Editing Windows in Autodesk Revit1 Jul, 2010 By: Daniel Stine
Revit Tutorial: Edit the window family to include the appropriate building features, and save a lot of modeling time.
Editor's Note: This is the first in a new series of Revit tutorials by Dan Stine, author of such textbooks as Residential Design Using Revit Architecture 2011.
The window family in Autodesk Revit can be edited to include building features such as trim, sills, and structural lintels. This can save a lot of modeling time, because placing one element instantly models the window and the other building features just mentioned. This tutorial will explain why various elements should sometimes be excluded from the window family, and describe a tricky sill condition.
Excluding elements from the window family. When working on a remodel project where windows are being replaced, utilizing Revit's phasing functionality, it is typically best to avoid placing the trim and sills in the window family. When a window family is set to be demolished, the entire family gets demolished, including the trim and sills. Often, the trim and sills do not get replaced, just the window — especially when the trim is stone. The image below shows the problem of a window being demolished; because the sill is in the window family, it is represented as being demolished.
A tricky windowsill. When a project has an exterior sill recessed into the wall, and the sloped top of the sill does not overlap all of the wall below the window opening, a strange situation occurs in Revit, as shown in the image below.
There are two ways to deal with this problem. First, the sill can be added to the family, if phasing is not an issue (as discussed above). In this case, a solid extrusion would be created for the sill and then a void extrusion set to cut the wall. This creates a problem as a host (wall) in a family (window) cannot have a void and an "opening" element acting upon it — Revit only allows one type or the other. All windows have an opening element by default; it is tied to the width and height parameters and is what cuts the wall. Therefore, the "opening" element would have to be deleted in the window family, and two voids created: one void for the window and another for the sill.
Note that it is possible to control the visibility of the sill using a yes/no parameter. This would allow some windows to have a sill and others not. However, it is not possible to tell a void not to cut something. The trick here would be to parametrically move the void outside of the host rather than turn it off.
Second, the exterior sill is a separate face-based family. This scenario supports phasing and easily allows some windows to not have a sill. It is a little extra work to place a window and then a sill. However, once one sill is placed in an elevation it can be copied around in that elevation (on the same host/plane).
An in-place family could also produce the same results, but is not recommended because each copy creates a new in-place family, making the project file larger — and making editing a nightmare.
The void in the family can be larger than the sill to create mortar joints if needed. The line weight of the sill can be controlled using Object Styles, Visibility/Graphics Overrides (VV), or the Linework tool. Object Styles controls the entire project, VV controls the current view, and the Linework tool controls the lines selected.
Even though the sill is started from a "generic model" family, it can be in the window category (set via the Family Category and Parameters tool in the family editor). A sub-category can be created and various solids, in the window family, can be placed on the sub-category. Then, the line weight of the sill (or trim) can be controlled via Object Styles and visibility per view via VV. This is a good way to turn off sills and/or trim in a plan view. Similar techniques can be used to develop the interior sill.
Finally, when a window is demolished, Revit automatically fills the opening with a new wall. In the image below, notice how the automatic infill wall extends down into the demolished sill when the sill is part of the window family. A project might have this special family (i.e., window with sill) just for situations like this — where the window and sill are being removed and the opening filled in.
This article just skims the surface of this topic and windows in general. Look for future tutorials about windows, covering material returns in plan and the new reporting parameter in Revit 2011.
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