The ability to link one file into another can be helpful in a collaborative environment. Perhaps someone on your team—a person working on details within your office or an external consultant—is working in a CAD environment while you build the project in Revit. Linking lets you have their latest work updated in your Revit model. If you import without linking, you get a static file that will not update if changes are made to the original file. When you link, however, it's possible to always get the latest state of the DWG by updating the link within Revit.

From the Insert tab, choose Manage Links to access the dialog box shown in Figure 21.3. Using this dialog box you can reload, unload, import, or remove a CAD link, or see what is already loaded.

Figure 21.3. The Manage Links dialog box.

Site plans, consultant files, and details or drawings done with CAD technologies on prior projects are all examples of information you may want to link or import into Revit. This isn't limited to 2D data; you can link 3D files as well. The data you import or link into your model can be view specific, meaning that it is imported in one view only—using the Current View Only import option—as opposed to all views. Start by opening the view into which you want to bring data. Go to the Insert tab, and then choose either the Import CAD or the Link CAD button, depending on your workflow. As shown in Table 21.1, you can link/import five types of CAD files in 2D or 3D in Revit.

There are a series of options that you will need to understand and set during the Import/Link function, depending on the result you would like to achieve with the file that will be imported or linked:

Real World Scenario: Tips on Importing CAD Details

It is not possible, or always desirable, to communicate the entire project in 3D. At times your workflow will demand using 2D graphics from a past project, manufacturer's library, or other resource. To optimize the performance of imported CAD files in your model, we strongly recommend that you delete all the superfluous data in the CAD file before importing it into Revit. Here are some general tips to help your workflow:

• If your import contains hatches or annotations that you don't intend to use in Revit, delete them before importing.

• Import only one detail at a time so you can take better advantage of Revit's ability to manage sheet referencing. If you have a series of details organized in a single CAD file that you'd like to import into Revit, isolate each detail, save it as a separate file, and then import.

• Consider annotating in Revit and removing the annotations from CAD. This can help keep consistency in your documents. If you use arrowheads or leaders in your CAD file, they will import into Revit (when exploded) as polylines. Consider drawing the arrows within Revit.

• Make sure you import the CAD details using the proper line weights, colors, and styles. Check your CAD file before importing into Revit to make sure it is consistent with your office's standards.

• Every time you explode a CAD file in Revit, you add objects to the database. An inserted CAD file is one object. An exploded CAD file in Revit consists of many objects—maybe thousands of objects. For best performance, we recommend you explode CAD files as seldom as possible. If you must explode the CAD file, be sure to remove any unwanted or unneeded linework from the file in CAD before inserting it and exploding it in Revit.

• Revit doesn't allow line segments shorter than 1/32″. Take care when exploding CAD details with very small line segments. Revit will remove them upon exploding.

The ability to communicate and share design intent with others is critical to any design and documentation process. With that inevitably comes the need to translate or transfer ideas, drawings, and information from one format to another to create a versatile workflow. Revit recognizes this need to share information and allows you to import and export CAD-based drawings to aid in communication.

If you're working with someone who produces details using only CAD, you can incorporate their work into your Revit model without disrupting the workflow.

It is common to have a library of existing details that can be used for many projects. This example demonstrates the process of getting these details into a Revit project using a DWG file you can download from the book's companion web page (www.sybex.com/go/masteringrevit2010):

In this detail, note that the wall tags are unnecessary. Unfortunately, they were not deleted in the original CAD file (the recommended practice) before we linked the file.

So, you have two options. One is to address the issue in CAD—delete the tags there and relink the file. For this exercise we'll assume that's not feasible. Your second option is to manage the layers of the link within Revit and simply turn off the layer on which the tag has been placed. As mentioned earlier, you can do this using the Visibility/Graphic Overrides dialog box. You can also do it through Revit's graphical interface. Selecting the detail will expose useful tools in the Ribbon, such as the Query tool:

Clicking the Query button allows you to select elements in an imported or linked CAD file and discover what layer they belong to. With Query enabled, you can select any of the lines or hatches of the CAD file. Choose the border of the wall tag. This gives you the dialog box shown here, which tells you the Entity, its Layer, Block Name, and Style:

The Import Instance Query dialog box also allows you to delete the entity (which we do not want to do here) or hide the layer. Choosing Hide in View turns that layer off in this view. It can be turned on again with the Visibility/Graphic Overrides dialog box.

Now the detail is complete, you can drag and drop the drafting view from the Project Browser onto the sheetA350 Details. If you need more details from CAD files for our project, simply create more drafting views.

The finished detail is shown here. The imported detail on the printed sheet should be indistinguishable from the details created in Revit.

A region consists of a boundary—which can be created using any line style—and a fill pattern, which fills the area defined in the boundary. Figure 21.11 shows a region with a tile hatch pattern used to show tile in an interior elevation. In lieu of a complex stacked wall condition for bathroom walls, a region with a 4″-square model pattern is used to represent tile on the restroom wall. While this will not be reflected in any material take-offs, it is a quick way to create interior elevations.

Figure 21.11. Regions used for quick graphic representation of tile wall finish.

Regions can be either transparent or opaque to show or hide what is behind them. Figure 21.12 shows two regions—the left one is opaque and the right one is transparent—and how they interact differently with a model component.

Figure 21.12. Opaque and transparent regions.

Region Type Properties

Region type properties define how a fill appears, including pattern, pattern color, and transparency (Figure 21.13). Notice that the boundary lines of the region are not part of the type properties and are defined independently when the sketch is edited. To change the line thickness of the boundary, select the pattern, click Edit Boundary in the contextual tab, and change the line pattern in the Element Properties dialog box or from the Type Selector.

Figure 21.13. Region type properties.

For each filled region that has a different pattern, transparency, or other variation in appearance, you need to make a new type. Remember that type properties propagate to all instances of the type, so making a change to one type may affect many instances in many different views. If you want to make a filled region that uses a new pattern, be sure to duplicate an existing type before you start changing type parameters.

Regions can use both drafting and model patterns, making them a flexible and handy tool for 2D workflows. As previously noted, drafting patterns are patterns that will maintain their separation distance relative to the printed sheet. Model patterns will maintain their separation distance relative to the model element. To describe this further, let's use two examples. If you were looking to use a cross-hatched pattern of lines, as in the example earlier for 4″ restroom wall tile, you would want to use a model pattern. The pattern would be set to 4″ and it would maintain a 4″ pattern regardless of what scale the drawing was set to. So, the pattern in a 1/8″ scale drawing will appear twice as tight as in a ¼″ scale drawing. In the example of a drafting pattern, you would want to use this in places where graphical consistency is more important than actual dimension. So, when creating a filled region that represents rigid insulation, the pattern might be set to a 1/8″ grid. It will always print as a 1/8″ grid regardless of what scale the view is set to. Just keep in mind that all of these are truly just 2D shapes with no 3D BIM characteristics.

In visual communications between architects and engineers, when one element obscures another, the hidden element is usually graphically represented with dashed lines. Often, just a portion of an element is hidden. In the 2D CAD application, it can take a lot of manual work to make this possible: you will need to explode the block representing the element that has to be half-hidden, and split lines so that one portion remains solid and another converts to dashed.

Revit has a special tool, Show Hidden Lines, for recognizing obscured elements and representing the portion that is hidden with dashed lines while still maintaining the complete object.

When you relocate or delete the obscuring element, the hidden element responds intelligently to those changes. Figure 21.14 shows an I-beam hidden by another beam. Figure 21.15 shows the results after using the Show Hidden Lines tool when the second beam is selected as an obscuring element and the I-beam is selected as an obscured element.

The Show Hidden Lines tool applies to 2D and 3D elements in all possible combinations: detail over detail, detail over model, model over detail, model over model. Right below the Show Hidden Lines tool is the Remove Hidden Lines tool, which resets the graphical display of the elements so they look as they did before you applied the hidden line behavior.

Figure 21.14. An I-beam hidden by another element.

Figure 21.15. The I-beam after using the Show Hidden Lines tool.

For printing purposes, the line weight for the default 2 × 4 detail component is too thick and needs to be adjusted. Because elements are so simple to modify, you will find yourself changing stock components to better meet the needs of your office.

There is one more element to add before we begin drafting lines to finish the detail. There is a ¾″ piece of plywood backing over the entryway in our detail that does not appear in our wall section. You can represent that with a filled region.

To complete the detail, use detail lines on the Annotate tab. These lines are similar in nature to most drafting applications. Choose the Detail Lines tool, select the desired line type from the Type Selector, and start drafting. By using some thin, medium, and hidden lines, you'll be able to quickly complete this detail (Figure 21.33).

Figure 21.33. The finished ceiling detail.

Design is cyclical in nature. Just because you think that in one phase you won't need more than one detail of a condition doesn't mean it will remain like that throughout the rest of the project. We have found it useful to use Copy and Paste and filtered selections together.

The first thing you need to modify for this detail is the floor condition. Since the project is using a structurally insulated panel (SIP) for the skin, we cannot have the floor slab bearing on the insulation inside the panel. In reality, the panel will be clipped and hung from the side of the floor system. You'll need to pull the edge of the floor back to 1 ½″ from the inside face of the wall. You can do this the same way you fixed the ceiling in the detail earlier.

The revised detail should look like Figure 21.36.

Figure 21.36. The modified floor.

Obviously, you can't run gypsum board back behind the slab and we still don't have a clip to hold up our structurally insulated panel (SIP) panel. However, based on all the wall sections and details we have, it doesn't make sense to create this out of detail lines, and there is no default Revit detail component for this condition. Instead, you will make your own detail component to reuse for this condition. Detail components are like any other family in Revit. Once added to the drawing, you can always reedit and update them with new information. In the next exercise, you will make a quick and simple detail component—a masking region to hide the gypsum board on the SIP wall system.

You need to create a masking region 7/8″ wide × 1′−8″ long to hide that run of gypsum board. You also want to make three sides (top, bottom, and right) medium lines because they will represent cut material and the left line an <Invisible Lines> type to keep it hidden. Invisible lines will show as gray when drawn in Sketch mode but will not appear at all and hide other lines (if on top) in model views. Since the masking region is overextended, you need to cut the top and bottom lines. Notice in Figure 21.37 that the left line of the rectangle appears as gray because it is an invisible line.

Figure 21.37. Creating the masking region.

Masking regions are very precisely shaped elements. The reason this masking region is 7/8″ wide is to cover the 5/8″ gypsum board, taking into account that the line weight of the gypsum adds thickness to the line; this needs to be covered by the masking region.

Now you need to draw the clip. For the moment, the clip can be represented by a simple filled region box 2″ high and 1″ wide, located 1½″ down from the top of the finished floor on the right side of the masking region.

To finish cleaning up this floor condition, a few more items can be added by placing base molding around the floor/wall condition and then bringing the ceiling finish of the second floor to meet the wall and the floor finish to meet the wall.

For this detail, it is easiest to make a simple detail component. This will make it reusable and taggable—something you wouldn't get with mere lines.

Figure 21.42. Setting the height as a parameter.

If you choose to change the height of the base later in the project, you don't have to reedit the family. It is simply a matter of changing the parameter using the following steps:

Figure 21.43. Creating a parameter to control the baseboard height.

In Revit there are a number of ways to create a detail. There is no single best solution, just as there is not one way to build something on site. We chose to cut the floor back from the wall and use filled regions to re-extend the floor to meet the wall condition. We could have left the floor connected to the wall and simply used masking regions and filled regions to give the appearance of the floor structure being pushed back instead of the floor finish being pulled forward. We chose our particular method because our contractor had requested the use of the Revit model to do some concrete take-offs, so we needed to make sure the volume of concrete was as accurate as possible. Overextending or underextending that condition, even by a few inches, would have changed the volume of concrete reported in the schedule. Before choosing a direction for a workflow, it's a good idea to understand all the uses for your model (beyond documentation) and keep those in mind when making these kinds of decisions. In the following steps, these techniques will be demonstrated.

The floor line has been cut back to make room for the clips; you still need to finish detailing the subfloor and finish floor to meet the wall. To do this, you're going to create some simple filled regions.

Once you click OK, the region should look like Figure 21.45. Somehow, it is not quite right. This is because the filled region and the detail components layer can rest on top of the others. You need to resolve their order by pushing the gyp-filled region to the top.

Figure 21.45. The region does not look correct yet.

Figure 21.46. The graphically modified condition.

Using this same example, you can build simple regions for the floor extension under our base. The floor condition looks like Figure 21.47.

To finish this portion of the detail, you need to add material definition to the floor. The concrete has been poured on top of a corrugated metal deck, but it is not possible to add a corrugated metal material pattern as part of our floor materials, so we want to make a repeating detail in the form of our 3¾″ corrugated deck. While the structural engineer will show this in detail, you still want to show the material architecturally in our sections and details. First, you'll need to make the profile of the deck.

Since this is a 2D element, you will also want to go back to the wall section and add the corrugated deck to all of the appropriate locations. The finished deck in detail and section looks like Figure 21.49.

Figure 21.49. The metal deck in section and detail.

There are a couple more conditions to address to finish this detail. The head and sill conditions for the storefront system will probably not be affixed directly to the rigid insulation as the detail currently shows. You'll need to add some blocking and flashing to those locations. Again, since you will want to reuse this condition in other views, you can make it with a detail component. This time, however, you are going to add a more significant level of detail to the detail component before inserting it into the model. You'll do this by nesting detail components within each other. Let's start with the storefront head condition.

To help finish the window on the exterior, place a stone header over the window opening. This can be created with a region and a new region type for stone. The stone head is 6″ high by 2¼″ wide and placed 1 ⅜″ from the edge of our 2 × 6. (This measurement isn't arbitrary: it is taken directly from the wall condition in the model.) Figure 21.50 shows your current progress.

Figure 21.50. Nested detail component.

Once the detail component is inserted into the model, you should see something that looks like Figure 21.51.

Figure 21.51. Inserting the nested detail component.

Using simple detail lines and filled regions, you can add any necessary flashing and gypsum returns to the window. The completed head condition should look like Figure 21.52.

Figure 21.52. Final detail at head condition.

By combining the simple tools used in the previous sections, you can easily complete this detail. As we have mentioned throughout this chapter, many of the elements that were imported or created need to be made only once. All of the families and detail components you built in the course of this detail are now available in the project for use in other views. The finished detail looks like Figure 21.53.

Figure 21.53. The completed detail with the nested component.

You can easily adapt this process to complete details for the other conditions.