Modeling Building Elements

BIM for Architecture, Engineering, and Construction Curriculum


Modeling Walls and Columns

If a wall is connected to other walls, how will moving one affect the others?

Moving a wall will typically affect other walls to which it is joined. The other walls will stretch or shrink to try to maintain the connection.

If two walls have been constrained using a locked dimension, then movements to one wall will be mirrored in the second wall to maintain the distance specified in the constraint.

What methods can you use to resize a wall?

You can select a wall and then drag on the blue dots that appear at its ends to stretch or reduce the length a wall. You can also enter a new value into the temporary dimension that appears when a wall is selected.

If you want to extend a wall to meet another wall, the trim tool offers an easy way to quickly and precisely join two walls.

Adding Doors and Windows

What do the temporary dimensions for a door or window element typically show?

By default, the temporary dimensions show the distance between the center of the door or window to the nearest adjacent wall or the nearest door or window. You can change the temporary dimension preferences for a project to show the distance to the edges of the door or window (rather than the center).

How can you indicate the hinge side and the flip of a door as you are placing it? After it has been placed?

As you place new doors, you can indicate the direction that the door will swing into by hovering the cursor near the face of the wall on the interior side of the door. The hinge side of a door can be changed by pressing the space bar.

After a door is placed, you can select a door and small blue arrows appear that enable you to quickly change the flip orientation and hinge side.

When you place doors or windows in 3D views, how is the level associated with them determined?

When you place doors or windows in 3D views, Revit tries to determine the appropriate level based on the closest level below the sill of the door or window. Often, this is a good assumption, but sometimes, it yields unexpected results.

For this reason, it is typically better to place doors and windows precisely in plan views (which implicitly specifies the associated level), and then adjust their height settings in the properties palette.

Creating Floors and Roofs

When you create a roof by footprint, how is the shape of each of the roof surfaces determined?

The shape of footprint roofs is determined by the intersection of the sloping planes that are created for each of the slope-defining edges specified.

The location and angle of the hip or valley intersections between the planes is determined by the relative angles of each plane. When two planes of equal slope intersect, the boundary between the planes typically creates a 45-degree angle with the roof edge. When planes of unequal slope intersect, the angle varies to resolve the difference.

The location of the roof ridge lines are determined by the distance from the roof edges and the slope of each surface.

What determines the roof slope?

The primary considerations for roof slopes are functional, such as drainage or snow removal. Once those requirements are met, adding slope is purely a matter of architectural style.

Flat roofs are rarely completely flat, so will typically have a slope of 1"/12" to provide needed drainage. For example, ranch houses and prairie school houses typically feature very low slopes: 3" or 4" in 12". For taller roof styles, such as Tudor houses, roofs can be 6"–9" in 12". Finally, A-frames are even greater than 12" in 12".