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BIM Modelling Guidelines - ArchiCAD

1. Single IFC file

Please combine all architectural models into a single IFC file; If your model includes MEP/HVAC
details, please save these as additional separate files
2. 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.
3. Storeys
Multi-storey buildings should be separated storey by storey. For example, each storey must
contain a ceiling, floor slabs and everything between them.
4. Continuous structures by storey
Structures like curtain walls usually continue from bottom to top. These continuous structures
need to be cut and placed according to each correct storey.
Correct:

Incorrect:

5. Structure/Object placement
All objects and structures should be placed on the correct story.
Incorrect:

Correct:

6. Wall connections – T-shaped walls
T-connections should be modelled so that the vertical part of the wall ends on the surface of
the horizontal part of the wall. If the vertical part continues through the horizontal and ends on
the same level, it will create flickering surfaces.
Incorrect:

Correct:

7. Wall connections – Corners
Connect 90-degree angled walls using a diagonal connection; this enables the visualisation
of different materials on each wall section. If the walls are not connected diagonally, the wall
material layers will be visible on the end of the wall.
Correct:
Incorrect:

Possible problems:

  • Most wall connections can be fixed by selecting two walls and using Intersect.
  • For ArchiCAD 16 and older versions 45 degree mitered join is preferable.
    Starting from ArchiCAD 17 walls use Priority Based Connections so Walls do not join as a mitered join in corners. Instead the Wall object are connected using a Building Material with the higher Intersection Priority cuts the other Wall.
  • Wall component priority settings can be accessed via Options > Element Attributes > Building Materials
    • Make sure Junction Order is correct, when:
      two Walls meet whose Building Materials have the same priority
      3 or more Walls meet in a junction
      A higher Junction Order number takes priority over the lower.
      When 3 or more Walls meet in a junction, the relative Junction Order of each Wall determines which two Walls are joined first.
  • If perpendicular wall’s cut surface is visible through the intersected wall, check Wall Selection Settings > End Surfaces: Override using Adjoining Walls: Check this box if you want the selected Wall’s end surface to take on the surface of the adjoining Wall.
    Note: Any adjustments to the surface texture alignment will be correctly reflected on both walls.
  • Align Texture to Wall Edges: Check this box to place the texture origin at the bottom corner of the wall. This can be useful, for example, on freestanding walls to avoid a fragmented texture on the edges.

8. Compound ceilings using slab tool

If slabs are used to represent compound ceilings, and you intend to specify different material finishes for ceilings in different spaces. Separate slab objects are required to represent the ceilings of different types. Please set different materials for each ceiling (slab object) as required.
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 IFC property
‘IsExternal’.
10. Wall endings
Visible wall endings of compound walls need to be cleaned up using wall end tool.
Incorrect:
Correct:
11. Materials – walls with two-sided wall materials
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. brick facade; plaster on living room side).
Correct:

Incorrect: wall direction is flipped

12. Materials – interior wall; a single room with multiple wall materials
Wall materials need to be defined separately on every wall that requires specific materials. For example, a single room that has multiple wall materials such as a bathroom, the materials for the wall tile section, the ‘effect’ wall section and the generic plaster section all need to be defined as separate parts in the wall.
For material finishes to be visible, wall finishes should be skins of the composite wall, setup can be accessed via Options > Element Attributes > Composite Structures.
Material finises that are not skins of a composite wall, that are set up via Wall Selection Settings > Surface Override do not contain IFC data and will not be visible after export.

Incorrect: Exposed brick surface finish is achieved via Override Surfaces. Note the layer of plaster visible on wall cut.

Correct: Exposed brick surface finish achieved by using separate composite wall type (Brick Single Plastered) for section of the wall that was intended to be exposed. Note the visible thickness of plaster layer on adjacent walls, and a different composite used for this wall section.

Incorrect: Wall paint color is set up via Override surfaces, but this data will not be preserved after IFC export.

Correct: Green Paint is a skin of a composite wall.

Correct: Wall that was intended to be painted green has appropriate Composite Wall Type. Note the Override Surface is not in use.

13. 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: Wall uses composite type with skin set up to represent white tile, but wall is uncut and same finish can be seen in the next room over.

This can be fixed by using Split tool, separating the wall according to spaces, and assigning different composite to different sections of the wall.

Correct: Only the walls that are intended to have white tile finish, have composite type that contains white tile

14. Materials – floor slabs
For each floor slab part that has a specific material, there needs to be a separate material
specified on that part of the floor i.e. the bathroom floor slab section might be stone and the
living room floor slab section might be wood.
Incorrect: Same composite slab is used for different rooms, where different finishes are intended.

Correct: Separate slab of different composite type is used for different finish.

How to fix:
Slabs can be split into multiple objects using Split tool, similarly as walls in case 14 above. Then different composite should be selected to ensure different finish.
15. Materials – floor slabs; balcony and floor slabs with 360 visibility
A balcony can be seen from every angle via the outside view so you’ll need to set at least two materials for the balcony floor slab. This provides the opportunity to specify the top surface in one material finish and the remaining/bottom of the balcony floor slab in another.
Incorrect: Same slab object continues outside to become balcony slab.

Correct: Separate object of different composite type is assigned for balcony floor.

Note that for balcony slabs you might want to have custom finish of the bottom surface as well, and that would require to a separate skin of composite material.
Example balcony floor slab composite has Green Paint skin, to ensure green paint finish at the bottom surface of balcony slab.
16. Spaces
Use spaces to separate different apartments from each other; apartment numbers can also be attached to these spaces. Tridify specific: If spaces are not used in a story, the story without spaces can automatically be included with the story below.
17. Coordinates, Location (GPS) and True North
GPS location of the building site is used to pinpoint correct sun angles and shadowing. True North and GPS location together will provide the most accurate shading and sunlight simulation effects.

Project Location can be set up via dialog box, that is available:
• from Options > Project Preferences > Project Location
• from the context menu of the Project Name in the Navigator
• from the Sun dialog box

Enter Location Data
Enter the Latitude and Longitude of the Project Location.
For maximum accuracy (e.g. for Energy Evaluation purposes), you should identify and fill in precise latitude/longitude data for the location of your project.
Click the pop-ups to switch between Latitude North and South, and Longitude East and West.
Choose your preferred unit of measure from the fly-out menu.

Project North
Enter an Azimuth (compass) angle value here to orient the Project North direction in the Floor Plan window, or drag the compass pointer to orient the Project North Azimuth graphically.
From the pop-up, choose the display unit for Project North.
Note that the accuracy of these units depends on the accuracy set for Angle Unit in Options > Working Units.

Another way to set Project North is graphically, right in the project:
• Click Options > Project Preferences > Set Project North, or
• Use the same command from the context menu of the Project Name in the Navigator (provided that the Floor Plan or 3D Window is open).

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