How to Create Roofs in BricsCAD BIM

Quick answer: Roof creation follows five general steps: create the footprint, extrude it into a hip roof with EXTRUDE, adjust face slopes with the Manipulator widget if needed, define the roof solid’s thickness with the Body/Shell option of SOLIDEDIT, and add any further components.

Creating the Roof Footprint

Build it either from the exterior walls’ boundary, or as a closed polyline drawn with points or other 2D methods.

From the exterior walls boundary:

Isolate the exterior walls, easiest via the Structure panel, or ISOLATEOBJECTS, the same command covered on this hub’s viewing entities page.
Run UCS, and when prompted for the origin, snap to a top corner of an exterior wall, then press Enter.
Turn on Enable boundary detection in the Selection Modes toolbar, or include Select detected boundaries under SELECTIONMODES, the same setting covered on this hub’s BIM entity selection page.
Move the cursor into a void area inside the exterior walls; the inside boundary highlights.
Choose Offset from the Draw tab of the Quad.
Either type a value in the dynamic distance field, or click to accept the current value.

Creating a Hip Roof

This is the foundational procedure several other roof types build on.

Create the roof footprint.
Hover over the roof outline and choose Extrude from the Model tab of the Quad.
Move the cursor vertically, then press Tab.
Type a value in the Taper Angle field (the complement of the roof’s inclination angle), then press Tab.
Either press Tab again and type another Taper Angle value, or press Enter to create the roof.
The result depends on the footprint’s shape: pyramid, L-shaped, T-shaped, U-shaped, or a complex hip roof.
To set the roof solid’s thickness, using the Body/Shell option of SOLIDEDIT: choose Shell from the Modeling/SOLID EDITING ribbon panel or the 3D Solid Editing toolbar, select the roof solid when prompted, select its bottom face to remove, then type a value for the shell offset distance (the thickness).

Creating a Gable Roof

Create a hip roof (the full procedure above).
Make both end faces vertical: hover over an end face and hold the left mouse button for about half a second to display the Manipulator widget (requires MANIPULATOR set to 2). Hover over the vertical rotation arc until it highlights, move the cursor to rotate the face dynamically, and click once it’s vertical.
Repeat step 7 of the hip roof procedure, removing the now-vertical faces of the roof solid.

Creating a Mansard Roof

A mansard roof is two solids, built as two separate extrusions, this is the second foundational procedure several other roof types reuse.

Create the roof footprint.
Hover over the roof outline and choose Extrude from the Model tab of the Quad.
Move the cursor vertically, then press Tab.
Type a Taper Angle value, then press Tab.
Type an Extrusion Height value, then either press Tab and type another Taper Angle, or press Enter to create the first solid.
Optionally press Tab to move back and forth between fields, pressing Enter once you’re satisfied.
Hover over the top face of the first solid and choose Extrude from the Quad.
Move the cursor vertically, then press Tab.
Type a Taper Angle value, then press Tab.
Either press Tab again for another Taper Angle, or press Enter to create the second solid.
Select both solids and choose Union from the Model tab of the Quad.
Repeat step 7 of the hip roof procedure to set thickness.

Creating a Jerkinhead Roof

Also composed of two solids, built by combining the mansard, gable, and hip procedures:

Execute steps 1 through 6 of the mansard roof procedure to create the first solid.
Execute step 2 of the gable roof procedure to make the end faces vertical.
Execute steps 7 through 11 of the mansard roof procedure (second solid, then union).
Execute step 7 of the hip roof procedure, removing the vertical faces.

Creating a Gambrel Roof

Also two solids, similar to the jerkinhead but with vertical faces applied to each solid separately before the union:

Execute steps 1 through 6 of the mansard roof procedure to create the first solid.
Execute step 2 of the gable roof procedure to make the first solid’s end faces vertical.
Execute steps 7 through 10 of the mansard roof procedure to create the second solid (stopping short of the union step).
Execute step 2 of the gable roof procedure again, this time on the second solid’s end faces.
Execute step 11 of the mansard roof procedure to union the two solids, now that both have vertical end faces.
Execute step 7 of the hip roof procedure, removing the vertical faces.

Creating a Dutch Gable Roof

Based on a hip roof, using the Imprint technique:

Create a hip roof.
Turn on Select Edges under SELECTIONMODES.
Hover over the bottom edge of a roof face and choose Offset from the Draw tab of the Quad.
Move the cursor and type a value in the dynamic distance field, or click a point.
Choose Imprint from the 3D Solid Editing toolbar, or run IMPRINT.
Select the roof solid when prompted.
Select the offset roof edge as the entity to imprint.
Choose Yes to delete the source object; a triangular face is created.
Execute step 2 of the gable roof procedure to make that triangular face vertical.
Execute step 7 of the hip roof procedure to set the roof solid’s thickness.

Creating Dormers

Building a dormer involves creating a box solid at the roof plane’s bottom edge and connecting it to the roof, defining its position and dimensions, then shaping its own roof.

Right-click and choose Box from the Model tab of the Quad. You’re prompted for a corner of the box; click a point at the bottom edge of the roof plane.
You’re prompted for the opposite corner, or Cube or Length of side; click a point, then define the box’s height by clicking or typing a value.
Select the box’s back face: hover over it and press Tab until it highlights (requires Select Faces on).
Choose Connect with nearest from the Model tab of the Quad.
Select the box’s front face, choose Push/Pull from the Model tab, and move the face to the roof plane.
Use PUSHPULL on the front, top, and side faces to set the dormer’s dimensions and position: select a side face and press Tab to set its width; select both side faces and choose Add rigid set from the Constraints tab of the Quad to fix that width; drag one side face to position the dormer (type a distance, click to accept, or hover a parallel face and press Tab to measure the distance to it instead); drag the top face to set the dormer’s height; drag the front face to set its distance from the roof eave, hovering the exterior wall face beneath it and pressing Tab to measure against that face specifically.
Modify the dormer’s shape as needed: add a hip roof (Hip); add a hip roof and rotate the front face vertical (Flat, a gable roof); add a vault (Vault); rotate the top and side faces (Special); starting from a gable roof, move the front face backward until it’s triangular (Triangle); or a further variant (Eyebrow).

Frequently Asked Questions

What’s the difference between a gable roof and a hip roof? A gable roof starts as a hip roof, then has both end faces rotated vertical using the Manipulator widget before defining thickness.

Which roof types are built from two separate solids? Mansard, jerkinhead, and gambrel roofs, each created as two extrusions that get unioned together.

How do I set a roof solid’s final thickness? Use the Body/Shell option of SOLIDEDIT: choose Shell, select the roof solid, remove its bottom face, then type the shell offset distance.

What technique does a Dutch gable roof rely on that other roof types don’t? Imprint, used to create a triangular face on the hip roof by offsetting and imprinting a roof edge before rotating that face vertical.