Working with Roofs
Roofs are AEC objects that you can use to model an entire multiple-face roof surface. You can create roofs independently of other objects or you can place a roof on a shape defined by a polyline or by a closed set of walls. After creating the roof, you can change its overall dimensions and slope or edit its edges and faces individually. For more flexibility in customizing a roof, you can convert it to a collection of individual roof slabs.
A roof slab models a single face of a roof. Roof slab objects also differ from roof objects in that each roof slab is a separate entity with no direct connection to other entities. When you use multiple roof slabs to model an entire roof surface, you have more flexibility in editing the roof, but the combined topology (3D geometry) of the roof is not calculated automatically. For this reason, it is recommended that when you design complex roofs, you start with a roof object. Then, when the design is substantially complete, but you need more flexibility for customizing edges and other details, you can convert the roof to individual roof slabs. While roof slabs do not dynamically interact with each other, they do allow significant control over the roof geometry. For example, you can trim roof slabs individually, extend them and miter them with other roof slabs. You can also cut holes in roof slabs, add or subtract mass elements, and apply detailed fascia and soffit profiles to any edge at any angle and orientation. Because roof slabs are style-based, you can apply design changes globally.
You can assign materials to a roof. Materials are displayed in wireframe and working shade views or when rendered. Materials have specific settings for the physical components of a roof such as slab. AutoCAD® Architecture provides predefined materials for common design purposes. These materials contain settings for roof components. You can use the predefined materials as they are or modify them for your designs. You can also create your own materials. Object styles provided with the software have appropriate materials already assigned to them.
Slabs and Roof Slabs
Slabs and roof slabs are AutoCAD Architecture objects that you use to model floors, roof faces, and other flat surfaces where edge conditions need to be specified. They are found on the Design tool palette (see Figure 1). The slab or roof slab object is a three-dimensional (3D) body bounded by a planar polygon (perimeter) of any shape and has multiple edges. The object is defined by its perimeter, edge conditions, and style. Though they share many of the same properties, slabs and roof slabs represent separate style categories and tool types. For instance, you cannot apply the properties of a slab tool to an existing roof slab object.
Using slab and roof slab tools, you can create slabs and roof slabs independently or you can create them from existing objects such as walls and polylines. Slabs and roof slabs created from other objects do not maintain a link to the original object. Pitched roofs are usually designed by specifying a plate line and a slope angle. Roof slabs are designed so you can use the same approach in laying them out. To add a roof slab, you simply specify two points and an angle. If you have a traditionally designed roof created from a two-dimensional (2D) plan showing ridge, hip, and valley lines, you can trace over that plan with roof slabs, specifying the desired height and slope. From these values and the specified points, the software creates the correct three-dimensional (3D) model.
You can customize each slab or roof slab edge individually, applying styles and making other adjustments as required by your design. A slab or roof slab edge style defines the fascia and soffit design from profiles that you create for these components. You can specify whether the style uses a fascia, a soffit, both, or neither. You also specify how the fascia and soffit are positioned relative to the slab or roof slab.
Slabs and roof slabs have their own distinct style categories in which individual styles specify the default properties for specific types of slabs or roof slabs. These properties include dimensions, edge styles for the fascia and soffit, and entity properties for layer, color, and linetype. Slab and roof slab styles allow you to use a different edge style for each edge. You can assign materials to a slab or roof slab. For example, a floor slab can be assigned a material representing tiles with concrete edges. These materials are displayed in wireframe or rendered views. Materials have specific settings for individual components of slabs or roof slabs such as the body, fascia, and soffit.
In addition to the control provided by slab or roof slab styles and edge styles, AutoCAD Architecture includes a variety of tools for editing slabs and roof slabs to fit unique conditions. For example, you can add holes to slabs for structures such as chimneys and vent pipes. You can also use roof slabs to create dormers.
Figure 1: Design tool palette
Slab and Roof Slab Styles
A slab or roof slab style is a set of parameters that determines the appearance and other characteristics of the slab or roof slab object to which it is assigned. By editing a style, you can control the properties of all objects that use that style, without having to change the properties of each such object in a drawing. For slabs and roof slabs, the style controls the following properties:
- default dimensions, including thickness
- default edge conditions, including fascia and soffit styles
- default display properties, including fascia and soffit
- physical components (concrete, metal deck, and so on)
- materials assigned to components of slabs
The default slab and roof slab tools provided with the software use standard styles (see Figure 2). You can use these as provided, edit the standard styles in the Style Manager, or create your own styles and use them to make new tools.
You can create a slab or roof slab tool from a slab or roof slab style by dragging the style from the Style Manager onto a tool palette. The default settings provided by the style are then applied to any object created with that tool.
To create, copy, edit, or purge styles for slabs and roof slabs, you use the Style Manager. The Style Manager provides a central location in AutoCAD Architecture where you can work with styles from multiple drawings and templates.
Figure 2: Style Manager
Editing Slabs and Roof Slabs
After placing a slab or roof slab object, you can change its style, location, size, shape, slope, edge styles, and other characteristics. You can miter its edges and trim or extend it using another object as a reference. You can also modify slabs and roof slabs using other objects as interference conditions or body modifiers.
Depending on the type of editing you want to perform, various methods may be available:
- After selecting a slab or roof slab, you can click any non-grip point along the perimeter and drag the entire object to a new location. You can also move the object by clicking a grip, pressing the space bar, and then moving the object to the new location and clicking again.
- You can drag the grips that are displayed on a selected slab or roof slab to reorient it, resize it, or change other physical characteristics (see Figure 3).
- For grip edits where you are changing a dimension or an angle, the Dynamic Input feature lets you enter a precise value instead of dragging a grip. (This feature is activated by default.)
- You can apply the properties of a slab tool to an existing slab or the properties of a roof slab tool to an existing roof slab.
- You can change settings on the object’s Properties palette. You can also use the Display tab of the Properties palette to change the display property settings for a selected object display component in the current display representation.
- You can use editing commands from the object’s contextual ribbon tab.
Figure 3: Roof grip edit
Create a Roof Tool
You may want to create your own roof tools if you are placing multiple roofs that have the same properties. For example, say you are creating an office building that has a multi-peaked roof. Although the entire roof is single sloped, each peak has a different slope. To work efficiently, you can create a roof tool for each slope and select the appropriate tool to place the roofs with the correct slope on each area of the building.
Open the tool palette where you want to create a tool. If you want to create a tool from a roof in the drawing, then select the object and drag it to the tool palette. If you want to copy a tool in the current tool palette, then right-click the tool and click Copy. Right-click and click Paste. If you want to copy a tool from another tool palette, then open the other tool palette, right-click the tool, and click Copy. Reopen the palette where you want to add the tool, right-click, and click Paste. If you want to copy a tool from the Content Browser, then click the Home tab, Build panel, Tools drop-down, Content Browser and locate the tool you want to copy. Position the cursor over the i-drop handle and drag the tool to the tool palette.
Now right-click the new tool and click Properties (see Figure 4). Enter a name for the tool. Click the setting for Description, enter a description of the tool, and click OK. Expand Basic and expand General. Click the setting for Description, enter a description of the roof created from this tool, and click OK. Specify a layer key and any layer key overrides if you do not want to use the layer assignments specified in the layer key style used in the drawing. Specify roof settings. Expand Dimensions and enter a value for Thickness and select a new setting for Edge cut. Expand Next Edge, select a new setting for Shape, and enter a value for Overhang. Expand Lower Slope and enter a value for Plate Height. Expand Upper Slope and enter a value for Upper Height. Expand Lower Slope or Upper Slope for a double slope roof and enter a value for Rise or Slope. Click OK.
Figure 4: Roof slab tool properties
Create a Roof
You can create a single slope or double slope roof object. You can add additional slopes to a roof face by right-clicking a roof object and clicking Edit Edges/Faces. Open the tool palette that contains the roof tool you want to use and select the tool. You can also click the Home tab on the ribbon, Build panel, Roof Slab drop-down, and select Roof. On the Properties palette, select Single slope or Double slope for Shape (see Figure 5). In the drawing area, specify points for the corners of the roof. When you are finished specifying points, press Enter.
You can create a single sloped roof and set each edge to gable as needed. You can specify a slope for the gable ends to create a hip. You can even create a gable on an existing roof by gripping any ridge line point and stretching it past the roof edge. Open the tool palette that contains the roof tool you want to use and select the tool or use the Build panel on the Home tab of the ribbon. On the Properties palette, select Single slope for Shape. In the drawing area, specify the first point for the first roof edge. Specify the second point to complete the first sloped roof edge. On the Properties palette, select Gable for Shape. In the drawing area, specify the next point to create a gable roof edge. Select Single slope for Shape. Specify the next point to create a sloped roof edge. Select Gable slope for Shape. Specify additional points as needed to define the roof and press Enter. To create a clipped gable roof, you first need to convert the gabled roof to roof slabs.
You can create a roof that is based on a selected closed set of walls and has the properties of the roof tool you select. You can edit these properties after creating the roof. The roof takes its plate height from the top of each wall segment. Open the tool palette that contains the roof tool you want to use. Right-click a roof tool and click Apply Tool Properties to Linework and Walls. Select the walls to convert and press Enter. If the walls you select are not closed, a roof is added to the top of each wall segment. When prompted to erase the original geometry, press Enter to keep the wall, or enter y (Yes) to erase it. Edit the properties of the roof on the Properties palette, if needed.
You can create a roof that is based on a 2D polyline and has the properties of the roof tool you select. You can edit these properties after creating the roof. Draw a closed 2D polyline in the shape of the intended roof in the location where you want to place the roof. Open the tool palette that contains the roof tool you want to use. Right-click a roof tool and click Apply Tool Properties to Linework and Walls. Select the polyline to convert and press Enter. When prompted to erase the original geometry, press Enter to keep the linework or enter y (Yes) to erase it. Edit the properties of the roof on the Properties palette, if needed.
Figure 5: Single slope roof properties
