings

It is important, to cover visible wall endings by using compound wall types with wrapping ‘membrane’ layer (e.g. plaster). Wall type needs to have appropriate wrapping.

 

Compound wall with no end-cap wrapping:
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Exterior wrapping at a wall’s end caps:
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Interior wrapping at the end caps:
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How to fix bare endings of the compound walls:

  • Select the Wraps checkbox in the Edit Assembly dialog to specify the layer of the compound wall to wrap at the ends of the wall, or when an insert (e.g., a door or window) is placed in the wall.
  • The Wrapping at Ends and Wrapping at Inserts parameters must be specified in the type properties of the wall for individual layers to wrap.
    Note: Wrapping is not enabled for roof and floor compound elements.
  • Wrapping at Ends
    End conditions of walls can be set to Interior or Exterior to control which side of the wall the materials will wrap to. If you do not want the layers of the wall to wrap, set end conditions to None.


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8. Compound ceilings

Compound ceilings provide the opportunity to define materials for ceilings and ceiling partitions. Please set different materials for the different parts of each ceiling as required. If different ceiling finishes are intended in different rooms, they should be separate (but joined) ceilings with different ceiling type. Same rules apply as in 12. Materials – interior walls that are continuous.

9. Materials – exterior walls

Exterior walls need to have at least two material layers and the material layers need to have thickness.
This provides the opportunity to specify walls (exterior and interior layers) in different materials (i.e. brick on the outside, plaster on the interior). Exterior walls must have wall type with function: Exterior.

 

Correct:

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10. Materials – interior walls with two-sided wall materials

Interior walls with two separate materials on different sides of the wall, need to have at least two material layers. This provides the opportunity to specify different materials on each side of the wall (i.e. ceramic tiles for the toilet side; plaster on living room side).

 

Correct: Interior side of the wall has 'interior' finish, outer side of the wall has ‘exterior’ finish.

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11. Materials – a single room with multiple wall finishes

If you intend multiple wall finishes in one room or space (e.g.the bathroom wall might have tile finish, and the living room wall finish might be plaster), each wall segment with different finish must have an appropriate wall type.
Wall finish is specified via Edit Type > Edit Assembly dialogue on that wall segment.

12. Materials – interior walls that are continuous

Interior walls that go through several rooms, and where each room needs to be finished in a different material, please provide separate material layers for each room’s wall elements i.e. a wall that continues from the toilet to the living room might require a ceramic tile for the toilet wall and plaster for the living room wall.

 

Incorrect: continuous wall will have uniform finish for both rooms.

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Correct: sections of the wall have materials corresponding to the walls.

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How to fix:
Splitting the wall, assigning different wall types allows distinct wall finishes in adjacent rooms. (e.g. tile in one, and plaster in the other)

13. Materials – floors and floor finishes

If you intend multiple floor finishes (e.g.the bathroom floor might have tile finish, and the living room floor finish might be wood), each floor object with different finish must have an appropriate floor type. Floor finish is specified via Edit Type > Edit Assembly dialogue on that floor object. It means you if you intend different finishes in every room of your project, there will be a separate floor object for each. One floor object per level will only allow one material finish per level.

 

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If you intend to have different floor finishes in every room/space and want them to be represented correctly in 3D and on section – use multiple floor objects of different type.

 

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14. Materials – balcony floors and floors with 360 visibility

A balcony can be seen from every angle via the outside view so you’ll need to set at least two finishes for the balcony floor. Dedicated floor object and floor type for balcony slab provides the opportunity to specify finishes of top, bottom and floor cut surface of the balcony floor slab in another.

 

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15. Areas and Rooms

Use Areas to separate different apartments from each other; apartment numbers can also be attached to Areas.
Tridify specific: If Areas or Rooms are not used in a level (e.g. basement level), the level without Areas or Rooms can automatically be included with the level above that has Areas or Rooms. If top level has no Areas or Rooms (e.g. roof level) it will be included in the level below that has Areas or Rooms.

16. Coordinates, Location (GPS), True North

GPS location of the building site is used to pinpoint correct sun angles and shadowing. Precise True North and GPS location together will provide the most accurate shading and sunlight simulation effects.

To rotate Project North:
Open a plan view, and, in the Properties palette, confirm that the Orientation property is defined as Project North.
When you rotate Project North for this view, the change also affects other plan views whose Orientation is set to Project North.
Click Manage tab > Project Location panel > Position drop-down > Rotate Project North.
In the Rotate Project dialog, select the desired option.
Click OK

To set up your Project Location:
Click Manage tab > Project Location panel > Location.
In the Location Weather and Site dialog, click the Location tab.
For Define Location by, select one of the following:
Default City List: Displays a list of major cities from which to select a location. Until you specify a different project location, the location is defined as <Default> and is set to the longitude and latitude of the major city specified for your locale. No Internet connection is required.

Internet Mapping Service: When your computer is connected to the Internet, this option displays an interactive map through the Bing™ mapping service. Until you specify a different project location, the location is defined as <Default> and is set to the longitude and latitude of the major city specified for your locale.

17. IFC export settings

Ensure that project is exported correctly to IFC.

Download free IFC exporter from Autodesk application store for better IFC quality.

IFC Export is available via File > Export > IFC
You can set up following export settings by clicking: Modify setup

  • IFC 2×3 format
  • Coordination View v2.0 export settings
  • If project contains ‘part’ objects, make sure that under tab Advanced – option Export Parts as Building Elements is selected
  • All other settings could be left by default. However, if you would like to export only part of your model:
    1. hide in view elements that you don't want to export
    2. when exporting IFC, select option Export only elements visible in view

18. Faulty smart objects (window families, door families)

There might be a problem with windows getting stuck inside a wall.

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Window created using void extrusion, doesn’t cut wall through.

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This happens when window family is created using void extrusion. Void extrusions, have thickness dimension and sometimes are not thick enough to cut the wall all the way through,if walls are even a millimetre thicker then void extrusion, the window will not be visible on wall surface.

 

Incorrectly created window family using 3D Void Extrusion:

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Correctly created window family using 2D Opening Cut:

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Note that Opening Cut is a 2D geometry, and it cuts through walls of any thickness.